Patent Application
20210148004
The present disclosure relates to methods of fabricating epitaxial films and quantum wells of halide perovskites and their use in optoelectronic devices. Halide perovskite epitaxy is enabled by vapor deposition onto single crystals.
This section provides background information related to the present disclosure which is not necessarily prior art.
Hybrid halide perovskites are a new class of semiconductors for solar harvesting, light emission, lasing, quantum dots, water splitting, and thin film electronics. Although efficiencies of solar cells based on hybrid organic-inorganic lead halide perovskites have exceeded 22%, the toxicity of lead devices and lead manufacturing combined with the instability of organic components are two key barriers to its widespread application. Tin-based inorganic halide perovskites, such as CsSnX3 (X=Cl, Br, and I), have been considered promising substitutes for their lead analogues because Sn is over 100 times less toxic than Pb and Cs has similar toxicity to Na or K. However, current research on photovoltaic and electronic applications of CsSnBr3 and CsSnI3 has, to date, been less encouraging, with solar cell efficiencies of less than 5% likely limited in large part by the low degree of crystalline ordering. Indeed, the degree of ordering has been linked to a) carrier transport, where mobilities increase from amorphous-Si (1 cm2/V-s) to single crystalline Si (1,400 cm2/V-s), b) recombination rates, where unpassivated grain boundaries act as quenching sites for charge carriers and excited states, and c) quantum confinement, which can make even Si a good near infrared (NIR) emitter with luminescent efficiency of greater than 50%. Thus, one of the main challenges for enhancing the properties of all-inorganic perovskites for opto-electronic applications is to obtain highly crystalline films with minimal defects that can also be integrated into heteroepitaxial structures. In regard to oxide perovskites, numerous phases can be derived from a perovskite structure with even minor changes in elemental compositions. For example, by removing one-sixth of the oxygen atoms, phase transitions can occur from perovskite to brownmillerite structures. Therefore, it is key to gain precise control over the crystal phase, crystalline order, orientation, and quantum confinement for the optimization of halide perovskite based optoelectronics.
While there has been significant research into the epitaxial growth of oxide perovskites, epitaxy has yet to be accomplished for halide perovksites. Such epitaxial growth has likely been hindered in large part due to alack of single crystalline substrates with suitable lattice constants and bonding interactions. Accordingly, a route to the epitaxial growth of halide perovskites that is enabled by lattice matching on a single crystal alkali halide salt substrates is desired. A platform demonstrating precise control in the fabrication of quantum well multilayer structures will guide new opportunities in emergent phenomena with halide perovskites.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
The current technology provides a method of fabricating a semiconductor structure. The method includes evaporating at least one precursor, and depositing an epitaxial film including a halide perovskite derived from the at least one precursor on a single crystal substrate.
In one variation, the evaporating and the depositing are performed by vapor deposition selected from the group consisting of molecular beam epitaxy, atomic layer deposition (ALD), thermal evaporation, sputtering, pulsed laser deposition, electron beam evaporation, chemical vapor deposition cathodic arc deposition, and electrohydrodynamic deposition.
In one variation, the at least one precursor includes a first precursor corresponding to the formula AX, A′X, A′X2, or a combination thereof, and a second precursor corresponding to the formula BX2, B′X4, CX3, DX, or a combination thereof, and the method further includes reacting the first precursor with the second precursor to form the halide perovskite, the halide perovskite corresponding to the formula AmBnXm+2n, Am′B′n′Xm′+4n′, Am″Bn″B′n″*Xm″+2n″+4n″*, AmCnXm+3n, AmCnDlXm+3n+l, (A′X)mBnXm+2n, (A′X)mB′n′Xm′+4n′, (A′X)m″Bn″B″n″*Xm″+2n″+4n″*, (A′X)mCnXm+3n, (A′X)mCnDlXm+3n+l, or a combination thereof, wherein A is a 1+alkali metal, a 1+transition metal, a 1+lanthanide, a 1+actinide, a 1+organic cation, or a 1+compound having the formula A′X, wherein A′ is an alkaline earth metal, a 2+transition metal, a 2+lanthanide, a 2+actinide, or a combination thereof; A′ is an alkaline earth metal, a 2+transition metal, a 2+lanthanide, a 2+actinide, or a combination thereof; B is a 2+alkaline earth metal, a 2+transition metal, a 2+crystallogen, a 2+lanthanide, a 2+actinide, or a combination thereof; B′ is a 4+metal or a combination of 4+metals; C is a 3+pnictogen, a 3+icosagen, a 3+transition metal, or a combination thereof; D is silver (Ag), copper (Cu), gold (Au), indium (In I), thallium (Tl I), or a combination thereof; X is an inorganic anion, an organic anion, or a combination thereof; and m, m′, m″, n, n′, n″, n″*, and l are individually integers having a value of 0 or greater.
In one variation, A is cesium (Cs), rubidium (Rb), potassium (K), sodium (Na), lithium (Li), copper (Cu I), methylammonium (MA), formamidinium (FA), organic cation, or a combination thereof; A′ is beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), iron (Fe II), chromium (Cr II), cobalt (Co II), nickel (Ni II), manganese (Mn II), lead (Pb II), copper (Cu II), vanadium (V II), zinc (Zn II) or a combination thereof; B is tin (Sn), lead (Pb), copper (Cu II), germanium (Ge), or a combination thereof; B′ is tin (Sn), germanium (Ge), lead (Pb), or a combination thereof; C is bismuth (Bi), antimony (Sb), indium (In II), iron (Fe), aluminum (Al) or a combination thereof; and X is an inorganic anion selected from the group consisting of a halogen, an oxalate, a hydroxide, a chlorate, an iodate, a nitrite, a sulfate, a thiosulfate, a phosphate, an antimonite, or a combination thereof, or an organic anion selected from the group consisting of acetate, formate, borate, carborane, phenyl borate, and combinations thereof, or a combination of inorganic anions and organic ions.
In one variation, the halide perovskite is CsSiCl3, CsSiBr3, CsSiI3, RbSiCl3, RbSiBr3, KSiCl3, KSiBr3, KSiI3, MASiCl3, MASiBr3, MASiI3, Cs2SiCl4, Cs2SiBr4, Cs2SiI4, MA2SiCl4, MA2SiBr4, MA2SiI4, Rb2SiCl4, Rb2SiBr4, Rb2SiI4, CsSi2Cl5, Cs2SiCl6, Cs2Si(II)Si(IV)Cl8, CsSiI2Br5, Cs2SiBr6, Cs2Si(II)Si(IV)Br8, CsSi2I5, Cs2SiI6, Cs2Si(II)Si(IV)I8, RbSi2Cl5, Rb2SiCl6, Rb2Si(II)Si(IV)Cl8, RbSi2Br5, Rb2SiBr6, Rb2Si(II)Si(IV)Br8, RbSi2I5, Rb2SiI6, Rb2Si(II)Si(IV)I8, KSi2Cl5, K2SiCl6, K2Si(II)Si(IV)Cl8, KSi2Br5, K2SiBr6, K2Si(II)Si(IV)Br8, KSi2I5, K2SiI6, K2Si(II)Si(IV)I8, MASi2Cl5, MA2SiCl6, MA2Si(II)Si(IV)Cl8, MASi2Br5, MA2SiBr6, MA2Si(II)Si(IV)Br8, MASi2I5, MA2SiI6, MA2Si(II)Si(IV)I8; CsGeCl3, CsGeBr3, CsGeI3, RbGeCl3, RbGeBr3, KGeCl3, KGeBr3, KGeI3, MAGeCl3, MAGeBr3, MAGeI3, Cs2GeCl4, Cs2GeBr4, Cs2GeI4, MA2GeCl4, MA2GeBr4, MA2GeI4, Rb2GeCl4, Rb2GeBr4, Rb2GeI4, CsGe2Cl5, Cs2GeCl6, Cs2Ge(II)Ge(IV)Cl8, CsGe2Br5, Cs2GeBr6, Cs2Ge(II)Ge(IV)Br8, CsGe2I5, Cs2GeI6, Cs2Ge(II)Ge(IV)I8, RbGe2Cl5, Rb2GeCl6, Rb2Ge(II)Ge(IV)Cl8, RbGe2Br5, Rb2GeBr6, Rb2Ge(II)Ge(IV)Br8, RbGe2I5, Rb2GeI6, Rb2Ge(II)Ge(IV)I8, KGe2Cl5, K2GeCl6, K2Ge(II)Ge(IV)Cl8, KGe2Br5, K2GeBr6, K2Ge(II)Ge(IV)Br8, KGe2I5, K2GeI6, K2Ge(II)Ge(IV)I8, MAGe2Cl5, MA2GeCl6, MA2Ge(II)Ge(IV)Cl8, MAGe2Br5, MA2GeBr6, MA2Ge(II)Ge(IV)Br8, MAGe2I5, MA2GeI6, MA2Ge(II)Ge(IV)I8; CsSnCl3, CsSnBr3, CsSnI3, RbSnCl3, RbSnBr3, KSnCl3, KSnBr3, KSn3, MASnCl3, MASnBr3, MASn3, Cs2SnCl4, Cs2SnBr4, Cs2SnI4, MA2SnCl4, MA2SnBr4, MA2SnI4, Rb2SnCl4, Rb2SnBr4, Rb2SnI4, CsSn2Cl5, Cs2SnCl6, Cs2Sn(II)Sn(IV)Cl8, CsSn2Br5, Cs2SnBr6, Cs2Sn(II)Sn(IV)Br8, CsSn2I5, Cs2SnI6, Cs2Sn(II)Sn(IV)I8, RbSn2Cl5, Rb2SnCl6, Rb2Sn(II)Sn(IV)Cl8, RbSn2Br5, Rb2SnBr6, Rb2Sn(II)Sn(IV)Br8, RbSn2I5, Rb2SnI6, Rb2Sn(II)Sn(IV)I8, KSn2Cl5, K2SnCl6, K2Sn(II)Sn(IV)Cl8, KSn2Br5, K2SnBr6, K2Sn(II)Sn(IV)Br8, KSn2I5, K2SnI6, K2Sn(II)Sn(IV)I8, MASn2Cl5, MA2SnCl6, MA2Sn(II)Sn(IV)Cl8, MASn2Br5, MA2SnBr6, MA2Sn(II)Sn(IV)Br8, MASn2I5, MA2SnI6, MA2Sn(II)Sn(IV)I8, Cs3Bi2Cl9, Cs3Bi2Br9, Cs3Bi2I9, Cs3Sb2Cl9, Cs3Sb2Br9, Cs3Sb2I9; CsPbCl3, CsPbBr3, CsPbI3, RbPbCl3, RbPbBr3, KPbCl3, KPbBr3, KPbI3, MAPbCl3, MAPbBr3, MAPbI3, Cs2PbCl4, Cs2PbBr4, Cs2PbI4, MA2PbCl4, MA2PbBr4, MA2PbI4, Rb2PbCl4, Rb2PbBr4, Rb2PbI4, CsPb2Cl5, Cs2PbCl6, Cs2Pb(II)Pb(IV)Cl8, CsPb2Br5, Cs2PbBr6, Cs2Pb(II)Pb(IV)Br8, CsPb2I5, Cs2PbI6, Cs2Pb(II)Pb(IV)I8, RbPb2Cl5, Rb2PbCl6, Rb2Pb(II)Pb(IV)Cl8, RbPb2Br5, Rb2PbBr6, Rb2Pb(II)Pb(IV)Br8, RbPb2I5, Rb2PbI6, Rb2Pb(II)Pb(IV)I8, KPb2Cl5, K2PbCl6, K2Pb(II)Pb(IV)Cl8, KPb2Br5, K2PbBr6, K2Pb(II)Pb(IV)Br8, KPb2I5, K2PbI6, K2Pb(II)Pb(IV)I8, MAPb2Cl5, MA2PbCl6, MA2Pb(II)Pb(IV)Cl8, MAPb2Br5, MA2PbBr6, MA2Pb(II)Pb(IV)Br8, MAPb2I5, MA2PbI6, MA2Pb(II)Pb(IV)I8; Cs2AgBiCl6, Cs2CuBiCl6, Cs2InAgCl6, Cs2InCuCl6, Cs2AgSbCl6, Cs2CuSbCl6, Cs2AgBiBr6, Cs2CuBiBr6, Cs2InAgBr6, Cs2InCuBr6, Cs2AgBiI6, Cs2CuBiI6, Cs2AgSbBr6, Cs2CuSbBr6, Cs2AgSbI6, Cs2CuSbI6, Cs2InAgI6, Cs2InCuI6, Cs3Bi2Cl9, Cs3Bi2Br9, Cs3Bi2I9, Cs3Sb2Cl9, Cs3Sb2Br9, Cs3Sb2I9, Cs3In2Cl9, Cs3In2Br9, Cs3In2I9; K2AgBiCl6, K2CuBiCl6, K2InAgCl6, K2InCuCl6, K2AgSbCl6, K2CuSbCl6, K2AgBiBr6, K2CuBiBr6, K2InAgBr6, K2InCuBr6, K2AgBiI6, K2CuBiI6, K2AgSbBr6, K2CuSbBr6, K2AgSbI6, K2CuSbI6, K2InAgI6, K2InCuI6, K3Bi2Cl9, K3Bi2Br9, K3Bi2I9, K3Sb2Cl9, K3Sb2Br9, K3Sb2I9, K3In2Cl9, K3In2Br9, K3In2I9; Na2AgBiCl6, Na2CuBiCl6, Na2InAgCl6, Na2InCuCl6, Na2AgSbCl6, Na2CuSbCl6, Na2AgBiBr6, Na2CuBiBr6, Na2InAgBr6, Na2InCuBr6, Na2AgBiI6, Na2CuBiI6, Na2AgSbBr6, Na2CuSbBr6, Na2AgSbI6, Na2CuSbI6, Na2InAgI6, Na2InCuI6, Na3Bi2Cl9, Na3Bi2Br9, Na3Bi2I9, Na3Sb2Cl9, Na3Sb2Br9, Na3Sb2I9, Na3In2Cl9, Na3In2Br9, Na3In2I9; Li2AgBiCl6, Li2CuBiCl6, Li2InAgCl6, Li2InCuCl6, Li2AgSbCl6, Li2CuSbCl6, Li2AgBiBr6, Li2CuBiBr6, Li2InAgBr6, Li2InCuBr6, Li2AgBiI6, Li2CuBiI6, Li2AgSbBr6, Li2CuSbBr6, Li2AgSbI6, Li2CuSbI6, Li2InAgI6, Li2InCuI6, Li3Bi2Cl9, Li3Bi2Br9, Li3Bi2I9, Li3Sb2Cl9, Li3Sb2Br9, Li3Sb2I9, Li3In2Cl9, Li3In2Br9, Li3In2I9, (BaF)2PbCl4, (BaF)2PbBr4, (BaF)2PbI4, (BaF)2SnCl4, (BaF)2SnBr4, (BaF)2SnI4, and (BaF)2PbCl6, (BaF)2PbBr6, (BaF)2PbI6, (BaF)2SnCl6, (BaF)2SnBr6, (BaF)2SnI6, or a combination thereof.
In one variation, the at least one precursor includes the halide perovskite, and the evaporating and depositing are performed by evaporating or sputtering of a target including the halide perovskite.
In one variation, there is a lattice misfit of less than or equal to about 10% between the single crystal substrate and the halide perovskite of the film.
In one variation, the at least one precursor includes a dopant.
In one variation, the single crystal substrate includes a halide salt, a halide perovskite, an oxide perovskite, a metal, or a semiconductor.
In one variation, the single crystal substrate includes ionic crystals.
In one variation, the single crystal substrate includes a halide salt selected from the group consisting of a metal halide salt, an alkali metal halide salt, an alkaline earth metal halide salt, a transition metal halide salt, and combinations thereof.
In one variation, the single crystal substrate includes a halide perovskite selected from the group consisting of CsSiCl3, CsSiBr3, CsSiI3, RbSiCl3, RbSiBr3, KSiCl3, KSiBr3, KSiI3, MASiCl3, MASiBr3, MASiI3, Cs2SiCl4, Cs2SiBr4, Cs2SiI4, MA2SiCl4, MA2SiBr4, MA2SiI4, Rb2SiCl4, Rb2SiBr4, Rb2SiI4, CsSiI2Cl5, Cs2SiCl6, Cs2Si(II)Si(IV)Cl8, CsSiI2Br5, Cs2SiBr6, Cs2Si(II)Si(IV)Br8, CsSiI2I5, Cs2SiI6, Cs2Si(II)Si(IV)I8, RbSi2Cl5, Rb2SiCl6, Rb2Si(II)Si(IV)Cl8, RbSi2Br5, Rb2SiBr6, Rb2Si(II)Si(IV)Br8, RbSi2I5, Rb2SiI6, Rb2Si(II)Si(IV)I8, KSi2Cl5, K2SiCl6, K2Si(II)Si(IV)Cl8, KSi2Br5, K2SiBr6, K2Si(II)Si(IV)Br8, KSi2I5, K2SiI6, K2Si(II)Si(IV)I8, MASi2Cl5, MA2SiCl6, MA2Si(II)Si(IV)Cl8, MASi2Br5, MA2SiBr6, MA2Si(II)Si(IV)Br8, MASi2I5, MA2SiI6, MA2Si(II)Si(IV)I8; CsGeCl3, CsGeBr3, CsGeI3, RbGeCl3, RbGeBr3, KGeCl3, KGeBr3, KGeI3, MAGeCl3, MAGeBr3, MAGeI3, Cs2GeCl4, Cs2GeBr4, Cs2GeI4, MA2GeCl4, MA2GeBr4, MA2GeI4, Rb2GeCl4, Rb2GeBr4, Rb2GeI4, CsGe2Cl5, Cs2GeCl6, Cs2Ge(II)Ge(IV)Cl8, CsGe2Br5, Cs2GeBr6, Cs2Ge(II)Ge(IV)Br8, CsGe2I5, Cs2GeI6, Cs2Ge(II)Ge(IV)I8, RbGe2Cl5, Rb2GeCl6, Rb2Ge(II)Ge(IV)Cl8, RbGe2Br5, Rb2GeBr6, Rb2Ge(II)Ge(IV)Br8, RbGe2I5, Rb2GeI6, Rb2Ge(II)Ge(IV)I8, KGe2Cl5, K2GeCl6, K2Ge(II)Ge(IV)Cl8, KGe2Br5, K2GeBr6, K2Ge(II)Ge(IV)Br8, KGe2I5, K2GeI6, K2Ge(II)Ge(IV)I8, MAGe2Cl5, MA2GeCl6, MA2Ge(II)Ge(IV)Cl8, MAGe2Br5, MA2GeBr6, MA2Ge(II)Ge(IV)Br8, MAGe2I5, MA2GeI6, MA2Ge(II)Ge(IV)I8; CsSnCl3, CsSnBr3, CsSnI3, RbSnCl3, RbSnBr3, KSnCl3, KSnBr3, KSn3, MASnCl3, MASnBr3, MASn3, Cs2SnCl4, Cs2SnBr4, Cs2SnI4, MA2SnCl4, MA2SnBr4, MA2SnI4, Rb2SnCl4, Rb2SnBr4, Rb2SnI4, CsSn2Cl5, Cs2SnCl6, Cs2Sn(II)Sn(IV)Cl8, CsSn2Br5, Cs2SnBr6, Cs2Sn(II)Sn(IV)Br8, CsSn2I5, Cs2SnI6, Cs2Sn(II)Sn(IV)I8, RbSn2Cl5, Rb2SnCl6, Rb2Sn(II)Sn(IV)Cl8, RbSn2Br5, Rb2SnBr6, Rb2Sn(II)Sn(IV)Br8, RbSn2I5, Rb2SnI6, Rb2Sn(II)Sn(IV)I8, KSn2Cl5, K2SnCl6, K2Sn(II)Sn(IV)Cl8, KSn2Br5, K2SnBr6, K2Sn(II)Sn(IV)Br8, KSn2I5, K2SnI6, K2Sn(II)Sn(IV)I8, MASn2Cl5, MA2SnCl6, MA2Sn(II)Sn(IV)Cl8, MASn2Br5, MA2SnBr6, MA2Sn(II)Sn(IV)Br8, MASn2I5, MA2SnI6, MA2Sn(II)Sn(IV)I8, Cs3Bi2Cl9, Cs3Bi2Br9, Cs3Bi2I9, Cs3Sb2Cl9, Cs3Sb2Br9, Cs3Sb2I9; CsPbCl3, CsPbBr3, CsPbI3, RbPbCl3, RbPbBr3, KPbCl3, KPbBr3, KPbI3, MAPbCl3, MAPbBr3, MAPbI3, Cs2PbCl4, Cs2PbBr4, Cs2PbI4, MA2PbCl4, MA2PbBr4, MA2PbI4, Rb2PbCl4, Rb2PbBr4, Rb2PbI4, CsPb2Cl5, Cs2PbCl6, Cs2Pb(II)Pb(IV)Cl8, CsPb2Br5, Cs2PbBr6, Cs2Pb(II)Pb(IV)Br8, CsPb2I5, Cs2PbI6, Cs2Pb(II)Pb(IV)I8, RbPb2Cl5, Rb2PbCl6, Rb2Pb(II)Pb(IV)Cl8, RbPb2Br5, Rb2PbBr6, Rb2Pb(II)Pb(IV)Br8, RbPb2I5, Rb2PbI6, Rb2Pb(II)Pb(IV)I8, KPb2Cl5, K2PbCl6, K2Pb(II)Pb(IV)Cl8, KPb2Br5, K2PbBr6, K2Pb(II)Pb(IV)Br8, KPb2I5, K2PbI6, K2Pb(II)Pb(IV)I8, MAPb2Cl5, MA2PbCl6, MA2Pb(II)Pb(IV)Cl8, MAPb2Br5, MA2PbBr6, MA2Pb(II)Pb(IV)Br8, MAPb2I5, MA2PbI6, MA2Pb(II)Pb(IV)I8; Cs2AgBiCl6, Cs2CuBiCl6, Cs2InAgCl6, Cs2InCuCl6, Cs2AgSbCl6, Cs2CuSbCl6, Cs2AgBiBr6, Cs2CuBiBr6, Cs2InAgBr6, Cs2InCuBr6, Cs2AgBiI6, Cs2CuBiI6, Cs2AgSbBr6, Cs2CuSbBr6, Cs2AgSbI6, Cs2CuSbI6, Cs2InAgI6, CS2InCuI6, Cs3Bi2Cl9, Cs3Bi2Br9, Cs3Bi2I9, Cs3Sb2Cl9, Cs3Sb2Br9, Cs3Sb2I9, Cs3In2Cl9, Cs3In2Br9, Cs3In2I9; K2AgBiCl6, K2CuBiCl6, K2InAgCl6, K2InCuCl6, K2AgSbCl6, K2CuSbCl6, K2AgBiBr6, K2CuBiBr6, K2InAgBr6, K2InCuBr6, K2AgBiI6, K2CuBiI6, K2AgSbBr6, K2CuSbBr6, K2AgSbI6, K2CuSbI6, K2InAgI6, K2InCuI6, K3Bi2Cl9, K3Bi2Br9, K3Bi2I9, K3Sb2Cl9, K3Sb2Br9, K3Sb2I9, K3In2Cl9, K3In2Br9, K3In2I9; Na2AgBiCl6, Na2CuBiCl6, Na2InAgCl6, Na2InCuCl6, Na2AgSbCl6, Na2CuSbCl6, Na2AgBiBr6, Na2CuBiBr6, Na2InAgBr6, Na2InCuBr6, Na2AgBiI6, Na2CuBiI6, Na2AgSbBr6, Na2CuSbBr6, Na2AgSbI6, Na2CuSbI6, Na2InAgI6, Na2InCuI6, Na3Bi2Cl9, Na3Bi2Br9, Na3Bi2I9, Na3Sb2Cl9, Na3Sb2Br9, Na3Sb2I9, Na3In2Cl9, Na3In2Br9, Na3In2I9; Li2AgBiCl6, Li2CuBiCl6, Li2InAgCl6, Li2InCuCl6, Li2AgSbCl6, Li2CuSbCl6, Li2AgBiBr6, Li2CuBiBr6, Li2InAgBr6, Li2InCuBr6, Li2AgBiI6, Li2CuBiI6, Li2AgSbBr6, Li2CuSbBr6, Li2AgSbI6, Li2CuSbI6, Li2InAgI6, Li2InCuI6, Li3Bi2Cl9, Li3Bi2Br9, Li3Bi2I9, Li3Sb2Cl9, Li3Sb2Br9, Li3Sb2I9, Li3In2Cl9, Li3In2Br9, Li3In2I9, and combinations thereof.
In one variation, the single crystal substrate includes an oxide perovskite selected from the group consisting of SrTiO3, LiNbO3, LiTaO3, CaTiO3, BaTiO3, MgTiO3, PbTiO3, EuTiO3, CdTiO3, MnTiO3, FeTiO3, ZnTiO3, CoTiO3, NiTiO3, BaSnO3, PbSnO3, SrSnO3, CaSnO3, CdSnO3, MnSnO3, ZnSnO3, CoSnO3, NiSnO3, MgSnO3, BeSnO3, PbHfO3, SrHfO3, CaHfO3, BaZrO3, PbZrO3, SrZrO3, CaZrO3, CdZrO3, MgZrO3, MnZrO3, CoZrO3, NiZrO3, TiZrO3, BeZrO3, BaCeO3, PbCeO3, SrCeO3, CaCeO3, CdCeO3, MgCeO3, MnCeO3, CoCeO3, NiCeO3, BeCeO3, BaUO3, SrUO3, CaUO3, MgUO3, BeUO3, BaVO3, SrVO3, CaVO3, MgVO3, BeVO3, BaThO3, LaAlO3, CeAlO3, NdAlO3, SmAlO3, BiAlO3, YAlO3, InAlO3, FeAlO3, CrAlO3, GaAlO3, LaGaO3, CeGaO3, NdGaO3, SmGaO3, YGaO3, LaCrO3, CeCrO3, NdCrO3, SmCrO3, YCrO3, FeCrO3, LaFeO3, CeFeO3, NdFeO3, SmFeO3, GdFeO3, YFeO3, InFeO3, LaScO3, CeScO3, NdScO3, YScO3, InScO3, LaInO3, NdInO3, YInO3, LaYO3, LaSmO3, and combinations thereof.
In one variation, the single crystal substrate includes a metal selected from the group consisting of gold (Au), silver (Ag), copper (Cu), platinum (Pt), tin (Sn), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), antimony (Sb), bismuth (Bi), titanium (Ti), molybdenum (Mo), niobium (Nb), nickel (Ni), chromium (Cr), magnesium (Mg), and combinations thereof.
In one variation, the single crystal substrate includes a semiconductor selected from the group consisting of silicon (Si), germanium (Ge), indium phosphide (InP), indium antiminide (InSb), indium arsenide (InAs), cadmium telluride (CdTe), cadmium sulfide (CdS), cadmium selenide (CdSe), gallium arsenide (GaAs), aluminum arsenide (AlAs), aluminum antimonide (AlSb), lead sulfide (PbS), lead selenide (PbSe), lead telluride (PbTe), zinc sulfide (ZnS), zinc oxide (ZnO), indium oxide (In2O3), titanium oxide (TiO2), tin oxide (SnO2), and combinations thereof.
In one variation, the method further includes disposing a buffer layer on the substrate prior to the depositing an halide perovskite on the substrate, wherein the buffer layer includes a halide salt alloy.
In one variation, the method further includes removing the film including a halide perovskite from the single crystal substrate by wet etching or epitaxial lift off.
In one variation, the method further includes transferring the film including a halide perovskite to a device.
The current technology also provides a method of fabricating a semiconductor structure. The method includes evaporating a first precursor corresponding to the formula AX, A′X, A′X2 or a combination thereof; evaporating a second precursor corresponding to a formula BX2, B′X4, CX3, DX, or a combination thereof; reacting the evaporated first precursor with the evaporated second precursor to form a halide perovskite corresponding to the formula AmBnXm+2n, AmB′n′Xm′+4n′, Am″Bn″B′n″*Xm″+2n″+4n″*, AmCnXm+3n, AmCnDlXm+3n+l, (A′X)mBnXm+2n, (A′X)mB′n′Xm′+4n′, (A′X)m″Bn″B′n″*Xm″+2n″+4n″*, (A′X)mCnXm+3n, (A′X)mCnDlXm+3n+l, or a combination thereof; and epitaxially growing a single domain film including the halide perovskite on a single crystal including a halide salt. A is a 1+alkali metal, a 1+transition metal, a 1+lanthanide, a 1+actinide, a 1+organic cation, or a 1+compound having he formula A′X, wherein A′ is an alkaline earth metal, a 2+transition metal, a 2+lanthanide, a 2+actinide, or a combination thereof; A′ is an alkaline earth metal, a 2+transition metal, a 2+lanthanide, a 2+actinide, or a combination thereof; B is a 2+alkaline earth metal, a 2+transition metal, a 2+crystallogen, a 2+lanthanide, a 2+actinide, or a combination thereof; B′ is a 4+metal or a combination of 4+metals; C is a 3+pnictogen, a 3+icosagen, a 3+transition metal, or a combination thereof; D is silver (Ag), copper (Cu), gold (Au), indium (In I), thallium (Tl I), or a combination thereof; X is an inorganic anion, an organic anion, or a combination thereof; and m, m′, m″, n, n′, n″, n″*, and l are individually integers having a value of 0 or greater.
In one variation, the method further includes disposing a first lattice matched layer on the film including the halide perovskite to generate a quantum well with a type I heterojunction, a type II heterojunction, or a type III heterojunction.
In one variation, the method further includes disposing at least one additional bilayer including a second film including a halide perovskite and a second lattice matched layer on the first lattice matched layer, such that a heterojunction is formed between the second film and the first lattice matched layer to generate a semiconductor structure including a at least one quantum well.
In one variation, the film including the halide perovskite has a thickness of a monolayer of the halide perovskite to less than or equal to about 3× the exciton Bohr radius of the halide perovskite.
In one variation, the current technology provides a semiconductor structure made according to the method.
Additionally, the current technology provides a semiconductor structure. The semiconductor structure includes a single crystal substrate, and a single-domain epitaxial film including a halide perovskite disposed on the single crystal substrate.
In one variation, the structure has a lattice misfit of less than about 10% between the single crystal substrate and the film including a halide perovskite.
In one variation, the structure has a lattice misfit of less than about 5% between the single crystal substrate and the film including a halide perovskite.
In one variation, the single crystal substrate is a halide salt, a halide perovskite, an oxide perovskite, a metal, or a semiconductor.
In one variation, the single crystal substrate is a halide salt selected from the group consisting of a metal halide salt, an alkali metal halide salt, an alkaline earth metal halide salt, a transition metal halide salt, and combinations thereof.
In one variation, the halide perovskite corresponds to the formula AmBnXm+2n, Am′B′n′Xm′+4n′, Am″Bn″B′n″*Xm″+2n″+4n″*, AmCnXm+3n, AmCnDlXm+3n+l, (A′X)mBnXm+2n, (A′X)mB′n′Xm′+4n′, (A′X)m″Bn″B′n″*Xm″+2n″+4n″*, (A′X)mCnXm+3n, (A′X)mCnDlXm+3n+l, or a combination thereof. A is a 1+alkali metal, a 1+transition metal, a 1+lanthanide, a 1+actinide, a 1+organic cation, or a 1+compound having the formula A′X, wherein A′ is an alkaline earth metal, a 2+transition metal, a 2+lanthanide, a 2+actinide, or a combination thereof; A′ is an alkaline earth metal, a 2+transition metal, a 2+lanthanide, a 2+actinide, or a combination thereof; B is a 2+alkaline earth metal, a 2+transition metal, a 2+crystallogen, a 2+lanthanide, a 2+actinide, or a combination thereof; B′ is a 4+metal or a combination of 4+metals; C is a 3+pnictogen, a 3+icosagen, a 3+transition metal, or a combination thereof; D is silver (Ag), copper (Cu), gold (Au), indium (In I), thallium (Tl I), or a combination thereof; X is an inorganic anion, an organic anion, or a combination thereof; and m, m′, m″, n, n′, n″, n″*, and l are individually integers having a value of 0 or greater.
In one variation, the single crystal substrate includes an epitaxial buffer layer and the film including a halide perovskite is disposed on the epitaxial buffer layer.
In one variation, the single crystal substrate comprises an epitaxial intermetallic layer and the film comprising a halide perovskite is disposed on the epitaxial intermetallic layer
In one variation, the film including a halide perovskite further includes a dopant.
In one variation, the semiconductor structure further includes a lattice matched layer disposed on the film including a halide perovskite, wherein the film including a halide perovskite is located between the substrate and the lattice matched layer to define a heterojunction or a quantum well.
In one variation, the semiconductor structure includes a plurality of quantum wells.
In one variation, the current technology provides a device including the semiconductor structure, wherein the device is a diode, a circuit, a sensor, a rectifier, a photocoupler, a photocatalyst, a catalyst, a photovoltaic cell, a photodetector, a photoconductor, alight emitting diode (LED), a laser, a memory, or a transistor.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, elements, compositions, steps, integers, operations, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Although the open-ended term “comprising,” is to be understood as a non-restrictive term used to describe and claim various embodiments set forth herein, in certain aspects, the term may alternatively be understood to instead be a more limiting and restrictive term, such as “consisting of” or “consisting essentially of.” Thus, for any given embodiment reciting compositions, materials, components, elements, features, integers, operations, and/or process steps, the present disclosure also specifically includes embodiments consisting of, or consisting essentially of, such recited compositions, materials, components, elements, features, integers, operations, and/or process steps. In the case of “consisting of,” the alternative embodiment excludes any additional compositions, materials, components, elements, features, integers, operations, and/or process steps, while in the case of “consisting essentially of,” any additional compositions, materials, components, elements, features, integers, operations, and/or process steps that materially affect the basic and novel characteristics are excluded from such an embodiment, but any compositions, materials, components, elements, features, integers, operations, and/or process steps that do not materially affect the basic and novel characteristics can be included in the embodiment.
Any method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed, unless otherwise indicated.
When a component, element, or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other component, element, or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers and/or sections, these steps, elements, components, regions, layers and/or sections should not be limited by these terms, unless otherwise indicated. These terms may be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially or temporally relative terms, such as “before,” “after,” “inner,” “outer,” “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially or temporally relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.
Throughout this disclosure, the numerical values represent approximate measures or limits to ranges to encompass minor deviations from the given values and embodiments having about the value mentioned as well as those having exactly the value mentioned. Other than in the working examples provided at the end of the detailed description, all numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term “about” whether or not “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. For example, “about” may comprise a variation of less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in certain aspects, optionally less than or equal to 0.1%.
In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges. As referred to herein, ranges are, unless specified otherwise, inclusive of endpoints and include disclosure of all distinct values and further divided ranges within the entire range. Thus, for example, a range of “from A to B” or “from about A to about B” is inclusive of A and B.
Example embodiments will now be described more fully with reference to the accompanying drawings.
The current technology provides methods of fabricating epitaxial films and quantum wells of halide perovskites. Epitaxy of halide perovskites is performed by vapor deposition onto single crystal substrates. Different phases of halide perovskite can be controlled by adjusting stoichiometry, which provides the ability to fabricate multilayer quantum wells of a perovskite/metal-halide system with tunable quantum confinement. Structures and devices made from the methods are also provided.
With reference to
The single crystal substrate 12 comprises a halide salt, a halide perovskite, an oxide perovskite, a metal, or a semiconductor. The halide salt can be, for example, a metal halide salt, an alkali metal halide salt, an alkaline earth metal halide salt, a transition metal halide salt, or a combination thereof with congruent interaction. Metal halide salts include, as non-limiting examples, PbX2, SnX2, GeX2, AlX3, BX3, GaX3, BiX3, InX3, SiX4, TiX4, SbX3, SbX5, and combinations thereof, where X is a halide or a combination of halides, wherein halides are F−, Cl−, Br−, or I−. Alkali metal halide salts correspond to the formula MX, where M is Li, Na, K, Rb, or Cs and X is a halide or a combination of halides. Alkali metal halide salts include, as non-limiting examples, LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbF, RbCl, RbBr, RbI, CsF, CsCl, CsBr, CsI, and combinations thereof. Alkaline earth metal halide salts have the formula M′X2, where M′ is Be, Mg, Ca, or Sr and X is a halide. Alkaline earth metal halide salts include, as non-limiting examples, BeF2, BeCl2, BeBr2, BeI2, MgF2, MgCl2, MgBr2, Mg2, CaF2, CaCl2, CaBr2, CaI2, SrF2, SrCl2, SrBr2, Sr2, and combinations thereof. Transition metal halide salts have the formula MX, where M is Mn, Fe, Co, Ni, Cr, V, or Cu; n is 1, 2, 3, 4, or 5; and X is a halide. Transition metal halide salts include, as non-limiting examples, MnF3, MnF4, MnCl2, MnCl3, MnBr2, MnI2, FeF2, FeF3, FeCl3, FeCl2, FeBr2, FeBr3, FeI2, FeI3, CoF2, CoF3, CoF4, CoCl2, CoCl3, CoBr2, CoI2, NiF2, NiCl2, NiI2, CrF2, CrF3, CrF4, CrF5, CrF6, CrCl2, CrCl3, CrCl4, CrBr2, CrBr3, CrBr4, CrI2, CrI3, CrI4, VF2, VF3, VF4, VF5, VCl2, VCl3, VCl4, VBr2, VBr3, VBr4, VI2, VI3, VI4, CuF, CuF2, CuCl, CuCl2, CuBr2, CuI, and combinations thereof. The halide perovskite can be CsSiCl3, CsSiBr3, CsSiI3, RbSiCl3, RbSiBr3, KSiCl3, KSiBr3, KSiI3, MASiCl3, MASiBr3, MASiI3, Cs2SiCl4, Cs2SiBr4, Cs2SiI4, MA2SiCl4, MA2SiBr4, MA2SiI4, Rb2SiCl4, Rb2SiBr4, Rb2SiI4, CsSiI2Cl5, Cs2SiCl6, Cs2Si(II)Si(IV)Cl8, CsSiI2Br5, Cs2SiBr6, Cs2Si(II)Si(IV)Br8, CsSiI2I5, Cs2SiI6, Cs2Si(II)Si(IV)I8, RbSi2Cl5, Rb2SiCl6, Rb2Si(II)Si(IV)Cl8, RbSi2Br5, Rb2SiBr6, Rb2Si(II)Si(IV)Br8, RbSi2I5, Rb2SiI6, Rb2Si(II)Si(IV)I8, KSi2Cl5, K2SiCl6, K2Si(II)Si(IV)Cl8, KSi2Br5, K2SiBr6, K2Si(II)Si(IV)Br8, KSi2I5, K2SiI6, K2Si(II)Si(IV)I8, MASi2Cl5, MA2SiCl6, MA2Si(II)Si(IV)Cl8, MASi2Br5, MA2SiBr6, MA2Si(II)Si(IV)Br8, MASi2I5, MA2SiI6, MA2Si(II)Si(IV)I8; CsGeCl3, CsGeBr3, CsGeI3, RbGeCl3, RbGeBr3, KGeCl3, KGeBr3, KGeI3, MAGeCl3, MAGeBr3, MAGeI3, Cs2GeCl4, Cs2GeBr4, Cs2GeI4, MA2GeCl4, MA2GeBr4, MA2GeI4, Rb2GeCl4, Rb2GeBr4, Rb2GeI4, CsGe2Cl5, Cs2GeCl6, Cs2Ge(II)Ge(IV)Cl8, CsGe2Br5, Cs2GeBr6, Cs2Ge(II)Ge(IV)Br8, CsGe2I5, Cs2GeI6, Cs2Ge(II)Ge(IV)I8, RbGe2Cl5, Rb2GeCl6, Rb2Ge(II)Ge(IV)Cl8, RbGe2Br5, Rb2GeBr6, Rb2Ge(II)Ge(IV)Br8, RbGe2I5, Rb2GeI6, Rb2Ge(II)Ge(IV)I8, KGe2Cl5, K2GeCl6, K2Ge(II)Ge(IV)Cl8, KGe2Br5, K2GeBr6, K2Ge(II)Ge(IV)Br8, KGe2I5, K2GeI6, K2Ge(II)Ge(IV)I8, MAGe2Cl5, MA2GeCl6, MA2Ge(II)Ge(IV)Cl8, MAGe2Br5, MA2GeBr6, MA2Ge(II)Ge(IV)Br8, MAGe2I5, MA2GeI6, MA2Ge(II)Ge(IV)I8; CsSnCl3, CsSnBr3, CsSnI3, RbSnCl3, RbSnBr3, KSnCl3, KSnBr3, KSnI3, MASnCl3, MASnBr3, MASnI3, Cs2SnCl4, Cs2SnBr4, Cs2SnI4, MA2SnCl4, MA2SnBr4, MA2SnI4, Rb2SnCl4, Rb2SnBr4, Rb2SnI4, CsSn2Cl5, Cs2SnCl6, Cs2Sn(II)Sn(IV)Cl8, CsSn2Br5, Cs2SnBr6, Cs2Sn(II)Sn(IV)Br8, CsSn2I5, Cs2SnI6, Cs2Sn(II)Sn(IV)I8, RbSn2Cl5, Rb2SnCl6, Rb2Sn(II)Sn(IV)Cl8, RbSn2Br5, Rb2SnBr6, Rb2Sn(II)Sn(IV)Br8, RbSn2I5, Rb2SnI6, Rb2Sn(II)Sn(IV)I8, KSn2Cl5, K2SnCl6, K2Sn(II)Sn(IV)Cl8, KSn2Br5, K2SnBr6, K2Sn(II)Sn(IV)Br8, KSn2I5, K2SnI6, K2Sn(II)Sn(IV)I8, MASn2Cl5, MA2SnCl6, MA2Sn(II)Sn(IV)Cl8, MASn2Br5, MA2SnBr6, MA2Sn(II)Sn(IV)Br8, MASn2I5, MA2SnI6, MA2Sn(II)Sn(IV)I8, Cs3Bi2Cl9, Cs3Bi2Br9, Cs3Bi2I9, Cs3Sb2Cl9, Cs3Sb2Br9, Cs3Sb2I9; CsPbCl3, CsPbBr3, CsPbI3, RbPbCl3, RbPbBr3, KPbCl3, KPbBr3, KPbI3, MAPbCl3, MAPbBr3, MAPbI3, Cs2PbCl4, Cs2PbBr4, Cs2PbI4, MA2PbCl4, MA2PbBr4, MA2PbI4, Rb2PbCl4, Rb2PbBr4, Rb2PbI4, CsPb2Cl5, Cs2PbCl6, Cs2Pb(II)Pb(IV)Cl8, CsPb2Br5, Cs2PbBr6, Cs2Pb(II)Pb(IV)Br8, CsPb2I5, Cs2PbI6, Cs2Pb(II)Pb(IV)I8, RbPb2Cl5, Rb2PbCl6, Rb2Pb(II)Pb(IV)Cl8, RbPb2Br5, Rb2PbBr6, Rb2Pb(II)Pb(IV)Br8, RbPb2I5, Rb2PbI6, Rb2Pb(II)Pb(IV)I8, KPb2Cl5, K2PbCl6, K2Pb(II)Pb(IV)Cl8, KPb2Br5, K2PbBr6, K2Pb(II)Pb(IV)Br8, KPb2I5, K2PbI6, K2Pb(II)Pb(IV)I8, MAPb2Cl5, MA2PbCl6, MA2Pb(II)Pb(IV)Cl8, MAPb2Br5, MA2PbBr6, MA2Pb(II)Pb(IV)Br8, MAPb2I5, MA2PbI6, MA2Pb(II)Pb(IV)I8; Cs2AgBiCl6, Cs2CuBiCl6, Cs2InAgCl6, Cs2InCuCl6, Cs2AgSbCl6, Cs2CuSbCl6, Cs2AgBiBr6, Cs2CuBiBr6, Cs2InAgBr6, Cs2InCuBr6, Cs2AgBiI6, Cs2CuBiI6, Cs2AgSbBr6, Cs2CuSbBr6, Cs2AgSbI6, Cs2CuSbI6, Cs2InAgI6, CS2InCuI6, C3Bi2Cl9, Cs3Bi2Br9, C3Bi2I9, Cs3Sb2Cl9, Cs3Sb2Br9, Cs3Sb2I9, Cs3In2Cl9, Cs3In2Br9, Cs3In2I9; K2AgBiCl6, K2CuBiCl6, K2InAgCl6, K2InCuCl6, K2AgSbCl6, K2CuSbCl6, K2AgBiBr6, K2CuBiBr6, K2InAgBr6, K2InCuBr6, K2AgBiI6, K2CuBiI6, K2AgSbBr6, K2CuSbBr6, K2AgSbI6, K2CuSbI6, K2InAgI6, K2InCuI6, K3Bi2Cl9, K3Bi2Br9, K3Bi2I9, K3Sb2Cl9, K3Sb2Br9, K3Sb2I9, K3In2Cl9, K3In2Br9, K3In2I9; Na2AgBiCl6, Na2CuBiCl6, Na2InAgCl6, Na2InCuCl6, Na2AgSbCl6, Na2CuSbCl6, Na2AgBiBr6, Na2CuBiBr6, Na2InAgBr6, Na2InCuBr6, Na2AgBiI6, Na2CuBiI6, Na2AgSbBr6, Na2CuSbBr6, Na2AgSbI6, Na2CuSbI6, Na2InAgI6, Na2InCuI6, Na3Bi2Cl9, Na3Bi2Br9, Na3Bi2I9, Na3Sb2Cl9, Na3Sb2Br9, Na3Sb2I9, Na3In2Cl9, Na3In2Br9, Na3In2I9; Li2AgBiCl6, Li2CuBiCl6, Li2InAgCl6, Li2InCuCl6, Li2AgSbCl6, Li2CuSbCl6, Li2AgBiBr6, Li2CuBiBr6, Li2InAgBr6, Li2InCuBr6, Li2AgBiI6, Li2CuBiI6, Li2AgSbBr6, Li2CuSbBr6, Li2AgSbI6, Li2CuSbI6, Li2InAgI6, Li2InCuI6, Li3Bi2Cl9, Li3Bi2Br9, Li3Bi2I9, Li3Sb2Cl9, Li3Sb2Br9, Li3Sb2I9, Li3In2Cl9, Li3In2Br9, Li3In2I9, and combinations thereof. The oxide perovskite can be SrTiO3, LiNbO3, LiTaO3, CaTiO3, BaTiO3, MgTiO3, PbTiO3, EuTiO3, CdTiO3, MnTiO3, FeTiO3, ZnTiO3, CoTiO3, NiTiO3, BaSnO3, PbSnO3, SrSnO3, CaSnO3, CdSnO3, MnSnO3, ZnSnO3, CoSnO3, NiSnO3, MgSnO3, BeSnO3, PbHfO3, SrHfO3, CaHfO3, BaZrO3, PbZrO3, SrZrO3, CaZrO3, CdZrO3, MgZrO3, MnZrO3, CoZrO3, NiZrO3, TiZrO3, BeZrO3, BaCeO3, PbCeO3, SrCeO3, CaCeO3, CdCeO3, MgCeO3, MnCeO3, CoCeO3, NiCeO3, BeCeO3, BaUO3, SrUO3, CaUO3, MgUO3, BeUO3, BaVO3, SrVO3, CaVO3, MgVO3, BeVO3, BaThO3, LaAlO3, CeAlO3, NdAlO3, SmAlO3, BiAlO3, YAlO3, InAlO3, FeAlO3, CrAlO3, GaAlO3, LaGaO3, CeGaO3, NdGaO3, SmGaO3, YGaO3, LaCrO3, CeCrO3, NdCrO3, SmCrO3, YCrO3, FeCrO3, LaFeO3, CeFeO3, NdFeO3, SmFeO3, GdFeO3, YFeO3, InFeO3, LaScO3, CeScO3, NdScO3, YScO3, InScO3, LaInO3, NdInO3, YInO3, LaYO3, LaSmO3, and combinations thereof. The metal can be, as non-limiting examples, gold (Au), silver (Ag), copper (Cu), platinum (Pt), tin (Sn), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), antimony (Sb), bismuth (Bi), titanium (Ti), molybdenum (Mo), niobium (Nb), nickel (Ni), chromium (Cr), magnesium (Mg), and combinations thereof. The semiconductor can be, as non-limiting examples, silicon (Si), germanium (Ge), indium phosphide (InP), indium antiminide (InSb), indium arsenide (InAs), cadmium telluride (CdTe), cadmium sulfide (CdS), cadmium selenide (CdSe), gallium arsenide (GaAs), aluminum arsenide (AlAs), aluminum antimonide (AlSb), lead sulfide (PbS), lead selenide (PbSe), lead telluride (PbTe), zinc sulfide (ZnS), zinc oxide (ZnO), indium oxide (In2O3), titanium oxide (TiO2), tin oxide (SnO2), and combinations thereof. In various embodiments, the single crystal substrate comprises ionic crystals, such that the single crystal substrate is a single ionic crystal substrate, where the halide salt, halide perovskite, oxide perovskite, metal, or semiconductor are in the form of ionic crystals.
The substrate 12 has a thickness Ts of greater than or equal to about 1 nm to less than or equal to about 1 m, of greater than or equal to about 100 nm to less than or equal to about 100 cm, or of greater than or equal to about 500 μm to less than or equal to about 10 mm.
The film 14 comprises a halide perovskite that corresponds to a formula AmBnXm+2n, Am′B′n′Xm′+4n′, Am″Bn″B′n″*Xm″+2n″+4n″*, AmCnXm+3n, AmCnDlXm+3n+l, (A′X)mBnXm+2n, (A′X)mB′n′Xm′+4n′, (A′X)m″Bn″B′n″*Xm″+2n″+4n″*, (A′X)mCnXm+3n, (A′X)mCnDlXm+3n+l, or a combination thereof, wherein A is a 1+alkali metal, a 1+transition metal, a 1+lanthanide, a 1+actinide, a 1+organic cation, or a 1+compound having he formula A′X, wherein A′ is an alkaline earth metal, a 2+transition metal, a 2+lanthanide, a 2+actinide, or a combination thereof; A′ is an alkaline earth metal, a 2+transition metal, a 2+lanthanide, a 2+actinide, or a combination thereof; B is a 2+alkaline earth metal, a 2+transition metal, a 2+crystallogen, a 2+lanthanide, a 2+actinide, or a combination thereof; C is a 3+pnictogen, a 3+icosagen, a 3+transition metal, or a combination thereof; D is silver (Ag), copper (Cu), gold (Au), indium (In I), thallium (Tl I), or a combination thereof; X is an inorganic anion, an organic anion, or a combination thereof; and m, m′, m″, n, n′, n″, n″*, and l are individually integers having a value of 0 or greater, such as a value of 0, 1, 2, 3, 4, 5, 6, 7, 8, or 9. In various embodiments, A is cesium (Cs), rubidium (Rb), potassium (K), sodium (Na), lithium (Li), copper (Cu I), methylammonium (MA), formamidinium (FA), organic cation, or a combination thereof; A′ is beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), iron (Fe II), chromium (Cr II), cobalt (Co II), nickel (Ni II), manganese (Mn II), lead (Pb II), copper (Cu II), vanadium (V II), zinc (Zn II) or a combination thereof; B is tin (Sn), lead (Pb), copper (Cu II), germanium (Ge), or a combination thereof; B′ is tin (Sn), germanium (Ge), lead (Pb), or a combination thereof; C is bismuth (Bi), antimony (Sb), indium (In II), iron (Fe), aluminum (Al) or a combination thereof; and X is an inorganic anion selected from the group consisting of a halogen (e.g., F, Cl, Br, I, or a combination thereof), an oxalate, a hydroxide, a chlorate, an iodate, a nitrite, a sulfate, a thiosulfate, a phosphate, an antimonite, or a combination thereof, an organic anion selected from the group consisting of acetate, formate, borate, carborane, phenyl borate, and combinations thereof, or a combination of inorganic anions and organic ions. When X is not a halide, it is understood that halide components are then provided from another precursor such that the non-halide X is substantially eliminated from a film during a reaction and deposition.
Non-limiting examples of halide perovskites include CsSiCl3, CsSiBr3, CsSiI3, RbSiCl3, RbSiBr3, KSiCl3, KSiBr3, KSi3, MASiCl3, MASiBr3, MASiI3, Cs2SiCl4, Cs2SiBr4, Cs2SiI4, MA2SiCl4, MA2SiBr4, MA2SiI4, Rb2SiCl4, Rb2SiBr4, Rb2SiI4, CsSiI2Cl5, Cs2SiCl6, Cs2Si(II)Si(IV)Cl8, CsSiI2Br5, Cs2SiBr6, Cs2Si(II)Si(IV)Br8, CsSiI2I5, Cs2SiI6, Cs2Si(II)Si(IV)I8, RbSi2Cl5, Rb2SiCl6, Rb2Si(II)Si(IV)Cl8, RbSi2Br5, Rb2SiBr6, Rb2Si(II)Si(IV)Br8, RbSi2I5, Rb2SiI6, Rb2Si(II)Si(IV)I8, KSi2Cl5, K2SiCl6, K2Si(II)Si(IV)Cl8, KSi2Br5, K2SiBr6, K2Si(II)Si(IV)Br8, KSi2I5, K2SiI6, K2Si(II)Si(IV)I8, MASi2Cl5, MA2SiCl6, MA2Si(II)Si(IV)Cl8, MASi2Br5, MA2SiBr6, MA2Si(II)Si(IV)Br8, MASi2I5, MA2SiI6, MA2Si(II)Si(IV)I8; CsGeCl3, CsGeBr3, CsGeI3, RbGeCl3, RbGeBr3, KGeCl3, KGeBr3, KGeI3, MAGeCl3, MAGeBr3, MAGeI3, Cs2GeCl4, Cs2GeBr4, Cs2GeI4, MA2GeCl4, MA2GeBr4, MA2GeI4, Rb2GeCl4, Rb2GeBr4, Rb2GeI4, CsGe2Cl5, Cs2GeCl6, Cs2Ge(II)Ge(IV)Cl8, CsGe2Br5, Cs2GeBr6, Cs2Ge(II)Ge(IV)Br8, CsGe2I5, Cs2GeI6, Cs2Ge(II)Ge(IV)I8, RbGe2Cl5, Rb2GeCl6, Rb2Ge(II)Ge(IV)Cl8, RbGe2Br5, Rb2GeBr6, Rb2Ge(II)Ge(IV)Br8, RbGe2I5, Rb2GeI6, Rb2Ge(II)Ge(IV)I8, KGe2Cl5, K2GeCl6, K2Ge(II)Ge(IV)Cl8, KGe2Br5, K2GeBr6, K2Ge(II)Ge(IV)Br8, KGe2I5, K2GeI6, K2Ge(II)Ge(IV)I8, MAGe2Cl5, MA2GeCl6, MA2Ge(II)Ge(IV)Cl8, MAGe2Br5, MA2GeBr6, MA2Ge(II)Ge(IV)Br8, MAGe2I5, MA2GeI6, MA2Ge(II)Ge(IV)I8; CsSnCl3, CsSnBr3, CsSnI3, RbSnCl3, RbSnBr3, KSnCl3, KSnBr3, KSn3, MASnCl3, MASnBr3, MASn3, Cs2SnCl4, Cs2SnBr4, Cs2SnI4, MA2SnCl4, MA2SnBr4, MA2SnI4, Rb2SnCl4, Rb2SnBr4, Rb2SnI4, CsSn2Cl5, Cs2SnCl6, Cs2Sn(II)Sn(IV)Cl8, CsSn2Br5, Cs2SnBr6, Cs2Sn(II)Sn(IV)Br8, CsSn2I5, Cs2SnI6, Cs2Sn(II)Sn(IV)I8, RbSn2Cl5, Rb2SnCl6, Rb2Sn(II)Sn(IV)Cl8, RbSn2Br5, Rb2SnBr6, Rb2Sn(II)Sn(IV)Br8, RbSn2I5, Rb2SnI6, Rb2Sn(II)Sn(IV)I8, KSn2Cl5, K2SnCl6, K2Sn(II)Sn(IV)Cl8, KSn2Br5, K2SnBr6, K2Sn(II)Sn(IV)Br8, KSn2I5, K2SnI6, K2Sn(II)Sn(IV)I8, MASn2Cl5, MA2SnCl6, MA2Sn(II)Sn(IV)Cl8, MASn2Br5, MA2SnBr6, MA2Sn(II)Sn(IV)Br8, MASn2I5, MA2SnI6, MA2Sn(II)Sn(IV)I8, Cs3Bi2Cl9, Cs3Bi2Br9, Cs3Bi2I9, Cs3Sb2Cl9, Cs3Sb2Br9, Cs3Sb2I9; CsPbCl3, CsPbBr3, CsPbI3, RbPbCl3, RbPbBr3, KPbCl3, KPbBr3, KPbI3, MAPbCl3, MAPbBr3, MAPbI3, Cs2PbCl4, Cs2PbBr4, Cs2PbI4, MA2PbCl4, MA2PbBr4, MA2PbI4, Rb2PbCl4, Rb2PbBr4, Rb2PbI4, CsPb2Cl5, Cs2PbCl6, Cs2Pb(II)Pb(IV)Cl8, CsPb2Br5, Cs2PbBr6, Cs2Pb(II)Pb(IV)Br8, CsPb2I5, Cs2PbI6, Cs2Pb(II)Pb(IV)I8, RbPb2Cl5, Rb2PbCl6, Rb2Pb(II)Pb(IV)Cl8, RbPb2Br5, Rb2PbBr6, Rb2Pb(II)Pb(IV)Br8, RbPb2I5, Rb2PbI6, Rb2Pb(II)Pb(IV)I8, KPb2Cl5, K2PbCl6, K2Pb(II)Pb(IV)Cl8, KPb2Br5, K2PbBr6, K2Pb(II)Pb(IV)Br8, KPb2I5, K2PbI6, K2Pb(II)Pb(IV)I8, MAPb2Cl5, MA2PbCl6, MA2Pb(II)Pb(IV)Cl8, MAPb2Br5, MA2PbBr6, MA2Pb(II)Pb(IV)Br8, MAPb2I5, MA2PbI6, MA2Pb(II)Pb(IV)I8; Cs2AgBiCl6, Cs2CuBiCl6, Cs2InAgCl6, Cs2InCuCl6, Cs2AgSbCl6, Cs2CuSbCl6, Cs2AgBiBr6, Cs2CuBiBr6, Cs2InAgBr6, Cs2InCuBr6, Cs2AgBiI6, Cs2CuBiI6, Cs2AgSbBr6, Cs2CuSbBr6, Cs2AgSbI6, Cs2CuSbI6, Cs2InAgI6, CS2InCuI6, Cs3Bi2Cl9, Cs3Bi2Br9, Cs3Bi2I9, Cs3Sb2Cl9, Cs3Sb2Br9, Cs3Sb2I9, Cs3In2Cl9, Cs3In2Br9, Cs3In2I9; K2AgBiCl6, K2CuBiCl6, K2InAgCl6, K2InCuCl6, K2AgSbCl6, K2CuSbCl6, K2AgBiBr6, K2CuBiBr6, K2InAgBr6, K2InCuBr6, K2AgBiI6, K2CuBiI6, K2AgSbBr6, K2CuSbBr6, K2AgSbI6, K2CuSbI6, K2InAgI6, K2InCuI6, K3Bi2Cl9, K3Bi2Br9, K3Bi2I9, K3Sb2Cl9, K3Sb2Br9, K3Sb2I9, K3In2Cl9, K3In2Br9, K3In2I9; Na2AgBiCl6, Na2CuBiCl6, Na2InAgCl6, Na2InCuCl6, Na2AgSbCl6, Na2CuSbCl6, Na2AgBiBr6, Na2CuBiBr6, Na2InAgBr6, Na2InCuBr6, Na2AgBiI6, Na2CuBiI6, Na2AgSbBr6, Na2CuSbBr6, Na2AgSbI6, Na2CuSbI6, Na2InAgI6, Na2InCuI6, Na3Bi2Cl9, Na3Bi2Br9, Na3Bi2I9, Na3Sb2Cl9, Na3Sb2Br9, Na3Sb2I9, Na3In2Cl9, Na3In2Br9, Na3In2I9; Li2AgBiCl6, Li2CuBiCl6, Li2InAgCl6, Li2InCuCl6, Li2AgSbCl6, Li2CuSbCl6, Li2AgBiBr6, Li2CuBiBr6, Li2InAgBr6, Li2InCuBr6, Li2AgBiI6, Li2CuBiI6, Li2AgSbBr6, Li2CuSbBr6, Li2AgSbI6, Li2CuSbI6, Li2InAg6, Li2InCu6, Li3Bi2Cl9, Li3Bi2Br9, Li3Bi2I9, Li3Sb2Cl9, Li3Sb2Br9, Li3Sb2I9, Li3In2Cl9, Li3In2Br9, Li3In2I9, (BaF)2PbCl4, (BaF)2PbBr4, (BaF)2PbI4, (BaF)2SnCl4, (BaF)2SnBr4, (BaF)2SnI4, and (BaF)2PbCl6, (BaF)2PbBr6, (BaF)2PbI6, (BaF)2SnCl6, (BaF)2SnBr6, (BaF)2SnI6, and combinations thereof.
In various embodiments, the film 14 comprising a halide perovskite further comprises a dopant. The dopant can be, for example, a p-type dopant or an n-type dopant. Non-limiting examples of dopants include BF3, BCl3, BBr3, BI3, B2S3, AlF3, AlCl3, AlBr3, AlI3, Al2S3, GaF3, GaCl3, GaBr3, GaI3, Ga2S3, MnF3, MnF4, MnCl2, MnCl3, MnBr2, MnI2, FeF2, FeF3, FeCl3, FeCl2, FeBr2, FeBr3, FeI2, FeI3, CoF2, CoF3, CoF4, CoCl2, CoCl3, CoBr2, CoI2, NiF2, NiCl2, NiI2, CrF2, CrF3, CrF4, CrF5, CrF6, CrCl2, CrCl3, CrCl4, CrBr2, CrBr3, CrBr4, CrI2, CrI3, CrI4, VF2, VF3, VF4, VF5, VCl2, VCl3, VCl4, VBr2, VBr3, VBr4, VI2, VI3, VI4, CuF, CuF2, CuCl, CuCl2, CuBr2, CuI, BaF2, BaCl2, BaBr2, Ba2, BiF3, BiCl3, BiBr3, BiI3, SnF4, SnCl4, SnBr4, SnI4, SiF4, SiCl4, SiBr4, SiI4, SnO, SnS, SnSe, SnTe, GeO, GeS, GeSe, GeTe, PbO, PbS, PbSe, PbTe. The dopant has a concentration in the film 14 of greater than or equal to about 0.00001% (weight) to 10% (weight), of greater than or equal to about 0.001% (weight) to 15% (weight), or of greater than or equal to about 0.1% (weight) to 1% (weight).
The film 14 comprising a halide perovskite has a thickness TI equal to a monolayer (ML) of the halide perovskite to less than or equal to about 3× the exciton Bohr radius. As used herein, a “monolayer” is one half of a particular halide perovskite unit cell. In various embodiments, the halide perovskite has a thickness TI of greater than or equal to about 1 μm to less than or equal to about 100 nm, or greater than or equal to about 1 nm to less than or equal to about 50 nm.
An interface 16, i.e., a heterojunction, is formed between the single crystal substrate 12 and the film 14 comprising a halide perovskite. The single crystal substrate 12 has a first lattice constant and the film 14 comprising a halide perovskite has a second lattice constant. As used herein, a “lattice constant” refers to a distance between atoms in a crystal, which provides a measure of structural compatibility of between different crystals. Lattices in three dimensions generally have three lattice constants, referred to as a, b, and c. However, in cubic crystal structures, a=b=c, such that the lattice constant is simply referred to as a. Here, the first lattice constant is substantially the same as the second lattice constant. Put another way, the semiconductor structure 10 is lattice matched. As used herein, a “lattice matched” structure is a structure comprising a plurality of thin layers of different chemical composition, but featuring substantially the same lattice constant. As used herein, “substantially the same lattice constant” refers to an absolute mismatch or misfit between lattice constants of less than or equal to about 10% or less than or equal to about 5%. As used herein, a “lattice mismatch” or a “lattice misfit” refers to a structure comprising a first layer of a first chemical composition and a second layer of a second chemical composition, wherein the lattice constant of the first chemical composition is different from the lattice constant of the second chemical composition. Lattice mismatch/misfit may prevent growth of defect-free epitaxial films unless the thickness of the film is below a critical thickness, in which case the lattice mismatch is compensated by strain in the film. Having a low lattice mismatch/misfit, such as a lattice mismatch/misfit of less than about 10% or less than about 5% allows energy gap changes between adjacent layers, which maintain substantially the same crystallographic structure. As a hypothetical example, if a single crystal substrate is a cubic crystal structure with asub=3.75 Å and a film comprising a halide perovskite is a cubic crystal structure with afilm=4.00 Å, the lattice misfit between the single crystal substrate and the film is (1−(4/3.75))/100=−6.25%, which is equivalent to an absolute lattice mismatch or misfit of 6.25%. Therefore, the semiconductor structure 10 has an absolute lattice mismatch or misfit of less than about 10% or less than about 5% at the interface 16 between the single crystal substrate 12 and the film 14 comprising a halide perovskite.
In various embodiments, the single crystal substrate 12 includes a buffer layer that provides a better lattice match with the film 14 comprising a halide perovskite than with the substrate 12.
The buffer layer 18 has a thickness Tbl of greater than or equal to about 1 Å to less than or equal to about 1010 Å, of greater than or equal to about 10 to less than or equal to about 108 Å, or from greater than or equal to about 20 Å to less than or equal to about 105 Å.
The buffer layer 18 comprises a material that has a lattice misfit of less than 3% or less than 1% with the film 14 comprising a halide perovskite. Accordingly, the buffer layer 18 comprises a pseudomorphic material with a lattice constant tuned to the lattice constant of the halide perovskite in the film 14. As used herein, a “pseudomorphic material” refers to a layer of a single-crystal material disposed on a single-crystal substrate, wherein the single-crystal material and the single-crystal substrate having different chemical compositions, but the single-crystal material adopts the substrate lattice. An epitaxial material maintains a substantially exact matched lattice constant to the substrate so that there is an induced strain (compressive or tensile) in the epitaxial film, wherein “substantially exact” refers to a difference of less than or equal to about 5% or less than or equal to about 1%. Here, the buffer layer 18 can comprise a pseudomorphic material that provides a pseudomorphic epitaxial overlayer. The pseudomorphic material is a salt or a salt alloy, i.e., a salt doped with another salt to create a lattice constant gradient, a perovskite, or a perovskite alloy. In various embodiments, the single crystal substrate 12 and the buffer layer 18 comprise the same halide salt, but the buffer layer 18 further comprises a second component, such as, for example, a second halide salt or a halide salt alloy. Therefore, the buffer layer 18 can be an epitaxial buffer layer. In some embodiments, the buffer layer 18 is an intermetallic layer that provides a transition between different types of bonding (e.g., ionic to covalent) between the single crystal substrate 12 and the film 14 via metallic bonding in the intermetallic layer. The intermetallic layer is epitaxial or epitaxial and pseudomorphic. In some embodiments, the intermetallic layer comprises elements from the single crystal substrate 12 and the film 14. For example, CswSiz (and other alkali metal silicides) are useful intermetallic layers for growing ABXe halide perovskite on Si and AwGez, GeX2 or GeX4 (X=F, Cl, Br, I) and other alkali metal germanides are useful intermetallic layers for modifying Ge for growing ABXe halide perovskite, where w and z are integers between 1 and 4. Analogous intermetallics could be used for GaAs, GaN, GaP, AlP, AlAs, InSb, InP, CdTe, CdS, ZnO, SrTiO3, LaTiO3, Ag, Au, Mo crystal substrates for growing ABXe halide perovskite.
With reference to
The lattice matched layer 22 has a thickness Tlm of greater than or equal to about 1 Å to less than or equal to about 10 Å and comprises a halide salt or halide salt alloy (as discussed above in regard to buffer layers), a semiconductor (such as the semiconductors described above in regard to the substrate 12), an insulator, a halide perovskite (including halide perovskites having different phases), Ge, InP, BaTiO3, ZnSe, or CdS that has a lattice misfit of less than about 10% or less than about 5% with respect to the film 14 comprising a halide perovskite at the interface 24. In some embodiments, as shown in
The current technology further provides a device comprising any of the semiconducting structures 10, 10b, 10c, 10d shown in
As shown in
In block 102, the method 100 comprises providing a single crystal substrate. The single crystal substrate can be any substrate described above. In some embodiments, the substrate has a polished surface on which a layer or film will be disposed. In other embodiments, the method 100 comprises cleaving the substrate from a larger substrate material to generate a fresh surface on which another layer or film will be disposed.
In various embodiments, the single crystal substrate has lattice constant that is substantially the same, i.e., has a lattice misfit of less than or equal to about 10% or less than or equal to about 5%, as the lattice constant of a halide perovskite that is to be disposed on the substrate. In other embodiments, the single crystal substrate has lattice constant that is not the same, i.e., has a lattice misfit of greater than or equal to about 5% or greater than or equal to about 10%, as the lattice constant of a halide perovskite that is to be disposed on the substrate. For example, many halide perovskites having the formula ABX3 have lattice constants of greater than or equal to about 5.5 Å to less than or equal to about 6.5 Å. Therefore, in block 104 the method 100 optionally includes disposing a buffer layer on the single crystal substrate, wherein the buffer layer comprises a halide salt or a halide salt alloy, i.e., a halide salt doped with another salt to create a lattice constant gradient, a perovskite, or a perovskite alloy. The buffer layer can be uniform, i.e., be a uniform halide salt alloy, or the buffer layer can be graded, i.e., have a decreasing or increasing concentration of an alloying halide salt in the direction of from the substrate to the film comprising a halide perovskite. Providing a buffer layer allows for lattice-matched single crystalline substrates for pseudomorphic hetero-epitaxial growth of halide perovskite thin-films with well-controlled defect and dislocation densities. The lattice constants of single crystalline substrates can be tailored by combination of multiple isostructural sources having similar lattice constants for, as non-limiting examples, NaX (NaI, NaCl, NaBr).
Therefore, in various embodiments, the disposing a buffer layer on the single crystal substrate comprises lattice tuning the buffer layer. The lattice tuning can be performed by epitaxial growth of alloyed salt layers prepared by co-deposition of different salt sources. Lattice tuning is based on the principle of Vegard's rule:
a
C
=xa
A+(1−x)aB,
where the alloyed lattice constant (aC) is a linear function of the lattice constants from two constituent materials A and B. This approach prevents or minimizes unwanted dislocation formation, allows precise strain engineering (tensile and compressive), allows pseudomorphic heteroepitaxial growth with controlled levels of defect/dislocation density, and leads to flat surfaces for halide perovskite film epitaxy.
In block 106, the method 100 comprises providing at least one precursor. The at least one precursor is provided based on a predetermined halide perovskite to be disposed on the single crystal substrate (or buffer layer). For example, the halide perovskite ABX3 can be generated reacting AX and BX2, in which AX can be halide salt such as CsCl, CsBr, CsI or other organic halide precursors such as methylammonium halide (MAX), formamidinium halide (FAX); and BX2 can be a halide salt such as SnCl2, SnBr2, SnI2 or a non-halide inorganic salts such as Sn(NO3)2, or an organo-metallic precursors, such as tin acetate Sn(Ac)2. Therefore, in various embodiments, the least one precursor comprises a first precursor corresponding to the formula AX, A′X, A′X2, or a combination thereof, and a second precursor corresponding to the formula BX2, B′X4, CX3, DX, or a combination thereof, wherein A, X, B, B′, and X are defined above. However, it is understood that there can be more than two precursors each being individually selected from the group consisting of AX, A′X, A′X2, BX2, B′X4, CX3, and DX. In other embodiments, the at least one precursor comprises the halide perovskite to be deposited onto the single crystal substrate. As non-limiting examples, the precursors CsBr and SnBr2 (and optionally a dopant, e.g., BaBr2) can react to form the halide perovskite CsSnBr3, the precursors CsI and SnI2 (and optionally a dopant, e.g., BaI2) can react to form the halide perovskite CsSnI3, the precursors CsBr, AgBr and BiBr3 can react to form the halide perovskite Cs2BiAgBr6, the precursors CsI, AgI and BiI3 can react to form the halide perovskite Cs2BiAgI6, the precursors CsBr, CuBr and BiBr3 can react to form the halide perovskite Cs2BiCuBr6, the precursors CsI, CuI and BiI3 can react to form the halide perovskite Cs2BiCuI6, the precursors CsBr, and BiBr3 can react to form the halide perovskite Cs3Bi2Br9, and the precursors CsI, and BiI3 can react to form the halide perovskite Cs3Bi2I9.
The at least one precursor is selected such that a halide perovskite with a stable crystal structure is generated. For example, the Goldschmidt tolerance factor, τ, can be used to estimate how well an A site cation can fit with a BX3 octahedral framework:
where, rA, rB and rX are corresponding ionic radii accounting for valence and coordination, and r=1 indicates an ideal fit. Additionally an octahedral factor is a second critical stability criteria for the formation of perovskite structures, defined as
which accounts for geometrical favorability of fitting a B atom in an octahedral hole. Favorable tolerance factors are in the range of greater than or equal to about 0.88 to less than or equal to about 1.05 for perovskite phases, while values less than about 0.88 can lead to non-perovskite structures; similarly, favorable octahedral factors μ are greater than or equal to about 0.41. therefore, selection of the halide perovskite; and therefore, of the at least one precursor, may be determined based on the foregoing factors. Non-limiting examples of halide perovskite that satisfy both the tolerance factor τ and the octahedral factor μ include CsSnCl3 (τ=0.94, μ=0.53), CsSnBr3 (τ=0.93, μ=0.49), CsSnI3 (τ=0.91, μ=0.44), RbSnCl3 (τ=0.90, μ=0.53), RbSnBr3 (τ=0.89, μ=0.49), KSnCl3 (τ=0.88, μ=0.53), MASnCl3 (τ=1.01, μ=0.53), MASnBr3 (τ=1.00, μ=0.49), and MASnI3 (τ=0.98, μ=0.44).
Moreover, in various embodiments, the at least one precursor comprises at least one dopant. The dopant can be, for example, a p-type dopant or an n-type dopant. Non-limiting examples of dopants are described above.
In block 108, the method 100 comprises disposing a film of halide perovskite derived from the at least one precursor on the substrate or buffer layer. The disposing comprises evaporating the at least one precursor, and depositing a film comprising a halide perovskite derived from the at least one precursor on a single crystal substrate. In various embodiments, the disposing comprises evaporating a first precursor corresponding to the formula AX, A′X or a combination thereof; evaporating a second precursor corresponding to a formula BX2, B′X4, CX3, DX, or a combination thereof; reacting the evaporated first precursor with the evaporated second precursor to form halide perovskite corresponding to the formula AmBnX3+2n, Am′Bn′Xm′+4n′, Am″Bn″B′n″*Xm″+2n″+4n″*, AmCnXm+3n, AmCnDlXm+3n+l, or (A′X)mBnXm+2n; and epitaxially growing a single domain film comprising the halide perovskite on the single crystal substrate (or buffer layer), wherein A, A′, B, B′, C, D, X, m, m′, m″, n′, n″, n′″, n″*, and l are defined above. Non-limiting examples of perovskites are provided above.
In various embodiments, the halide perovskite is generated at a deposition rate of greater than or equal to about 0.01 Å/s to less than or equal to about 20 Å/s The film comprising the halide perovskite has a thickness TI equal to a monolayer of the halide perovskite to less than or equal to about 3× the exciton Bohr radius of the halide perovskite. In various embodiments, the halide perovskite has a thickness TI of greater than or equal to about 1 pm to less than or equal to about 100 nm, or greater than or equal to about 1 nm to less than or equal to about 50 nm.
The evaporating and depo siting are performed by vapor deposition method selected from the group consisting of molecular beam epitaxy, atomic layer deposition (ALD), thermal evaporation, evaporating, sputtering, pulsed laser deposition, electron beam evaporation, chemical vapor deposition, cathodic arc deposition, and electrohydrodynamic deposition. The epitaxial growth of halide perovskites can be monitored in real-time and in situ using reflection high-energy electron diffraction using (RHEED). The vapor deposition is performed at a temperature of greater than or equal to about room temperature (or lower) to less than or equal to about 1000° C. In other embodiments, the at least one precursor comprises the predetermined halide perovskite, and the evaporating and depositing are performed by sputtering. Regardless of the deposition method, there is a lattice misfit of less than or equal to about 10%, or less than or equal to about 5% between the single crystal substrate and the halide perovskite of the film or a lattice misfit of less than or equal to about 3% or less than or equal to about 1% between the buffer layer and the halide perovskite of the film.
The structure of the halide perovskite can be manipulated by adjusting the amounts of the precursors and optional dopant. For example, first and second precursors can be varied at a first precursor:second precursor ratio of about 1-100:1, 1:1, or 1:1-100.
Referring again to
In various embodiments, the method 100 further comprises disposing at least one additional bilayer comprising a second film comprising a halide perovskite and a second lattice matched layer on the first lattice matched layer, such that a second quantum well or heterojunction is formed between the second film and the first lattice matched layer to generate a semiconductor structure comprising a plurality of quantum wells and/or heterojunctions. The second film may comprise the same or different halide perovskite as the film comprising a halide perovskite and the second lattice matched layer may comprise the same or different material as the lattice matched layer.
Halide-perovskites are often polymorphic with complex, temperature dependent phase diagrams. Stoichiometry, temperature, and strain can all affect the crystal structure and symmetry of halide perovskites and drive additional phase transitions. Here, phase transitions can be induced to design coupling of phases with distinct properties. There are unique properties that can occur at the interface of coupled oxide perovskite including superconductivity, ferroelectricity, and magnetism, which can be controlled by engineering the symmetries and degrees of freedom of correlated electrons at the interface of oxide perovskite and suitable for application such as magnetic superconductors, non-centrosymmetric superconductors and multiferroics. Also, the introduction of strain during a cubic-tetragonal phase transition could lead to the formation of ferroelastic twin domains. Therefore, tunable phases of halide perovskite in multilayers leads to properties, such as ferroic, multiferroic and superconducting systems. The in-situ and real time diffraction techniques described for the deposition of halide perovskite films halide perovskite quantum well growth where each layer is monitored before being buried by the next.
By tuning the strain and stoichiometry, phase transitions can be controlled to different phases. For example, the phase transition of epitaxial CsSnBr3 on NaCl from cubic to tetragonal and then back to cubic phase demonstrates that control over multilayer phases is achievable. Similarly, lattice constant engineering and stoichiometry control can be utilized to achieve controllable phase transition so that as-designed multi-phase film stack structures, i.e., semiconductor structures, with specific thickness and morphology can be fabricated.
Referring again to
The current technology further provides a semiconductor structure made by the method 100, such as the structures describe above with reference to
Embodiments of the present technology are further illustrated through the following non-limiting examples.
The growth of epitaxial semiconductors and oxides has revolutionized the electronics and optics fields and continues to be exploited to uncover new physics stemming from quantum interactions. While the recent emergence of halide perovskites offer exciting new opportunities for a range of thin-film electronics, the principles of epitaxy have yet to be applied to this new class of materials and the full potential of these materials is still not yet known. Methods of inorganic halide perovskite epitaxy are now provided. The epitaxy is enabled by reactive vapor phase deposition onto single crystal metal halide substrates. For the archetypical halide perovskites, CsSnBr3 and CsSnI3, different epitaxial phases that emerge via stoichiometry control that are both stabilized epitaxially with vastly differing lattice constants and that are accommodated via epitaxial rotation are described. This epitaxial growth is exploited to demonstrate multilayer quantum wells of a halide-perovskite/metal-halide system. These methods push halide perovskites to their full potential.
Epitaxial and Quantum Well Growth
Vapor deposition of perovskites was performed in a multisource custom thermal evaporator (Angstrom Engineering) equipped with a real-time and in situ reflection high-energy electron diffraction (RHEED) system (STAIB Instruments). The precursors, CsBr and SnBr2, (or CsI and SnI2), were co-evaporated from separate tungsten boats to form a perovskite layer. Prior to growth, NaCl (100) (and KCl (200)) single crystal substrates were freshly prepared by cleaving in a glovebox. Epitaxial growth was performed under a base pressure of less than 3×10−6 torr and deposition rates were measured in situ with a quartz crystal microbalance. The crystal structure was monitored in situ and in real-time using RHEED (30.0 keV) optimized with an ultra-low current (less than 10 nA) to eliminate damage and charging of the film over the growth times investigated. RHEED oscillations were monitored with substrates fixed at various in-plane orientations (KSA400). Rotation dependent RHEED patterns were collected after each deposition was halted via source and substrate shutters. Quantum well multilayers were fabricated under similar growth conditions where epitaxial NaCl (or KCl) was vapor deposited from a NaCl (or KCl) powder source at a rate of 0.02 Å/s. In the quantum well samples, the top layer of NaC (or KCl) is 1.5 nm.
Material Characterization
Cross-section transmission electron microscope (TEM) samples were prepared by focused ion beam (FIB) attached to a FEI Nova 200 Nanolab SEM/FIB and then analyzed by JEOL 3100R05 Double Cs Corrected TEM/STEM. A carbon top-layer was deposited on the cutting area to protect the epitaxial film. Scanning electron microscopy (SEM, Carl Zeiss Auriga Dual Column FIB SEM) was performed for ex situ film thickness calibration and morphology characterization. Photoluminescence spectra were measured using a PTI Quanta Master 40 spectroflurometer under a nitrogen atmosphere and various excitation wavelengths. Dielectric long-pass filters were used during the PL measurement to prevent both wavelength doubling and light bleeding. UV-VIS transmission spectra were taken using a Perkin Elmer UV-VIS Spectrometer for CsSnBr3 and CsSn2Br5 samples (Lambda 900) and CsSnI3 (Lambda 1050). X-ray diffraction was characterized with use of a Bruker D2 Phaser XRD instrument with a Cu Kα source at 30 kV and 10 mA and a Ni filter in the Bragg-Brentano configuration. X-ray photoelectron spectroscopy was performed in a separate chamber with a Kratos Axis Ultra XPS using a monochromated AlKα (1.486 keV) as X-ray source. Before taking XPS, the films were etched by Argon ion for 1.5 min to prevent the interference of surface contamination.
Simulation of Crystal and Band Structures
Electronic band structures and densities of states (DOS) of CsSnBr3 and CsSn2Br5 were simulated using density functional theory (DFT). Electronic band structures and densities of states (DOS) of CsSnBr3 and CsSn2Br5 were simulated using density functional theory (DFT). The exchange-correlation functional is the Perdew-Burke-Ernzerhof (PBE) functional, which belongs to the generalized gradient approximations (GGA) class, and the Heyd-Scuseria-Ernzerhof (HSE06), which is a screened hybrid functional. The structures of the materials were optimized using DFT with the PBE functional, resulting in a cubic unit cell with a=5.888 Å for CsSnBr3 and a tetragonal unit cell with a=b=8.483 Å, c=15.28 Å for CsSn2Br5. Additional computational details are described below. Crystal structures were drawn using VESTA and SAED patterns and were simulated with CrystalMaker.
Computational Details
All the DFT calculations were performed using the Vienna Ab initio Simulation package (VASP) with the implemented projector augmented wave (PAW) potentials. All electronic self-consistent energy calculations converge within the accuracy of 1E−5 eV between each electronic iteration. Gaussian smearing with a smearing width of 0.05 eV is used to treat bands with partial occupancies. For the cubic unit cell, an energy cutoff of the plane wave basis set (ECUT) equal to 300 eV and a gamma-centered 8×8×8 k-point mesh were used for both PBE and HSE06 calculations. For the tetragonal unit cell, using a gamma-centered 4×4×2 k-point mesh (i.e., k-point spacing of 0.03 Å−1) was suitable. For HSE06 calculations, ECUT=250 eV was used, which yields an error of about 10 meV, but reduces computational cost. For PBE and HSE06 band structure calculations, paths connecting high-symmetry k-points were divided into 10-15 k-points. The high symmetry points in the plots were previously defined. For PBE DOS calculations, a finer grid of k-point that has the separation between k-points of around 0.01 Å−1 was used, i.e., gamma-centered 16×16×16 and 11×11×6 grids were used for the CsSn2Br5 and CsSnBr3 DOS calculations, respectively. For HSE06 DOS calculations, the gamma-centered 8×8×8 and 4×4×2 k-point meshes for CsSnBr3 and CsSn2Br5 were used, respectively. These grids result in a k-point spacing of around 0.02-0.03 Å−1, which is sufficient for DOS calculations.
Cesium Tin Bromide
A. Epitaxial Growth
Metal halide salts have been used in the epitaxial growth studies of organic semiconducting materials. Here, they provide an ideal range of lattice constants (5.4-6.6 Å) closely matched to those of the halide perovskites (5.5-6.2 Å) that can be exploited for halide perovskite epitaxy with similar bonding interactions (congruent interaction), low cost, and can be wet-etched for transferring epitaxial films for a range of applications. CsSnBr3 is a promising and air-stable candidate in optoelectronics with a bandgap of 1.8 eV. The lattice constant of cubic CsSnBr3 (5.80 Å, see
Thin film cesium tin bromide was grown epitaxially on NaC single crystalline substrates via reactive thermal deposition of CsBr and SnBr2. The crystal growth was monitored in situ and in real-time with ultra-low current reflection high-energy electron diffraction (RHEED) that enables continuous monitoring even on insulating substrates. RHEED patterns captured during the epitaxial growth of the perovskite are shown in
When depositing CsSnBr3 using a molar ratio of 1:1 (CsBr:SnBr2), the RHEED patterns remain streaky, indicating the formation of a smooth crystalline layer. After the deposition of the first monolayer, the underlying substrate Kikuchi lines disappear as expected due to the shift in elemental composition. The geometry and spacing of these reciprocal lattice points obtained along the [110] and [100] indicate that the crystal structure of the perovskite is cubic with a calculated lattice constant of 5.8±0.1 Å (shown in
During this 1:1 growth, clear RHEED oscillations that vary with deposition rate are observed. Such oscillations are a hallmark of layer-by-layer growth (
In contrast to the growth with a 1:1 stoichiometry, growth with a 0.5:1 stoichiometry results in a phase transition from the cubic CsSnBr3 to a stable tetragonal phase that takes place at the earliest stages of growth within the first 2 monolayers. Rotation dependent RHEED patterns for the tetragonal phase are shown in
Epitaxial growth with both a greater CsBr deficiency (0.25:1) and excess (1.5:1) were also investigated as shown in
To further confirm the phases shown in the RHEED patterns, X-ray diffraction (XRD) was used to determine the out-of-plane lattice parameter for the epitaxial films. As the ratio of CsBr to SnBr2 increases from 0.25:1 to 1:1, the peaks at 11.57° (d=7.678±0.007 Å) and 23.46° are replaced by peaks at 15.31° (d=5.795±0.005 Å) and 30.83° as shown in
1:1
Epitaxial films were also characterized by X-ray photoelectron spectroscopy (XPS) as shown in
The combination of RHEED, XRD and XPS analysis indicates that the growth of CsSnBr3 is more favorable when Cs is stoichiometric or in slight excess, while CsSn2Br5 dominates when there is a Cs deficiency. Both selective elemental vacancies and lattice mismatch can ultimately play a role in initiating strain-driven phase transitions in these systems.
B. Optical Properties and Electronic Band Structures
Experimental and theoretical studies were performed on the CsSn2Br5 and CsSnBr3 phases. Absorption spectra of as-prepared epitaxial film are shown in
C. Fabrication of CsSnBr3 Quantum Well
Quantum wells with varying well thickness with 1:1 stoichiometry using vapor deposited NaCl as the well barrier were fabricated. In general, quantum well devices are important in a range of opto-electronic devices and provide critical insight into the physical properties of quantum confined charge carriers, two-dimensional electron gas, and tunable luminescence.
The growth process was analyzed by RHEED to confirm the formation of epitaxial multilayers as shown in
When the well thickness was reduced from 100 nm to 5 nm, the emission peak shifted from 685 nm to 654 nm (
where Eg is the bulk band gap, ΔE is the confinement energy of both electrons and holes, h is reduced Planck constant, Lz is the thickness of the quantum well, and m* is the reduced mass that can be obtained from the effective masses of the electron (me) and the hole (mh*) as
q is the charge of electron, εr is the relative permittivity, and ε0 is the vacuum permittivity. Because the exciton binding energy of CsSnBr3 has been reported to be less than 1 meV, the size dependence of the quantum well bandgap can be expressed as:
where the value of m* obtained by fitting the PL data of quantum well PL data can be extracted and then used for calculation of Bohr radius of this material by using Equation (2):
where aB is the Bohr radius, e is the electron charge, ε0 is the vacuum permittivity, and ε is the dielectric constant of the semiconductor which has been reported for CsSnBr3 to be 32.4. Emission energies of CsSnBr3 quantum wells with various widths are shown in Table 5.
D. Doping Engineering of Epitaxial CsSnBr3
Doping engineering is a conventional method for controlling the semiconducting properties of epitaxial film. Here, we use BiBr3 as the dopant to adjust the charge carrier concentration within the epitaxial film. I-V measurement was carried out to evaluate the property change along with varying dopant concentration from 0% to 2.5%, as shown in
Cesium Tin Iodide
A. Epitaxial Growth
In situ RHEED patterns captured during epitaxial growth of the perovskite are shown in
The out of plane XRD in
XPS was also performed to identify the real elemental ratios in the epitaxial film (shown in
UV-Vis spectra in
RHEED patterns (
A route to the epitaxial growth of an inorganic halide perovskites using metal halide crystals and show the emergence of different epitaxial phases of CsSnBr3 (CsSnBr3 and CsSn2Br5) and CsSnI3 based on control over stoichiometry is demonstrated. Phase transitions between the cubic CsSnBr3 and tetragonal CsSn2Br5 phases is observed in real-time. The epitaxial growth of CsSnBr3 and CsSnI3 is exploited to demonstrate multilayer epitaxial quantum wells of halide perovskites. These demonstrations unlock the epitaxial exploration to the full range of halide perovskites and help realize their full potential.
Epitaxial growth of inorganic halide perovskites is affected by various factors, such as, for example, substrate and temperature.
To obtain highly ordered epitaxial films, substrates can be chosen that have a lattice parameter close to that of an epitaxy to be grown on the substrate. Table 7 shows substrates that are most promising and less promising for CsSnBr3 and Table 82 shows substrates that are most promising and less promising for CsSnI3.
For example, and as shown in
One of the most widely used methods to remove the natural oxide on the surface is acid-treatment, e.g., HCl treatment. However, after HCl treatment, the growth still results in the formation of polycrystalline CsSnBr3.
As shown in
Growth temperature is another factor that can largely affect the quality of an epitaxial film. Growth at various temperatures was studied, which shows that at higher temperature, the epitaxial film can also be obtained.
Lattice tuning is performed by epitaxial growth of alloyed salt layers prepared by co-deposition of different salt sources based on the principle of Vegard's rule. Such behavior is seen
Alloyed NaCl—NaBr was epitaxially grown on NaCl to improve lattice matching and reduce dislocation density.
A sample comprises a CsSnBr3 film epitaxially grown on a single crystal substrate. Tape (which may be conductive or non-conductive, transparent or non-transparent, polymer or metal) was adhered to the CsSnBr3 film (which may or may not include a gold layer on top). The sample was immersed into liquid nitrogen for from about 5 seconds to about 30 seconds. The sample was removed from the liquid nitrogen and immediately immersed in diethyl ether (which could have been any other solvent that does not dissolve or destroy the sample at low boiling temperature). Diethyl ether was used to prevent the sample from adsorbing water when it is removed from the liquid nitrogen and subsequently slowly warms toward ambient temperature. The sample was removed from the diethyl ether and the tape was tapped onto the surface of the sample. The tape was then slowly peeled away. Photographs of the process are shown in
A photovoltaic (PV) device was fabricated by transferring the CsSnBr3 crystalline film to coper tape. The procedure was: 1) depositing a layer of gold to make good contact and provide mechanical support during film transferring; 2) immersing the epitaxial film grown on the substrate (the “sample”) into liquid nitrogen for 5-30 s and then immersing the sample into diethyl ether or any other solvent which cannot dissolve or destroy the sample with low boiling temperature (to prevent the sample adsorbing water when it is taken out from the liquid nitrogen); 3) removing the sample from the solvent after it is warm and pressing tape onto the surface of the sample with or without gold layer on the top and where the tape is conductive or non-conductive, transparent or non-transparent, polymer or metal; and 4) slowly peeling the tape. After transferring, the CsSnBr3 film was on the top and then the sample was coated with C60 and bathocuproine (BCP). The measurement was done via conductive probe AFM and results are shown in
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
This application claims the benefit of U.S. Provisional Application No. 62/518,808, filed on Jun. 13, 2017. The entire disclosure of the above application is incorporated herein by reference.
This invention was made with government support under DE-SC0010472 awarded by the U.S. Department of Energy. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2018/037220 | 6/13/2018 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62518808 | Jun 2017 | US |
