Patent Application
20070252507
The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:
Korean Patent Application No. 10-2006-0037677, filed on Apr. 26, 2006, in the Korean Intellectual Property Office, and entitled: “Electron Emission Device and Method of Manufacturing the Same,” is incorporated by reference herein in its entirety.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are illustrated. The invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout.
The present invention provides an electron emission device in which a carbon material or a nano material forming an electron emission source may be uniformly distributed and formed facing upwards, through which uniform electron emission may be achieved and electron emission efficiency is increased, and a method of manufacturing the electron emission device.
Referring to
The first substrate 110 may be a board member having a predetermined thickness, and may be, e.g., a glass substrate formed of quartz, glass containing small amounts of impurities such as Na, sheet glass, glass coated with SiO2, borosilicate glass, phosphate glass, an aluminum oxide substrate, a ceramic substrate, etc. In order to obtain a flexible display apparatus, the first substrate 110 may be formed of a flexible material.
The cathode 120 may extend in a direction on the first substrate 110, and may be formed of an electrically conductive material, e.g., a metal including at least one of Al, Ti, Cr, Ni, Au, Ag, Mo, W, Pt, Cu, Pd, Ru, etc. The cathode 120 may also be formed from an alloy or oxide of these metals, e.g., RuO2, Pd—Ag, etc., a printed conductive material including a metal oxide and glass, a transparent conductive material, e.g., ITO, In2O3, or SnO2, etc., or a semiconductor material, e.g., polysilicon.
The gate electrode 140 may be insulated from the cathode 120 by the first insulating layer 130. The gate electrode 140 may be formed of an electrically conductive material similar to the cathode 120. The first insulating layer 130 may be interposed between the gate electrode 140 and the cathode 120 to insulate the gate electrode 140 from the cathode 120, thereby preventing short circuits between the electrodes.
The electron emission source 250 may be in an electron emission source hole 131, which may be formed in the first insulating layer 130 and the gate electrode 140. The electron emission source hole 131 may expose a portion of the cathode 120, allowing the electron emission source 250 to be electrically connected to the cathode 120. The electron emission source 250 may include a first electron emission material layer 251 electrically connected to the cathode 120 and a second electron emission material 253 grown on an upper part of the first electron emission material layer 251. A catalyst layer 252 used for growing the second electron emission material 253 may optionally be on the upper part of the first electron emission material layer 251.
The first electron emission material layer 251 may be formed using, e.g., a chemical vapor deposition (CVD) direct growing method on the cathode 120, but the present invention is not limited thereto. The catalyst layer 252 may be formed of a metal or a metal salt. When the catalyst layer 252 is formed of a metal salt, the catalyst layer 252 may be formed by coating a solution on a predetermined seed layer, followed by drying. The solution may be formed from the metal salt dissolved in a predetermined solvent. The solution may be coated on the predetermined seed layer (not shown) using, e.g., a spin coating method, a dipping method, etc.
The metal salt may contain weak acid negative ion radicals so that the salt may be dissolved in a strong salt developing solution such as tetramethylammonium hydroxide (TMAH). The weak acid negative ion radicals may be at least one selected from, e.g., acetate radicals, oxalate radicals, formate radicals, propionate radicals, butyrate radicals, carbonate radicals, etc. Also, the metal salt may be formed from at least one of, e.g., Fe, Ni, Co, Y, etc. The solvent may be one of, e.g., ethylene glycol, propylene glycol, methanol, ethanol, etc. The metal salt may have a solubility of approximately 1 mM or more with respect to the solvent at room temperature. Also, the metal salt may be insoluble in, e.g., acetone, isopropyl alcohol, a photoresist strip, etc.
In the electron emission sources 250, an uppermost part of the second electron emission material 253 may be located lower than the top or bottom surfaces of the gate electrode 140. The first and second electron emission material layers 251 and 253 used for the electron emission sources 250 may be formed of, e.g., a carbon material, a nano material, etc. The carbon material may be, e.g., carbon nano tubes (CNTs) having a low work function and a high β function, graphite, diamond, diamond like carbon (DLC), etc. The carbon material may also be, e.g., nano materials including CNTs, nano wires, nano rods, etc. In particular, the CNTs have an electron emission characteristic, and thus permit driving of an electron emission display device at a low voltage. Therefore, the use of the CNTs as an electron emission source may be advantageous for manufacturing a large screen display device.
In the electron emission device 201 having the above-described structure, electrons may be emitted from the electron emission sources 250 due to an electric field formed between the cathode 120 and the gate electrode 140 when a negative voltage is applied to the cathode 120 and a positive voltage is applied to the gate electrode 140.
Also, the electron emission device 201 may be utilized in an electron emission display device that creates images by generating visible light. In order to function as a display device, the electron emission device 201 may further include a phosphor layer (not shown) on a front surface of the electron emission device 201. The phosphor layer may be formed together with an anode (not shown) that accelerates electrons towards the phosphor layer, and a front substrate (not shown) that supports the anode and the phosphor layer.
The second substrate, i.e., the front substrate, may be a board member having a predetermined thickness, and may be formed of the same materials as the first substrate 110. The anode may be formed of an electrically conductive material similar to the material forming the cathode 120 and the gate electrode 140.
The phosphor layer may be formed of a cathode luminescence (CL) type of phosphor material that may generate visible light when the phosphor layer is excited by accelerated electrons. The phosphor material that may be used for the phosphor layer includes, e.g., a red color phosphor material such as SrTiO3:Pr, Y2O3:Eu, Y2O3S:Eu, etc., a green color phosphor material such as Zn(Ga, Al)2O4:Mn, Y3(Al, Ga)5O12:Tb, Y2SiO5:Tb, ZnS:Cu,Al, etc., and a blue color phosphor material such as Y2SiO5:Ce, ZnGa2O4, ZnS:Ag, Cl, etc., but the phosphor material of the present invention is not limited thereto.
In order to display images, i.e., to not simply function as a lamp that generates visible light, the cathode 120 and the gate electrode 140 may be alternately arranged. Also, in regions where the cathode 120 and the gate electrode 140 are alternately arranged, the electron emission source hole 131 may be formed to contain the electron emission source 250 therein.
The electron emission device 201, which includes the first substrate 110 and the front panel 102 (see
Operation of the electron emission display device 100 having the above structure will now be described.
A negative (−) voltage may be applied to the cathode 120 and a positive (+) voltage may be applied to the gate electrode 140 so that the electron emission source 250 formed on the cathode 120 may emit electrons. Also, a high positive (+) voltage may be applied to the anode 80 to accelerate the electrons toward the anode 80. When the high positive (+) voltage is applied to the anode 80, the electrons emitted from the electron emission source 250 may proceed toward the gate electrode 140 and accelerate towards the anode 80. The electrons accelerated towards the anode 80 may collide with the phosphor layer 70. Then, the phosphor material of the phosphor layer 70 may become excited and emit visible light. The portion of the electron emission source 250 that mainly emit electrons may be the upper parts of the second electron emission material 253.
A method of manufacturing an electron emission device 201 according to an embodiment of the present invention will now be described with reference to
Referring to
Referring to
Referring to
Since an upper surface of the first electron emission material layer 251 has a corrugated surface, the catalyst layer 252 formed on the first electron emission material layer 251 may also have a corrugated rough upper surface. Accordingly, the second electron emission material 253 may have small grains, and a carbonization rate may thus be increased. Therefore, the density of the electron emission material formed on the catalyst layer 252 may be reduced, and accordingly, the causes that reduce the electron emission, e.g., a screen effect, may be avoided.
Referring to
In the electron emission device 301 depicted in
As described above, in the electron emission device according to the present invention, the electron emission characteristics of an electron emission material may be greatly improved and uniform electron emission may be achieved.
Exemplary embodiments of the present invention have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2006-0037677 | Apr 2006 | KR | national |
