Patent Application
20140312335
The present disclosure relates to a manufacturing method of an organic semiconductor element, an organic semiconductor element, a growth method of an organic single crystal thin film, an organic single crystal thin film, an electronic device, and an organic single crystal thin film group.
Recent years, research and development of organic semiconductor elements is being widely conducted using organic semiconductor crystal thin films. It is important for the organic semiconductor elements to control the position, dimensions, crystal orientation and the like of the organic semiconductor crystal thin films.
Conventionally, the following method has been proposed for a growth method of an organic semiconductor crystal thin film (see Non-Patent Literature 1). Namely, a silicon piece which is a barrage is provided on an impurity-doped silicon substrate on whose surface a SiO2 film is formed. A droplet composed of a raw material solution containing a [1]benzothieno[3,2-b]benzothiophene derivative (C8-BTBT) is held on the lower edge of the silicon piece in a state where the silicon substrate inclines relative to the horizontal plane. Then, the droplet is being dried, and thereby, an organic semiconductor crystal thin film composed of C8-BTBT is allowed to grow on the silicon substrate toward the upper side of the droplet from the lower side thereof. It is reported that this organic semiconductor crystal thin film attains high electron mobility (5 cm2/Vs).
Patent Literature 1: JP 2010-6794A
Non-Patent Literature 1: T. Uemura, Y. Hirose, M. Uno, K. Takimiya and J. Takeya: Applied Physics Express 2 (2009)111501
Non-Patent Literature 2: N. Kobayashi, M. Sasaki and K. Nomoto: Chem. Mater. 21 (2009)552
However, the conventional growth method of an organic semiconductor crystal thin film proposed in Non-Patent Literature 1 has a demerit of incapability of controlling the position, dimensions and crystal orientation at all.
Therefore, a problem to be solved according to the present disclosure is to provide a growth method of an organic single crystal thin film and an organic single crystal thin film, the method being capable of controlling the position, dimensions, crystal orientation and the like of various kinds of organic single crystal thin films such as an organic semiconductor single crystal thin film.
Another problem to be solved according to the present disclosure is to provide a manufacturing method of an organic semiconductor element using the above-mentioned growth method of an organic single crystal thin film, and an organic semiconductor element using an organic semiconductor single crystal thin film allowed to grow by the growth method.
Still another problem to be solved according to the present disclosure is to provide an electronic device using the above-mentioned organic semiconductor element.
Still another problem to be solved according to the present disclosure is to provide an organic single crystal thin film group in which the crystal orientations of various kinds of organic single crystal thin films such as organic semiconductor single crystal thin films coincide with one another.
In order to solve the above-mentioned issues, the present disclosure provides a manufacturing method of an organic semiconductor element, including a step of supplying an unsaturated organic solution obtained by dissolving an organic compound in a solvent to a growth control region and at least one nucleation control region of a base body having, on one principal plane, the growth control region and the nucleation control region which is provided on one side of the growth control region to be coupled with the growth control region, and a step of allowing an organic semiconductor single crystal thin film composed of the organic compound to grow by evaporating the solvent of the organic solution.
Further, the present disclosure provides an organic semiconductor element manufactured by supplying an unsaturated organic solution obtained by dissolving an organic compound in a solvent to a growth control region and at least one nucleation control region of a base body having, on one principal plane, the growth control region and the nucleation control region which is provided on one side of the growth control region to be coupled with the growth control region, and allowing an organic compound single crystal thin film composed of the organic semiconductor to grow by evaporating the solvent of the organic solution.
Further, the present disclosure provides electronic device having an organic semiconductor element manufactured by supplying an unsaturated organic solution obtained by dissolving an organic compound in a solvent to a growth control region and at least one nucleation control region of a base body having, on one principal plane, the growth control region and the nucleation control region which is provided on one side of the growth control region to be coupled with the growth control region, and allowing an organic semiconductor single crystal thin film composed of the organic compound to grow by evaporating the solvent of the organic solution.
In the above-mentioned manufacturing method of an organic semiconductor element, organic semiconductor element and electronic device, typically, by evaporating the solvent of the organic solution, the state of the organic solution is configured as the metastable region between the solubility curve and the supersolubility curve in the solubility-supersolubility diagram of the organic solution in the growth control region (or the growth region) and the state of the organic solution is configured as the unstable region on the lower side of the supersolubility curve in the solubility-supersolubility diagram in the nucleation control region (or the crystal nuclei forming region). Namely, the organic solution immediately after supplied to the growth control region and the nucleation control region is in the stable region on the upper side of the solubility curve in the solubility-supersolubility diagram. During the process of evaporating the solvent of the organic solution, the state of the organic solution is configured as the metastable region between the solubility curve and the supersolubility curve in the growth control region and the state of the organic solution is configured as the unstable region on the lower side of the supersolubility curve in the nucleation control region. Such states can be easily attained by selecting the area of the nucleation control region to be sufficiently smaller compared with the area of the growth control region. Namely, since the amount of the organic solution retained in the nucleation control region is sufficiently smaller compared with the amount of the organic solution retained in the growth control region, the evaporation rate of the solvent from the organic solution retained in the nucleation control region is sufficiently larger compared with the evaporation rate of the solvent from the organic solution retained in the growth control region. Therefore, the state of the organic solution comes to the unstable region in the nucleation control region due to the concentration increasing along with the rapid evaporation of the solvent. Meanwhile, simultaneously in the growth control region, the state of the organic solution can be allowed to come to the metastable region due to the increase of the concentration being slow along with the slow evaporation of the solvent. In this case, the nucleation from the organic solution can be allowed to take place only in the nucleation control region in which the state of the organic solution is in the unstable region. At this stage, a number of crystal nuclei of the organic compound are formed in the organic solution on the nucleation control region. Eventually, only one crystal having grown from the crystal nuclei formed due to the nucleation from the organic solution in the nucleation control region closes the nucleation control region. Then, originating from this crystal, a crystal grows on the growth control region, and thereby, a crystal with a single domain (single crystal) is allowed to grow. Thus, the organic semiconductor single crystal thin film has grown on the growth control region. In this case, typically, the organic solution is held at a constant temperature, for example, of 15° C. or more and 20° C. or less but not necessarily limited to the above.
Generally, the lower the temperature of the organic solution is, the more the evaporation of the solvent is suppressed. Therefore, the solute molecules, that is, molecules of the organic compound are tend to be sufficiently supplied to the crystal. Moreover, the lower the temperature of the organic solution is, the more the evaporation of the solvent is suppressed. Therefore, the degree of supersaturation on the surface of the organic solution hardly increases and the growth in the lateral direction is suppressed to the more extent. This allows the growth to proceed in the film thickness direction, causing the tendency of the film thickness of the organic semiconductor single crystal thin film being large.
Preferably, the growth control region and the nucleation control region have the lyophilic surfaces. Further preferably, the surface of the base body in the periphery of the growth control region and the nucleation control region has the lyophobic surface. Due to the above, when the organic solution is supplied to the growth control region and the nucleation control region, the organic solution can be retained securely only on the growth control region and the nucleation control region.
Typically, the nucleation control region has the first part in a straight line shape which is coupled with the growth control region and inclines by 90°±10° relative to the above-mentioned one side of the growth control region, or further has the second part in a straight line shape which is coupled with the first part and inclines relative to the above-mentioned one side. Or, the nucleation control region has the third part in a triangular shape which is coupled with the growth control region and has the first side on the above-mentioned one side and the fourth part in a straight line shape which is coupled with the third part and inclines relative to the above-mentioned one side. The first part inclines preferably by 90°±5°, still preferably by 90°±2°, most preferably by 90°±1°, relative to the one side of the growth control region. The second part inclines by 0° or more (or greater than 0°) and less than 90°, for example, 25° or more and 65° or less, preferably by 30° or more and 60° or less relative to the one side of the growth control region but is not limited to the above. The fourth part inclines by 0° or more (or greater than 0°) and 90° or less, for example, 25° or more and 65° or less, preferably by 30° or more and 60° or less relative to the one side of the growth control region but is not limited to the above. The angle between the second side and the third side of the third part is selected, for example, as an angle of a polygon defined by the crystal structure of the organic semiconductor single crystal thin film. The widths of the first part, the second part and the fourth part are generally 0.1 μm or more and 50 μm or less, preferably 1 μm or more and 50 μm or less, still preferably 1 μm or more and 30 μm or less, further preferably 1 μm or more and 20 μm or less or 1 μm or more and 10 μm or less but are not limited to the above. The shape of the growth control region is selected as needed and typically a rectangular or square shape.
Typically, the dimensions of the growth control region are selected sufficiently larger compared with the dimensions of the nucleation control region. For example, the growth control region typically has a rectangular shape with a length of the above-mentioned one side being 1000 μm or more and 10000 μm or less and a length of the other side being 100 μm or more and 800 μm or less, for example, sufficiently larger compared with the nucleation control region. In one typical example, the growth control region is a rectangle and the first part of the nucleation control region is a smaller rectangle than the growth control region which part is provided on one long side of the growth control region to be perpendicular to the long side.
In one typical example, the organic semiconductor single crystal thin film has a π-electron stacking structure in a direction substantially parallel to one principal plane of the base body. The organic semiconductor single crystal thin film has, for example, a triclinic, monoclinic, orthorhombic, or tetragonal crystal structure and has the above-mentioned π-electron stacking structure in the a-axis direction or the b-axis direction. In this case, the a-axis and the b-axis of the organic semiconductor single crystal thin film are parallel to the one principal plane of the base body. Typically, the organic semiconductor single crystal thin film grows such that its {110} plane is parallel to the above-mentioned first part, the second part, one side other than the first side of the third part or the fourth part. Moreover, the organic semiconductor single crystal thin film typically has a tetragonal or pentagonal shape having the first vertex with a vertical angle of 82° and the second vertex with a vertical angle of 98°. The second side and the third side of the third part are parallel to the {110} plane of the organic semiconductor single crystal thin film, for example.
Only one or a plurality of nucleation control regions may be provided on the one side of the growth control region. Moreover, only one or a plurality of growth control regions may be provided on the one principal plane of the base body to separate from one another. Preferably, when the plurality of growth control regions are provided to separate from one another, at least two growth control regions of these growth control regions are provided opposite to each other and a plurality of nucleation control regions are provided on each of sides of the two growth control regions which sides oppose each other not to overlap with one another.
The organic compound can employ various kinds of conventionally known ones and, for example, can employ the followings.
(1) polypyrrol and its derivatives
(2) polythiophene and its derivatives
(3) isothianaphthenes such as polyisothianaphthene
(4) thienylene vinylenes such as poly(thienylene vinylene)
(5) polymers with p-phenylene vinylenes such as poly(p-phenylene vinylene)
(6) polyaniline and its derivatives
(7) polyacetylenes
(8) polydiacetylenes
(9) polyazulenes
(10) polypyrenes
(11) polycarbazoles
(12) polyselenophenes
(13) polyfurans
(14) polymers with p-phenylenes
(15) polyindoles
(16) polypyridazines
(17) acenes such as naphthacene, pentacene, hexacene, heptacene, dibenzopentacene, tetrabenzopentacene, pyrene, dibenzopyrene, chrysene, perylene, coronene, terrylene, ovalene, quaterrylene and circumanthracene
(18) derivatives having an atom such as nitrogen, sulfur and oxygen or a functional group such as carbonyl group substituted for a part of carbons in acenes, for example, triphenodioxazine, triphenodiazine, hexacene-6,15-quinone and the like
(19) macromolecular materials such as polyvinylcarbazole, polyphenylenesulfide and polyvinylenesulfide and their polycyclic fused rings
(20) oligomers having repeating units same as those of the macromolecular materials in item (19)
(21) metal phthalocyanines
(22) tetrathiafulvalene and its derivatives
(23) tetrathiapentalene and its derivatives
(24) naphthalene-1,4,5,8-tetracarboxylic diimide, N,N′-bis(4-trifluoromethylbenzyl)naphthalene-1,4,5,8-tetracarboxylic diimide, N,N′-bis(1H,1H-perfluorooctyl), N,N′-bis(1H,1H-perfuluorobutyl) and N,N′-dioctylnaphthalene-1,4,5,8-tetracarboxylic diimide derivatives
(25) naphthalenetetracarboxylic diimides such as naphthalene-2,3,6,7-tetracarboxylic diimide
(26) fused-ring tetracarboxylic diimides represented by anthracenetetracarboxylic diimides such as anthracene-2,3,6,7-tetracarboxylic diimide
(27) dyes such as merocyanine dyes and hemicyanine dyes
Preferably, the organic compound employs aromatic compounds or their derivatives. The aromatic compounds are categorized into benzene-based aromatic compounds, heterocyclic aromatic compounds and non-benzene-based benzene-based aromatic compounds. The benzene-based aromatic compounds are fused-ring aromatic compounds, for example, benzo-fused-ring compounds and the like. The heterocyclic aromatic compounds are furan, thiophene, pyrrole, imidazole and the like, for example. The non-benzene-based aromatic compounds are annulene, azulene, cyclopentadienyl anion, cycloheptatrienyl cation (tropylium ion), tropone, metallocene, acepleiadylene and the like, for example.
Preferably, fused-ring compounds are used from among the above-mentioned aromatic compounds. Examples of the fused-ring compounds can include acenes (naphthalene, anthracene, tetracene, pentacene and the like), phenanthlene, chrysene, triphenylene, tetraphene, pyrene, picene, pentaphene, perylene, helicene, coronene and the like, whereas they are not limited to the above.
Preferably, the aromatic compounds also employ dioxaanthanthrene-based compounds such as 6,12-dioxaanthanthrene (so-called perixanthenoxanthene or 6,12-dioxaanthanthrene; sometimes abbreviated as “PXX”) (see Non-Patent Literature 2 and Patent Literature 1).
The organic semiconductor element may employ anything basically as long as it uses the organic semiconductor single crystal thin film. For example, examples thereof include an organic transistor, an organic photoelectric transducer and the like. One or two or more organic semiconductor single crystal thin films may be used for the organic semiconductor element and the two or more organic semiconductor single crystal thin films may include a same kind of those or different kinds of those. In the organic transistor, the organic semiconductor single crystal thin film is a semiconductor layer in which channels are formed, for example. In the organic photoelectric transducer, the organic semiconductor single crystal thin film is an organic photoelectric conversion layer. For example, for organic transistors, the crystal orientation of the organic semiconductor single crystal thin film is configured such that a direction of electrons traveling coincides with the direction high in mobility of carriers in the organic semiconductor single crystal thin film, and thereby, an organic transistor high in mobility can be attained. Moreover, for organic photoelectric transducers, the crystal orientation of the organic semiconductor single crystal thin film is configured to be in the direction of the polarization axis, and thereby, a polarization organic photoelectric transducer high in sensitivity to polarized light can be attained. The polarization organic photoelectric transducer can be used, for example, for a polarization organic imaging device, a ranging functional device and the like.
The electronic device may employ various kinds of electronic devices using one or two or more electronic elements such as organic semiconductor elements and may be either mobile or settled regardless of functions or purposes. Specific examples of the electronic device include a display such as a liquid crystal display and an organic electroluminescent display, a mobile phone, a mobile device, a personal computer, a game machine, in-car devices, home appliances, industrial products and the like. Moreover, the polarization organic photoelectric transducer is applied to various kinds of electronic devices using polarized light, for example, a three-dimensional camera using a polarization organic imaging device composed of polarization organic photoelectric transducers.
Further, the present disclosure provides a growth method of an organic single crystal thin film including supplying an unsaturated organic solution obtained by dissolving an organic compound in a solvent to a growth control region and at least one nucleation control region of a base body having, on one principal plane, the growth control region and the nucleation control region which is provided on one side of the growth control region to be coupled with the growth control region, and allowing an organic single crystal thin film composed of the organic compound to grow by evaporating the solvent of the organic solution.
Further, the present disclosure provides an organic single crystal thin film allowed to grow by supplying an unsaturated organic solution obtained by dissolving an organic compound in a solvent to a growth control region and at least one nucleation control region of a base body having, on one principal plane, the growth control region and the nucleation control region which is provided on one side of the growth control region to be coupled with the growth control region, and allowing the organic single crystal thin film composed of the organic compound to grow by evaporating the solvent of the organic solution.
Further, the present disclosure provides a growth method of an organic single crystal thin film including supplying an unsaturated organic solution obtained by dissolving an organic compound in a solvent to a growth control region and at least one nucleation control region of a base body having, on one principal plane, the growth control region and the nucleation control region which is provided on one side of the growth control region to be coupled with the growth control region, and closing the nucleation control region with only one crystal obtained by growth of a crystal nucleus formed due to nucleation from the organic solution in the nucleation control region by evaporating the solvent of the organic solution to allow the crystal to grow on the growth control region, and thereby, allowing an organic single crystal thin film composed of the organic compound to grow.
Further, the present disclosure provides an organic single crystal thin film group including a plurality of organic single crystal thin films which are allowed to grow on one principal plane of a base body and composed of an organic compound. Organic single crystal thin films not less than 17% and not more than 47% in terms of number among the organic single crystal thin film group have pentagonal shapes each having a first vertex with a vertical angle of 82° and a second vertex with a vertical angle of 98°. Organic single crystal thin films not less than 16% and not more than 41% in terms of number among the organic single crystal thin film group have tetragonal shapes each having the first vertex with the vertical angle of 82° and the second vertex with the vertical angle of 98°.
In the above-mentioned organic single crystal thin film, growth method of an organic single crystal thin film, and organic single crystal thin film group, examples of the organic single crystal thin film include not only the organic semiconductor single crystal thin film but also various kinds of organic single crystal thin films other than the organic semiconductor single crystal thin film, for example, an organic insulator single crystal thin film and the like. The organic compound forming the organic single crystal thin film is properly selected according to the kind of the organic single crystal thin film.
The above-mentioned organic single crystal thin film or organic semiconductor single crystal thin film can be used for various kinds of electronic elements. The electronic elements may employ anything basically as long as they use the organic single crystal thin film or the organic semiconductor single crystal thin film. The organic semiconductor element is one kind of those. The electronic element may include one or two or more other thin films such, for example, as an insulation film as well as one or two or more organic semiconductor single crystal thin films. The thin films may be either organic thin films or inorganic thin films. Moreover, a bioelectronic element can be attained by combining a biological material such as protein with the organic semiconductor single crystal thin film, for example.
In the above-mentioned organic single crystal thin film group, the organic single crystal thin film is typically allowed to grow by performing: the step of supplying the unsaturated organic solution obtained by dissolving the organic compound in the solvent onto the growth control region and the nucleation control region of the base body having the growth control region and at least one nucleation control region which is provided on the one side of the growth control region and is coupled with the growth control region on the one principal plane; and the step of allowing the organic single crystal thin film composed of the organic compound to grow by evaporating the solvent of the organic solution.
The description in relation to the above-mentioned manufacturing method of an organic semiconductor element and organic semiconductor element applies to the above-mentioned organic single crystal thin film, growth method of an organic single crystal thin film, and organic single crystal thin film group except the above as long as it is consistent with their nature.
According to the present disclosure, the position, dimensions, crystal orientation and the like of the organic semiconductor single crystal thin film or the organic single crystal thin film can be easily controlled. Using the organic semiconductor single crystal thin film or the organic single crystal thin film can attain a high-performance organic semiconductor element or electronic element. Using the organic semiconductor element or the electronic element can attain a high-performance electronic device.
Hereafter, modes for implementing the invention (hereinafter referred to as embodiments) will be described. Incidentally, the description is made in the following order.
One example of the growth method of an organic semiconductor single crystal thin film is described based on
Here, when a droplet of the organic solution is placed on the comb-shape pattern P, the droplet stays on the lyophilic surface S1 of the comb-shape pattern P but does not move onto the lyophobic surface S2 outside the comb-shape pattern P. State transition of the droplet of the organic solution to the supersaturated region can be realized by increasing the concentration of the organic solution, taking advantage of evaporation of the solvent. The broken line ABC in
Referring to
As to the rectangular region enclosed by broken lines illustrated in
The evaporation rate of the solvent is expressed by the following differential equation.
dw/dt=−C(Psat.−P)
where w, C, Psat., P and t denote a mass of the solvent molecules, a constant factor, the saturated vapor pressure of the solvent, a vapor pressure of the solvent and time, respectively.
The above-mentioned simulation results provide a support for the transition from the stable state A to the unstable state C in
As an organic compound for a raw material of the organic semiconductor single crystal thin film, the ones that have been already mentioned can be employed, and among those, specific examples of the perixanthenoxanthene(PXX)-based compound are the followings.
(where R is an alkyl group regardless of linear one or branched one)
(where R is an alkyl group regardless of linear one or branched one)
(where R is an alkyl group regardless of linear one or branched one)
(where R is an alkyl group and the number of Rs is 2 to 5)
(where R is an alkyl group and the number of Rs is 1 to 5)
(where R is an alkyl group and the number of Rs is 1 to 5)
(where A1 and A2 are indicated by equation (8))
(where R is an alkyl group or another substituent and the number of Rs is 1 to 5)
Investigation results of the growth mechanism as mentioned above by actually performing the growth of an organic semiconductor single crystal thin film are described.
A Si wafer with a size of 4 inch was used as a substrate on which an organic semiconductor single crystal thin film was allowed to grow, which wafer was doped with high concentration of impurity and on the surface of which wafer a SiO2 film was formed. After cleansing the surface of the Si wafer, a comb-shape pattern P was formed thereon as follows. Namely, an amorphous fluorocarbon resin film (Cytop; Asahi Glass Co., Ltd.) was formed on the part except a part in which the comb-shape pattern P was formed out of the surface of the Si wafer due to the lift-off method to form a lyophobic surface S2. The surface of the part inside the lyophobic surface S2 was a lyophilic surface S1 and was configured to be the comb-shape pattern P. The dimensions of a back part P1 of the comb-shape pattern P were 200 μm×6.5 mm and 12 comb-shape patterns P were formed to separate from one another by 300 μm and to be parallel to one another. Comb tooth parts P2 of the comb-shape pattern P had a width of 5 μm or 10 μm and a length of 40 μm and spacings between the comb tooth parts P2 were 200 μm. The number of the comb tooth parts P2 per comb-shape pattern P was 32. Namely, the comb tooth parts P2 were formed into a 12×32 matrix array. As a raw material of the organic semiconductor single crystal thin film, C2Ph-PXX indicated by equation (9) was selected. This is because C2Ph-PXX is sufficiently dissolved in a solvent at room temperature and exhibits excellent stability in the air. The C2Ph-PXX powder was dissolved in tetralin at room temperature to prepare an organic solution of C2Ph-PXX with a concentration of 0.4 wt. %. After the organic solution was dropped on the above-mentioned Si wafer in the air, the Si wafer was placed on a holder provided inside a film forming apparatus mentioned later to allow C2Ph-PXX thin films to grow on the Si wafer. The temperature of the holder was held at 17° C. Namely, the growth temperature was 17° C. When the Si wafer was introduced inside the film forming apparatus, nitrogen (N2) gas was allowed to flow from a gas introduction tube which was held at approximately 60° C. at a flow rate of 0.3 L/min. After completion of the growth, the Si wafer was dried in a vacuum oven for 8 hours at 80° C. completely to remove the solvent remaining on the Si wafer surface.
In order to study the structure of the above-mentioned C2Ph-PXX thin film in detail, electron microscope observation was performed using a transmission electron microscope (TEM) (JEOL JEM-4000FXS) at an acceleration voltage of 400 kV and under low dose conditions.
In order to study the crystal orientation of the C2Ph-PXX thin film in detail, the rotational angles of all the C2Ph-PXX thin films illustrated in
According to the above, the following important results have been obtained. First, a C2Ph-PXX thin film with a single domain, that is, in single crystal can be allowed to grow. Second, the crystal orientation of the C2Ph-PXX thin film depends on the width of the comb tooth part P2. These results are considered closely to relate to the phenomena in the region of the comb tooth part P2.
Since the facet of the crystal is a stable surface, the crystal nucleus N contacts with the interface between the droplet L and the lyophobic surface S2 to form the {110} plane. When the crystal nucleus N does not touch the interface between the droplet L and the lyophobic surface S2 to move to the uppermost part of the droplet L, the crystal nucleus N is arranged such that the surface tension becomes largest. The smaller the width of the comb tooth part P2 becomes, the smaller the curvature radius of the droplet L becomes. Accordingly, the smaller the width of the comb tooth part P2 becomes, the much more favorable the thinner crystal nucleus N in shape becomes. There are two cases of a case where the crystal nucleus N does not undergo the touch immediately and a case where it does not undergo the touch to be slow. In the case of no immediate touch, as illustrated in portion (1) of
[Film Forming Apparatus]
One example of a film forming apparatus used for growth of the above-mentioned organic semiconductor single crystal thin film is described.
In the solvent tank 23, a co-solvent 26 of the same kind as the solvent in the organic solution used for growth of organic semiconductor single crystal thin films is retained. The temperature of the co-solvent 26 can be adjusted by heating means such as an oil bath omitted in the figure. Gas can be introduced into the co-solvent 26 through a gas introduction tube 27 settled in the inside of the solvent tank 23 from the outside thereof. The solvent tank 23 can supply vapor containing the vapor of the co-solvent 26 to the chamber 21 through the coupling tube 22. Thereby, the peripheral environment of the organic solution, that is, a pressure (vapor pressure) P of the vapor inside the chamber 21 according to the temperature of the co-solvent 26 is controlled. In addition, the vapor supplied to the chamber 21 can be vented to the outside through the exhaust tube 24 as needed.
The growth of organic semiconductor single crystal thin films using the film forming apparatus includes introducing a substrate 11 in the chamber 21 of the film forming apparatus to place it on the holder 25 as illustrated in
Meanwhile, an organic solution 30 obtained by dissolving an organic compound used for the growth of organic semiconductor single crystal thin films in a solvent is prepared. Conventionally known ones can be used as the solvent which is selected as needed and specifically employs at least one, for example, of xylene, p-xylene, mesitylene, toluene, tetralin, anisole, benzene, 1,2-dichlorobenzene, o-dichlorobenzene, cyclohexane and ethylcyclohexane.
Then, the organic solution 30 thus prepared is supplied onto the substrate 11, as illustrated in
Next, similarly to the above-mentioned growth method, the solvent in the organic solution 30 is evaporated holding the temperature of the organic solution 30 at Tg. Thereby, crystal nuclei are formed from the organic solution 30 retained on the comb tooth part P2, only one crystal C having grown from the crystal nuclei closes a coupling part of the comb tooth part P2 with the back part P1, the crystal C starts to grow in the organic solution 30 retained on the back part P1, and the organic semiconductor single crystal thin film is allowed to grow on the back part P1.
As mentioned above, according to the first embodiment, the crystal orientation, position and dimensions of an organic semiconductor single crystal thin film can be controlled. Hence, for example, in an organic transistor, the crystal orientation of the organic semiconductor single crystal thin film can be configured such that the direction of electrons traveling coincides with the direction high in mobility of carriers in the organic semiconductor single crystal thin film, this attaining a high-performance organic transistor high in mobility. Moreover, in an organic photoelectric transducer, the crystal orientation of the organic semiconductor single crystal thin film can be configured to be in the direction of the polarizing axis, this attaining a polarization organic photoelectric transducer high in sensitivity to polarized light.
As illustrated in
The growth control region 32 has a rectangular shape in this example. The area of the growth control region 32 is defined by a width W1 and a length L1. The width W1 and the length L1 are properly selected according to the shape and dimensions of the organic semiconductor single crystal thin film, and preferably, the width W1 and the length L1 are selected sufficiently large in order to secure the amount of the organic solution. For example, such selection is made as the width W1=1000 to 10000 μm and the length L1=100 to 800 μm.
The nucleation control region 33 is constituted of a first part 33a perpendicular to a one side 32a which is a long side of the growth control region 32 and a second part 33b which is coupled with the first part 33a and inclines by an angle θ1 of 0° or more and smaller than 90°, for example, 25° or more and 65° or less relative to the above-mentioned one side 32a of the growth control region 32. A width W2 of the first part 33a and the second part 33b is smaller than the width W1 of the growth control region 32 and a coupling position 34 of the growth control region 32 with the nucleation control region 33 is provided with corner parts 35 which are convex toward the inside. Preferably, the width W2 is selected sufficiently small and, for example, such selection is made as the width W2=0.1 to 30 μm. The length L2 of the first part 33a is selected, for example, as L2=5 to 50 μm and the length L3 of the second part 33b is selected, for example, as L3=10 to 150 μm, whereas these are not limited to the above.
The tip shape of the corner parts 35 is not particularly limited but is a pointing shape preferably. Moreover, the angle θ2 of the corner parts 35 is not particularly limited but is substantially 90°.
As illustrated in
Finally, the organic solution 36 is removed from the one principal plane of the substrate 31 as needed, and thereby, the organic semiconductor single crystal thin film 39 is obtained as illustrated in
As illustrated in
After the growth of the organic semiconductor single crystal thin film 39, the organic semiconductor single crystal thin film 39 may undergo patterning using the etching method or the like as needed to be a desired planer shape.
A Si wafer similar to that in Example 1 was used as the substrate 31.
Lyophobic processing was performed on a predetermined part of its surface to arrange basic patterns with a size of 7 mm×7 mm constituted of the growth control regions 32 and the nucleation control regions 33 having the lyophilic surfaces into 10 rows by 9 columns. Note that the first to fourth rows and the eighth to tenth rows had columns less than 9 since the Si wafer is circular. The basic patterns employed ones in cases where an angle θ3 (=90°−θ1) between the first part 33a and the second part 33b of the nucleation control region 33 were 45°, 60° and 30°. The dimensions of the growth control region 32 was 200 μm×6.5 mm and 10 growth control regions 32 were formed to separate from one another by 300 μm and to be parallel to one another. Spacings between the nucleation control regions 33 in the direction of the one long side of the growth control region 32 were 200 μm. The nucleation control region 33 had the width W2 of 5 μm or 10 μm, the first part 33a had the length L2 of 40 μm and the second part 33b had a length L3 of 100 μm. As illustrated in
As the raw material of the organic semiconductor single crystal thin films 39, C2Ph-PXX indicated by equation (9) was used.
As illustrated in
According to
Based on the above results, a growth model of the organic semiconductor single crystal thin film 39 is considered. As described for the first embodiment, in the initial stage of growth, crystal nuclei are formed in the first part 33a or the second part 33b of the nucleation control region 33.
Comparing the shapes of the organic semiconductor single crystal thin films 39 on the growth control regions 32 illustrated in
According to the second embodiment, the similar merit to that in the first embodiment can be attained.
In a third embodiment, patterns for the growth control region 32 and the nucleation control region 33 provided on the one principal plane of the substrate 31 as illustrated in
As illustrated in
The width W2 of the fourth part 33d is smaller than the width W1 of the growth control region 32. In other words, the nucleation control region 33 in this case has a constant width W2 in the fourth part 33d and a gradually increasing width W2 in the third part 33c. Preferably, the width W2 is selected sufficiently small and, for example, such selection is made as width W2=0.1 to 30 μm. The length L3 of the second side 33e of the third part 33a is selected, for example, as L3=5 to 50 μm and the length L4 of the fourth part 33d is selected, for example, as L4=10 to 150 μm.
The shapes of the nucleation control regions 33 are selected as mentioned above, and thereby, in the initial stage of growth, crystal nuclei are formed on the fourth part 33d of the nucleation control region 33 and only one crystal grows to close the fourth part 33d. The crystal grows on the growth control region 32 through the third part 33a and the crystal growth proceeds such that the facet defined by the angle between the second side 33e and the third side 33f of the third part 33c arises during this. As a result, the organic semiconductor single crystal thin film 39 has grown in a tetragonal or pentagonal shape, for example, having the first vertex having a vertical angle of 82° and the second vertex having a vertical angle of 98°.
According to the third embodiment, the similar merit to that in the first embodiment can be attained.
In a fourth embodiment, patterns for the growth control region 32 and the nucleation control region 33 provided on the one principal plane of the substrate 31 as illustrated in
The fourth embodiment is similar to the first embodiment except the above.
According to the fourth embodiment, the following merit can be attained in addition to the similar merit to that in the first embodiment. Namely, The nucleation control regions 33 are provided on each of the sides of two neighboring growth control regions 32 which sides oppose each other not to overlap with one another. The nucleation control regions 33 for one growth control region 32 are provided close to the nucleation control regions 33 for the other growth control region 32. Due to this, while evaporation of the solvent of the organic solution 36 supplied to the growth control regions 32 is suppressed, evaporation of the solvent of the organic solution 36 supplied to the nucleation control regions 33 can be promoted, this improving the growth rate of the organic semiconductor single crystal thin films 39.
In a fifth embodiment, an organic transistor and a manufacturing method of the same using the organic semiconductor single crystal thin film is described.
Preferably, a channel length direction (direction from the source electrode 55 to the drain electrode 56) is configured to be a direction high in carrier mobility of the organic semiconductor single crystal thin film 54 in the organic transistor.
The organic semiconductor single crystal thin film 54 is composed of the already-mentioned organic compound. The gate insulation film 53 is composed, for example, of an inorganic insulator, organic insulator, organic insulative polymer, or the like. Examples of the inorganic insulator include, for example, silicon dioxide (SiO2), silicon nitride (Si3N4 or SiNx) and the like. Examples of the organic insulator and the organic insulative polymer includes, for example, poly(vinylphenol), poly(methyl methacrylate), polyimide, fluorine resin, PVP-RSiCl3, DAP, isoDAP, poly(α-methylstyrene), cycloolefin copolymer and the like. Thicknesses of the organic semiconductor single crystal thin film 54 and the gate insulation film 63 are properly selected according to characteristics and the like required for the organic transistor.
The material of the substrate 51 is selected from among conventionally known materials and may be a transparent material or an opaque material to visible light. Moreover, the substrate 51 may be conductive or non-conductive. Moreover, the substrate 51 may be flexible (resilient) or inflexible. Specifically, examples of the material of the substrate 51 include various kinds of plastics (organic polymers) such as poly(methyl methacrylate) (polymethyl methacrylate, PMMA), poly(vinylalcohol) (PVA), poly(vinylphenol) (PVP), polyethersulfone (PES), polyimide, polycarbonate, poly(ethylene telephthalate) (PET) and poly(ethylene naphthalate) (PEN), mica, various kinds of glass substrates, quartz substrates and silicon substrates, various kinds of alloy such as stainless steel, various kinds of metals, and the like. Using plastics as the material of the substrate 51 allows the substrate 51 to be flexible, eventually attaining a flexible organic transistor. The plastic substrate is composed, for example, of polyimide, polycarbonate, poly(ethylene telephthalate), poly(ethylene naphthalate), polyethersulfon, and the like.
Example of the materials composing the gate electrode 52, source electrode 55 and drain electrode 56 include, for example, metals such as platinum (Pt), gold (Au), palladium (Pd), chromium (Cr), molybdenum (Mo), nickel (Ni), aluminum (Al), silver (Ag), tantalum (Ta), tungsten (W), copper (Cu), titanium (Ti), indium (In) and tin (Sn), alloy containing these metal elements, conductive particles composed of these metals, conductive particles of alloy containing these metals, various kinds of conductive substances such as polysilicon containing impurity. The examples of the materials composing the gate electrode 52, source electrode 55 and drain electrode 56 also include organic conductive materials (conductive polymers) such as poly(3,4-ethylenedioxythiophene)/polystyrenesulfonic acid [PEDOT/PSS] and tetrathiafulvalene-7,7,8,8-tetracyanoquinodimethane (TTF-TCNQ). Each of the gate electrode 52, source electrode 55 and drain electrode 56 may have a layered structure constituted of two or more layers composed of these substances. The width of the gate electrode 52 in the channel length direction (gate length) and the distance between the source electrode 55 and drain electrode 56 (channel length) are selected according to characteristics and the like required for the organic transistor.
Manufacturing Method of Organic Transistor
As illustrated in
Meanwhile, similarly to the first embodiment, the organic solution obtained by dissolving the organic compound in the solvent is prepared. Then, the organic semiconductor single crystal thin film 39 is allowed to grow on the gate insulation film 53 using the organic solution, for example, by any of the methods in the first to fourth embodiments.
Next, the organic semiconductor single crystal thin film 39 thus formed undergoes patterning into a predetermined shape using etching or the like, and after that, the source electrode 55 and drain electrode 56 are formed on the organic semiconductor single crystal thin film 39 by the conventionally known method.
As above, the desired top contact and bottom gate-type organic transistor is manufactured.
According to the fifth embodiment, since the crystal orientation of the organic semiconductor single crystal thin film 39 can be controlled, the direction high in carrier mobility of the organic semiconductor single crystal thin film 39 can be configured to the channel length direction, this attaining a high-performance organic transistor high in mobility.
In a sixth embodiment, various kinds of layered structure bodies including the organic semiconductor single crystal thin film are described. These layered structure bodies are used for various kinds of electronic elements.
In a layered structure body according to a first example illustrated in
In a layered structure body according to a second example illustrated in
In a layered structure body according to a third example illustrated in
In a layered structure body according to a fourth example illustrated in
In a layered structure body according to a fifth example illustrated in
In a layered structure body according to a sixth example illustrated in
In a layered structure body according to a seventh example illustrated in
In a layered structure body according to an eighth example illustrated in
In a layered structure body according to a ninth example illustrated in
According to the sixth embodiment, a layered structure body which is a base of various kinds of electronic elements such as an organic transistor, a light-emitting diode (LED) and a semiconductor laser can be obtained.
In a seventh embodiment, a growth method of a large-area organic semiconductor single crystal thin film is described.
As described in reference to
Therefore, in the seventh embodiment, first, the comb-shape pattern P in which the width of the comb tooth parts P2 is small (for example, a width of 5 μm) and the spacing between the comb tooth parts P2 is small as illustrated in
Next, similarly to the first embodiment, crystals are allowed to grow at the bases of the comb tooth parts P2 as illustrated in
The growth proceeding, due to the small spacing between the comb tooth parts P2, the organic semiconductor single crystal thin films F having grown from the bases of the comb tooth parts P2 are combined with one another in the parallel direction to the side of the comb-shape pattern P which side is in its longitudinal direction, and additionally, the orientations of the organic semiconductor single crystal thin films F coincide with one another due to the small width of the comb tooth parts P2, this affording a single organic semiconductor single crystal thin film F in a long and thin shape. Conversely, the spacing between the comb tooth parts P2 is selected such that the organic semiconductor single crystal thin films F having grown from the bases of the comb tooth parts P2 are combined with one another in a short time after the growth. The growth further proceeding, a large-area rectangular organic semiconductor single crystal thin film F which has the same width as the width of the back part P1 in its longitudinal direction on the back part P1 of the comb-shape pattern P as illustrated in
As mentioned above, according to the seventh embodiment, a merit that a large-area organic semiconductor single crystal thin film F is allowed to grow can be attained as well as the similar merit to that in the first embodiment.
In an eighth embodiment, a growth method of a large-area organic semiconductor single crystal thin film is described similarly to the seventh embodiment.
In the eighth embodiment, first, the comb-shape pattern P in which the width of the comb tooth part P2 is small (for example, a width of 5 μm) as illustrated in
Next, as illustrated in
The growth further proceeding, as illustrated in
According to the eighth embodiment, the similar merit to the seventh embodiment can be attained.
It is imaged that the crystal C (initial crystal) grows at the base of the comb tooth part P2 of the comb-shape pattern P and the organic semiconductor single crystal thin film F has grown from the crystal C in the first embodiment, and herein, the results are described. The organic semiconductor single crystal thin film F employs a C2Ph-PXX thin film.
Next, the process of the growth of the organic semiconductor single crystal thin film (grown crystal) from the initial crystal having grown at the base of the comb tooth part of the comb-shape pattern was studied in detail and the results are described. The organic semiconductor single crystal thin film employed a C2Ph-PXX thin film.
An electron microscope observation sample was prepared similarly to the above except the growth temperature forcibly lowered in the middle of the growth from the organic solution and the cross-sectional transmission electron microscope observation was performed, and the results are described.
Next, the planar shape of the coupling part of the transition region and the grown crystal while the grown crystal is growing from the initial crystal via the transition region is described.
Next, based on the results of the above-mentioned electron microscope observation, a growth model of the grown crystal growing from the initial crystal via the transition region is considered and the result is described.
The organic solution is supplied onto the lyophilic surface S1 of the comb-shape pattern P in
In the above process, the organic solution L remaining below the organic semiconductor single crystal thin film F may be forcibly removed, for example, since the further growth is not needed when the organic semiconductor single crystal thin film F with a desired thickness has grown on the surface of the organic solution L on the back part P1. For this purpose, for example, providing grooves for draining below the back part P1 on the substrate 11 is sufficient. All of the bottom surfaces and both of the lateral faces of the grooves are configured to be lyophilic surfaces. The cross-sectional shape of the grooves is not limited particularly and selected as needed, and is rectangular, semicircular, U-shaped, V-shaped or the like, for example. The planar shape of the grooves is not limited particularly and selected as needed, and is slit-shaped, grid-shaped or the like, for example. Typically, at least one end of the groove is configured to be exposed on the edge face of the substrate 11. By doing so, the organic solution L can be drained from the one exposed end of the groove to the outside of the substrate 11.
Next, a method for forming a layered structure composed of two organic semiconductor single crystal thin films whose crystal orientations are different each other using the organic solution obtained by dissolving the organic compound which is the raw material of the organic semiconductor single crystal thin films in the organic solvent is described.
For this purpose, the organic semiconductor single crystal thin film for the first layer is allowed to grow by the similar method to the above. Next, after the substrate 11 is allowed to incline such that the organic solution flow down again into the comb tooth part P2 (nucleation control region), the organic semiconductor single crystal thin film for the second layer is allowed to grow by the similar method to the above again, holding the substrate 11 horizontally. Preferably, in order that the organic solution remains on the comb-shape pattern P, the widths of the back part P1 and the comb tooth part P2 are configured to be sufficiently large.
Next, methods for forming a hetero-structure composed of two or more layers of organic semiconductor single crystal thin films composed of semiconductors different from one another are described.
A first method includes formation of the hetero-structure as follows. First, two or more kinds of organic compounds which are raw materials of the organic semiconductor single crystal thin films and have different solubilities from one another are dissolved in the organic solvent. Next, the organic solution is supplied onto the comb-shape pattern P to evaporate the organic solvent of the organic solution, holding the growth temperature constant. This allows a crystal of the organic compound lowest in solubility to grow, succeedingly, a crystal of the organic compound second lowest in solubility to grow, and so on. The crystals are allowed to grow from the organic compound lower in solubility to the organic compound higher in solubility. The substrate 11 is allowed to incline such that the organic solution flows down again into the comb tooth part P2 (nucleation control region) as needed as already mentioned. Thus, the hetero-structure in which the different organic semiconductor single crystal thin films from one another are allowed to make junction between them is formed.
A second method includes formation of the hetero-structure as follows. First, the organic semiconductor single crystal thin film for the first layer is allowed to grow by the above-mentioned method using a first organic solution obtained by dissolving a first organic compound which is the raw material of the organic semiconductor single crystal thin film in a first organic solvent. Next, the organic semiconductor single crystal thin film for the second layer is allowed to grow on the organic semiconductor single crystal thin film for the first layer by the above-mentioned method using a second organic solution obtained by dissolving a second organic compound different from the first organic compound in a second organic solvent. The second organic solvent employs an organic solvent in which the organic semiconductor single crystal thin film for the first layer is not dissolved or the solubility of the first organic compound is exceedingly low. The above processes are repeated required times. Thus, the hetero-structure in which the different organic semiconductor single crystal thin films from one another are allowed to make junction between them is formed.
As above, the embodiments and examples are specifically described, whereas the present disclosure is not limited to the above-mentioned embodiments and examples.
For example, the numerical values, structures, configurations, shapes, materials and the like presented in the above-mentioned embodiments and examples are simply exemplary and numerical values, structures, configurations, shapes, materials and the like different from these may be employed.
Additionally, the present technology may also be configured as below.
(1)
A manufacturing method of an organic semiconductor element, including: supplying an unsaturated organic solution obtained by dissolving an organic compound in a solvent to a growth control region and at least one nucleation control region of a base body having, on one principal plane, the growth control region and the nucleation control region which is provided on one side of the growth control region to be coupled with the growth control region; and allowing an organic semiconductor single crystal thin film composed of the organic compound to grow by evaporating the solvent of the organic solution.
(2)
The manufacturing method of an organic semiconductor element according to (1),
wherein a state of the organic solution is configured as a metastable region between a solubility curve and a supersolubility curve in a solubility-supersolubility diagram of the organic solution in the growth control region and the state of the organic solution is configured as an unstable region on a lower side of the supersolubility curve in the solubility-supersolubility diagram in the nucleation control region by evaporating the solvent of the organic solution.
(3)
The manufacturing method of an organic semiconductor element according to (1) or (2),
wherein only one crystal obtained by growth of a crystal nucleus formed due to nucleation from the organic solution in the nucleation control region closes the nucleation control region, and
wherein the crystal is allowed to grow on the growth control region.
(4)
The manufacturing method of an organic semiconductor element according to any one of (1) to (3),
wherein the organic solution is held at a constant temperature.
(5)
The manufacturing method of an organic semiconductor element according to any one of (1) to (4),
wherein the growth control region and the nucleation control region have lyophilic surfaces.
(6)
The manufacturing method of an organic semiconductor element according to any one of (1) to (5),
wherein the nucleation control region has a first part in a straight line shape which is coupled with the growth control region and inclines by 90°±10° relative to the one side of the growth control region.
(7)
The manufacturing method of an organic semiconductor element according to any one of (1) to (6),
wherein a width of the first part is not less than 0.1 μm and not more than 50 μm.
(8)
The manufacturing method of an organic semiconductor element according to any one of (1) to (7),
wherein the growth control region is a rectangle, and
wherein the first part of the nucleation control region is a rectangle which is provided on one long side of the growth control region to be perpendicular to the long side and is smaller than the growth control region.
(9)
The manufacturing method of an organic semiconductor element according to any one of (1) to (8),
wherein the nucleation control region has a second part in a straight line shape which is coupled with the first part and inclines relative to the one side.
(10)
The manufacturing method of an organic semiconductor element according to any one of (1) to (8),
wherein the nucleation control region has a third part in a triangular shape which is coupled with the growth control region and has a first side on the one side, and a fourth part in a straight line shape which is coupled with the third part and inclines relative to the one side.
(11)
The manufacturing method of an organic semiconductor element according to any one of (1) to (10),
wherein the organic semiconductor single crystal thin film has a π-electron stacking structure in a direction substantially parallel to the one principal plane of the base body.
(12)
The manufacturing method of an organic semiconductor element according to any one of (1) to (11),
wherein the organic semiconductor single crystal thin film has a triclinic, monoclinic, orthorhombic or tetragonal crystal structure and has the π-electron stacking structure in an a-axis direction or a b-axis direction.
(13)
The manufacturing method of an organic semiconductor element according to any one of (1) to (12),
wherein the organic semiconductor single crystal thin film on the growth control region has a tetragonal or pentagonal shape having a first vertex with a vertical angle of 82° and a second vertex with a vertical angle of 98°.
(14)
The manufacturing method of an organic semiconductor element according to any one of (1) to (13),
wherein a plurality of the growth control regions are provided on the one principal plane of the base body separately from one another, wherein at least two growth control regions of the growth control regions are provided to oppose each other, and
wherein a plurality of the nucleation control regions are provided on each of sides of the two growth control regions, the sides opposing each other, such that the nucleation control regions do not overlap with one another.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-242460 | Nov 2011 | JP | national |
| 2012-008666 | Jan 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/077633 | 10/25/2012 | WO | 00 | 4/24/2014 |
