JP2010073946A - Transistor element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-performance longitudinal thin-film transistor element that can control a charge implantation barrier of a base electrode and a collector semiconductor, and to provide a method of manufacturing the same. <P>SOLUTION: The transistor element having a first electrode 20, a collector semiconductor layer 30, the base electrode 40, an emitter semiconductor layer 31, and a second electrode 21 stacked in order on a substrate 10 is characterized in that the base electrode is present between the collector semiconductor layer and emitter semiconductor layer, and the collector semiconductor layer is made of metal oxide. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vertical thin film current injection type transistor element that allows a current to flow in a direction perpendicular to a thin film surface, and a method of manufacturing the same.

  In the present invention, a first electrode (collector electrode or emitter electrode), a collector semiconductor layer, a base electrode, an emitter semiconductor layer, and a second electrode (collector electrode or emitter electrode) are formed on a substrate, and the base is formed on the semiconductor layer. The present invention relates to a vertical thin film transistor that controls a current value between an emitter electrode and a collector electrode by a voltage applied through the electrode.

  Thin film field effect transistors using silicon materials are already well-known as industrial products. For example, as shown in FIG. 4, these are arranged laterally with respect to the substrate 71. The source electrode layer 75 and the drain electrode layer 76 are provided by being separated by a semiconductor layer (channel layer region) 74 that is electrically neutral. The gate electrode 72 is electrically separated from the semiconductor layer 74 by the gate insulating layer 73 and is disposed on the substrate 71. As a semiconductor material constituting the semiconductor layer 74, hydrogenated amorphous silicon, a polycrystalline silicon material, or the like is used.

  A thin film field effect transistor using an organic material for a semiconductor layer is also well known (Non-Patent Document 1). This conventional thin film field effect transistor using an organic material also has basically the same configuration as the thin film field effect transistor using a silicon material, and many of them are arranged laterally with respect to the substrate 71. It is being considered. As the organic semiconductor material constituting the semiconductor layer 74, organic materials such as p-electron conjugated polymer compounds and aromatic compounds have been used.

  In addition, in recent years, development of oxide semiconductors has been remarkable. For example, a thin film transistor having relatively high mobility using zinc oxide or indium / gallium / zinc composite oxide for a semiconductor layer has been reported (Non-Patent Document 2 and Non-Patent Document 3). In these thin film field effect transistors, the electric field applied from the gate electrode layer through the gate insulating layer acts on the semiconductor layer (channel portion) to control the current flowing between the source electrode layer and the drain electrode layer. Thus, transistor operation is realized. In particular, thin-film field-effect transistors using organic materials or oxide-based semiconductors in the semiconductor layer can produce a uniform device with a large area compared to transistors using crystalline silicon in the semiconductor layer, Can be produced, and therefore has an advantage that a plastic substrate can be used. In particular, when an organic material is used, there is an advantage that an element can be manufactured at a low cost by making them into a solution and performing a liquid process such as coating or printing. However, thin-film field-effect transistors have (a) low carrier mobility (showing transistor performance), (b) inability to carry large currents, and (c) inability to operate at high speed compared to crystalline silicon transistors. There was a problem.

  As means for solving these problems, a vertical element structure in which the current direction is perpendicular to the thin film semiconductor layer has been proposed. For example, Yang et al. Proposed a device using mesh-like polyaniline as a gate electrode (Non-patent Document 4). Muraishi et al. Have formed electrodes with nanoscale voids using LATEX spheres as vapor deposition masks when depositing gate electrodes (Non-patent Document 5). In addition, Patent Document 1 discloses a method of arranging a gate electrode on the side wall of an organic film. In general, the thickness of the organic semiconductor layer can be reduced to about 100 nm, but the patterning accuracy in the direction parallel to the substrate is on the order of 10 μm. Therefore, if the current direction is perpendicular to the organic semiconductor layer, the current direction Compared with the case where is horizontal to the organic semiconductor layer, the cross-sectional area of the current path is large (approximately 100 nm × 10 μm → 10 μm × 10 μm) and the length of the current path is short (approximately 10 μm → 100 nm). Can be several orders of magnitude larger. The basic parts of these element structures are known as static induction transistors.

  However, the electrostatic induction transistor has the following problems. That is, in a general field-effect transistor, the dependency of the drain current on the drain voltage exhibits saturation characteristics above a certain threshold value under an operation condition where the gate voltage is constant. However, such a characteristic is generally not recognized in the static induction transistor, and the drain current increases monotonously with respect to the drain voltage. This is due to the fact that the channel length is short in the static induction transistor and the so-called pinch-off effect is difficult to appear.

  As a means for solving this problem, a metal base transistor has been proposed in which a thin film of a conductive material such as a metal thin film is used as a control electrode and current is controlled by an electric field applied thereto (Non-patent Document 6). In the metal base transistor, the current from the emitter electrode to the collector electrode flows through the base electrode, and the current value is controlled by the voltage applied to the base electrode. Therefore, the base electrode divides the collector semiconductor layer and the emitter semiconductor layer. In the formation process of the metal base transistor element, only a semiconductor / metal / semiconductor laminated structure is produced. As a similar structure, there is a bipolar transistor widely known as a silicon semiconductor. However, many organic semiconductors and oxide semiconductors have not yet realized a PN junction, and a bipolar transistor cannot be formed. According to the structure of the metal base transistor, it is possible to construct a transistor even for a semiconductor material for which a PN bipolar material has not yet been developed, and there is no problem in saturation characteristics even if the base electrode as a control electrode is thin. It is suitable for a vertical thin film transistor. In addition, since there is no diffusion capacitance due to the PN junction, an advantage of improving the high-frequency characteristics of the transistor is also expected.

In this metal base transistor, it is necessary that most of the charges injected from the emitter electrode to the base electrode flow into the collector electrode without being recombined with the base electrode. If the base electrode transmittance of the charge is α under the base ground condition, the current multiplication factor h _FE is
h _FE = a / (1-a)
It is represented by For example, when the a = of _0.99, about 100 is obtained as _{h FE.} As conditions for realizing this, the charge injected from the semiconductor on the emitter electrode side to the base electrode must have sufficient kinetic energy (hot electrons), and the charge injection from the base electrode to the semiconductor on the collector side The barrier is small enough.

In general, the electron transmission distance in a thin film (distance that attenuates to 1 / e) is said to be about 1 cm in silicon. For example, most of the electrons are transmitted even if the thickness of the base electrode of silicon is 1 μm. A high current multiplication factor can be obtained. However, the electron transmission distance in the metal material is said to be approximately 10 nm, and it has been thought that only a low value can be obtained for the current multiplication factor when the metal material is used for the base electrode. On the other hand, MS Meruvia et al. Recently obtained a- = 0.99 and h _FE = 100 in the structure of C60 / Au (film thickness 6 nm) / silicon (Non-Patent Document 7), and S. Fujimoto et al. Obtained CFE / Al (film thickness 20 nm) / perylene compound, and obtained h _FE = 180 to 1000 (Non-patent Document 8). However, considering these electron transmission distances, these results have not yet been able to explain the operation mechanism, and further elucidation is necessary. As described above, although the mechanism of the metal base transistor has not been sufficiently elucidated, it has been confirmed that it exhibits excellent characteristics as a vertical thin film transistor.

  Conventional semiconductors of metal base transistors mainly use organic materials. It is necessary to select the energy level of the base electrode of the metal base transistor and the semiconductor on the collector side so that the charge injection barrier is sufficiently low. The charge injection barrier is the work function of the base electrode and the electron affinity (in the case of n-type) of the semiconductor on the collector side when the work function of the base electrode and the Fermi level of the semiconductor on the collector side match. Since impurity doping technology has not yet been established for materials, fine control of Fermi energy levels is generally difficult, and improvements have been desired.

  In addition, the conventional metal base transistor is manufactured by forming an organic material by a vapor deposition process. The reason why the low-cost process (wet process such as coating or liquid process), which is a feature of organic materials, is not applied, is that the upper layer process damages the lower layer when forming a metal base transistor stack structure using the liquid process. Because there is a risk of doing. In particular, when the semiconductor layer is formed by an application process using an organic material, there is a possibility that the collector semiconductor layer (first semiconductor layer) may be damaged when the emitter semiconductor layer is formed. As a means for avoiding this, there are examples in which measures such as providing an extremely thin protective layer are taken (Non-Patent Document 9). However, this method increases the electrical resistance and increases the process, resulting in an increase in cost. The problem of becoming. Further, for example, in Non-Patent Document 7, there is an example in which it is formed on a silicon substrate. In this case, since the element area is limited by the size of the silicon wafer, a thin film transistor that forms a large element area or a plastic substrate is formed. It is not possible to make use of the features of.

JP 2003-110110 A C. D. Dimitrakopoulos et al., Advanced Materials, Vol. 14, pp. 99-117 P. F. Carcia et al., Journal of the SID, Vol. 13/7, pp. 547-554 K. Nomura et al., Nature, Vol. 432, pp. 488-492 Y. Yang et al, Nature, Vol. 372, pp344 (1994) Muraishi et al., IEICE Technical Report of IEICE, OME2002-15 (2002-05) 13 S. M. Sze et al, Solid State Electron, 9 (1966) 751 M. S. Meruvia et al, Appl. Phys. Lett. 84 (2004) 3978 S. Fujimoto et al, Appl. Phys. Lett. 87 (2005) 133503 Yu-Chiang et al, Appl. Phys. Lett. 87 (2005) 253508

The present invention has been made in view of the above problems of the prior art, and provides a high-performance vertical thin film transistor element capable of controlling a charge injection barrier between a base electrode and a collector semiconductor, and a method for manufacturing the same. With the goal.
Another object of the present invention is to provide a high-performance vertical thin film transistor element that can be manufactured by a low-cost process and a method for manufacturing the transistor element.

  That is, the present invention is a transistor element in which a first electrode, a collector semiconductor layer, a base electrode, an emitter semiconductor layer, and a second electrode are sequentially stacked on a substrate, the collector semiconductor layer and the emitter Provided is a transistor element in which the base electrode is present between semiconductor layers, and the collector semiconductor layer is made of a metal oxide. The transistor element of the present invention is characterized in that a current flowing between the second electrode and the first electrode is transmitted through the base electrode and controlled by the voltage of the base electrode.

  Furthermore, the transistor element provided in the present invention is characterized in that at least one of the base electrode, the emitter semiconductor layer, and the second electrode is formed by a liquid process. In the transistor element provided in the present invention, the collector semiconductor layer is mainly composed of at least one of zinc oxide and indium oxide, and the current flowing between the second electrode and the first electrode is mainly due to electrons. It is characterized by being. The transistor element provided in the present invention is characterized in that the collector semiconductor layer is formed by a liquid process. A transistor element provided by another embodiment of the present invention is a metal base transistor element in which a base electrode is made of a metal material.

  As another aspect of the present invention, a step of forming a first electrode on a substrate, a step of forming a collector semiconductor layer on the first electrode, and a step of forming a base electrode on the collector semiconductor layer, A method of manufacturing a transistor element, comprising: forming an emitter semiconductor layer on the base electrode; and forming a second electrode on the emitter semiconductor layer, wherein the collector semiconductor layer and the emitter semiconductor layer There is provided a method of manufacturing a transistor element in which a base electrode exists between the collector semiconductor layer and a metal oxide. The method for manufacturing a transistor element provided by the present invention is characterized in that at least one of the base electrode, the emitter semiconductor layer, and the second electrode is formed by a liquid process.

The collector semiconductor layer in the present invention is made of a metal oxide, and in this oxide semiconductor, the Fermi level can be controlled by selecting the amount of metal element or doping impurities. In general, at the interface between a metal and a semiconductor, the work function of the metal matches the Fermi level of the semiconductor, and the difference between the work function of the metal and the electron affinity of the semiconductor becomes an electron injection barrier. As described above, if the Fermi level of the semiconductor can be controlled, the charge injection barrier of the semiconductor on the base electrode and collector side can be precisely controlled. In addition, since the metal oxide constituting the collector semiconductor layer in the present invention generally has high resistance to the liquid process, even if the base electrode, the emitter semiconductor layer, and the second electrode are formed thereon by the liquid process, the collector The semiconductor layer is not damaged. In addition, since the metal oxide can form a thin film element by sputtering, vacuum deposition, coating, or the like, the element area is not limited by the wafer area such as silicon. Therefore, it becomes possible to manufacture a laminated element at low cost. In addition, the charge mobility of the organic semiconductor material is 10 cm ² / Vs or less, whereas the oxide semiconductor has a high value of 10 to 50 cm ² / Vs, and thus the characteristics are remarkably improved.

As described above, since the collector semiconductor layer of the present invention is made of a metal oxide, the energy level (electron affinity) can be easily controlled, and the energy level matches the material characteristics of the base electrode and the emitter semiconductor layer. It is possible to control the charge injection barrier between the base electrode and the collector semiconductor layer.
Further, according to the present invention, since the collector semiconductor layer is made of a metal oxide, a liquid process is used in the formation process of the base electrode, the emitter semiconductor layer, and the second electrode formed on the collector semiconductor layer. However, the collector semiconductor layer is not damaged, and a transistor element can be provided at low cost.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing an example of an embodiment of a vertical transistor element according to the present invention.

As shown in FIG. 1, the transistor element includes a first electrode layer 20, a collector semiconductor layer (first semiconductor layer) 30, a base electrode layer 40, and an emitter semiconductor layer (second semiconductor layer) on a substrate 10. 31 and the second electrode layer 21 are sequentially laminated as a thin film.
In the following description, it is assumed that electrons flow from the second electrode 21 to the first electrode 20, and the discussion proceeds with the first electrode 20 as a collector electrode and the second electrode 21 as an emitter electrode. Of course, the same content can be discussed even if it is reversed.

  In the present invention, what is used as the substrate 10 is not particularly limited, but a conventionally known glass substrate or plastic substrate is preferably used.

  What is used as the material of the first electrode 20 of the present invention is a metal material such as aluminum, gold, silver, nickel and iron, an inorganic material such as ITO and carbon, a conjugated organic material, an organic material such as liquid crystal, silicon A semiconductor material such as can be selected as appropriate, and is not particularly limited.

    As a method for forming the first electrode layer 20, a conventionally known thin film forming method such as a vacuum deposition method or a coating method is preferably used, and it is not particularly limited, but for cost reduction, spin coating, ink jet, dip It is desirable to use a liquid process such as When forming a thin film by vacuum vapor deposition, the substrate temperature at the time of vapor deposition is appropriately selected depending on the electrode material used, but is preferably 0 to 150 ° C. The film thickness of the first electrode 20 is preferably 50 to 200 nm.

  When the electrode is formed by a liquid process for cost reduction, for example, a dispersion liquid in which metal fine particles such as gold, platinum, silver, and carbon are dispersed in an appropriate liquid is preferable. A polythiophene-based or polyaniline-based conductive polymer can also be used as an electrode.

Examples of the metal oxide semiconductor material used for the collector semiconductor layer (first semiconductor layer) 30 of the present invention include zinc oxide, indium oxide, tin oxide, cadmium oxide, and composite oxides of these oxides. In addition, materials in which conductivity is controlled by adding a doping material to these materials are also suitable. Most of these oxide semiconductors are n-type semiconductors, and the number of materials that become p-type semiconductors is still limited. These materials are preferably used because the energy level and conductivity can be controlled by alloying an appropriate doping material (for example, Mg, Al, Ga, etc.). For example, it is preferable to add the doping material in the range of 10 ¹⁵ to 10 ¹⁷ l / cm ³ . Specifically, when a metal oxide thin film is formed by a known method such as sputtering, the conductivity can be controlled by blending a dope material with the target material.

  As a method for forming the collector semiconductor layer 30, a conventionally known thin film forming method such as sputtering, vacuum deposition, or coating is preferably used, and is not particularly limited, but a liquid process such as spin coating, ink jet, or dip is used. It can also be formed. Although there is no restriction | limiting in particular in the film thickness of the collector semiconductor layer 30, 10-300 nm which is easy to obtain a flat continuous film practically and electrical resistance does not become excessive is suitable.

  As the material used for the base electrode 40 of the present invention, various metal materials can be used. For example, a metal material such as aluminum, chromium, titanium, gold, silver, copper, platinum, or rhodium can be used. It is also possible to use a polythiophene-based or polyaniline-based conductive polymer material.

  The formation method of the base electrode 40 is basically the same as that of the first electrode and the second electrode described above, but the film thickness needs to be extremely thin in order to ensure charge transmittance, and its controllability Is required. The film thickness of the base electrode 40 is basically desirably thin, but is practically preferably 5 to 50 nm so that a flat continuous film is easily obtained and the electric resistance is not excessive.

  In particular, when the electrode is formed using a dispersion liquid in which metal fine particles are dispersed in an appropriate liquid, the base electrode 40 is also formed on the collector semiconductor layer (first semiconductor layer) 30 by application such as spin coating. May be. In this case, particularly when a metal such as platinum or rhodium is used as the fine particles as the coating solvent, alcohol-based ethyl alcohol, methyl alcohol, propyl alcohol, glycol-based ethylene glycol, THF, ethylene, which facilitates dispersion of the material. Glycol dimethyl ether or pure water is preferred. In this case, the metal fine particles are dispersed in the liquid in a range of 0.001 to 30% by mass, for example. The spin coating conditions can be appropriately set according to the target film thickness, but the rotation speed is preferably in the range of 200 to 3600 rpm.

  Further, particularly in the case of platinum fine particles, as disclosed in, for example, JP-A-7-8807, etc., platinum ions are obtained by using a dinitrodiaminonitric acid solution as a platinum ion solution and ethanol as a reducing agent. It is also possible to reduce and deposit platinum fine particles on the substrate. Such nano-order level metal fine particles can also be obtained from Tanaka Kikinzoku Co., Ltd. or Vacuum Metallurgical Co., Ltd. as a general commercial product.

  As a semiconductor material used for the emitter semiconductor layer (second semiconductor layer) 31 of the present invention, various semiconductor materials such as an oxide semiconductor, an organic semiconductor, amorphous silicon hydride, a group IIIV semiconductor, and a group IIVI semiconductor can be used. It is. Among these, as an oxide semiconductor, the same material system (zinc oxide, indium oxide, tin oxide, cadmium oxide, and complex oxide of these oxides) as the above-mentioned 1st semiconductor material layer 30 can be used. The organic semiconductor is preferably a pigment selected from the group consisting of acene molecular materials selected from the group consisting of naphthalene, anthracene, tetracene, pentacene, hexacene and derivatives thereof, phthalocyanine compounds, azo compounds, and perylene compounds. And its derivatives, aminoimidazole compounds, carbazole compounds, styryl compounds, stilbene compounds, butadiene compounds, hydrazone compounds, triphenylmethane compounds, diphenylmethane compounds, arylvinyl compounds, pyrazoline compounds, triphenylamine compounds, phenylene derivatives And low molecular weight compounds selected from the group consisting of triarylamine compounds and derivatives thereof, or poly-N-vinylcarbazole, halogenated poly-N-vinylcarbazo , Polyvinylpyrene, polyvinylanthracene, polythiophene derivatives, thiophene oligomer derivatives, high molecular compounds selected from the group consisting of pyrene formaldehyde resins, polyacetylene derivatives, and ethylcarbazole formaldehyde resins, fluorenones, diphenoquinones, benzoquinones, anthraquinones Indenone-based compounds may be mentioned, but the invention is not limited thereto. In particular, as a p-type organic semiconductor, pentacene and thiophene polymers are known as materials having high mobility.

  As a method for forming the emitter semiconductor layer 31, a conventionally known thin film forming method such as a vacuum deposition method or a coating method is preferably used, and is not particularly limited, but for cost reduction, spin coating, ink jet, dip, etc. It is desirable to use the liquid process. Although there is no restriction | limiting in particular in the film thickness of the emitter semiconductor layer 31, 10-300 nm which is easy to obtain a flat continuous film practically and electrical resistance does not become excessive is suitable.

  What is used as the material of the second electrode 21 of the present invention is basically the same as that of the first electrode 20, and the formation method of the second electrode 21 is basically the same as that of the first electrode 20. The film thickness of the second electrode 21 is preferably 50 to 200 nm.

  The transistor element of the present invention thus obtained has the energy level shown in FIG. When a forward bias electric field is applied between the emitter semiconductor layer (second semiconductor layer) 31 and the base electrode 40, electrons flow into the base electrode. At this time, the electrons correspond to the energy difference between the emitter semiconductor layer 31 and the base electrode 40 and are electrons (hot electrons) having an energy higher than that of room temperature, and most of the electrons flowing into the base electrode 40 are the base electrode 40. And flows into the collector semiconductor layer (first semiconductor layer) 30. The electrons flowing into the collector semiconductor layer 30 reach the first electrode 20 by the electric field between the base electrode 40 and the first electrode 20.

  Further, the energy levels of the collector semiconductor layer 30, the base electrode 40, and the emitter semiconductor layer 31, for example, when the moving charge is an electron, as shown in FIG. 3, the electron affinity (the base electrode is a metal). In this case, the absolute value of the work function) needs to be collector semiconductor layer <emitter semiconductor layer <base electrode. Further, as described above, it is desirable that the electron affinity of the emitter semiconductor layer 31 and the work function of the base electrode 40 be an electron injection barrier, and therefore low.

Hereinafter, the transistor element of the present invention will be described in more detail using examples.
Example 1
A transistor element having a configuration as shown in FIG. 1 was prepared by the following procedure. That is, a glass substrate is used as the substrate 10, and the first electrode layer 20, the collector semiconductor layer (first semiconductor layer) 30, the base electrode layer 40, the emitter semiconductor layer (second semiconductor layer) 31, and the second electrode layer 21 are The transistor element of Example 1 was formed by sequentially forming thin films with thicknesses of 100 nm, 100 nm, 20 nm, 100 nm, and 100 nm, respectively, by sputtering or vacuum evaporation. The substrate temperature at the time of forming each layer was room temperature.

The material of each layer is copper and silver for the first electrode layer 20 and the second electrode layer 21 respectively, and a composite oxide film (InGaO ₃ (ZnO)) of indium, gallium, and zinc as the collector semiconductor layer (first semiconductor layer) 30. , In: Ga: Zn = 1: 1: 1), and zinc oxide (ZnO) was used as the emitter semiconductor layer (second semiconductor layer) 31 and formed by sputtering. The base electrode layer 40 was an aluminum vapor deposition film.

(Example 2)
A transistor element of Example 2 was obtained by depositing zinc oxide (ZnO) of the emitter semiconductor layer (second semiconductor layer) 31 under the same conditions as in Example 1 except that it was formed by the following method. That is, the collector semiconductor layer 30 and the aqueous solution of Zn (NO ₃ ) ₂ .6H ₂ O (concentration 0.1 mol / L) and LiOH / H ₂ O (concentration 0.15 mol / L) are mixed. The substrate 10 on which the base electrode 40 was formed was immersed and heated at 60 ° C. for 4 hours. As a result, a zinc oxide (ZnO) thin film could be formed on the base electrode 40.

(Example 3)
The second electrode layer 21 was formed as a thin film having a thickness of 200 nm by applying an Ag fine particle dispersion (Ag Nano Metal Ink, manufactured by Vacuum Metallurgical Co., Ltd.). Except for the second electrode layer, a film was formed under the same conditions as in Example 1 to obtain a transistor element of Example 3. Film formation using the Ag fine particle dispersion was applied at a predetermined position by an ink jet method and then dried at 240 ° C. for 30 minutes.

Example 4
The base electrode layer 40 was formed as a thin film having a thickness of 20 nm by applying a thiophene-based conductive polymer solution (Baytron PTP Al 4083 manufactured by Bayer) made of the following compounds. Except for the base electrode 40, a film was formed under the same conditions as in Example 1 to obtain a transistor element of Example 4. The film formation with the thiophene-based conductive polymer solution was performed by applying at 120 ° C. for 120 minutes after applying by spin coating (rotation speed: 3000 rpm).

（実施例５）
以下の手順で、図１に示すような構成のトランジスタ素子を作成した。すなわち、基板１０としてガラス基板を用い、第一電極層２０、コレクタ半導体層（第１半導体層）３０、ベース電極層４０、エミッタ半導体層（第２半導体層）３１、第二電極層２１を、塗布法、もしくは真空蒸着法により、それぞれ１００ｎｍ、１００ｎｍ、２０ｎｍ、１００ｎｍ、１００ｎｍの厚さで順次薄膜形成し、実施例５のスイッチング素子を形成した。各層成膜時の基板温度は室温とした。

(Example 5)
A transistor element having a configuration as shown in FIG. 1 was prepared by the following procedure. That is, a glass substrate is used as the substrate 10, and the first electrode layer 20, the collector semiconductor layer (first semiconductor layer) 30, the base electrode layer 40, the emitter semiconductor layer (second semiconductor layer) 31, and the second electrode layer 21 are A switching element of Example 5 was formed by sequentially forming thin films with thicknesses of 100 nm, 100 nm, 20 nm, 100 nm, and 100 nm, respectively, by a coating method or a vacuum evaporation method. The substrate temperature at the time of forming each layer was room temperature.

  The material of each layer is silver and gold for the first electrode layer 20 and the second electrode layer 21, respectively, zinc oxide (ZnO) as the collector semiconductor layer (first semiconductor layer) 30, and the emitter semiconductor layer (second semiconductor layer). C60 (manufactured by Aldrich) was used as 31 and formed by a coating method and a vacuum deposition method, respectively. The base electrode layer 40 was an aluminum vapor deposition film. Zinc oxide (ZnO) was formed by the same method as the emitter semiconductor layer of Example 2.

(Comparative Example 1)
A glass substrate is used as the substrate 10, and the first electrode layer 20, the collector semiconductor layer (first semiconductor layer) 30, the base electrode layer 40, the emitter semiconductor layer (second semiconductor layer) 31, and the second electrode layer 21 are vacuum-deposited. By the method, thin films were sequentially formed in thicknesses of 100 nm, 100 nm, 20 nm, 100 nm, and 100 nm, respectively, and the transistor element of Comparative Example 1 was formed. The substrate temperature at the time of forming each layer was room temperature.

  The material of each layer uses copper and silver as the first electrode layer 20 and the second electrode layer 21, respectively, and the perylene-based material (made by Aldrich) shown in the chemical formula (II) as the collector semiconductor layer (first semiconductor layer) 30, As the emitter semiconductor layer (second semiconductor layer) 31, fullerene (manufactured by Tokyo Chemical Industry) represented by the chemical formula (III) was used. The base electrode layer 40 was an aluminum vapor deposition film.

  In Examples 1 to 5 and Comparative Example 1, the semiconductor is n-type. In Examples 1 to 4 and Comparative Example 1, electrons are flown from the second electrode (emitter electrode) 21 to the first electrode (collector electrode) 20. In Example 5, the first electrode (collector electrode) is used. ) The electron is designed to flow from 20 to the second electrode (emitter electrode) 21. For the transistor elements of Examples 1 to 5 and Comparative Example 1 described above, when the collector electrode voltage (collector voltage) with respect to the base electrode is 5 V and the emitter electrode (emitter voltage) with respect to the base electrode is changed from 0 V to −3 V The change in collector current was measured. The measurement was performed at room temperature in a vacuum. The results are shown in Table 1.

In Examples 1 to 5, good transistor characteristics were obtained, and the collector current was controlled by the emitter voltage. In particular, in Example 1, a collector current of 500 mA / cm ² or more was obtained, and a large current density was obtained in the same configuration as in Comparative Example 1 using only an organic material. In Examples 2 to 5, at least one of the base electrode, the emitter semiconductor layer, and the second electrode was formed by a liquid process, but good element characteristics were obtained. The cost ratio of the liquid process to the vacuum process is considered to be approximately 30 to 60% although it depends on the manufacturing scale. In the five-layer structure shown in Examples 1 to 5 and Comparative Example 1, the cost can be considerably reduced per layer of the coating process.
Based on these results, by using a metal oxide for the collector semiconductor layer, device characteristics such as current density are improved, and a liquid process can be applied, thereby reducing costs.

It is a schematic sectional drawing which shows one Embodiment of the transistor element of this invention. The explanatory view showing the principle of operation at the time of using the n type semiconductor in the transistor element of the present invention. Explanatory drawing which showed the energy level at the time of using an n-type semiconductor in the transistor element of this invention. It is a schematic sectional drawing which shows one Embodiment of the conventional horizontal transistor element.

Explanation of symbols

10: Substrate 20: First electrode layer 30: Collector semiconductor layer (first semiconductor layer)
40: Base electrode 31: Emitter semiconductor layer (second semiconductor layer)
21: Second electrode layer 71: Substrate 72: Gate electrode 73: Gate electrical insulating layer 74: Semiconductor layer 75: Source electrode layer 76: Drain electrode layer

Claims (6)

  A transistor element in which a first electrode, a collector semiconductor layer, a base electrode, an emitter semiconductor layer, and a second electrode are sequentially stacked on a substrate, wherein the transistor element is disposed between the collector semiconductor layer and the emitter semiconductor layer. A transistor element in which a base electrode is present and the collector semiconductor layer is made of a metal oxide.   The transistor element according to claim 1, wherein at least one of the base electrode, the emitter semiconductor layer, and the second electrode is formed by a liquid process.   3. The transistor element according to claim 1, wherein the collector semiconductor layer includes at least one of zinc oxide and indium oxide, and a current flowing between the second electrode and the first electrode is due to electrons. .   The transistor element according to claim 1, wherein the collector semiconductor layer is formed by a liquid process.   Forming a first electrode on the substrate; forming a collector semiconductor layer on the first electrode; forming a base electrode on the collector semiconductor layer; and forming an emitter semiconductor layer on the base electrode. Forming a second electrode on the emitter semiconductor layer, wherein a base electrode exists between the collector semiconductor layer and the emitter semiconductor layer, and A method for producing a transistor element, wherein the collector semiconductor layer is made of a metal oxide.   6. The method of manufacturing a transistor element according to claim 5, wherein at least one of the base electrode, the emitter semiconductor layer, and the second electrode is formed by a liquid process.

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