JP6515668B2 - Organic semiconductor transistor - Google Patents

Description

  The present invention relates to a top gate organic semiconductor transistor.

  Conventionally, an organic semiconductor transistor using an organic semiconductor film is known. In the organic semiconductor transistor, if the relative dielectric constant of the gate insulating film in contact with the organic semiconductor thin film is high, the mobility is lowered by the formation of the trap. Therefore, in Patent Document 1, the portion of the gate insulating film in contact with the organic semiconductor thin film is a low dielectric constant polymer with a relative permittivity of 1.5 to 3.5, and the portion not in contact with the organic semiconductor thin film is a relative permittivity. The structure which makes 4 or more polymers is proposed.

JP 2005-175386 A

  As an organic semiconductor transistor, there is a top gate organic semiconductor transistor in which a gate electrode is disposed above the source electrode and the drain electrode. Since the organic semiconductor transistor of the top gate structure has a structure in which the organic semiconductor thin film is covered with the gate insulating film, the organic semiconductor thin film can be isolated from oxygen and moisture in the air, which is extremely advantageous in terms of durability and the like. It is.

  In this top gate organic semiconductor transistor, the gate insulating film is disposed on the organic semiconductor thin film, but a SAM (Self-Assembled Monolayers) is formed on the organic semiconductor thin film. Can not. If the gate insulating film can be formed after the SAM is formed on the organic semiconductor thin film, the characteristics of the organic semiconductor transistor are improved and the same as the case where the relative dielectric constant of the portion of the gate insulating film in contact with the organic semiconductor thin film is lowered. An effect is obtained. However, such an effect can not be obtained because SAM can not be formed on the organic semiconductor thin film. Therefore, as disclosed in Patent Document 1, lowering the relative dielectric constant of the portion of the gate insulating film in contact with the organic semiconductor thin film is effective in suppressing the decrease in mobility.

  However, in the organic semiconductor transistor of Patent Document 1, since the polymer is used for the gate insulating film, the withstand voltage is lowered. In general, the withstand voltage of the polymer material is low, and in particular, the withstand voltage of the polymer material having pi electrons and non-shared electron pairs is considered to decrease. For this reason, in order to compensate for the decrease in withstand voltage, it is necessary to thicken the polymer material, the total relative dielectric constant of the gate insulating film can not be increased, and the capacity of the gate insulating film is lowered. The decrease in capacitance of the gate insulating film affects the gate drive voltage, and a higher gate drive voltage is required to drive the organic semiconductor transistor. Therefore, it is desirable to suppress the decrease in mobility while suppressing the rise of the gate drive voltage by increasing the total relative dielectric constant to increase the capacitance of the gate insulating film.

  An object of the present invention is to provide an organic semiconductor transistor having a top gate structure capable of improving mobility while suppressing an increase in gate drive voltage.

In order to achieve the above object, the invention according to claims 1 to 5 comprises a substrate (1), a source electrode (2) and a drain electrode (3) spaced apart on the substrate, and a source An organic semiconductor thin film (4) disposed so as to connect the electrode and the drain electrode, and a portion of the organic semiconductor thin film disposed between the source electrode and the drain electrode as a channel region are in contact with the channel region And a gate electrode (6) disposed on the opposite side of the channel region with the gate insulating film interposed therebetween, and at least in contact with the organic semiconductor thin film of the gate insulating film. And the insulating material is a mixture of an organometallic compound and a metal oxide, and the constituent material in the mixture is chemically Being connected It is characterized.

  Thus, at least a portion of the gate insulating film in contact with the organic semiconductor thin film is a mixture of an organic metal compound or an organic compound and a metal oxide. Thus, it is possible to suppress the decrease in mobility due to the formation of the trap in at least a portion in contact with the organic semiconductor thin film of the gate insulating film. Then, since the relative dielectric constant of the mixture can be made higher than in the case where it is configured with only 4 to 6 and the organic metal compound alone, it is also possible to suppress an increase in the gate drive voltage. Therefore, it is possible to suppress an increase in gate drive voltage while suppressing a decrease in mobility.

  In addition, the code | symbol in the parenthesis of each said means shows an example of the correspondence with the specific means as described in embodiment mentioned later.

It is a figure showing the section composition of the organic semiconductor transistor of the top gate structure concerning a 1st embodiment of the present invention. It is a figure which shows the cross-sectional structure of the organic-semiconductor transistor of the top gate structure concerning 2nd Embodiment of this invention. It is the figure which showed the relationship of the film thickness and internal stress of the mixture inserted between the organic semiconductor and the alumina. It is the figure which showed the breakdown pressure resistance in, when a metal oxide is comprised with an alumina.

  Hereinafter, an embodiment of the present invention will be described based on the drawings. In the following embodiments, parts that are the same as or equivalent to each other will be described with the same reference numerals.

First Embodiment
A top gate organic semiconductor transistor according to an embodiment of the present invention will be described. The organic semiconductor transistor described in the present embodiment is applied to, for example, a transistor for driving an organic EL element.

  First, the configuration of the organic semiconductor transistor according to the present embodiment will be described with reference to FIG.

  The organic semiconductor transistor of the top gate structure concerning this embodiment is formed by providing each component of an organic semiconductor transistor on the insulating base material 1. For example, as the substrate 1, a glass substrate or a film (ethylene naphthalate (PEN) or polyimide (PI)) or the like is used.

  At a desired position on the substrate 1, the source electrode 2 and the drain electrode 3 are disposed apart from each other. The source electrode 2 and the drain electrode 3 are formed of, for example, a metal made of an electrode material such as gold (Au), silver (Ag) or copper (Cu).

  Then, an organic semiconductor thin film 4 made of, for example, a high molecular weight organic semiconductor material or a low molecular weight organic semiconductor material is formed on the base material 1 so as to cover the source electrode 2 and the drain electrode 3. The organic semiconductor material is preferably a heat-resistant material having a low thermal expansion coefficient. For example, a low molecular weight organic semiconductor represented by the chemical formula 1, a pentacene-based material, a thiophene-based material or the like is used. Then, an organic semiconductor material is dissolved in an organic solvent to form an ink containing the organic semiconductor material, which is applied and then dried to form the organic semiconductor thin film 4. Here, the organic semiconductor thin film 4 is formed using, for example, a material in which n = 1 as the low molecular weight organic semiconductor represented by the chemical formula 1, and the thickness is 20 nm.

このような構成とされることで、有機半導体薄膜４はソース電極２とドレイン電極３との間を連結するように配置されている。

With such a configuration, the organic semiconductor thin film 4 is disposed so as to connect the source electrode 2 and the drain electrode 3.

  Furthermore, a gate insulating film 5 is formed to cover the surface of the organic semiconductor thin film 4. The gate insulating film 5 is formed by atomic layer deposition (hereinafter referred to as ALD (Atomic Layer Deposition)). According to the ALD method, a very dense film is formed, which is particularly preferable in terms of improving the withstand voltage.

  The portion of the gate insulating film 5 in contact with at least the organic semiconductor thin film 4, that is, all or part of the gate insulating film 5 is made of an insulating material having a dielectric constant of 4 to 6 which is not a polymer. In that case, the portion is constituted by a mixture of an organometallic compound and a metal oxide. The film thickness of the portion of the gate insulating film 5 which is formed of a mixture of the organometallic compound and the metal oxide is less than 3 nm. In this mixture, the constituent materials of the mixture, that is, the organometallic compound and the metal oxide are chemically bonded, and the two regions can not be physically and physically separated. For example, even if the mixture is analyzed using an electron microscope, the materials of the mixture can not be distinguished.

  For example, when the molecular structure of the mixture constituting the portion of the gate insulating film 5 in contact with the organic semiconductor thin film 4 is confirmed, the organometallic compound and the metal oxide are in a chemically bonded state The

  An organometallic compound is a material whose dielectric constant is lower than that of a metal oxide, and a material in which a trap is difficult to be formed. The metal oxide is a material whose dielectric constant is higher than that of the organometallic compound, and when the gate insulating film 5 is formed only of the metal oxide, a trap is formed to cause a decrease in mobility, but with the organometallic compound Chemical bonding makes it difficult to form a trap. In addition, metal oxides which may be unreacted with the organometallic compound may be present, and traps may be formed in that portion, but there are not many unreacted ones, and many are formed even if traps are formed. Is not formed. As compared with the case where the gate insulating film 5 is formed only with metal oxide at least, the structure of this embodiment can significantly reduce the number of traps.

As such an organometallic compound, for example, Alcone (Alucone) can be used, and as a metal oxide, alumina can be used. Alcone can be formed, for example, by the reaction of trimethylaluminum (AlCH ₃ , hereinafter referred to as TMA (trimethylaluminum)) and ethylene glycol (C ₂ H ₂ (OH) ₂ ). When alumina is formed by the reaction of TMA and water (H ₂ O), TMA can be used as a common material in the production of alcon and alumina.

  However, it is not preferable to use only Alcone as the gate insulating film 5 because Alcone is cohesive, has poor flatness and adhesion, and reduces mobility. In addition, the relative dielectric constant is low when using only Alcone, and the relative dielectric constant can be improved by using a mixture with alumina. Therefore, a portion of the gate insulating film 5 in contact with at least the organic semiconductor thin film 4 is configured using a mixture of alcon and alumina.

  As a result, it is possible to suppress a decrease in mobility due to the formation of a trap in at least a portion in contact with the organic semiconductor thin film 4 of the gate insulating film 5. Then, since the relative dielectric constant of the mixture can be made higher than in the case where it is configured with only 4 to 6 and the organic metal compound alone, it is also possible to suppress an increase in the gate drive voltage.

  Furthermore, the gate electrode 6 is formed on the gate insulating film 5 configured as described above. Specifically, a portion of the organic semiconductor thin film 4 located between the source electrode 2 and the drain electrode 3 is used as a channel region, and the gate insulating film 5 is disposed in contact with the channel region. A gate electrode 6 is formed at a position facing the channel region with 5 interposed therebetween. The gate electrode 6 is made of, for example, an electrode material such as gold (Au), silver (Ag), copper (Cu), aluminum (Al), chromium (Cr) or molybdenum (Mo).

  As described above, the top gate organic semiconductor transistor according to the present embodiment is configured.

  In the organic semiconductor transistor configured as described above, at least a portion of the gate insulating film 5 in contact with the organic semiconductor thin film 4 is a mixture of the organic metal compound and the metal oxide. This makes it possible to suppress the increase in gate drive voltage while suppressing the decrease in mobility.

  Further, the film thickness of a portion of the gate insulating film 5 which is formed of a mixture of an organic metal compound and a metal oxide is less than 3 nm. This is because the thermal expansion coefficient of the mixture is smaller than the thermal expansion coefficient of the organic semiconductor thin film 4 in contact with the mixture. When there is a difference in the thermal expansion coefficient between the mixture and the organic semiconductor thin film 4, a stress corresponding to the temperature change is generated. Therefore, if the mixture is thick, cracks may occur between the gate insulating film 5 and the organic semiconductor thin film 4 due to the influence of stress, or cracks may occur in the portion of the mixture to cause gate leak, and durability is obtained. It may not be possible.

  As a result of investigations by the present inventors, when the film thickness of the portion of the gate insulating film 5 constituted by the mixture of the organic metal compound and the metal oxide is 3 nm or more, the durability is lowered, and the film thickness is It was confirmed that when it is less than 3 nm, durability can be obtained. For this reason, in the present embodiment, the film thickness of the portion of the gate insulating film 5 which is formed of a mixture of the organometallic compound and the metal oxide is less than 3 nm. Thereby, even if at least a part of the gate insulating film 5 is formed of a mixture of an organometallic compound and a metal oxide, it is possible to secure the durability of the organic semiconductor transistor.

  Furthermore, in the case of a top gate type organic semiconductor transistor, since a SAM can not be used, a low molecular weight organic semiconductor having a side chain at the end and having crystallinity is preferable as the organic semiconductor material. In the case of forming the gate insulating film 5 by the ALD method, it is preferable to use a higher heat-resistant organic semiconductor material because the gate insulating film 5 with better quality can be obtained by forming the film at a higher temperature.

  When the organic semiconductor thin film 4 is made of the low molecular weight organic semiconductor represented by the above-mentioned chemical formula 1, it is excellent in heat resistance and has an end chain at the end, so the interface with the base material 1 to be the base It is also possible to generate a structure similar to SAM. When a structure similar to such a SAM can be generated, it is possible to make it difficult to form a trap as in the case where the dielectric constant of the portion of the gate insulating film 5 at the interface with the organic semiconductor thin film 4 is lowered. Therefore, by using the low molecular weight organic semiconductor represented by the chemical formula 1, it is possible to improve the heat resistance and to further improve the mobility.

  In the case of the gate insulating film having a large relative dielectric constant, since the dipole moment is large, the trap is easily formed due to the interaction with the organic semiconductor molecule, particularly the π electron cloud portion having a high electron density. For this reason, the characteristics are improved by inserting the SAM that prevents the interaction at the interface between the gate insulating film and the organic semiconductor. It is generally known that a thiophene-based organic semiconductor having an alkyl chain in its side chain has a herringbone type crystal structure. In this case, since the organic semiconductor molecule has a structure in which the organic semiconductor molecule stands in the direction of the major axis with respect to the gate insulating film, the alkyl chain exerts the effect of preventing the above-mentioned interaction like SAM.

  Then, the manufacturing method of the organic semiconductor transistor of the top gate structure concerning this embodiment is demonstrated.

  First, the source electrode 2 and the drain electrode 3 are formed on the surface of the substrate 1. For example, the source electrode 2 and the drain electrode 3 are formed using a film formation method such as printing or vapor deposition, or a patterning method such as photolithography. Specifically, the portions other than the planned formation positions of the source electrode 2 and the drain electrode 3 are masked with a resist, a mask or the like, and film formation by printing or vapor deposition is performed in this state. Thereafter, the masking is released to form the source electrode 2 and the drain electrode 3. Here, the source electrode 2 and the drain electrode 3 are formed by, for example, forming 50 nm of gold by vapor deposition.

  Subsequently, the organic semiconductor thin film 4 is disposed on the substrate 1 on which the source electrode 2 and the drain electrode 3 are formed. For example, the organic semiconductor thin film 4 is formed by forming an organic semiconductor thin film 4 from a high molecular weight organic semiconductor material or a low molecular weight organic semiconductor material, and printing using an ink composed of a solution in which the organic semiconductor material is dissolved in a solvent. It is formed. Here, a 20 nm compound was formed by printing as a low molecular weight organic semiconductor represented by the above-mentioned chemical formula 1 with n = 10.

  Further, the gate insulating film 5 is formed by ALD to cover the source electrode 2 and the drain electrode 3 and the organic semiconductor thin film 4. At this time, a mixture of an organic metal oxide and a metal oxide is formed by alternately switching the atmosphere in the chamber between the film forming atmosphere of the organic metal oxide and the film forming atmosphere of the metal oxide. To make

  For example, in the case where the organic metal oxide is made of alcone, TMA is introduced into the chamber, and the excess TMA is exhausted to adsorb one molecule of TMA on the substrate. Thereafter, ethylene glycol is similarly introduced into the chamber and the excess is evacuated, whereby one ethylene glycol molecule is adsorbed onto one TMA molecule, and an alcon equivalent to one molecule is formed on the substrate by the chemical reaction of both molecules. . By repeating this cycle, it is possible to form an alkone having a desired film thickness while controlling the film thickness at the molecular layer level.

  When the metal oxide is made of alumina, TMA is introduced into the chamber, and the excess TMA is exhausted to adsorb one molecule of TMA on the substrate. Thereafter, water is similarly introduced into the chamber and the excess is evacuated, whereby one molecule of water is adsorbed onto one molecule of TMA, and an alumina equivalent to one molecule is formed on the substrate by the chemical reaction of both molecules. By repeating this cycle, it is possible to form alumina of a desired film thickness while controlling the film thickness at the molecular layer level.

  At this time, before the organic metal oxide and the metal oxide become filmy, for example, the gas introduction time is made so that the average thickness is less than 1 nm, specifically, the gas molecules are not adsorbed uniformly on the substrate. By switching the atmosphere in the chamber while controlling for a short time, the organic metal oxide and the metal oxide do not become a bilayer that alternately forms a film, and a mixture in which these are chemically bonded is created. Can. If these alcons and alumina are each formed on an average of 2 nm or more, a clear bilayer structure is obtained. From the viewpoint of controlling the relative dielectric constant, although it may be a mixture or a bilayer structure, it has been experimentally found that the adhesion is significantly improved in the case of the mixture. This is because there is a clear interface in the bilayer structure, and peeling from the interface is likely to occur. Therefore, as in the present embodiment, by using a mixture having a non-bilayer structure, high adhesion can be obtained.

  Further, the control of the relative dielectric constant of the mixture at this time is determined by the mixing ratio of the organic metal oxide and the metal oxide, and specifically, is performed by controlling the thickness of these. Here, the ratio of alcon and alumina was controlled to 1: 1, and a mixture having a relative dielectric constant of 4 was formed to 3 nm.

  Thus, by alternately switching the atmosphere in the chamber between the film formation atmosphere of the organic metal oxide and the film formation atmosphere of the metal oxide, the organic metal oxide and the metal oxide are chemically changed. A combined mixture can be formed. When the organic metal oxide is made of alcone and the metal oxide is made of alumina, TMA can be used as the common material, so it is only necessary to switch between ethylene glycol and water, thereby simplifying the manufacturing process. It can also be done.

  Thereafter, gold (Au), silver (Ag), copper (Cu), aluminum (Al), chromium (Cr), molybdenum (Mo) or the like is formed on gate insulating film 5 as a constituent material of gate electrode 6. Membrane. For example, the gate electrode 6 is formed by employing a film formation method such as printing or vapor deposition or a patterning method such as photolithography. Specifically, masking is performed using a resist, a mask, or the like, and film formation by printing or evaporation is performed in this state. Thereafter, the masking is released to form the gate electrode 6. Here, the gate electrode 6 is formed by, for example, forming 50 nm of gold by vapor deposition. Thus, the organic semiconductor transistor according to the present embodiment is completed.

Second Embodiment
A second embodiment of the present invention will be described. The present embodiment is the same as the first embodiment except that the configuration of the gate insulating film 5 is modified with respect to the first embodiment. Therefore, only the parts different from the first embodiment will be described.

  As shown in FIG. 2, in the organic semiconductor transistor of this embodiment, the gate insulating film 5 has a two-layer structure. Specifically, the first layer 5a in contact with the organic semiconductor thin film 4 is formed of a mixture of the organic metal compound and the metal oxide described in the first embodiment, and the second layer 5b on the metal layer is a metal. Composed of oxide. Alumina is used as the metal oxide constituting the second layer 5b.

  The metal oxide such as alumina constituting the second layer 5 b has a high dielectric constant as compared with the mixture constituting the first layer 5 a. Therefore, the total relative dielectric constant of the gate insulating film 5 can be increased. In particular, the dielectric constant of the mixture constituting the first layer 5a is also a high value as compared to the case where the first layer 5a is formed of a polymer or the like. The total relative dielectric constant obtained by adding up the relative dielectric constants of the layer 5b is a high value. For example, in the case of the present embodiment, the total relative dielectric constant of the gate insulating film 5 can be made 6 or more. Therefore, it is possible to further suppress an increase in gate drive voltage.

  Further, the metal oxide constituting the second layer 5 b has a thermal expansion coefficient higher than that of the mixture constituting the first layer 5 a. Therefore, the mixture forming the first layer 5a having a low thermal expansion coefficient can be sandwiched by the organic semiconductor thin film 4 having a high thermal expansion coefficient and the metal oxide forming the second layer 5b. It is possible to reduce the stress caused by the difference between the thermal expansion coefficients of the first layer 5a and the first layer 5a.

  Therefore, it is possible to suppress the occurrence of gate leakage by causing a crack between the gate insulating film 5 and the organic semiconductor thin film 4 under the influence of stress, or a crack at the portion of the first layer 5a formed of a mixture. The organic semiconductor transistor can be more durable. Furthermore, as described in the first embodiment, when the thickness of the first layer 5a is less than 3 nm, the influence of the low thermal expansion coefficient of the first layer 5a can be particularly suppressed, and an organic semiconductor transistor having more excellent durability can be obtained. .

  As an experiment, the amount of warpage was measured on a film sample in which a mixture of an organic metal oxide and a metal oxide or alumina which is a metal oxide was formed on a quartz substrate. The internal stress calculated from the measurement was reversed in sign between the mixture and the alumina. Specifically, since alumina is positive, it has a tensile stress, and since the mixture has a negative, it has become compressive stress. From this, at least the relationship of the thermal expansion coefficient is interpreted as: mixed layer <quartz substrate <alumina.

  In the top gate type structure as shown in the present embodiment, since a mixture having a small thermal expansion coefficient is formed on an organic semiconductor having a large thermal expansion coefficient, the internal stress is large as compared with the case without the mixture. Cracks are likely to occur.

  Actually, in a top gate type structure in which a mixture of an organic metal oxide and a metal oxide and alumina which is a metal oxide are laminated on an organic semiconductor, the film thickness of the mixture inserted between the organic semiconductor and alumina The relationship between the stress and the internal stress was investigated. The relationship is shown in FIG. As can be seen from this figure, when the film thickness of the mixture is larger than 3 nm, a change in stress is observed, and it is confirmed that a crack is actually generated at about 10 nm. When a crack occurs in the gate insulating film, the upper and lower electrodes are shorted, and the transistor does not operate. Therefore, from the viewpoint of crack prevention, the film thickness of the mixture is preferably 3 nm or less.

Furthermore, as an experiment, the organic semiconductor transistor according to the present embodiment was manufactured using the same manufacturing method as that of the first embodiment. However, with regard to the organic semiconductor thin film 4, after the first layer 5 a is formed by forming a mixture having a relative dielectric constant of 4 and a thickness of 3 nm by controlling the ratio of alcon and alumina to 1: 1, Furthermore, the second layer 5 b was formed by forming alumina with a relative dielectric constant of 8 in thickness to 100 nm. The total relative dielectric constant of the gate insulating film 5 by the 1st layer 5a and the 2nd layer 5b by this was 7.8. Moreover, the withstand voltage was 4.5 MV / cm. Moreover, when the transfer characteristic of the organic-semiconductor transistor formed in this way was evaluated, the mobility in gate voltage 10V and voltage 15V between source-drains was 3.0 cm < ² > / Vs. Also from these results, it can be understood that high withstand voltage is obtained and high mobility is obtained.

  More specifically, when the breakdown voltage in the case where the metal oxide was made of alumina was examined, the result shown in FIG. 4 was obtained. As can be seen from this figure, a high dielectric breakdown voltage of 4 MV / cm or more is obtained. Therefore, the compensation of the withstand voltage by thickening the gate insulating film 5 is not required.

  Here, the breakdown voltage means an electric field point at which the slope of the leak current changes. When the second layer 5b composed of a metal oxide is made of alumina, if the film thickness is less than 70 nm, the breakdown withstand voltage significantly decreases. Therefore, the film thickness is preferably 70 nm or more.

(Modification of the second embodiment)
In the organic semiconductor transistor of the structure of the second embodiment described above, the one in which the configurations of the first layer 5a and the second layer 5b were changed was created.

  Specifically, for the organic semiconductor thin film 4, the first layer 5a is formed by forming a mixture having a relative dielectric constant of 5.1 and a thickness of 3 nm by controlling the ratio of alcon to alumina to 1: 2. After film formation, a second layer 5b was formed by further forming alumina having a relative dielectric constant of 8 to a thickness of 100 nm. The total relative dielectric constant of the gate insulating film 5 by the 1st layer 5a and the 2nd layer 5b by this was 7.9. Moreover, the withstand voltage was 4.5 MV / cm. The other structure is the same as that of the second embodiment.

The transfer characteristics of the organic semiconductor transistor thus formed were evaluated. The mobility at a gate voltage of 10 V and a source-drain voltage of 15 V was 2.8 cm ² / Vs. Also from these results, it can be understood that high withstand voltage is obtained and high mobility is obtained.

(Comparative example)
In the organic semiconductor transistor of the structure of the second embodiment described above, the gate insulating film 5 was prepared without the first layer 5a made of a mixture. The other structure is the same as that of the second embodiment.

The transfer characteristics of the organic semiconductor transistor thus formed were evaluated. The mobility at a gate voltage of 10 V and a source-drain voltage of 15 V was 1.2 cm ² / Vs. This result also shows that high mobility can not be obtained unless the first layer 5a is provided.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and appropriate modifications can be made within the scope of the claims.

  For example, the structure of the organic semiconductor transistor called a top gate structure is other than the structures shown in FIGS. 1 and 2, and the present invention can be applied to any structure. Specifically, the organic semiconductor thin film 4 is disposed only between the source electrode 2 and the drain electrode 3 which are disposed apart from each other on the substrate 1, and the source electrode 2, the drain electrode 3 and the organic semiconductor thin film 4 are The gate electrode 6 may be provided on the upper side via the gate insulating film 5. In addition, the source electrode 2 and the drain electrode 3 are disposed apart from each other on the organic semiconductor thin film 4 disposed on the substrate 1, and a gate insulating film is further formed on the source electrode 2 and the drain electrode 3 or the organic semiconductor thin film 4. A structure in which the gate electrode 6 is provided via 5 may be employed.

  In each of the above embodiments, the case where the mixture forming the portion in contact with the organic semiconductor thin film 4 in the gate insulating film 5 is formed of the organic metal compound and the metal oxide has been described. Not limited to this, the portion may be formed of a mixture of an organic compound and a metal oxide. For example, polyethylene terephthalate (PET) can be used as the organic compound, and alumina can be used as the metal oxide.

  Furthermore, although the case where the gate insulating film 5 has a two-layer structure of the first layer 5a and the second layer 5b has been described in the second embodiment, a plurality of layers may be used. That is, in the case of multiple layers of two or more layers, the first layer 5a of the gate insulating film 5 in contact with the organic semiconductor thin film 4 is formed of an organic metal compound or a mixture of an organic compound and a metal oxide; If at least one layer composed of a metal oxide is provided in the upper layer, the same effect as that of the second embodiment can be obtained.

  Further, the materials, dimensions, and the like of the respective parts constituting the organic semiconductor transistor are merely an example. Furthermore, although each part constituting the organic semiconductor transistor is directly formed on the base material 1, each part constituting the organic semiconductor transistor after forming an insulating film or the like on the base material 1 as necessary It may be formed.

REFERENCE SIGNS LIST 1 base material 2 source electrode 3 drain electrode 4 organic semiconductor thin film 5 gate insulating film 5 a first layer 5 b second layer 6 gate electrode

Claims (5)

A substrate (1),
A source electrode (2) and a drain electrode (3) spaced apart on the substrate;
An organic semiconductor thin film (4) arranged to connect between the source electrode and the drain electrode;
A portion of the organic semiconductor thin film disposed between the source electrode and the drain electrode as a channel region, and a gate insulating film (5) provided in contact with the channel region;
And a gate electrode (6) disposed on the opposite side of the channel region with the gate insulating film interposed therebetween,
At least a portion of the gate insulating film in contact with the organic semiconductor thin film is made of an insulating material having a dielectric constant of 4 to 6, and the insulating material is an organometallic compound and a metal oxide. Consisting of a mixture, the constituent materials in the mixture being chemically bonded ,
The organic semiconductor transistor is characterized in that the organometallic compound is an alcone produced by the reaction of trimethylaluminum and ethylene glycol, and the metal oxide is an alumina produced by the reaction of trimethylaluminum and water. . The gate insulating film includes at least two layers of a first layer (5a) constituting a portion in contact with the organic semiconductor thin film and a second layer (5b) formed above the first layer. Has a multi-layered structure,
The organic semiconductor transistor according to claim 1, wherein the second layer is made of metal oxide. The organic semiconductor transistor according to claim 2 , wherein a total relative dielectric constant of the gate insulating film having the multi-layer structure is 6 or more. The organic semiconductor according to any one of claims 1 to 3 , wherein a thickness of the mixture forming a portion in contact with the organic semiconductor thin film is less than 3 nm. Transistor. The organic semiconductor constituting the organic semiconductor thin film is

It is a material represented by these, The organic-semiconductor transistor as described in any one of the Claims 1 thru | or 4 characterized by the above-mentioned.

Images