JP2010056504A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device using a semiconductor and an organic material as active roles and having completely new functions different from those in the prior art. <P>SOLUTION: An organic electrode 2 is formed on a GaN semiconductor 1, and an Au film 3 is formed on the organic electrode 2. On the rear surface of the GaN semiconductor 1, an electrode formed of a multilayer metal film of a Ti film 4 and an Au film 5 is formed so as to oppose the organic electrode 2. The interface of bonding between the organic electrode 2 and the GaN semiconductor 1 is in a state such as schottky junction, and a rectification action is generated between them. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor element in which an organic electrode is formed on an inorganic semiconductor.

  In recent years, there is a conductive polymer as an interesting substance that is actively applied and researched as a multifunctional substance. There is a voice that organic materials will be the main role of electronic devices in the next generation because organic materials can be made very easily by combining them with printing technology. In order to make an electronic device, something that conducts electricity is necessary, and a conductive polymer is also effective for that purpose.

  Semiconductors and organic materials, which are inorganic materials, have been developed independently, and have not had much contact so far, but in recent years there has been much research into merging them. Among semiconductors, oxides have many types and functions, and organic substances are rich in materials and multifunctional. Therefore, by combining these, various types of devices may be manufactured. In addition, since the material is abundant, it can often be manufactured at a low cost, and if an organic material is used, patterning can be performed by a printing technique or the like, and the process cost is reduced.

By the way, in the combination of an inorganic semiconductor and an organic substance, as shown in Patent Documents 1 to 3, it is mainly used passively as an electrode, and the combined part is used as a device having some active function. There are very few examples.
JP 2005-277339 A JP 2006-518471 A JP 2006-58730 A

  Further, in the prior art, no proposal has been made for a combination of an organic substance with a GaN-based semiconductor, SiGe-based semiconductor, GaAs-based semiconductor or the like often used in a semiconductor. In particular, it has not been considered to produce a device for the purpose of controlling the organic / semiconductor interface and actively controlling the physical state of the interface.

  On the other hand, Patent Documents 1 to 3 show examples of forming a conductive polymer that is an organic substance as an electrode on a ZnO-based material thin film or a substrate, but these are passively combined as an electrode for supplying current to a transistor. It does not play an active role to control the organic / semiconductor interface.

  Conventionally, inorganic semiconductors are often used in electronic devices, such as LSIs and photodiodes. Usually, the photodiode is basically a pn junction type of Si (silicon) which is a kind of inorganic semiconductor. In a pn junction photodiode, a PIN photo diode having a layer junction structure in which an i-type layer is inserted between pn layers of p-type layer-i-type layer-n-type layer, a depletion layer is expanded, and a capacitance between terminals is reduced. Diodes are the mainstream and are used where high-speed response is required. Since this photodiode is based on silicon, the sensitivity decreases as the wavelength of light decreases. The photodiode has the highest photocurrent conversion efficiency when light enters the pn junction region at the pn junction and the i-type layer at the pin junction. However, as the wavelength becomes shorter, the absorption coefficient of silicon increases, so the distance that light in the depth direction can reach becomes shorter.

  For silicon, for example, the limit is to reach a depth of about 1000 mm with light having a wavelength of around 400 nm. Therefore, it is necessary to make a pn junction and a pin junction in a shallow portion. In this case, the p-type layer must be made thin and thin. However, by doping p-type impurities or n-type impurities by diffusion, ion implantation, or the like, it is difficult to form a thin p-type layer with Si, which is generally used for junction formation. Fabricating a p-type layer in a very shallow region up to a depth of 1000 mm is a technology that is performed at the most advanced LSI level, and cannot be made at a cost that is quite commensurate with the price of a photodiode.

  Even if the p-type layer can be made shallow and thin, if light-induced carrier generation occurs only in the shallow region, the current path between the electrodes when the carriers are taken out of the photodiode becomes narrow and the resistance is reduced. Get higher. In order to lower the resistance value, the impurity concentration in the p-type layer may be increased. However, if the resistance value is increased, impurity scattering is caused and carrier mobility is lowered, and the response speed is lowered. In addition, deterioration of the lifetime of the carrier causes a decrease in light detection sensitivity.

  As described above, in the conventional electronic device using the inorganic material p-type semiconductor and n-type semiconductor, there is a limit to the improvement in characteristics.

  The present invention was created to solve the above-described problems, and an object of the present invention is to provide a semiconductor device that uses an inorganic semiconductor and an organic substance in an active role and has a completely new function different from the conventional one. It is said.

  In order to achieve the above object, the invention according to claim 1 is characterized in that an organic electrode is formed in contact with any one of a group IV semiconductor, a group III-V semiconductor, or a group III nitride semiconductor, and the semiconductor and the organic electrode And a rectifying characteristic.

  The invention according to claim 2 is the semiconductor element according to claim 1, wherein a work function of the organic electrode is larger than an electron affinity of the semiconductor.

  The invention according to claim 3 is the semiconductor element according to claim 1 or 2, wherein the main surface of the semiconductor in contact with the organic electrode is a + C surface.

  The invention according to claim 4 is the semiconductor device according to any one of claims 1 to 3, wherein at least a part of the organic electrode is made of a conductive polymer. .

  The invention according to claim 5 is the semiconductor element according to claim 4, wherein the resistivity of the organic electrode is 1 Ωcm or less.

  According to a sixth aspect of the present invention, in the semiconductor according to the fourth or fifth aspect, the conductive polymer is composed of at least one of a polyaniline derivative, a polypyrrole derivative, and a polythiophene derivative. It is an element.

  The invention according to claim 7 is the semiconductor element according to claim 6, wherein the polyaniline derivative, the polypyrrole derivative, and the polythiophene derivative each contain a carrier dopant.

  The invention according to claim 8 is the semiconductor according to any one of claims 1 to 7, wherein the organic electrode has translucency in an ultraviolet light region and an infrared light region. It is an element.

  The invention according to claim 9 is the semiconductor element according to claim 8, wherein the organic electrode is made of a hole conductor.

  In the invention of claim 10, 3 volts is applied in a reverse bias state in which a negative voltage is applied to the organic electrode side of the semiconductor element, and the reverse current is 1 nanoampere or less in the absence of light irradiation. The semiconductor element according to claim 8 or 9, wherein

  The invention according to claim 11 is the semiconductor element according to any one of claims 8 to 10, wherein the semiconductor element is a photoelectric conversion element.

  According to a twelfth aspect of the present invention, at least one layer of the semiconductor is formed on a substrate, the organic electrode functions as a Schottky gate electrode, and has a transistor function. 8. The semiconductor device according to any one of items 7.

Further, an invention according claim 13, for the group III-V _{semiconductors, In X (Al Y Ga 1} -Y) 1-X As, In X (Al Y Ga 1-Y) 1-X P, ( In _X Ga _1-Y ) _Z (P _X As _1-X ) _1-Z , the Group III nitride semiconductor is composed of In _X (Al _Y Ga _1-Y ) _1-X N The semiconductor element according to claim 1, wherein 0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, and 0 ≦ Z ≦ 1 are satisfied.

  The invention according to claim 14 is characterized in that the group III-V semiconductor or group III nitride semiconductor is constituted by a stacked body in which semiconductors having at least two different compositions are stacked. This is a semiconductor element.

The invention according to claim 15 is characterized in that the group IV semiconductor is composed of Si _1-W Ge _W (0 ≦ W ≦ 1) or a stack of Si _1-W Ge _{W having} different compositions. It is a semiconductor element of any one of Claims 1-12.

  The invention according to claim 16 is the semiconductor element according to any one of claims 13 to 15, wherein an electron accumulation region generated at an interface of the stacked body is a channel region.

  The invention according to claim 17 is the semiconductor element according to claim 16, wherein the electrons generated by the photoelectric conversion action are taken out through the electron accumulation region.

  The invention according to claim 18 is a semiconductor device characterized in that an organic electrode is formed in contact with an inorganic semiconductor and has a rectifying characteristic between the inorganic semiconductor and the organic electrode.

The invention according to claim 19 is characterized in that the inorganic semiconductor is composed of Mg _Z1 Zn _1-Z1 O (0 ≦ Z1 <1) and functions as a photoelectric conversion layer, and the organic electrode has translucency. In a state where no bias is applied to the organic electrode, the light receiving sensitivity is substantially 0 in the wavelength region exceeding 400 nm, and the wavelength region in which the light receiving sensitivity is 10 ⁻³ A / W or more in the wavelength region below 400 nm. The semiconductor element according to claim 18, wherein the semiconductor element is provided.

In the twentieth aspect of the invention, the Mg composition Z1 is configured such that a photoelectric conversion wavelength in the MgZnO is in a range of 280 nm to 400 nm in the wavelength region where the light receiving sensitivity is 10 ⁻³ A / W or more. The semiconductor device according to claim 19, wherein the semiconductor device is a semiconductor device.

The invention according to claim 21 is characterized in that the Mg composition Z1 of the Mg _Z1 Zn _{1 -Z1} O is 0.25 or more, and the photoelectric conversion wavelength is 320 nm. It is a semiconductor element.

The invention according to claim 22 is characterized in that the Mg composition Z1 of the Mg _Z1 Zn _{1 -Z1} O is 0.45 or more and the photoelectric conversion wavelength is 280 nm. It is a semiconductor element.

  The invention according to claim 23 is the semiconductor element according to any one of claims 19 to 22, wherein the organic electrode is made of a hole conductor.

  According to a twenty-fourth aspect of the present invention, when a negative voltage is applied to the organic electrode side of the semiconductor element in a reverse bias state, 3 volts is applied, and in the absence of light irradiation, the reverse current is 1 nanoampere or less. 24. The semiconductor device according to claim 23.

The invention according to claim 25 is characterized in that the Mg _Z1 Zn _{1 -Z1} O is constituted by 0 <Z1 <1. It is a semiconductor element.

  According to the present invention, an organic electrode is formed in contact with an inorganic semiconductor such as a group IV semiconductor, a group III-V semiconductor, a group III nitride semiconductor, or a ZnO-based semiconductor, so that a potential barrier is formed at the interface between the semiconductor and the organic electrode. Due to the energy band relationship, a rectifying action is generated between the semiconductor and the organic electrode. Therefore, it can be applied to a novel device such as a photoelectric conversion element.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a cross-sectional structure of a semiconductor device according to the present invention.

An organic electrode 2 is formed on the GaN semiconductor 1, and an Au film 3 used for wire bonding or the like is formed on the organic electrode 2. On the other hand, an electrode composed of a multilayer metal film of a Ti film 4 and an Au film 5 is formed on the back surface of the GaN semiconductor 1 so as to face the organic electrode 2. The GaN semiconductor 1 corresponds to In _X (Al _Y Ga _1-Y ) _1-X N (0 ≦ X ≦ 1, 0 ≦ Y ≦ 1), which is a group III nitride semiconductor, and X = Y = 0. It corresponds to the compound in the case of.

  On the other hand, part of the organic electrode 2 is made of a conductive polymer. Examples of the conductive polymer include a polythiophene derivative (PEDOT: poly (3,4) -ethylenedioxythiophene) shown in FIG. 5B, a polyaniline derivative shown in FIG. 6, and FIG. 7A. Polypyrrole derivatives and the like are used.

  Specifically, a substance obtained by doping each of the above-described derivatives with a substance for controlling electrical characteristics such as conduction characteristics is used. For example, a polythiophene derivative (PEDOT) is made of polystyrene shown in FIG. A sulfonic acid (PSS) -doped one or a polypyrrole derivative doped with TCNA shown in FIG. 7B is used.

  As for the connection of the power supply, as shown by the solid connection line in FIG. 1, a state where the Au film 3 is connected to the + side of the DC power supply and the Au film 5 is connected to the − side of the DC power supply is considered. As will be described later, this shows a state in which the semiconductor element of FIG. 1 has a rectifying action like a diode, but a forward bias is applied at that time. In this case, the organic electrode 2 functions as a positive electrode (p electrode), and the Ti film 4 functions as a negative electrode (n electrode).

  FIG. 2 is a schematic diagram for explaining the operation of the semiconductor element formed as described above. FIG. 2 shows an energy band diagram at the junction interface between the GaN semiconductor 1 and the organic electrode 2 when the organic electrode 2 is composed of PEDOT: PSS.

2A shows the case where the bias applied to the semiconductor element is 0, FIG. 2B shows the case where the bias is forward, and FIG. 2C shows the case where the bias is reverse. E _FO is the Fermi level of the organic electrode 2, E _FZ is the Fermi level of the GaN semiconductor 1, VL is the vacuum level, φ _O is the work function of the organic electrode 2, and φ _Z is the GaN semiconductor 1. the work function of, e _C is the level of the conduction band, e _V is the level of the valence band, χ _Z represents the electron affinity of GaN semiconductor 1.

When the bias is zero as shown in FIG. 2A, the Fermi levels of the GaN semiconductor and the organic electrode are in agreement and in an equilibrium state. A barrier (built-in potential) φ _O −φ _Z against the flow of electrons from the GaN semiconductor to the organic electrode and a Schottky barrier φ _O −χ _Z against the flow of electrons from the organic electrode to the GaN semiconductor are generated.

On the other hand, as shown by the solid connection line in FIG. 1, when forward bias is applied, the direction is to cancel φ _O −φ _Z , so that the barrier of the GaN semiconductor is lowered by qV as shown in FIG. Become. On the other hand, since the barrier on the organic electrode side does not change, the electron flow from the GaN semiconductor to the organic electrode increases. On the other hand, as shown by the broken connection line in FIG. 1, when the DC power source is connected in the reverse direction (reverse bias), the barrier on the GaN semiconductor side is increased by qV, contrary to FIG. Since the barrier on the organic electrode side does not change, it becomes as shown in FIG. Therefore, almost no electron flow from the GaN semiconductor to the organic electrode occurs.

As described above, when the GaN semiconductor 1 and the organic electrode 2 are joined in a relationship of φ _O > χ _Z , the same rectifying action as that of the pn junction occurs. Thus, in the present invention, the organic electrode 2 is configured as an electrode that plays an active role to control the organic / semiconductor interface.

  FIG. 3 shows the result of actually measuring the IV characteristics (current-voltage characteristics) between the GaN semiconductor and the organic electrode. The semiconductor element shown in FIG. 4 was used for the measurement. On the sapphire substrate 11, an n-type GaN layer 12, an undoped GaN layer 13, and an organic electrode 14 are formed in this order, and mesa etching is performed until the n-type GaN layer 12 is exposed from the organic electrode 14. A p-electrode 15 is formed on the organic electrode 14, and an n-electrode 16 is formed on the exposed n-type GaN layer 12.

Specifically, the n-type GaN layer 12 is doped with Si as an n-type impurity so that the electron concentration is in the range of 7 × 10 ¹⁷ cm ⁻³ to 2 × 10 ¹⁸ cm ⁻³ . The undoped GaN layer 13 is not intentionally doped with impurities, but is formed with an electron concentration in the range of 1 × 10 ¹⁵ cm ⁻³ to 1 × 10 ¹⁶ cm ⁻³ . The organic electrode 14 is made of PEDOT: PSS.

  In the configuration of FIG. 4, a direct current power source was connected between the p electrode 15 and the n electrode 16 to measure the relationship between current and voltage. The forward bias (hereinafter referred to as forward bias) is a state in which the positive voltage side of the DC power supply is connected to the p electrode 15 and the negative voltage side of the DC power supply is connected to the n electrode 16. The reverse bias (hereinafter referred to as reverse bias) is a state in which the positive voltage side of the DC power supply is connected to the n electrode 16 and the negative voltage side of the DC power supply is connected to the p electrode 15.

  The two curves in FIG. 3 are measurement results when the voltage is swept in the direction of the arrow, that is, when the voltage is changed from reverse bias to forward bias and subsequently from forward bias to reverse bias. Here, when the voltage V is 0, the + side voltage is a forward bias, and the − side voltage is a reverse bias. As shown in FIG. 3, almost no current flows when applying a reverse bias (almost the lower limit of this element), but when a forward bias is applied, it can be seen that the current increases rapidly, Has rectification characteristics. Also, as shown at the branch point in the figure, even if the applied voltage becomes a positive voltage, the current does not flow immediately, and in order for the current to flow, it is necessary to apply a voltage higher than the predetermined positive bias voltage. I understand.

  On the other hand, in the ideal situation as described with reference to FIG. 2, the above two measurement results match, but there are extra levels due to the contact and surface of different materials, so-called interface levels and surface levels. If it exists, the two measurement results do not match because there is charge and discharge of carriers to that level. Accordingly, when the degree of coincidence is good, it indicates that there are few surface and interface states. Referring to FIG. 3, the degree of coincidence between the two curves is very good, indicating that the organic electrode / GaN interface is in good contact.

  By the way, GaN-based semiconductors and ZnO-based semiconductors have a hexagonal crystal structure called wurzeite. The expressions C-plane and a-axis can be expressed by a so-called Miller index. For example, the C-plane is expressed as a (0001) plane. In addition, there are an A plane (11-20), an M plane (10-10) which is a column surface, and the like. The m-axis indicates the vertical direction of the M-plane, and the c-axis indicates the vertical direction of the C-plane.

  Unlike a GaN-based semiconductor, when an organic electrode is formed on a ZnO-based semiconductor, the characteristics of the element differ depending on the crystal plane on the side of forming the organic electrode in the ZnO-based semiconductor. How to choose the face is important. For example, PEDOT: PSS is formed as an organic electrode on an n-type ZnO substrate. Here, when the PEDOT: PSS is formed on the + C plane of the n-type ZnO substrate and the PEDOT: PSS is formed on the −C plane of the n-type ZnO substrate, there is not much difference in current-voltage characteristics. . However, the -C face of ZnO-based semiconductors is weaker to acids and alkalis than the + C face, and is difficult to process. In particular, when PEDOT: PSS is used for the organic electrode, it shows an acidity of about PH1, as can be seen from the structural formula of FIG. It was observed. Therefore, when using a ZnO-based semiconductor, it is desirable to form an organic electrode on the + C plane.

  Next, FIG. 8 shows a structure which is basically the same as that of FIG. 1, but particularly has a different electrode structure. The same reference numerals as those in FIG. 1 denote the same configurations. When a forward bias is applied as shown in FIG. 8, in FIG. 8A, instead of forming a negative electrode on the back surface of the GaN semiconductor 1, a positive electrode and a negative electrode are formed on the same surface side of the GaN semiconductor 1, The negative electrode is formed in an annular shape so as to surround the laminate composed of the organic electrode 2 and the Au film 3. FIG. 8B shows a structure in which a substrate 6 serving as a support substrate is attached to the structure of FIG.

FIG. 9 shows an example of a manufacturing process when PEDOT: PSS is used for the organic electrode 2 in the semiconductor element of FIG. First, the GaN semiconductor 1 is heat-treated at a temperature of about 1100 ° C., subjected to ultrasonic cleaning in a solution of acetone or ethanol, and then subjected to hydrophilic treatment by UV-ozone irradiation (FIG. 9A). Next, as shown in FIG. 9B, PEDOT: PSS is formed on the GaN semiconductor 1 by spin coating and is baked at a temperature of about 200.degree. Thereafter, Au metal is deposited as shown in FIG. 9C to produce the Au film 3, and then a resist 11 is formed as shown in FIG. 9D, and mesa structure is formed by dry etching using Ar ⁺ plasma or the like. Is formed as shown in FIG. After removing the resist by ultrasonic cleaning in an acetone solution (FIG. 9F), Ti metal is deposited to form a Ti film 4, and further Au metal is deposited to form an Au film 5. Complete.

  As an example of the semiconductor element described above, a photoelectric conversion element can be configured. It is preferable to use an organic electrode 2 having translucency in the ultraviolet region and the near infrared region. Here, having translucency in the ultraviolet region means having a transmittance of 70% or more in the wavelength region of 400 nm or less of light when the organic electrode 2 is irradiated with light. In addition, having translucency in the infrared region means that when the organic electrode 2 is irradiated with light, it has a transmittance of 50% or more in the near-infrared wavelength region of light of 800 nm or more. It means having a transmittance of 70% or more in a wavelength region close to the light region.

  Specifically, the organic electrode 2 was made of PEDOT: PSS, and the thickness thereof was 50 nm, so that the semiconductor element of FIG. 1 was produced. As the GaN semiconductor 1, a single crystal GaN substrate is used, PEDOT: PSS is formed on the GaN substrate, an Au film 3 is formed on the PEDOT: PSS, and a Ti film 4 and an Au film 5 are sequentially formed on the back surface of the GaN substrate. Formed. The DC power supply is connected as indicated by the broken line in FIG.

  PEDOT: PSS used for the organic electrode 2 has properties as shown in FIG. FIG. 10 compares the light transmittance of the sapphire substrate, which is an oxide, with the light transmittance of PEDOT: PSS. The horizontal axis in FIG. 10 indicates the wavelength (nm) of light, the vertical axis on the left side indicates the light transmittance (%), and the vertical axis on the right side indicates the light reflectance (%). Further, the curve drawn on the upper side of the figure represents the transmittance curve, and the curve drawn on the lower side represents the reflectance curve.

FIG. 10 shows transmittance and reflectance up to a wavelength of 0 to 2500 nm. SA represents a sapphire substrate, and P1 to P4 represent PEDOT: PSS curves. By changing the resistivity of PEDOT: PSS, a curve from P1 to P4 is obtained. P1 has a resistivity of 10 ⁵ Ωcm, P2 has a resistivity of 10 ³ Ωcm, P3 has a resistivity of 10 Ωcm, and P4 has a resistivity of 10 ^−3. The transmittance curve in the case of Ωcm is shown. Although there is not much difference in characteristics in the ultraviolet light region and the visible light region, in the near infrared region, the difference appears in the curves of P1 to P4, particularly as the wavelength approaches 2500 nm. However, although there is a difference in resistivity between P3 and P4, the difference between the curves is decreasing.

  Thus, PEDOT: PSS has a transmittance of 70% or more in the wavelength region of 400 nm or less of light. Further, in the near infrared wavelength region of 800 nm or more of light, the light has a transmittance of 50% or more near the wavelength of 2500 nm, and has a transmittance of 70% or more in the wavelength region close to the visible light region. However, in order to improve the current-voltage characteristics when a forward bias is applied, it is preferable that the resistivity is low, and it is desirable to set it to 1 Ωcm or less.

Next, FIG. 11 is an enlarged view of the range of 0 to 800 nm in the wavelength range of FIG. In FIG. 11, the horizontal axis indicates the wavelength (nm) of light, and the vertical axis indicates the light transmittance (%). SA represents a sapphire substrate, and PE represents a PEDOT: PSS curve. PE corresponds to P4 having a resistivity of 10 ⁻³ Ωcm among the curves P1 to P4 in FIG.

  As shown in the drawing, the ultraviolet light region is further classified into ultraviolet light A (wavelength 320 nm to 400 nm), ultraviolet light B (wavelength 280 nm to 320 nm), and ultraviolet light C (wavelength 280 nm or less). PEDOT: PSS exhibits a transmittance of 80% or more in the ultraviolet light region with a wavelength of less than 400 nm, particularly in the ultraviolet light A and ultraviolet light B regions, indicating that it has excellent translucency. . In the ultraviolet light C region, the absorption due to the C—C bond (C is carbon) in the organic matter increases, and the transmittance decreases rapidly. As described above, when an organic electrode material and a semiconductor bonded thereto are appropriately selected, an ultraviolet light detector or a near infrared light detector can be configured.

  FIG. 12 is a schematic diagram showing a state near the interface between the organic electrode 2 and the GaN semiconductor 1 when light is incident from above. Since the organic electrode and the GaN semiconductor are in a Schottky junction, a Schottky barrier appears, and a depletion layer spreads at the interface between the organic electrode and the GaN semiconductor. When light is irradiated in the vicinity of this depletion layer, as shown in the figure, electrons are excited to the conduction band, and holes remain in the valence band. Electrons are accelerated in the conduction band and flow toward the lower energy level (positive electrode side) as shown by the arrows in the figure, and the holes flow in the reverse direction (negative electrode side). Therefore, the photocurrent flows as a reverse current that flows from the positive electrode to the negative electrode during reverse bias. That is, the organic electrode 2 plays a role as a hole conductor through which holes pass.

Further, as shown in FIG. 13B, it is possible to change the band profile at the interface with GaN by changing the material and the layer structure on the organic electrode side. For example, in PEDOT: PSS, the doping amount of polystyrene sulfonic acid (PSS) is changed, or an acceptor substance such as TCNQ (takes electrons from the other party) or a donor characteristic such as TTF (electrons are delivered to the other party) near the interface. ) Current-voltage characteristics change when materials are used or when self-assembled molecular films (Self-Aligned Molecules: SAMs) are formed. Assuming that the band profile shown by the broken line in FIG. 13B is X, Y and Z band profiles are generated depending on the doping amount of PSS as shown in the figure. Current-voltage characteristics corresponding to these band profiles are shown in FIG. Y represents a case where the resistivity of the organic electrode is higher than X, and Z represents a case where the resistivity of the organic electrode is lower than X. Thus, even if the conduction characteristic on the organic electrode side is changed, under reverse bias, the reverse current of the element in the state where reverse bias of 3 V is applied is 1 nA (10 ⁻⁹ A in the state without light irradiation. ) It can be seen that

FIG. 14 shows the spectral sensitivity characteristics of the photoelectric conversion element of FIG. 1 operating as described above. The horizontal axis represents wavelength (nm), the left vertical axis represents light receiving sensitivity (A / W), and the right vertical axis represents transmittance (%). The light receiving sensitivity is represented by a ratio between an incident light quantity (watts) with respect to the element and a photocurrent (ampere) flowing through the element. The amount of incident light was measured at 16 μW / cm ² .

  In addition, GaN PD is described as a Schottky GaN photoelectric conversion element, and Si PD is described as a light reception sensitivity of a conventional PIN silicon photodiode. TH represents a theoretical curve of light receiving sensitivity. PE represents the light transmittance of PEDOT: PSS, and GA represents the light transmittance of the GaN semiconductor. As can be seen from FIG. 14, in the ultraviolet light A and B regions, the light receiving sensitivity of the GaN PD of the present invention is superior to that of the conventional Si PD. The GaN PD acts as a visible light blind ultraviolet light detector that is not sensitive to visible light. The position of the highest light receiving sensitivity of GaN PD is about 360 nm.

  On the other hand, FIG. 15 shows spectral sensitivity characteristics of the Schottky type ZnO photoelectric conversion element. The meanings of the horizontal axis and the vertical axis in FIG. 15 are the same as those in FIG. 14, and the same reference numerals as those in FIG. What is different from FIG. 14 is the description of ZnO and ZnO PD. What is described as ZnO PD represents the light receiving sensitivity of a Schottky-type ZnO photoelectric conversion element formed so that PEDOT: PSS is in contact with the ZnO substrate. The curve indicated by ZnO in the figure represents the light transmittance of the ZnO semiconductor. As can be seen from the figure, ZnO PD is very similar to the spectral sensitivity characteristic of GaN PD in FIG. 14, but is much closer to the visible light region than GaN PD, and also sensitive in the ultraviolet light region near the wavelength of 400 nm. Have

As described above, an example of a photoelectric conversion element using a Schottky barrier between an organic electrode and a semiconductor is shown in FIG. FIG. 16 shows a configuration example of a Schottky photodiode, and (a) and (b) are those using Si _1-W Ge _W (0 ≦ W ≦ 1) among group IV semiconductors. In particular, it is composed of a Si semiconductor when W = 0. (B) uses an InGaAs semiconductor among III-V semiconductors. The group III-V _{semiconductor, In X (Al Y Ga 1} -Y) 1-X As, In X (Al Y Ga 1-Y) 1-X P, (In X Ga 1-Y) Z (P X As _1-X ) _1-Z may be used, and the InGaAs is included in these.

In FIG. 16A, an organic electrode 23 is formed on an n-type Si substrate 20 with an SiO ₂ film 22 serving as an insulating film interposed therebetween. Here, the organic electrode 23 was made of PEDOT: PSS having a resistivity of 2.5 × 10 ⁻³ Ωcm. The main surface of the n-type Si substrate 20 on which the SiO ₂ film 22 is laminated is constituted by a (111) plane, and the n-type Si substrate 20 has an electron concentration in the range of 10 ¹³ to 10 ¹⁷ cm ^−3. So that it is donor-doped. A p-type impurity doped region 20a is formed at a part of both ends of the n-type Si substrate 20 and is connected to electrodes 24 and 25 for taking out current. The SiO ₂ film 22 is formed in a thickness range of 1 nm to 100 nm.

Here, although no band structure in the SiO ₂ film 22, the opposing n-type Si substrate 20 and the organic electrode 23 sandwiching the SiO ₂ film 22, the band profile as shown in FIG. 11 is generated. Therefore, when light is incident on the depletion layer DP, a photocurrent flows and light can be detected.

On the other hand, FIG. 16B shows the structure of FIG. 16A in which the organic electrode 23 is formed so as to cover either one of the electrodes 24 and 25. In both FIGS. 16A and 16B, a p-type Si substrate may be used instead of the n-type Si substrate 20. The SiO ₂ film 22 is formed to stabilize the interface state, but the n-type Si substrate 20 and the organic electrode 23 may be directly bonded without forming the SiO ₂ film 22.

On the other hand, FIG. 16C shows a slightly different type and structure of the substrate. An organic electrode 23 is directly bonded on the n-type InGaAs layer 30. An n-type GaN layer may be used for 30 instead of the n-type InGaAs layer. The n-type InGaAs layer 30 is donor-doped so that the electron concentration is in the range of 10 ¹³ to 10 ¹⁷ cm ⁻³ . The p-type impurity doped region 30 a is doped with a p-type impurity, and each p-type impurity doped region 30 a is connected to the electrodes 24 and 25. The SiO ₂ film 22 is formed in a thickness range of 1 nm to 100 nm on the surface of the n-type InGaAs layer 30 excluding the region where the organic electrode 23 and the electrodes 24 and 25 are formed. When an InGaAs semiconductor is used as shown in FIG. 16C, light in the near infrared region can be detected by the action of the depletion layer DP.

Next, a photodiode in which the photodetection sensitivity and responsiveness are improved by using a two-dimensional electron gas in a photoelectric conversion element using a group III nitride semiconductor will be described. Group III nitride _{semiconductor, In X (Al Y Ga 1} -Y) composed of _{1-X N (0 ≦ X} ≦ 1,0 ≦ Y ≦ 1,0 ≦ Z ≦ 1) and the like, of which A stacked body of Al _X1 Ga _1-X1 N (0 ≦ X1 <1) and Al _Y1 Ga _1-Y1 N (0 <Y1 ≦ 1) is used. Here, X1 <Y1. Hereinafter, Al _X1 Ga _1-X1 N is referred to as Al _X1 GaN, and Al _Y1 Ga _1-Y1 N is referred to as Al _Y1 GaN.

It is known that a two-dimensional electron gas is generated at the interface between GaN-based semiconductors having different compositions, such as the interface between AlGaN and GaN, and the electron mobility is 14000 cm ² V ^{− at an} absolute temperature of 0.5 Kelvin. ^It has a value of about ¹ s ^-1 . Therefore, if a photocurrent is taken out using a two-dimensional electron gas, a photodiode with high-speed response and high sensitivity can be obtained.

FIG. 17A shows an example of a photoelectric conversion element using a two-dimensional electron gas. On the sapphire substrate 41, an undoped Al _X1 GaN layer 42, an n-type Al _Y1 GaN layer 43, and an organic electrode 44 are formed. In FIG. 17A, the element is formed in a columnar shape, and the outer peripheral portion of the column is mesa-etched until the undoped Al _X1 GaN layer 42 is exposed to form a columnar extraction electrode 46 on the side surface of the column. On the other hand, another extraction electrode 45 is formed at the center of the surface of the organic electrode 44. Here, the organic electrode 44 is made of, for example, PEDOT: PSS with a film thickness of 50 nm. The extraction electrode 45 is made of Au, for example, and the extraction electrode 46 is made of, for example, a metal multilayer film of Ti / Al / Ti / Au from the side in contact with the semiconductor layer.

Even when no bias is applied, a band profile in which Schottky junction is formed between the organic electrode 44 and the n-type Al _Y1 GaN layer 43 is formed as shown in FIG. Is incident, near the depletion layer at the interface, as shown in FIG. 12, electrons are excited to the conduction band, and holes remain in the valence band. Electrons are accelerated in the conduction band and flow to the undoped Al _X1 GaN layer 42 side, and holes flow to the organic electrode 44 side. On the other hand, at the interface between the undoped Al _X1 GaN layer 42 and the n-type Al _Y1 GaN layer 43, as described above, a two-dimensional electron gas region (2DEG) is generated, and electrons are diffused in a planar shape. Therefore, the electrons that have reached the undoped Al _X1 GaN layer 42 are transferred to 2DEG electrons, and the electrons in the 2DEG move in the horizontal direction as indicated by the arrows in FIG. Then, it is taken out from the take-out electrode 46 and detected as a current.

On the other hand, FIG. 17B has substantially the same configuration as FIG. 17A, except that the extraction electrode 47 is provided only on one side surface of the element. For example, when the element shape is not a cylindrical shape but a rectangular parallelepiped, mesa etching is performed on only one side surface until the undoped Al _X1 GaN layer 42 is exposed, and the extraction electrode 47 is provided on the side surface.

Next, FIG. 18 illustrates a configuration example of a photoelectric conversion element using a stacked body of two different compositions of a group III-V semiconductor. As described above, as a type of Group III-V _{semiconductor, In X (Al Y Ga 1} -Y) 1-X As, In X (Al Y Ga 1-Y) 1-X P, (In X Ga 1- _{Y) Z} (although P _X as _1-X) can be any of _{1-Z, these, in X (Al Y Ga 1} -Y) included in the _{1-X as, Al X2 GaAs} , in _{(Al X2 Ga 1-X2)} As, configured with either _{InGa 1-X2} As. If the above-described Al _X2 GaAs, In (Al _X2 Ga ₁ -X ₂ ) As, and InGa ₁ -X ₂ As are called GaAs-based layers, they can be configured as shown in FIG.

  A first GaAs layer 34, a second GaAs layer 35, and an organic electrode 36 are formed on the GaAs substrate 33. An AuGe / Ni film 32 and a Ti / Au film 31 are formed on the back surface of the GaAs substrate 33 as electrodes. On the other hand, an Au film 37 is formed on the organic electrode 36 as an electrode.

The first GaAs-based layer 34 and the second GaAs-based layer 35 are composed of different compositions. For example, if the first GaAs-based layer 34 represents one of n-type Al _X2 GaAs, n-type In (Al _X2 Ga _1-X2 ) As, and n-type InGa _1-X2 As, the second GaAs-based layer 35 is It is represented by n-type Al _X3 GaAs, n-type In (Al _X3 Ga _1-X3 ) As, n-type InGa _1-X3 As, and has a relationship of 0 ≦ X2 <1, 0 <X3 ≦ 1, and X2 <X3. is doing.

  The organic electrode 36 is made of PEDOT: PSS with a film thickness of 50 nm, for example. Here, the light absorption is mainly performed in the second GaAs-based layer 35 and converted into a current. The first GaAs-based layer 34 is for providing a potential gradient so that electrons generated by photoelectric conversion easily flow to the AuGe / Ni film 32 side.

Next, FIG. 19 illustrates a configuration example of a photoelectric conversion element using a stacked body of two different compositions of a group IV semiconductor. As a kind of group IV semiconductor, Si _1-W Ge _W (0 ≦ W ≦ 1) can be used, which is formed by stacking SiGe layers having different compositions. On the n-type Si substrate 52, an undoped Ge _X4 Si layer 53, an n-type Ge _Y4 Si layer 54, and an organic electrode 55 are sequentially stacked. An Au film 56 is formed as an electrode on the organic electrode 55, and an Al film 51 is also formed as an electrode on the back surface of the n-type Si substrate 52.

The organic electrode 55 is made of PEDOT: PSS with a film thickness of 50 nm, for example. Light absorption is mainly performed in the n-type Ge _Y4 Si layer 54 and converted into a current. The undoped Ge _X4 Si layer 53 is for providing a potential gradient so that electrons generated by photoelectric conversion easily flow to the Al film 51 side. When the Ge concentration of the upper GeSi layer (n-type Ge _Y4 Si layer 54) is high, the lower GeSi layer (undoped Ge _X4 Si layer 53) has a concentration gradient. For example, the Ge concentration is increased in order from the substrate toward the upper GeSi layer. In this case, although it is a two-layer laminate, it is preferable to form a plurality of GeSi layers so as to increase the Ge concentration stepwise so that the upper GeSi layer can be grown with good crystallinity.

  The present invention is not limited to the embodiment described above, and modifications including combinations of elements of each configuration example are also included in the scope of the present invention.

  Next, an example of a photoelectric conversion element using a ZnO-based semiconductor that is one type of inorganic semiconductor will be described. The spectral sensitivity characteristic of the Schottky-type ZnO photoelectric conversion element has already been shown and described with reference to FIG. 15. The basic configuration of this photoelectric conversion element is shown in FIG.

  An organic electrode 62 is formed on the ZnO-based semiconductor 61, and a metal film 63 used for wire bonding or the like, for example, an Au film is formed on the organic electrode 62. On the other hand, an electrode made of a multilayer metal film of a Ti film 64 and an Au film 65 is formed on the back surface of the ZnO-based semiconductor 61 so as to face the organic electrode 62. The ZnO-based semiconductor 61 is composed of ZnO or a compound containing ZnO. Specific examples include ZnO, IIA group element and Zn, IIB group element and Zn, or IIA group element and IIB group element. There are those containing each oxide of Zn.

  As an example corresponding to FIG. 20, the ZnO-based semiconductor 61 is formed of an n-type ZnO substrate. The organic electrode 62 is made of PEDOT: PSS with a film thickness of 50 nm. The same logic holds even if the GaN semiconductor in the energy band diagram of FIG. 2 is replaced with a ZnO-based semiconductor, and the semiconductor element of FIG. 20 has a rectifying action like a diode. When used as a diode, as shown by the solid connection line in FIG. 20, the metal film 63 is connected to the + side of the DC power supply and the Au film 65 is connected to the − side of the DC power supply to be forward biased.

On the other hand, when used as a photodiode or the like which is a photoelectric conversion element, the metal film 63 is connected to the negative side of the DC power source and the Au film 65 is connected to the positive side of the DC power source as shown by the broken line in FIG. . Since PEDOT: PSS and ZnO are in Schottky contact, the same holds true even if the GaN semiconductor is replaced with a ZnO-based semiconductor in the description of FIG. Therefore, the organic electrode 62 in the ZnO-based photoelectric conversion element plays a role as a hole conductor. In addition, the current-voltage characteristics shown in FIG. 13A and the band profile of FIG. 13B can be explained in the same way for the ZnO-based semiconductor, so that the conduction characteristics on the organic electrode side are changed. However, under the reverse bias, the reverse current of the element in the state where the reverse bias of 3 V is applied is 1 nA (10 ⁻⁹ A) or less in the absence of light irradiation.

As a specific configuration, the photoelectric conversion element shown in FIG. 21 can be used. FIG. 21 shows an application example of the basic structure of FIG. The same reference numerals as those in FIG. 20 represent the same configurations. FIG. 21A shows an example in which an n-type Mg _Z1 Zn _{1 -Z1} O (0 ≦ Z1 <1) layer 72 formed on an n-type ZnO substrate 71 is used as a ZnO-based semiconductor in contact with the organic electrode 62. is there. A stacked body of the n-type ZnO substrate 71 and the n-type Mg _Z1 Zn _{1 -Z1} O (0 ≦ Z1 <1) layer 72 corresponds to the ZnO-based semiconductor 61. On the other hand, FIG. 21B shows that the p-type MgZnO layer 73 is formed in contact with the n-type MgZnO layer 72 in the structure of FIG. It is a small one. The manufacturing method of this photoelectric conversion element is demonstrated below.

After the n-type ZnO substrate 71 is treated with thin hydrochloric acid and heated, an n-type MgZnO layer 72 having a carrier concentration of 1 × 10 ¹⁷ cm ⁻³ or less, for example, is grown. Mg is added to widen the band gap. MBE (molecular beam epitaxy) was used as a method for forming a thin film of the n-type MgZnO layer 72. In addition to MBE, CVD (chemical vapor deposition), MOCVD (metal organic chemical vapor deposition), PLD (pulse laser deposition), and the like are also applicable.

As the growth substrate, the + C plane of the n-type ZnO substrate 71 was used. In addition, the oxygen polar plane and the M plane of the ZnO substrate can be used. In addition to the ZnO substrate, a sapphire substrate (C surface, A surface, R surface), a ScAlMgO ₄ substrate, or the like can also be used. The growth substrate is held at 250 ° C. for 20 minutes in a preheating chamber. It is then transported to the growth chamber and heated to 800 ° C. and then kept at the growth temperature. The growth temperature is 300 to 1000 ° C. The main raw materials used were Zn (purity 99.99999%) and oxygen gas (purity 99.99999%). Nitrogen gas was used as a raw material for the p-type dopant. In addition, ozone (O ₃ ), nitrogen dioxide (NO ₂ ), dinitrogen monoxide (N ₂ O), nitrogen monoxide (NO), and the like are also suitable as the gas used for the raw material.

  Zn is heated to 250 to 350 ° C. in the crucible of the K cell and supplied to the growth substrate surface. When Mg is used, it is heated to 300 to 400 ° C. in the crucible of the K cell similarly to Zn and supplied to the growth substrate surface. Oxygen gas reaches the growth substrate surface through each radical cell. In the radical cell, a high frequency is applied, and the gas is in a plasma state and has a high chemical activity. A high frequency of 13.56 MHz and an output of 300 to 400 W are applied, but other frequencies (2.4 GHz) and outputs (50 W to 2 kW) are also applicable. The oxygen gas was 0.3-3 sccm, and the flow rate of nitrogen gas was 0.2-1 sccm.

  As described above, an n-type MgZnO layer and a p-type MgZnO layer are formed. Thereafter, an organic electrode, a metal film, and the like are formed as in the manufacturing method of FIG. By the way, in the case of FIG. 21B, after forming the p-type MgZnO layer 73, an opening is formed by etching. After that, it is manufactured by the same method as the step of forming the organic electrode in FIG. 9, but the organic electrode 62 is placed on a part of the p-type MgZnO layer 73. By doing so, the leak can be reduced. In order to form p-type ZnO such as the p-type MgZnO layer 73, the + C plane is desirable. In addition, it can produce by the method shown by "A. Tsukazaki et al Nature Material 4 (2005) 42" also on -C side.

Here, the use of photoelectric conversion element of FIG. 21, by changing the n-type _{Mg Z1 Zn 1-Z1 O (} 0 ≦ Z1 <1) layer 72 of Mg composition Z1, well region of the ultraviolet light A, It will be described below that the ultraviolet light detector can be configured as an ultraviolet light detector that can also individually measure the ultraviolet light B and ultraviolet light C regions.

The characteristics of PEDOT: PSS used for the organic electrode 62 have already been described with reference to FIGS. 10 and 11 and will not be described in detail. However, PEDOT: PSS transmits 70% or more of light in a wavelength region of 400 nm or less. Have a rate. FIG. 22 shows spectral sensitivity characteristics when _{Z1 of the} n-type Mg _Z1 Zn _{1 -Z1} O layer 72 is changed. As described above, the ultraviolet light region is classified into ultraviolet light A (wavelength greater than 320 nm and less than or equal to 400 nm), ultraviolet light B (wavelength greater than 280 nm and less than or equal to 320 nm), and ultraviolet light C (wavelength less than 280 nm). The horizontal axis represents wavelength (nm), and the vertical axis represents light receiving sensitivity (A / W). The light receiving sensitivity is represented by a ratio between an incident light quantity (watts) with respect to the element and a photocurrent (ampere) flowing through the element. The amount of incident light was measured at 16 μW / cm ² . In addition, the Schottky type ZnO photoelectric conversion element of FIG. 21 was measured in a state where neither forward bias nor reverse bias was applied, that is, bias 0.

  Si PIN PD indicates the light receiving sensitivity of a conventional PIN type silicon photodiode, and Q.E. = 100% indicates the light receiving sensitivity theoretical curve, that is, the light receiving sensitivity when the internal quantum efficiency is 100%. In other curves, the Mg composition Z1 of the Schottky-type ZnO-based photoelectric conversion element was changed in seven stages, 0, 0.10, 0.16, 0.31, 0.43, 0.50, and 0.57. In this case, the light receiving sensitivity is shown.

FIG. 23 is an enlarged view of the range of 200 nm to 500 nm in the wavelength range of FIG. The horizontal axis represents wavelength (nm), the left vertical axis represents light receiving sensitivity (A / W), and the right vertical axis represents transmittance (%). In this figure, PEDOT indicates a transmittance curve with respect to the wavelength of PEDOT: PSS. If attention is paid only to the curve of Mg composition Z1 = 0 in FIG. 23, it becomes the same as the graph of FIG. As can be seen from FIGS. 22 and 23, the Schottky-type ZnO photoelectric conversion element has a light receiving sensitivity of less than 10 ⁻³ A / W in the wavelength region exceeding 400 nm and is substantially 0, and receives light in the wavelength region below 400 nm. It has a wavelength range where the sensitivity is 10 ⁻³ A / W or more.

  Now, as the Mg composition Z1 increases, the band gap of MgZnO increases, so that the absorption wavelength decreases. The Schottky-type ZnO-based photoelectric conversion element acts as a visible light blind ultraviolet light detector that does not react to visible light exceeding 400 nm. On the other hand, it can be seen that the wavelength width of the light receiving sensitivity is greatest when the Mg composition Z1 is 0, and becomes narrower as the Mg composition Z1 increases. When the Mg composition Z1 is about 0.16, the sensitivity is still in a part of the wavelength range of the ultraviolet light A, but when Z1 is 0.31, the sensitivity to the ultraviolet light A region is almost zero. Further, when Z1 is 0.50, there is no sensitivity to the ultraviolet light A, and the sensitivity to the ultraviolet light B is almost zero. Thus, by changing the Mg composition Z1, the boundary wavelength on the visible light side of the spectral width in the sensitivity characteristic curve can be changed, and by combining these, the ultraviolet light A, B, C can be detected respectively. Is possible.

FIG. 24 shows the relationship between the Mg content (Z1) of Mg _Z1 Zn _{1 -Z1} O, the band gap energy, and the wavelength. The horizontal axis indicates the Mg content of Mg _Z1 Zn _{1 -Z1} O, the left vertical axis indicates the band gap energy (eV), and the right vertical axis indicates the absorption wavelength (nm). Here, the absorption wavelength represents a band gap equivalent wavelength. Further, λ_resp1 / 2 indicates a boundary wavelength on the long wavelength side where the sensitivity is ½ of the maximum sensitivity, and λ_resp1 / 10 indicates a boundary wavelength on the long wavelength side where the sensitivity is 1/10 of the maximum sensitivity.

  As the Mg composition Z1 increases, the boundary wavelength also increases. At the position of M1, the boundary wavelength of λ_resp1 / 2 is the boundary between the ultraviolet light A region and the ultraviolet light B region. M1 represents Z1 = 0.25. Therefore, if Z1 is set to 0.25 or more, a wavelength of 320 nm or less can be detected. On the other hand, at the position of M2, the boundary wavelength of λ_resp1 / 2 is the boundary between the ultraviolet light B region and the ultraviolet light C region. M1 indicates Z1 = 0.5. Therefore, if Z1 is 0.5 or more, a wavelength of 280 nm or less can be detected.

As described above, by changing the Mg composition of Mg Z1 _{Zn 1-Z1 O} layer formed in contact with the organic electrode, it is possible to change the absorption wavelength region of the photoelectric conversion element. Therefore, by changing the Mg composition and setting the boundary wavelength of the absorption wavelength region to 400 nm, which is the boundary between the ultraviolet light A and the visible light wavelength region, wavelengths up to the ultraviolet light A, B, and C wavelength regions can be detected. . In addition, by changing the Mg composition and setting the boundary wavelength of the absorption wavelength region to 320 nm, which is the boundary between the ultraviolet light A and the ultraviolet light B, the wavelengths up to the ultraviolet light B and C wavelength regions can be detected. Further, by changing the Mg composition and setting the boundary wavelength of the absorption wavelength region to 280 nm, which is the boundary between the ultraviolet light B and the ultraviolet light C, the wavelength in the wavelength region of the ultraviolet light C can be detected.

  On the other hand, for comparison, FIG. 25 shows spectral sensitivity characteristics of an AlGaN-PIN photodiode as an example of a GaN-based photoelectric conversion element. This is a quotation from “E. Munoz et al., Phys. Stat. Sol. (B) 244 (2007) 2859” as shown in FIG. As introduced in the paper, the AlGaN-PIN photodiode has a structure in which an undoped AlGaN layer is sandwiched between a Mg-doped AlGaN layer and a Si-doped AlGaN layer. The spectral sensitivity characteristics when the Al content of the AlGaN layer is changed to 0%, 15%, 30%, 45%, and 70% are shown. As the Al composition is increased, the spectrum width is reduced and the boundary wavelength of the absorption wavelength region is also reduced. However, when the Al composition is around 45% or 70% indicated by F, the spectral shape is disturbed, and the sensitivity suddenly increases. This is considered to be a composition variation in AlGaN, which is not preferable for use as an ultraviolet light detector.

FIG. 26 shows spectral sensitivity characteristics when a reverse bias is applied to the AlGaN-PIN photodiode. This is a quotation from “T. Tut et al., APL92 (2008) 103502” as shown in FIG. As introduced in the paper, the AlGaN-PIN photodiode basically has an AlN layer, an undoped Al _0.4 Ga _0.6 N layer, and a Si-doped Al _0.4 Ga _0.6 N layer on the substrate. It has a stacked structure in which a layer, an undoped Al _0.4 Ga _0.6 N layer, and an Mg-doped Al _0.4 Ga _0.6 N layer are stacked in this order. The Al composition of the AlGaN layer is close to 40%. In addition, the spectral sensitivity characteristics of the case where the Mg _Z1 Zn _1-Z1 O layer of the Schottky-type ZnO-based photoelectric conversion element of the present invention is Mg _0.57 ZnO and Mg _0.50 ZnO are also shown. ing. The Schottky-type ZnO-based photoelectric conversion element is in a state where no bias is applied.

  In the Schottky type ZnO photoelectric conversion element, the spectrum shape covers the wavelength range of the ultraviolet light C, but in the AlGaN-PIN photodiode, the spectrum shape is disturbed. At reverse bias 0, the absorption wavelength region is very narrow. When the reverse bias is lowered to −40 V, the spectral shape is improved, but the light receiving sensitivity is inferior to that of the Schottky-type ZnO photoelectric conversion element. Therefore, in particular, when detecting the ultraviolet light C, a Schottky-type ZnO-based photodiode is preferable.

It is a figure which shows an example of the cross-sectional structure in the semiconductor element of this invention. It is a figure which shows the energy band in the junction interface area | region of a semiconductor and an organic substance electrode. In the semiconductor element of this invention, it is a figure which shows the voltage-current characteristic at the time of sweeping the voltage applied between a semiconductor and an organic substance electrode. It is a figure which shows the cross-section of the semiconductor element used for the measurement of the voltage-current characteristic of FIG. It is a figure which shows the chemical structural formula of a polythiophene derivative and polystyrene sulfonic acid. It is a figure which shows the chemical structural formula of a polyaniline derivative. It is a figure which shows the chemical structural formula of a polypyrrole derivative. It is a figure which shows the other cross-section of a semiconductor element. It is a figure which shows the manufacturing process of the semiconductor element of this invention. It is a figure which shows the wavelength dependence of the light transmittance and reflectance of PEDOT: PSS. It is the figure which expanded the part below wavelength 800nm of FIG. It is a figure which shows the state of the interface vicinity of an organic substance electrode and GaN. It is a figure which shows a band profile and a voltage-current characteristic when changing the conduction characteristic of an organic substance electrode. It is a figure which shows each spectral sensitivity characteristic of a GaN photoelectric conversion element and the conventional Si photodiode. It is a figure which shows each spectral sensitivity characteristic of a ZnO photoelectric conversion element and the conventional Si photodiode. It is a figure which shows an example of a photoelectric conversion element with the semiconductor element of this invention. It is a figure which shows an example of a photoelectric conversion element with the semiconductor element of this invention. It is a figure which shows an example of a photoelectric conversion element with the semiconductor element of this invention. It is a figure which shows an example of a photoelectric conversion element with the semiconductor element of this invention. It is a figure which shows the example of a basic structure of a ZnO type photoelectric conversion element. It is a figure which shows the specific structural example of a ZnO type photoelectric conversion element. It is a figure which shows the spectral sensitivity characteristic at the time of changing Mg composition of a ZnO type photoelectric conversion element. It is the figure which expanded the area | region of wavelength 200nm-500nm of FIG. It is a figure which shows the relationship between Mg composition and absorption wavelength of MgZnO. It is a figure which shows the spectral sensitivity characteristic at the time of changing Al composition of an AlGaN-PIN photodiode. It is a figure which shows the spectral sensitivity characteristic when the reverse bias of an AlGaN-PIN photodiode is changed.

Explanation of symbols

1 GaN Semiconductor 2 Organic Electrode 3 Au Film 4 Ti Film 5 Au Film 6 Substrate

Claims (25)

  An organic electrode is formed in contact with any one of a group IV semiconductor, a group III-V semiconductor, or a group III nitride semiconductor, and has a rectifying characteristic between the semiconductor and the organic electrode.   The semiconductor element according to claim 1, wherein a work function of the organic electrode is larger than an electron affinity of the semiconductor.   The semiconductor element according to claim 1, wherein a main surface of the semiconductor in contact with the organic electrode is a + C plane.   The semiconductor element according to claim 1, wherein at least a part of the organic electrode is made of a conductive polymer.   The semiconductor element according to claim 4, wherein a resistivity of the organic electrode is 1 Ωcm or less.   The semiconductor element according to claim 4, wherein the conductive polymer is composed of at least one of a polyaniline derivative, a polypyrrole derivative, and a polythiophene derivative.   The semiconductor device according to claim 6, wherein the polyaniline derivative, the polypyrrole derivative, and the polythiophene derivative each contain a carrier dopant.   The semiconductor element according to claim 1, wherein the organic electrode has translucency in an ultraviolet light region and an infrared light region.   9. The semiconductor device according to claim 8, wherein the organic electrode is made of a hole conductor.   The reverse current is 1 nanoampere or less in a state in which 3 volts is applied in a reverse bias state in which a negative voltage is applied to the organic electrode side of the semiconductor element and no light is irradiated. Item 10. The semiconductor element according to Item 9.   The said semiconductor element is a photoelectric conversion element, The semiconductor element of any one of Claims 8-10 characterized by the above-mentioned.   8. The device according to claim 1, wherein at least one layer of the semiconductor is formed on a substrate, the organic electrode functions as a Schottky gate electrode, and has a transistor function. Semiconductor element. For the Group III-V _{semiconductor, In X (Al Y Ga 1} -Y) 1-X As, In X (Al Y Ga 1-Y) 1-X P, (In X Ga 1-Y) Z (P _X As _1-X ) _1-Z , Group III nitride semiconductors are composed of In _X (Al _Y Ga _1-Y ) _1-X N, and 0 ≦ X ≦ 1, 0 ≦ Y The semiconductor element according to claim 1, wherein ≦ 1, 0 ≦ Z ≦ 1 is satisfied.   14. The semiconductor element according to claim 13, wherein the group III-V semiconductor or group III nitride semiconductor is formed of a stacked body in which semiconductors having at least two different compositions are stacked. The group IV _{semiconductor, Si 1-W Ge W (} 0 ≦ W ≦ 1) or a different composition Si _1-W Ge _W of claims 1 to 12, characterized in that it is constituted by a laminate of The semiconductor element of any one of Claims.   The semiconductor element according to any one of claims 13 to 15, wherein an electron accumulation region generated at an interface of the stacked body is a channel region.   17. The semiconductor device according to claim 16, wherein electrons generated by a photoelectric conversion action are taken out through the electron storage region.   An organic electrode is formed in contact with an inorganic semiconductor, and has a rectifying characteristic between the inorganic semiconductor and the organic electrode. The inorganic semiconductor functions as a photoelectric conversion layer formed of _{Mg Z1 Zn 1-Z1 O (} 0 ≦ Z1 <1), and the organic electrode has a light-transmitting property, a bias is applied to the organic electrode The light receiving sensitivity is substantially 0 in a wavelength region exceeding 400 nm, and has a wavelength region in which the light receiving sensitivity is 10 ⁻³ A / W or more in a wavelength region of 400 nm or less. The semiconductor element as described. The Mg composition Z1 is configured so that the photoelectric conversion possible wavelength in the MgZnO is in the range of 280 nm to 400 nm in the wavelength region where the light receiving sensitivity is 10 ⁻³ A / W or more. The semiconductor element as described in. 21. The semiconductor element according to claim 20, wherein the Mg composition Z1 of the Mg _Z1 Zn _{1 -Z1} O is 0.25 or more, and the photoelectric conversion wavelength is 320 nm. 21. The semiconductor device according to claim 20, wherein the Mg composition Z1 of the Mg _Z1 Zn _{1 -Z1} O is 0.45 or more, and the photoelectric conversion wavelength is 280 nm.   The semiconductor element according to any one of claims 19 to 22, wherein the organic electrode is made of a hole conductor.   24. The reverse current is 1 nanoampere or less when 3 volts is applied in a reverse bias state in which a negative voltage is applied to the organic electrode side of the semiconductor element and no light is irradiated. Semiconductor element. The Mg _Z1 Zn _1-Z1 O is, 0 <Z1 <semiconductor device according to any one of claims 19 to claim 24, characterized in that it is constituted by one.

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