JP2013183012A - Photoelectric conversion device and manufacturing method thereof and photoelectric conversion module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photoelectric conversion device which exhibits excellent photoelectric conversion efficiency achieved by improving the conductivity of connections made via a transparent conductive oxide film in a photoelectric conversion device, as well as a manufacturing method therefor and a photoelectric conversion module.SOLUTION: The photoelectric conversion device comprises a photoelectric conversion layer including at least a p-type semiconductor layer 6d and an n-type semiconductor layer 4d and at least one side of a laminate structure in the p-type semiconductor layer 6d having an n-type transparent conductive oxide film layer 5b disposed between a p-type transparent conductive oxide film layer 5a disposed on the opposite side of the n-type semiconductor layer 4d and the p-type semiconductor layer 6d in proximity to the p-type semiconductor layer 6d and the p-type transparent conductive oxide film layer 5a and a laminate structure in the n-type semiconductor layer 4d having the p-type transparent conductive oxide film layer 5a disposed between the n-type transparent conductive oxide film layer 5b disposed on the opposite side of the p-type semiconductor layer 6d and the n-type semiconductor layer 4d in proximity to the n-type semiconductor layer 4d and the n-type transparent conductive oxide film layer 5b.

Description

  The present invention relates to a photoelectric conversion device that converts light energy into electrical energy, a manufacturing method thereof, and a photoelectric conversion module.

  In a photoelectric conversion device that converts light energy into electric energy, a stacked thin film solar cell in which a plurality of thin film photoelectric conversion layers having different light absorption wavelength characteristics are stacked is known in order to increase photoelectric conversion efficiency. In such a conventional laminated thin film solar cell, for example, a photoelectric conversion element comprising a photoelectric conversion layer in which a thin film semiconductor is deposited in the order of a p-type layer, an i-type layer, and an n-type layer on an insulating transparent substrate on which a transparent electrode is formed. Are stacked. Then, a reflective conductive film is formed as a back electrode, and a photovoltaic force is generated by light incidence from the insulating transparent substrate side.

  In order to transmit current between the plurality of stacked photoelectric conversion elements without any delay, an intermediate layer having conductivity is inserted between each of the photoelectric conversion elements. As the intermediate layer, a material having an optical characteristic of reflecting or transmitting light in a specific wavelength region may be used. For example, as disclosed in Patent Document 1, a GaAs compound semiconductor has a low resistance structure that uses a tunnel junction formed by a high electron concentration n layer having a wide band gap and a high hole concentration p layer as an intermediate layer. Yes.

On the other hand, in the Si-based photoelectric conversion element that is most widely used in general homes and the like, there is no intermediate layer using such a wide band gap tunnel junction. As a Si-based photoelectric conversion element, Patent Document 2 discloses that n-type transparent conductive oxide (TCO) -based ZnO, ITO, or SnO ₂ is used as an intermediate layer material.

  According to the technique disclosed in Patent Document 2, in the junction between n-type Si and an n-type transparent conductive oxide, an n-n junction in which n-types are joined (hereinafter, p-type in which p-types are joined together). Together with the −p junction, these same conductivity type junctions are referred to as isotype junctions). Further, in the junction of p-type Si and n-type transparent conductive oxide, a p-n junction in which p-type and n-type are joined (hereinafter referred to as an n-p junction in which n-type and p-type are joined). In addition, junctions of different conductivity types are referred to as an anisotype junction).

Further, according to the technique disclosed in Patent Document 3, a technique using an n-p junction of an n-type transparent conductive oxide and a p-type transparent conductive oxide as an intermediate layer is disclosed. The technique disclosed in Patent Document 3 forms n-type transparent conductive oxide and p-type transparent conductive oxide isotype junctions on n-type Si and p-type Si, respectively. Is an anisotype junction, and this technology can reduce the junction resistance to a level of 300 mΩcm ² or less.

Japanese Patent Application Laid-Open No. 06-061513 JP 2006-120747 A JP 2011-181608 A

  By the way, in an anisotype junction, tunnel generation and recombination are promoted by controlling carrier doping to generate sufficient carriers up to the junction interface, thereby reducing junction resistance. On the other hand, in the isotype junction, depending on the combination of the band gap and ionization potential of the material to be used, a potential barrier is generated at the band connection portion, which causes a problem that the interface resistance cannot be sufficiently reduced.

  Furthermore, when lattice defects or interface states occur at the interface, the potential barrier becomes higher because the band is deformed so that the energy level here approaches the Fermi level, and the junction resistance tends to increase as the interface state increases. Occurs.

For this reason, it has been found that when the overall junction resistance is reduced to a level of 100 mΩcm ² or less, the isotype junction portion becomes a bottleneck and difficulty in reducing the resistance may occur. As a result, the output voltage is lowered by the connection resistance (junction resistance) of the intermediate layer, particularly when the current that is collected and generated is large, and the light conversion efficiency of the photoelectric conversion device may decrease. was there.

  Further, even in a single-layer photoelectric conversion device including a single photoelectric conversion layer, in the connection resistance with the photoelectric conversion layer when a transparent conductive oxide film is used as a transparent electrode, the isotype junction is similarly a bottleneck. Thus, it may be difficult to reduce the resistance.

  The present invention has been made in view of the above, a photoelectric conversion device having improved photoelectric conversion efficiency by improving the conductivity of the connection through the transparent conductive oxide film in the photoelectric conversion device, and a manufacturing method thereof, and An object is to obtain a photoelectric conversion module.

  In order to solve the above-described problems and achieve the object, a photoelectric conversion device according to the present invention includes a photoelectric conversion layer having at least a p-type semiconductor layer and an n-type semiconductor layer, and the n-type in the p-type semiconductor layer. An n-type transparent conductive film is in contact with the p-type semiconductor layer and the p-type transparent conductive oxide film layer between a p-type transparent conductive oxide film layer disposed on the opposite side of the semiconductor layer and the p-type semiconductor layer. A stacked structure in which an oxide film layer is disposed, or the n-type semiconductor layer between the n-type semiconductor layer and the n-type transparent conductive oxide film layer disposed on the opposite side to the p-type semiconductor layer in the n-type semiconductor layer. It comprises at least one of a semiconductor layer and a laminated structure in which a p-type transparent conductive oxide film layer is disposed in contact with the n-type transparent conductive oxide film layer.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the electroconductivity of the connection through the transparent conductive oxide film in a photoelectric conversion apparatus can be improved, and photoelectric conversion efficiency can be improved.

FIG. 1 is a cross-sectional view showing a schematic configuration of a first embodiment of a photoelectric conversion device according to the present invention. FIG. 2 is a diagram for explaining a layer in the vicinity of the intermediate layer shown in FIG. 1, FIG. 2 (a) is an enlarged view of the layer in the vicinity of the intermediate layer, and FIG. 2 (b) is a diagram in FIG. It is a figure which shows the energy band of each layer shown by a). 3A and 3B are diagrams for explaining the configuration in the vicinity of the intermediate layer of the conventional structure. FIG. 3A is an enlarged view of the layer in the vicinity of the intermediate layer of the conventional structure, and FIG. It is a figure which shows the energy band of each layer shown by (a). FIG. 4 is a characteristic diagram showing an experimental result of evaluating the connection resistivity in the intermediate layer structure according to the second embodiment of the present invention using a model element. FIG. 5 is a diagram illustrating a structure of a model element for measuring connection resistance in the intermediate layer structure according to the second embodiment of the present invention. FIG. 6 is a sectional view showing a schematic configuration of Embodiment 3 of the photoelectric conversion apparatus according to the present invention. FIG. 7: is sectional drawing which shows the manufacturing method of the photoelectric conversion apparatus concerning Embodiment 3 of this invention.

  Embodiments of a photoelectric conversion device, a manufacturing method thereof, and a photoelectric conversion module according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view showing a schematic configuration of a first embodiment of a photoelectric conversion device according to the present invention. In FIG. 1, a photoelectric conversion device 1 includes a transparent electrode 3 having a surface texture structure that is fine irregularities, an amorphous Si photoelectric conversion layer 4, an intermediate layer 5 on an insulating and translucent substrate 2. A microcrystalline Si photoelectric conversion layer 6 and a back electrode 7 are sequentially stacked. An undercoat layer 8 may be formed on the substrate 2 as an impurity blocking layer as necessary. Note that a silicon oxide film can be used as the material of the undercoat layer 8.

  Both the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6 are mainly composed of Si, but have different band gaps due to differences in crystal structures, and thus have different light absorption wavelength characteristics. In this photoelectric conversion device 1, the power generation element of the amorphous Si photoelectric conversion layer 4 and the power generation element of the microcrystalline Si photoelectric conversion layer 6 are connected in series in the stacking direction. When light enters from the substrate 2 side, a voltage is generated in the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6, and the electric power is extracted from the transparent electrode 3 and the back electrode 7.

  This photoelectric conversion device 1 constitutes a tandem solar cell. The photoelectric conversion device 1 includes an amorphous Si photoelectric conversion layer 4 having a large band gap that absorbs light of a short wavelength mainly on the light incident side and converts the light into electric energy, and an amorphous Si photoelectric conversion on the back side. A microcrystalline Si photoelectric conversion layer 6 having a small band gap that absorbs light having a wavelength longer than that of the conversion layer 4 and converts the light into electric energy is disposed.

  In the first embodiment, the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6 are used in order to make the light absorption wavelength characteristics of the stacked photoelectric conversion layers different, and the crystallization rate is mutually changed. Although the method of making it different was demonstrated, you may make it make the elemental composition of a photoelectric converting layer mutually differ. For example, the ratio of Ge or C added to the Si semiconductor layer may be changed, and the band gap may be adjusted to adjust the light absorption wavelength characteristics of the stacked photoelectric conversion layers. In addition, three or more photoelectric conversion layers may be stacked. In that case, it is good also as a structure which has two or more so that the intermediate | middle layer 5 may exist between each photoelectric converting layer. Alternatively, the stacking order from the substrate 2 may be reversed, and light may be incident from the film surface side opposite to the substrate 2. When light is incident from the film surface side, the substrate 2 does not have to be transparent.

  The amorphous Si photoelectric conversion layer 4 is a layer in which a p-type amorphous Si semiconductor layer 4a, an i-type amorphous Si semiconductor layer 4b, and an n-type amorphous Si semiconductor layer 4c are stacked in this order from the substrate 2 side. It is configured. Further, an i-type amorphous Si semiconductor layer may be inserted between the p-type amorphous Si semiconductor layer 4a and the i-type amorphous Si semiconductor layer 4b. The microcrystalline Si photoelectric conversion layer 6 is composed of a layer in which a p-type microcrystalline Si semiconductor layer 6a, an i-type microcrystalline Si semiconductor layer 6b, and an n-type microcrystalline Si semiconductor layer 6c are stacked in this order from the substrate 2 side. Yes.

  An n-type amorphous Si semiconductor layer 4d having a carrier density higher than that of the n-type amorphous Si semiconductor layer 4c may be inserted between the intermediate layer 5 and the n-type amorphous Si semiconductor layer 4c. Good. Further, a p-type microcrystalline Si semiconductor layer 6d having a carrier density higher than that of the p-type microcrystalline Si semiconductor layer 6a may be inserted between the intermediate layer 5 and the p-type microcrystalline Si semiconductor layer 6a. Here, a case where the n-type amorphous Si semiconductor layer 4d and the p-type microcrystalline Si semiconductor layer 6d are provided will be described as an example.

  For the back electrode 7, for example, a metal having high reflectivity such as Al or Al alloy is used. Ag may be used instead of Al. When the back electrode 7 having excellent reflection performance is used, the light transmitted through the microcrystalline Si photoelectric conversion layer 6 is reflected again by the back electrode 7 toward the microcrystalline Si photoelectric conversion layer 6 and is photoelectrically converted, thereby improving the conversion efficiency. To do. A transparent conductive layer 11 such as ZnO having appropriate optical characteristics is provided between the back electrode 7 and the n-type microcrystalline Si semiconductor layer 6c as shown in FIG. It may be inserted. In addition, about structures other than the intermediate | middle layer 5 shown below, it laminates | stacks sequentially on the board | substrate 2 by a conventionally well-known method.

  Between the n-type amorphous Si semiconductor layer 4d of the amorphous Si photoelectric conversion layer 4 and the p-type microcrystalline Si semiconductor layer 6d of the microcrystalline Si photoelectric conversion layer 6, there is an n-type amorphous Si semiconductor layer 4d. An intermediate layer 5 in which a p-type transparent conductive oxide film layer 5a and an n-type transparent conductive oxide film layer 5b are stacked in this order is disposed. That is, the p-type transparent conductive oxide film layer 5a is in contact with the n-type amorphous Si semiconductor layer 4d. Further, the n-type transparent conductive oxide film layer 5b is in contact with the p-type microcrystalline Si semiconductor layer 6d. The p-type transparent conductive oxide film layer 5a is in contact with the n-type transparent conductive oxide film layer 5b.

  The intermediate layer 5 is a layer sandwiched between the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6. The intermediate layer 5 needs to transmit light that has not been absorbed by the amorphous Si photoelectric conversion layer 4 to the microcrystalline Si photoelectric conversion layer 6 side. For this reason, the band gap of the intermediate layer 5 needs to be at least wider than the band gap of the amorphous Si photoelectric conversion layer 4. For this reason, the intermediate layer 5 needs a band gap of 1.7 eV or more, preferably 2.0 eV or more here.

  At the same time, the intermediate layer 5 needs to electrically connect the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6. The intermediate layer 5 transmits light in the wavelength region absorbed by the microcrystalline Si photoelectric conversion layer 6, while the light in the wavelength region absorbed by the amorphous Si photoelectric conversion layer 4 transmits the light in the amorphous Si photoelectric conversion layer 4 side. If the optical characteristic is reflected, the light passing through the amorphous Si photoelectric conversion layer 4 passes through the amorphous Si photoelectric conversion layer 4 again and undergoes photoelectric conversion, so that the conversion efficiency is improved.

  Since the intermediate layer 5 must transmit carriers between the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6 bonded to both sides of the intermediate layer 5 without any delay, carrier conductivity is essential. If carrier conduction is hindered between the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6, the effective inter-element connection resistance increases, and the fill factor (FF) of the solar cell is increased. As a result, the power generation efficiency decreases. Therefore, the intermediate layer 5 must satisfy both the transmittance and the carrier conductivity.

  FIG. 2 is a diagram for explaining a layer in the vicinity of the intermediate layer 5 shown in FIG. FIG. 2A is an enlarged view showing a layer near the intermediate layer 5. FIG. 2B is a diagram showing energy bands of the layers shown in FIG. The arrows indicate the carrier flows in the respective regions when a current flows from the p-type microcrystalline Si semiconductor layer 6d side toward the n-type amorphous Si semiconductor layer 4d. As shown in FIG. 1 and FIG. 2A, the structure of the intermediate layer 5 in the present embodiment is an n-type amorphous Si semiconductor layer 4d, a p-type transparent conductive oxide film layer 5a, and an n-type transparent conductive layer. Junction structure (hereinafter referred to as n-type amorphous Si semiconductor layer 4d / p-type transparent conductive oxide film layer 5a / n-type transparent) in which the conductive oxide film layer 5b and the p-type microcrystalline Si semiconductor layer 6d are laminated in this order. The conductive oxide film layer 5b / p-type microcrystalline Si semiconductor layer 6d may be described). That is, the structure of the intermediate layer 5 in the present embodiment is that the n-type amorphous Si semiconductor layer 4d / p-type transparent conductive oxide film layer 5a is an anisotype junction, the p-type transparent conductive oxide film layer 5a / n-type. Three anisotype junctions are combined, that is, an anisotype junction of the transparent conductive oxide film layer 5b and an anisotype junction of the n-type transparent conductive oxide film layer 5b / p-type microcrystalline Si semiconductor layer 6d.

  Further, both the p-type transparent conductive oxide film layer 5 a and the n-type transparent conductive oxide film layer 5 b have a band gap larger than the band gap of the amorphous Si photoelectric conversion layer 4. Both the p-type transparent conductive oxide film layer 5a and the n-type transparent conductive oxide film layer 5b have a band larger than the band gap corresponding to the light absorption energy of the photoelectric conversion layer located closest to the light incident side. It is preferable to have a gap.

In FIG. 2, as the p-type transparent conductive oxide film layer 5a, a NiO layer doped with Li, and as the n-type transparent conductive oxide film layer 5b, an In ₂ O ₃ layer doped with Zn (mainly composed of indium oxide). In this example, a material containing a small amount of zinc oxide is used, and an InZnO layer is described below.

  The NiO layer doped with Li as the p-type transparent conductive oxide film layer 5a has a film thickness of, for example, 10 nm by RF (radio frequency) sputtering using a NiO target doped with Li at a concentration of 20% in atomic composition ratio. The film was formed. A gas in which oxygen was added at a flow rate ratio of 5% was used for the atmosphere during the film formation.

The pressure in the film formation chamber was 0.5 Pa, and the substrate temperature during film formation was 200 ° C. The substrate temperature at the time of film formation is determined in consideration of the heat treatment temperature after film formation. Although it can be formed at room temperature, in this case, the heat treatment temperature after film formation is high, and heating for a long time is required. As the p-type transparent conductive oxide film layer 5a, NiO, Cu ₂ O, ZnM ₂ O ₄ (M = Co, Rh, Ir) or ZnMgO may be used.

A Zn-doped In ₂ O ₃ layer (InZnO layer) as the n-type transparent conductive oxide film layer 5b is formed by RF sputtering using an In ₂ O ₃ target to which ZnO is added at a concentration of 10% by weight. For example, the film was formed with a thickness of 10 nm. The substrate temperature during film formation was 200 ° C. The atmosphere during the film formation was an atmosphere in which 5% nitrogen was added to Ar at a flow rate ratio, and the pressure in the film formation chamber during the film formation was about 0.2 Pa.

The n-type transparent conductive oxide film layer 5b may be formed by a plasma CVD method or a vapor deposition method. Further, n-type transparent conductive oxide layer 5b, using the InGaZnO ₄ as a target, may be used InGaZnO ₄ film of this composition. The InGaZnO ₄ film may have a composition in which the atomic ratio of In: Ga: Zn is approximately 1: 1: 1, but is not necessarily limited to this composition. A compound having a composition ratio of InxGayZnzO ₄ (3x + 3y + 2z = 8, 0 <x <1, 0 <y <1, 0 <z <1) and may be a material expressed as InGaZnO or IGZO. The n-type transparent conductive oxide film layer 5b has In ₂ O ₃ , InSnO (a material containing indium oxide as a main component and a small amount of tin oxide, In ₂ O ₃ doped with Sn, hereinafter referred to as InSnO) InZnSnO (a material containing indium oxide as a main component and containing a small amount of zinc and tin oxide, Zn, Sn doped In ₂ O ₃ , hereinafter referred to as InZnSnO) may be used.

  In the intermediate layer 5 in the present embodiment, current flows through tunnel conduction and carrier generation / recombination at all junction interfaces. This operation will be described in comparison with a conventional structure. FIG. 3 is a diagram illustrating a configuration in the vicinity of an intermediate layer having a conventional structure. FIG. 3A is an enlarged view showing a layer in the vicinity of the intermediate layer having the conventional structure. FIG. 3B is a diagram illustrating energy bands of the layers illustrated in FIG. The conventional structure referred to here is a junction structure (hereinafter referred to as an n-type amorphous silicon semiconductor layer 4d, an n-type transparent conductive oxide film layer 50, and a p-type microcrystalline Si semiconductor layer 6d). Si semiconductor layer 4d / n-type transparent conductive oxide film layer 50 / p-type microcrystalline Si semiconductor layer 6d).

  The junction structure of the n-type amorphous Si semiconductor layer 4d / n-type transparent conductive oxide film layer 50 is an (n−n) isotype junction in which the conductivity type of both layers to be joined is the same. On the other hand, the junction structure of the n-type transparent conductive oxide layer 50 / p-type microcrystalline Si semiconductor layer 6d is an (np) anisotype junction in which the conductivity types of the both side layers to be joined are different. In the conventional structure, these junctions are joined in series.

  On the other hand, as shown in FIGS. 1 and 2A, the structure of the intermediate layer 5 in this embodiment is an n-type amorphous Si semiconductor layer 4d / p-type transparent conductive oxide film layer 5a / n-type. This is a junction structure of transparent conductive oxide film layer 5b / p-type microcrystalline Si semiconductor layer 6d. That is, the structure of the intermediate layer 5 in the present embodiment is such that the n-type amorphous Si semiconductor layer 4d / p-type transparent conductive oxide film layer 5a has an anisotype junction, a p-type transparent conductive oxide film layer as described above. Three anisotype junctions are combined, that is, an anisotype junction of 5a / n-type transparent conductive oxide film layer 5b and an anisotype junction of n-type transparent conductive oxide film layer 5b / p-type microcrystalline Si semiconductor layer 6d.

According to the present inventors' previous research, the resistance of the anisotype junction is reduced by reducing the width of the depletion layer generated at each junction interface to 5 nm or less, and the current due to tunnel conduction and carrier generation / recombination is promoted. It turns out that it is realized. For this reason, the resistance can be reduced by controlling the doping so that the carrier concentration of each layer is 1 × 10 ¹⁹ cm ⁻³ or more.

On the other hand, the resistance of the isotype junction may not be able to sufficiently reduce the junction resistance. The current transport mechanism in isotype junctions is dominated by current due to diffusion or emission. In the isotype junction, depending on the combination of the band gap and ionization potential of the material to be used, a potential barrier is generated at the band connection portion, which causes a problem that the interface resistance cannot be sufficiently reduced. Furthermore, in the case of an isotype junction, if an interface trap occurs due to the influence of lattice defects or interface states existing at the junction interface and the band is bent, a potential barrier for electron conduction occurs and the potential barrier becomes higher. Therefore, even if the doping control is performed so that the carrier concentration of each layer is 1 × 10 ¹⁹ cm ⁻³ or more, ohmic characteristics cannot be obtained, and the resistance cannot be lowered.

  Therefore, as shown in FIG. 3, in the case of the connection structure using the n-type transparent conductive oxide film layer 50 as an intermediate layer, both types of (nn) isotype junction and (np) anisotype junction are used. Therefore, the junction resistance between the n-type amorphous Si semiconductor layer 4d and the p-type microcrystalline Si semiconductor layer 6d through the intermediate layer may not be sufficiently lowered. That is, in the example shown in FIG. 3, in the (np) anisotype junction of the n-type transparent conductive oxide film layer 50 / p-type microcrystalline Si semiconductor layer 6d, carrier tunnel conduction occurs in the region indicated by the thick line arrow. Current flows due to carrier generation and recombination. However, in the (nn) isotype junction of the n-type amorphous Si semiconductor layer 4d / n-type transparent conductive oxide film layer 50, an interface trap occurs due to the influence of lattice defects and interface states existing at the junction interface. As a result, the band is bent, a potential barrier for electron conduction is generated, the potential barrier is increased, and electrons are difficult to conduct.

  On the other hand, as described above, the structure of the intermediate layer 5 in this embodiment is the n-type amorphous Si semiconductor layer 4d / p-type transparent conductive oxide film layer 5a / n-type transparent conductive oxide film layer 5b. / P-type microcrystalline Si semiconductor layer 6d junction structure, and all three junctions in the intermediate layer 5 are also non-isotype junctions. In this case, the current transport mechanism in each junction is all governed by the current due to tunnel conduction and carrier generation / recombination. For example, in the example shown in FIG. 3, carrier tunnel conduction occurs in the region indicated by a thick arrow at the interface of each layer, and a current due to carrier generation / recombination flows. In this case, even if a carrier interface trap exists and the band is bent due to the influence of defects or the like existing at the junction interface, a potential barrier is hardly generated for both electrons and holes. Further, when the carrier trap concentration increases, the electron-hole recombination through the trap is promoted, so that the junction resistance decreases. And since the level of a defect or an n / p junction interface (aniso-type junction interface) contributes to trap assist tunneling, resistance reduction is promoted as the interface level is larger. Accordingly, by using the intermediate layer 5 in the present embodiment, the junction resistance between the n-type amorphous Si semiconductor layer 4d and the p-type microcrystalline Si semiconductor layer 6d via the intermediate layer is low. Resisted.

  As described above, in the first embodiment, between the n-type amorphous Si semiconductor layer 4 d of the amorphous Si photoelectric conversion layer 4 and the p-type microcrystalline Si semiconductor layer 6 d of the microcrystalline Si photoelectric conversion layer 6. The p-type transparent conductive oxide film layer 5a and the n-type transparent conductive oxide film layer 5b are stacked from the n-type amorphous Si semiconductor layer 4d side to form the intermediate layer 5. The p-type transparent conductive oxide film layer 5a is in contact with the n-type amorphous Si semiconductor layer 4d, and the n-type transparent conductive oxide film layer 5b is in contact with the p-type microcrystalline Si semiconductor layer 6d. As a result, all the junctions between the n-type amorphous Si semiconductor layer 4d and the p-type microcrystalline Si semiconductor layer 6d are formed as an anisotype heterojunction, and current between each layer is generated by tunnel conduction and carrier generation / recombination. Thus, a low junction resistance can be realized through an intermediate layer between the n-type amorphous Si semiconductor layer 4d and the p-type microcrystalline Si semiconductor layer 6d. In addition, low resistance connection is possible even in the connection between films having poor crystallinity and many interface states, and a low resistance connection structure through an intermediate layer can be realized.

  As a result, it is possible to connect the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6 to a low resistance without consuming almost any energy. Even in the situation, it is possible to suppress a decrease in photoelectric conversion efficiency due to the junction resistance.

  Therefore, according to the first embodiment, the conductivity between the two photoelectric conversion layers is improved without depending on the material characteristics of the both side layers in which the intermediate layer is inserted in the stacked photoelectric conversion device, When the generated current is large, such as when generating electricity, the photoelectric conversion efficiency can be improved as compared with the conventional structure.

Embodiment 2. FIG.
In the second embodiment, in the photoelectric conversion device having the configuration described in the first embodiment, a Li-doped NiO layer as the p-type transparent conductive oxide film layer 5a and a n-type transparent conductive oxide film layer 5b as Zn An InO layer doped with is used. The atmosphere during the formation of the intermediate layer 5 was an atmosphere in which 5% nitrogen (N) was added to Ar in a flow rate ratio. By adding nitrogen to the atmosphere during film formation, the p-type transparent conductive oxide film layer 5a and the n-type transparent conductive oxide film layer 5b are doped with nitrogen. In the formation of the intermediate layer 5, first, a Ni-doped NiO layer as a p-type transparent conductive oxide film layer 5a was formed on the n-type amorphous Si semiconductor layer 4d.

  The Li-doped NiO layer as the p-type transparent conductive oxide film layer 5a was formed to a thickness of 10 nm by RF sputtering using a NiO target doped with Li at a concentration of 20% atomic composition ratio. Prior to film formation, pre-sputtering for cleaning the target was performed for 10 seconds with the target shutter closed.

  The atmosphere at the time of forming the NiO layer doped with Li was an atmosphere in which 5% nitrogen was added to Ar in a flow rate ratio. The pressure in the film formation chamber during film formation was 0.2 Pa, and the substrate temperature during film formation was 200 ° C. The substrate temperature at the time of film formation is determined in consideration of the heat treatment temperature after film formation. Although it can be formed at room temperature, in this case, the heat treatment temperature after film formation is high, and heating for a long time is required.

  After the formation of the p-type transparent conductive oxide film layer 5a, the target is exchanged while the substrate is held in vacuum, and the next n-type transparent conductive oxide film layer 5b is formed without exposing the substrate to an oxygen atmosphere. went.

The Zn-doped InO layer as the n-type transparent conductive oxide film layer 5b is formed to a thickness of 10 nm by RF sputtering using an In ₂ O ₃ target to which ZnO is added at a concentration of 10% by weight. did. The substrate temperature during film formation was 200 ° C. The atmosphere during the film formation was an atmosphere in which 5% nitrogen was added to Ar at a flow rate ratio, and the pressure in the film formation chamber during the film formation was about 0.2 Pa.

By performing the film formation as described above, the interface between the n-type amorphous Si semiconductor layer 4d and the p-type transparent conductive oxide film layer 5a, p-type, due to the effect of the oxygen-free atmosphere and the effect of nitrogen doping. In the vicinity of the interface between the transparent conductive oxide film layer 5a and the n-type transparent conductive oxide film layer 5b and the interface between the n-type transparent conductive oxide film layer 5b and the p-type microcrystalline Si semiconductor layer 6d, p To prevent the lowering of the carrier concentration due to oxidation and reduction of the surface of the underlayer when the n-type transparent conductive oxide film layer 5a, the n-type transparent conductive oxide film layer 5b and the p-type microcrystalline Si semiconductor layer 6d are formed. Can do. As a result, the width in the thickness direction of the depletion layer in the vicinity of the interface can be more surely set to 5 nm or less, and the current due to tunnel conduction and carrier generation / recombination is promoted to realize low resistance. At this time, the doping control is performed so that the carrier concentration of each layer is 1 × 10 ¹⁹ cm ⁻³ or more.

  In an n-type transparent conductive oxide film such as ZnO or InO, the cause of generation of electrons as n-type carriers is a dopant atom (for example, Al) and oxygen deficiency in the film. Therefore, n-type carriers are reduced when a film is formed in an atmosphere containing excess oxygen. This also applies to the surface after film formation. When the surface of the n-type transparent conductive oxide film after film formation is exposed to active oxygen, excessive oxidation proceeds, oxygen vacancies formed during film formation disappear, and carriers (movable electrons) decrease.

  On the other hand, in the p-type transparent conductive oxide film, the generation cause of holes which are p-type carriers is due to doped atoms and metal defects in the film. For this reason, excess oxygen is required during the formation of the p-type transparent conductive oxide film. Therefore, the p-type transparent conductive oxide film is usually formed in an oxygen supply atmosphere.

  In the conventional film formation, the p-type transparent conductive oxide film is formed under the optimal film formation conditions for reducing the resistivity of the p-type film. The film was formed under a disadvantageous condition for the type transparent conductive oxide film. For this reason, the n-type carrier concentration near the surface has decreased due to excessive oxidation of the n-type transparent conductive oxide film in the process of forming the p-type transparent conductive oxide film.

  Therefore, in the present embodiment, when the intermediate layer 5 made of a transparent conductive oxide film and having a pn junction is formed, a film of a depletion layer generated near the interface between the p-type transparent conductive oxide film 5b and its upper and lower layers. In order to suppress the spread (width) in the thickness direction to 5 nm or less, the p-type transparent conductive oxide film 5b is formed under the conditions that do not deteriorate the n-type transparent conductive oxide film 5a, that is, nitrogen without supplying oxygen gas. Set the gas supply conditions.

In order to enable such a process, in the second embodiment, indium oxide is used as the n-type transparent conductive oxide film layer 5b whose resistivity can be reduced by nitrogen gas supply (nitrogen doping) during film formation. In ₂ O ₃ , InZnO (In: Zn = 9: 1), InSnO (a material containing indium oxide as a main component and containing a small amount of tin oxide, In ₂ O doped with Sn ₃ and described below as InSnO). Then, these materials are formed as an n-type transparent conductive oxide film layer 5b in an Ar gas atmosphere containing nitrogen gas, and low resistance film formation is possible without using oxygen gas which may oxidize the interface. .

As the p-type transparent conductive oxide film layer 5a, the above-described Li-doped NiO layer, NiO, Cu ₂ O, ZnM ₂ O ₄ (M = Co, Rh, Ir), ZnMgO, or the like may be used. .

FIG. 4 is a characteristic diagram showing an experimental result of evaluating the connection resistivity in the intermediate layer structure according to the second embodiment using a model element. FIG. 4 shows the relationship between the current flowing through the junction of the intermediate layer structure and the junction resistivity (mΩcm ² ) of the intermediate layer structure. FIG. 5 is a diagram illustrating the structure of the model element 101 for measuring the connection resistance in the intermediate layer structure according to the second embodiment. In the model element 101, a ZnO (ZnO: Al) film 103 doped with Al, an n-type microcrystalline Si semiconductor layer 104, an intermediate layer 105, a p-type microcrystalline Si semiconductor layer 106, and Al are doped on a glass substrate 102. A ZnO (ZnO: Al) film 111 and an Ag film 107 are stacked. By calculating the differential resistivity per unit area from the current-voltage characteristics when a current of -5 mA to 5 mA is passed with the Ag electrode side as a plus for this model element 101, the connection resistivity in the intermediate layer structure is obtained. It was measured. The atmosphere during the formation of the intermediate layer 105 was based on Ar, and oxygen or nitrogen was added.

  In FIG. 4, plot a corresponds to the case where a bonding film (ZnO / NiO) of n-type ZnO and p-type NiO formed in an oxygen-containing atmosphere is used as the intermediate layer 105 in the model element 101. Each junction between the n-type microcrystalline Si semiconductor layer 104 and the p-type microcrystalline Si semiconductor layer 106 includes an (n−n) isotype junction, an (n−p) anisotype junction, and a (p−p) junction. 3 junctions with an isotype junction.

Plot b corresponds to the case where a junction film (ZnO / ZnIr ₂ O ₄ ) of n-type ZnO and p-type ZnIr ₂ O ₄ formed in an oxygen-free atmosphere is used as the intermediate layer 105 in the model element 101. Each junction between the n-type microcrystalline Si semiconductor layer 104 and the p-type microcrystalline Si semiconductor layer 106 includes an (n−n) isotype junction, an (n−p) anisotype junction, and a (p−p) junction. 3 junctions with an isotype junction.

  Plot c corresponds to the case where a junction film (InZnO / NiO) of n-type InZnO and p-type NiO formed in a nitrogen-containing atmosphere (containing no oxygen) is used as the intermediate layer 105 in the model element 101. Each junction between the n-type microcrystalline Si semiconductor layer 104 and the p-type microcrystalline Si semiconductor layer 106 includes an (n−n) isotype junction, an (n−p) anisotype junction, and a (p−p) junction. 3 junctions with an isotype junction.

  Plot d corresponds to the case where a junction film (NiO / InZnO) of p-type NiO and n-type InZnO formed in an oxygen-containing atmosphere is used as the intermediate layer 105 in the model element 101. Each junction between the n-type microcrystalline Si semiconductor layer 104 and the p-type microcrystalline Si semiconductor layer 106 includes (np) anisotype junction, (pn) anisotype junction, and (np). And three anisotype junctions.

  Plot e corresponds to the case where a junction film (NiO / InZnO) of p-type NiO and n-type InZnO formed in a nitrogen-containing atmosphere (containing no oxygen) is used as the intermediate layer 105 in the model element 101. Each junction between the n-type microcrystalline Si semiconductor layer 104 and the p-type microcrystalline Si semiconductor layer 106 includes (np) anisotype junction, (pn) anisotype junction, and (np). And three anisotype junctions. The plot e corresponds to the intermediate layer structure of the second embodiment.

  4, the same junction state ((n−n) isotype junction + (n−p) anisotype junction + (p−p) between the n-type microcrystalline Si semiconductor layer 104 and the p-type microcrystalline Si semiconductor layer 106. When the plot a, the plot b, and the plot c having the isotype junction)) are compared, the effects of film formation in an oxygen-free atmosphere are shown in the plot b and the plot c. In addition, when plot c and plot e, which are the same nitrogen-containing atmosphere conditions as the formation conditions of intermediate layer 105, are compared, in plot e where all three junctions are anisotype junctions, the resistance junction ratio is greatly reduced and plot c. A resistance that is an order of magnitude lower than that is obtained. On the other hand, in plot d in which the formation condition of the intermediate layer 105 is an oxygen-containing atmosphere, it can be seen that all three junctions are anisotype junctions, but become high.

  As described above, in the second embodiment, the intermediate layer 5 is formed by laminating the p-type transparent conductive oxide film layer 5a and the n-type transparent conductive oxide film layer 5b in an Ar gas atmosphere containing nitrogen gas. Configured. The p-type transparent conductive oxide film layer 5a is in contact with the n-type amorphous Si semiconductor layer 4d, and the n-type transparent conductive oxide film layer 5b is in contact with the p-type microcrystalline Si semiconductor layer 6d. As a result, all the junctions between the n-type amorphous Si semiconductor layer 4d and the p-type microcrystalline Si semiconductor layer 6d are formed as an anisotype heterojunction, and current is generated by current due to tunnel conduction and carrier generation / recombination. By being transported, a low-resistance junction resistance can be realized through an intermediate layer between the n-type amorphous Si semiconductor layer 4d and the p-type microcrystalline Si semiconductor layer 6d. In addition, low resistance connection is possible even in the connection between films having poor crystallinity and many interface states, and a low resistance connection structure through an intermediate layer can be realized.

  As a result, it is possible to connect the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6 to a low resistance without consuming almost any energy. Even in the situation, it is possible to suppress a decrease in photoelectric conversion efficiency due to the junction resistance.

  Furthermore, in the second embodiment, due to the effect of nitrogen doping, the interface between the n-type amorphous Si semiconductor layer 4d and the p-type transparent conductive oxide film layer 5a, the p-type transparent conductive oxide film layer 5a and n P-type transparent conductive oxide film layer 5a in the vicinity of the interface with the transparent conductive oxide film layer 5b and the interface between the n-type transparent conductive oxide film layer 5b and the p-type microcrystalline Si semiconductor layer 6d, When the n-type transparent conductive oxide film layer 5b and the p-type microcrystalline Si semiconductor layer 6d are formed, it is possible to prevent the surface of the base layer from being oxidized and reduced to cause a decrease in carrier concentration. As a result, the width in the thickness direction of the depletion layer in the vicinity of the interface can be reduced to 5 nm or less, the current due to tunnel conduction and carrier generation / recombination is promoted, and a lower resistance is realized.

  Therefore, according to Embodiment 2, the conductivity between the two photoelectric conversion layers is further improved without depending on the material characteristics of the both side layers in which the intermediate layer is inserted in the stacked photoelectric conversion device, and in particular, the light is condensed. In the case where the generated current is large such that power is generated, the photoelectric conversion efficiency can be improved as compared with the conventional structure.

In the above description, the case where Ar and nitrogen gas are mixed as the atmospheric gas at the time of film formation is shown. However, NH ₃ or the like that decomposes and generates nitrogen may be mixed in the atmospheric gas instead of the nitrogen gas. Good.

  Also, in the above, an example of doping nitrogen into the p-type transparent conductive oxide film 5a and the n-type transparent conductive oxide film 5b by the atmospheric gas has been shown. However, nitrogen in the form of AlN, TiN, GaN is added to the sputtering target. It is possible to dope nitrogen into the n-type transparent conductive oxide film 5a and the p-type transparent conductive oxide film 5b by mixing them. In this case, it is also possible to use in combination with nitrogen doping with an atmospheric gas.

  Further, in the above, an example is shown in which nitrogen is doped into the p-type transparent conductive oxide film 5a and the n-type transparent conductive oxide film 5b. However, in addition to nitrogen, any one of P, As, and Sb, which are group V elements, is used. The same effect can be obtained even if these elements are used. Further, a plurality of these elements may be doped.

  The concentration of these doped elements (doping elements) is set to 0.1 atomic% to 5 atomic% when the doping elements and oxygen are combined to be 100%. Atomic ratio). If the concentration of the doping element is less than 0.1 atomic%, the effect of reducing the junction resistance of the intermediate layer 5 does not appear. On the other hand, when the concentration of the doping element is higher than 5 atomic%, the effect of reducing the junction resistance of the intermediate layer 5 is saturated, while the light transmission spectrum has a remarkable tendency to reduce the transmittance in the region of wavelength of 500 nm or less. The composition ratio of such a doping element can be analyzed by SIMS (secondary ion mass spectrometer).

Embodiment 3 FIG.
In Embodiment 1 and Embodiment 2 described above, the photoelectric conversion device formed by sequentially laminating each layer on the same substrate has been described. In Embodiment 3, an example in which one photoelectric conversion device is formed by bonding photoelectric conversion layers formed over different substrates is described.

  FIG. 6 is a sectional view showing a schematic configuration of Embodiment 3 of the photoelectric conversion apparatus according to the present invention. In FIG. 6, the photoelectric conversion device 21 includes a transparent electrode 3, an amorphous Si photoelectric conversion layer 4, an intermediate layer 51, and a single crystal / amorphous Si photoelectric conversion layer 16 on an insulating and translucent substrate 2. The back electrode 7 is laminated in order. An undercoat layer 8 may be formed on the substrate 2 as an impurity blocking layer as necessary. In addition, detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol about the member equivalent to the photoelectric conversion apparatus 1 concerning Embodiment 1. FIG.

  The amorphous Si photoelectric conversion layer 4 includes a p-type amorphous Si semiconductor layer 4a, an i-type amorphous Si semiconductor layer 4b, an n-type amorphous Si semiconductor layer 4c, and an n-type amorphous in order from the substrate 2 side. It is composed of a layer in which an Si semiconductor layer 4d is laminated. Further, an i-type amorphous Si semiconductor layer may be inserted between the p-type amorphous Si semiconductor layer 4a and the i-type amorphous Si semiconductor layer 4b. The single crystal / non-crystal Si photoelectric conversion layer 16 is configured by stacking a p-type amorphous Si semiconductor layer 16a, an i-type amorphous Si semiconductor layer 16b, and an n-type single crystal Si substrate 16c in this order from the substrate 2 side. Yes.

  Between the n-type amorphous Si semiconductor layer 4d of the amorphous Si photoelectric conversion layer 4 and the p-type amorphous Si semiconductor layer 16a of the single crystal / amorphous Si photoelectric conversion layer 16, there is n-type amorphous Si. An intermediate layer 51 in which a p-type transparent conductive oxide film layer 5a, a third transparent conductive film layer 5c, and an n-type transparent conductive oxide film layer 5b are stacked in this order from the semiconductor layer 4d side is disposed. That is, the p-type transparent conductive oxide film layer 5a is in contact with the n-type amorphous Si semiconductor layer 4d. Further, the n-type transparent conductive oxide film layer 5b is in contact with the p-type amorphous Si semiconductor layer 16a. The p-type transparent conductive oxide film layer 5a is in contact with the n-type transparent conductive oxide film layer 5b.

  The photoelectric conversion device 21 includes an intermediate layer in which a transparent electrode 3, an amorphous Si photoelectric conversion layer 4, a p-type transparent conductive oxide film layer 5a, and a third transparent conductive film layer 5c are sequentially stacked on the substrate 2. The back electrode 7 is laminated on one surface side of the body 21a and the n-type single crystal Si substrate 16c, and the i-type amorphous Si semiconductor layer 16b and p-type amorphous Si semiconductor are formed on the other surface side of the n-type single crystal Si substrate 16c. The layer 16a and the intermediate body 21b on which the n-type transparent conductive oxide film layer 5b is sequentially laminated are laminated and integrated. FIG. 7 is a cross-sectional view illustrating the method of manufacturing the photoelectric conversion device according to the third embodiment.

  The intermediate 21a is formed on the substrate 2 by sequentially forming the transparent electrode 3, the amorphous Si photoelectric conversion layer 4, the p-type transparent conductive oxide film layer 5a, and the third transparent conductive film layer 5c. . In the intermediate body 21a, the n-type amorphous Si semiconductor layer 4d is present on the surface side (the side opposite to the substrate 2) in the order of lamination, and the p-type transparent conductive oxide film layer 5a and the third transparent conductive film are formed thereon. Layer 5c is formed.

  The intermediate body 21b has a back electrode 7 laminated on one surface side of an n-type single crystal Si substrate 16c, and an i-type amorphous Si semiconductor layer 16b and p-type amorphous Si on the other surface side of the n-type single crystal Si substrate 16c. The semiconductor layer 16a and the n-type transparent conductive oxide film layer 5b are sequentially formed and formed. The intermediate body 21b has the p-type microcrystalline Si semiconductor layer 6a on the front surface side (opposite side to the back electrode 7) in the order of lamination, and the n-type transparent conductive oxide film layer 5b is formed thereon.

In FIG. 7, a Li-doped NiO layer is used as the p-type transparent conductive oxide film layer 5a, and a Zn-doped In ₂ O ₃ layer (InZnO layer) is used as the n-type transparent conductive oxide film layer 5b. An example is shown.

  The Ni-doped NiO layer as the p-type transparent conductive oxide film layer 5a was formed by RF (radio frequency) sputtering using a NiO target doped with Li at a concentration of 20%. A gas in which oxygen was added at a flow rate ratio of 5% was used for the atmosphere during the film formation.

  The pressure in the film formation chamber was 0.5 Pa, and the substrate temperature during film formation was 200 ° C. The substrate temperature at the time of film formation is determined in consideration of the heat treatment temperature after film formation. Although it can be formed at room temperature, in this case, the heat treatment temperature after film formation is high, and heating for a long time is required.

A Zn-doped In ₂ O ₃ layer (InZnO layer) as the n-type transparent conductive oxide film layer 5b is formed by RF sputtering using an In ₂ O ₃ target to which ZnO is added at a concentration of 10% by weight. The film was formed with a thickness of 10 nm. The substrate temperature during film formation was 200 ° C. The atmosphere during the film formation was an atmosphere in which 5% nitrogen was added to Ar at a flow rate ratio, and the pressure in the film formation chamber during the film formation was about 0.2 Pa.

The n-type transparent conductive oxide film layer 5b may be formed by a plasma CVD method or a vapor deposition method. Further, n-type transparent conductive oxide layer 5b, using the InGaZnO ₄ as a target, may be used InGaZnO ₄ film of this composition.

The third transparent conductive film layer 5c is formed by RF sputtering or the like in order to bond the p-type transparent conductive oxide film layer 5a and the n-type transparent conductive oxide film layer 5b. As the third transparent conductive film layer 5c, an n-type or p-type transparent conductive oxide film can be selected. For example, amorphous n-type In ₂ O ₃ was formed at room temperature. Other layers are formed by a conventionally known method.

  Then, the intermediate body 21a and the intermediate body 21b are brought into contact with each other in a state where the third transparent conductive film layer 5c of the intermediate body 21a and the n-type transparent conductive oxide film layer 5b of the intermediate body 21b face each other. Then, the intermediate body 21a and the intermediate body 21b were bonded and integrated by annealing at 200 ° C. while applying pressure.

  Instead of forming the third transparent conductive film 5c to bond the intermediate 21a and the intermediate 21b together, the transparent conductive of the intermediate layer 51 of one or both of the intermediate 21a and the intermediate 21b is used. A method may be implemented in which a transparent conductive adhesive is applied to the conductive oxide film layer and pressure-bonded.

  Further, instead of forming the third transparent conductive film 5 layer c in order to bond the intermediate body 21a and the intermediate body 21b, the n-type transparent conductive film is formed on the p-type transparent conductive oxide film layer 5a of the intermediate body 21a. An n-type transparent conductive oxide film layer may be formed, and this n-type transparent conductive oxide film layer may be bonded to the n-type transparent conductive oxide film layer 5b of the intermediate 21b.

  As described above, in the third embodiment, the intermediate layer 5 includes the p-type transparent conductive oxide film layer 5a and the n-type transparent conductive oxide film layer 5b formed by using different substrates, and the intermediate layer is bonded thereto. 5 junctions are formed. The p-type transparent conductive oxide film layer 5a is in contact with the n-type amorphous Si semiconductor layer 4d, and the n-type transparent conductive oxide film layer 5b is in contact with the p-type amorphous Si semiconductor layer 16a. The p-type transparent conductive oxide film layer 5a and the n-type transparent conductive oxide film layer 5b are joined via an n-type or p-type third transparent conductive film 5 layer c. As a result, all the junctions between the n-type amorphous Si semiconductor layer 4d and the p-type microcrystalline Si semiconductor layer 6d are formed as an anisotype heterojunction, and current is generated by current due to tunnel conduction and carrier generation / recombination. By being transported, a low-resistance junction resistance between the n-type amorphous Si semiconductor layer 4d and the p-type amorphous Si semiconductor layer 16a can be realized. In addition, low resistance connection is possible even in the connection between films having poor crystallinity and many interface states, and a low resistance connection structure through an intermediate layer can be realized.

  As a result, it is possible to connect the amorphous Si photoelectric conversion layer 4 and the p-type amorphous Si semiconductor layer 16a with a low resistance without consuming much energy, and a high current at the time of high concentration power generation. Even in this situation, it is possible to suppress a decrease in photoelectric conversion efficiency due to the junction resistance.

  Note that, in the above embodiment, it is particularly suitable for improving the conversion efficiency of a photoelectric conversion layer composed of a semiconductor layer containing Si as a main component, but it can also be applied to a compound semiconductor system other than a Si system or an organic material. is there. The semiconductor layer may be any of a single crystal, an amorphous film, and a microcrystalline film as described above.

  As described above, the present invention is applied to a portion where the upper and lower photoelectric conversion layers are connected as an intermediate layer of a photoelectric conversion device having two or more photoelectric conversion layers, but is transparent in the case of a single layer photoelectric conversion device. It can also be applied as a technique for reducing connection resistance with a semiconductor layer when a transparent conductive oxide film is used as an electrode. For example, when an n-type transparent conductive oxide film layer is connected to n-Si, an isotype heterojunction is formed as it is, but an p-type transparent conductive oxide layer is interposed between the n-Si and an anisotype heterojunction to form a tunnel conduction and a carrier. A low junction resistance can be realized by transporting the current by the current generated and recombined.

  In addition, a plurality of photoelectric conversion devices having the configuration described in the above embodiment are formed on a transparent insulating substrate, and at least two or more photoelectric conversion devices are electrically connected in series or in parallel, thereby The conductivity of the connection through the transparent conductive oxide film in the conversion device is improved, and a photoelectric conversion module excellent in photoelectric conversion efficiency can be realized. For example, one transparent electrode 3 and the other back electrode 7 of the adjacent photoelectric conversion device may be electrically connected in series. A plurality of photoelectric conversion devices may be electrically connected in parallel. For example, the transparent electrodes 3 and the back electrodes 7 of adjacent photoelectric conversion devices may be electrically connected.

  As described above, the photoelectric conversion device according to the present invention improves the conductivity of the connection through the transparent conductive oxide film in the photoelectric conversion device, and provides a highly efficient photoelectric conversion device with little energy loss. become able to. In particular, it is suitable for a method for suppressing heat generation and efficiency reduction due to energy loss and realizing high-efficiency power generation at the time of power generation with high current density such as collecting light and generating power.

1 photoelectric conversion device 2 substrate 3 transparent electrode 4 amorphous Si photoelectric conversion layer 4a p-type amorphous Si semiconductor layer 4b i-type amorphous Si semiconductor layer 4c n-type amorphous Si semiconductor layer 4d n-type amorphous Si semiconductor layer 5 Intermediate layer 5a p-type transparent conductive oxide film layer 5b n-type transparent conductive oxide film layer 5c third transparent conductive film layer 6 microcrystalline Si photoelectric conversion layer 6a p-type microcrystalline Si semiconductor layer 6b i-type Microcrystalline Si semiconductor layer 6c n-type microcrystalline Si semiconductor layer 6d p-type microcrystalline Si semiconductor layer 7 back electrode 8 undercoat layer 11 transparent conductive layer 21 photoelectric conversion device 21a intermediate 21b intermediate 50 n-type transparent conductive oxide film Layer 51 intermediate layer 101 model element 102 glass substrate 103 ZnO (ZnO: Al) film doped with Al 104 n-type microcrystalline Si semiconductor layer 105 intermediate layer 106 p-type microcrystalline Si semiconductor Layer 107 Ag film 111 Al-doped ZnO (ZnO: Al) film

Claims (16)

A photoelectric conversion layer having at least a p-type semiconductor layer and an n-type semiconductor layer;
The p-type semiconductor layer and the p-type transparent conductive oxide film between the p-type semiconductor layer and the p-type transparent conductive oxide film layer disposed on the opposite side to the n-type semiconductor layer in the p-type semiconductor layer A laminated structure in which an n-type transparent conductive oxide film layer is disposed in contact with the layer, or an n-type transparent conductive oxide film layer disposed on the opposite side to the p-type semiconductor layer in the n-type semiconductor layer and the n-type Having at least one of a stacked structure in which a p-type transparent conductive oxide film layer is disposed in contact with the n-type semiconductor layer and the n-type transparent conductive oxide film layer between the semiconductor layer,
A photoelectric conversion device characterized by the above. Both the p-type transparent conductive oxide film layer and the n-type transparent conductive oxide film layer have a band larger than the band gap corresponding to the light absorption energy of the photoelectric conversion layer located closest to the light incident side. Having a gap,
The photoelectric conversion device according to claim 1. The carrier concentration of the n-type transparent conductive oxide film layer and the p-type transparent conductive oxide film layer is 1 × 10 ⁻¹⁹ cm ⁻³ or more,
The photoelectric conversion device according to claim 1, wherein: The p-type semiconductor layer and the n-type semiconductor layer are any one or more of a silicon-based single crystal, an amorphous film, and a microcrystalline film;
The photoelectric conversion device according to claim 1, wherein: The n-type transparent conductive oxide film layer and the p-type transparent conductive oxide film layer are doped with nitrogen atoms,
The photoelectric conversion device according to claim 1, wherein: The concentration of the doped nitrogen atom is 0. 0 based on the sum of oxygen in the n-type transparent conductive oxide film layer or the p-type transparent conductive oxide film layer and the doped nitrogen element. 1 atomic% to 5 atomic%,
The photoelectric conversion device according to claim 5. Said substrate of n-type transparent conductive oxide _layer, In ₂ O 3, Zn in the doped _In 2 _O 3, Sn-doped _In 2 _O 3, Zn and _In 2 _{O 3} or InGaZnO doped Sn There is,
The photoelectric conversion device according to claim 1, wherein: The base material of the p-type transparent conductive oxide film layer is NiO, Cu ₂ O, ZnM ₂ O ₄ (M = Co, Rh, Ir) or ZnMgO,
The photoelectric conversion device according to claim 1, wherein: The photoelectric conversion layer includes a first photoelectric conversion layer having at least a first p-type semiconductor layer and a first n-type semiconductor layer, at least a second p-type semiconductor layer and a second n-type semiconductor layer, and the first photoelectric conversion layer. And a second photoelectric conversion layer having different light absorption wavelength characteristics,
The p-type transparent conductive oxide film layer disposed on the side in contact with the first n-type semiconductor layer between the first n-type semiconductor layer and the second p-type semiconductor layer;
The n-type transparent conductive oxide film layer disposed on the side in contact with the second p-type semiconductor layer between the first n-type semiconductor layer and the second p-type semiconductor layer;
With
The first n-type semiconductor layer, the p-type transparent conductive oxide film layer, the p-type transparent conductive oxide film layer, the n-type transparent conductive oxide film layer, the n-type transparent conductive oxide film layer, and the second p The type semiconductor layer is in contact with each other,
The photoelectric conversion device according to claim 1, wherein: A transparent conductive material for bonding the p-type transparent conductive oxide film layer and the n-type transparent conductive oxide film layer between the p-type transparent conductive oxide film layer and the n-type transparent conductive oxide film layer That the adhesive layer has been placed,
The photoelectric conversion device according to claim 9. A first step of forming a photoelectric conversion layer having at least a p-type semiconductor layer and an n-type semiconductor layer;
At least one before and after the first step,
On the opposite side of the p-type semiconductor layer from the n-type semiconductor layer, the p-type semiconductor layer, the n-type transparent conductive oxide film layer, and the p-type transparent conductive oxide film layer are stacked in this order. A second step of forming a structure, and the n-type semiconductor layer, the p-type transparent conductive oxide film layer, and the n-type transparent conductive oxide film layer on the opposite side of the n-type semiconductor layer from the p-type semiconductor layer. Including any one of the third steps of forming the laminated structure to be laminated in this order;
A method of manufacturing a photoelectric conversion device characterized by the above. In the second step or the third step, the n-type transparent conductive oxide film layer or the p-type transparent conductive oxide film layer is formed by sputtering, and nitrogen or NH ₃ is added to the atmosphere gas in addition to Ar. Using the added gas,
The method for producing a photoelectric conversion device according to claim 11. In the second step or the third step, the n-type transparent conductive oxide film layer and the p-type transparent conductive oxide film layer are formed by sputtering, and AlN and TiN are previously formed in the sputtering target for film formation. , Mixing any of GaN,
The method for producing a photoelectric conversion device according to claim 11 or 12, wherein: Forming a first photoelectric conversion layer having a first p-type semiconductor layer and a first n-type semiconductor layer in this order on a substrate;
Forming a p-type transparent conductive oxide film layer on the first n-type semiconductor layer;
Forming an n-type transparent conductive oxide film layer on the p-type transparent conductive oxide film layer;
A second p-type semiconductor layer having a second p-type semiconductor layer and a second n-type semiconductor layer and having a light absorption wavelength characteristic different from that of the first photoelectric conversion layer is the n-type transparent conductive oxide film layer. Forming to be in contact with,
The manufacturing method of the photoelectric conversion apparatus as described in any one of Claims 11-13 characterized by the above-mentioned. A first photoelectric conversion layer having a first p-type semiconductor layer and a first n-type semiconductor layer in this order is formed on the substrate, and a p-type transparent conductive oxide film layer is formed on the first n-type semiconductor layer. Forming an intermediate;
A second photoelectric conversion layer having a second p-type semiconductor layer is formed on a second n-type semiconductor substrate, and an n-type transparent conductive oxide film layer is formed on the second p-type semiconductor layer to form a second intermediate. Process,
The first intermediate in a state where the p-type transparent conductive oxide film layer of the first intermediate and the n-type transparent conductive oxide film layer of the second intermediate are opposed to each other through a transparent conductive adhesive layer. Adhering and integrating the intermediate and the second intermediate; and
The manufacturing method of the photoelectric conversion apparatus as described in any one of Claims 11-13 characterized by the above-mentioned. At least two or more of the photoelectric conversion devices according to any one of claims 1 to 10 are electrically connected in series or in parallel;
A photoelectric conversion module characterized by the above.

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