JP5377732B2 - Semiconductor, p-type semiconductor, semiconductor junction element, pn junction element, and photoelectric conversion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor, a p-type semiconductor, a semiconductor bonding element, a pn-junction element, and a photoelectric converter capable of correctly controlling at least one of a prohibition band width and a conductivity type according to an application purpose and capable of being put into practical use. <P>SOLUTION: A semiconductor is manufactured by mixing an Ia-group element in iron sulfide. In addition, this semiconductor is used to manufacture a semiconductor bonding element or a photoelectric converter. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to a semiconductor, a p-type semiconductor, a semiconductor junction element, a pn junction element, and a photoelectric conversion device. The present invention particularly relates to a semiconductor junction element using a p-type semiconductor and a photoelectric conversion device using a p-type semiconductor.

Since iron sulfide has a high light absorption coefficient, it is expected to be applied to light receiving and emitting elements. Here, when considering application, at least a conductivity type control (pn control) technique is indispensable, and energetic research and development for that purpose is being carried out. It is known that the light receiving / emitting wavelength is greatly influenced by the forbidden bandwidth of the semiconductor. In iron sulfide, even in the case of FeS ₂ single crystal having the largest forbidden band width, it is about 0.95 eV. In order to expand the application range, development of forbidden bandwidth control (particularly wide forbidden bandwidth) technology is strongly demanded.

As iron sulfide, compositions of FeS, FeS ₂ and Fe ₂ S ₃ are known. FeS and FeS ₂ have a bivalent iron valence, whereas Fe ₂ S ₃ has a trivalent iron valence. Here, Fe ₂ S ₃ is unstable and decomposes into FeS and FeS ₂ when ignited, and easily decomposes into iron oxide hydrate and sulfur in humid air. Not suitable for.

  It is known that iron sulfide exhibits p-type conductivity when sulfur is excessive as compared with the stoichiometric ratio and n-type conductivity when sulfur is insufficient when impurity doping is not performed.

  On the other hand, studies on the control of the conductivity type by doping impurities into iron sulfide have been conducted energetically.

For example, JP-A-61-106499 (Patent Document 1) discloses that the stoichiometric deviation of pyrite material is in accordance with the formula: FeS _{2 ± X} [0 <x ≦ 0.05] and the concentration of impurities. Is less than 10 ²⁰ per cm ³ , and manganese (Mn), arsenic (As), cobalt (Co), or chlorine (Cl) is used as a doping material, and the doping concentration of the doping material It is disclosed that when a photoactive pyrite layer having a thickness of about 10 ¹⁶ to 10 ¹⁹ per cm ³ is applied to a solar cell, the solar cell exhibits good characteristics. In addition, n-type conductivity can be obtained by doping pyrite FeS ₂ with Ni or Co, while p-type conductivity can be obtained by doping Cu or As with pyrite FeS _2. Is disclosed.

In addition, in Japanese Translation of PCT International Publication No. 2002-516651A (Patent Document 2), at least one of boron (B) and phosphorus (P) is added to a semiconductor substrate made of pyrite having a chemical composition FeS ₂ at least partially. It has been disclosed that bonded semiconductor components or semiconductor components doped with these are optimal and extremely efficient, especially for applications for solar cells.

However, the techniques disclosed in Patent Documents 1 and 2 have a problem that the conductivity type control (pn control) is insufficient. For example, taking Patent Document 2 as an example, the technology described therein is about what matters necessary for practical use, such as which conductivity type boron (B) or phosphorus (P) is a dopant of? There is also a problem that it is far from practical use. Further, due to insufficient conductivity type control (pn control), for example, an all-solid solar cell using pyrite FeS ₂ as a photoactive layer is taken as an example. P. Altermatt, et. Al. Solar Energy MateriaAls & Solar Cells 71 (2002) p. As described in H.181 (Non-Patent Document 1), there is a problem that the photoelectric conversion efficiency is an extremely low value of 1% or less in an all-solid-state solar cell such as a Schottky diode structure.

Furthermore, Patent Documents 1 and 2 describe a doping technique for controlling the conductivity type, but do not describe any technique for controlling the forbidden bandwidth. Further, in the following Non-Patent Document 1 and the cited reference, there is a description that it may be possible to increase the forbidden band width by doping FeS ₂ with zinc. The grounds are not shown either theoretically or theoretically, and there is no specific and practicable description in the following Non-Patent Document 1 and its cited documents. As described above, there is no established method for controlling the forbidden band width of iron sulfide, and there is no way to control the forbidden band width of iron sulfide. It is desirable to clarify how to control the width.
JP 61-106499 A JP 2002-516651A P. P. Altermatt, et. al. ; Solar Energy Materials & Solar Cells 71 (2002);

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor containing iron sulfide that can control the forbidden bandwidth without any problem and can be used as a practical product, a p-type semiconductor, a semiconductor junction element, a pn junction element, and a photoelectric conversion device. Is to provide. In addition, the present invention can perform conductivity type control (pn control) without any problem and can be used as a practical product. A semiconductor containing iron sulfide, a p-type semiconductor, a semiconductor junction element, a pn junction element, and a photoelectric conversion device Is to provide.

In order to solve the above problems, the semiconductor of the present invention is
Iron sulfide,
Forbidden band control element contained in the iron sulfide,
The forbidden band control element has a property capable of controlling the forbidden band of the iron sulfide based on the number density of the forbidden band control element in the iron sulfide.

  According to the present invention, the forbidden band control element has the property of controlling the forbidden band of the iron sulfide based on the number density of the forbidden band control element in the iron sulfide. By controlling the number density of the forbidden band control element to be contained, the forbidden band of iron sulfide can be controlled to a predetermined value.

  In one embodiment of the semiconductor, the forbidden band control element is Mg.

  The inventor tried to control the forbidden bandwidth of iron sulfide by including Mg. As a result, it was discovered that iron sulfide having a desired forbidden band within a wide range of forbidden band widths can be produced.

According to the above embodiment, since the iron sulfide and Mg are included, the forbidden bandwidth can be controlled well. The iron sulfide may have a crystal structure, or may have a structure with a slight deviation from the stoichiometric ratio. Further, the iron sulfide, if has a crystalline structure, the iron sulfide is particularly preferably valence of iron is divalent, it is preferably FeS or FeS _2.

  In the semiconductor of one embodiment, 0.001 ≦ b / a ≦ 0.45, where a is the number of Fe atoms and b is the number of Mg atoms.

  According to the above embodiment, when the number of Fe atoms is a and the number of Mg atoms is b, 0.001 ≦ b / a ≦ 0.45, and therefore the forbidden band width is precisely controlled. Can do.

In one embodiment, the iron sulfide includes FeS ₂ having a pyrite-type crystal structure.

  According to the above embodiment, a large forbidden bandwidth can be obtained.

  In addition, the semiconductor according to one embodiment includes a group Ia element.

  According to the said embodiment, p-type electroconductivity can be provided.

  In one embodiment, the group Ia element is Na.

  According to the above embodiment, the hole carrier concentration can be particularly increased.

  Moreover, the semiconductor of one Embodiment contains the III group element.

  According to the said embodiment, n-type electroconductivity can be provided.

  In one embodiment of the semiconductor, the group III element is Al.

  According to the above embodiment, the electron carrier concentration can be particularly increased.

  Moreover, the semiconductor junction element of one Embodiment contains the semiconductor of this invention.

  According to one embodiment, since the semiconductor of the present invention capable of controlling the forbidden band is included, the device characteristics can be appropriately controlled in accordance with the application purpose.

  Moreover, the pn junction element of one Embodiment has a pn junction containing the semiconductor of this invention.

  According to one embodiment, since the pn junction including the semiconductor of the present invention is provided, the forbidden bandwidth can be controlled according to the application purpose, and the rectification characteristics can be improved.

  Moreover, the pn junction element of one embodiment has a pn junction composed of a p-type semiconductor containing iron sulfide and Mg and an n-type semiconductor, and the forbidden band width of the p-type semiconductor is set to Eg1. When the forbidden band width of the n-type semiconductor is Eg2, Eg1 <Eg2.

  According to the embodiment, for example, when the pn junction element is a photoelectric conversion element, the photoelectric conversion efficiency can be increased.

  In one embodiment of the pn junction element, the n-type semiconductor contains Mg.

  According to the embodiment, the concentration gradient can be controlled by appropriately adjusting the heat treatment conditions.

  A photoelectric conversion device according to an embodiment includes the semiconductor junction element according to an embodiment or the pn junction element according to an embodiment.

  According to one embodiment, when the semiconductor junction element according to one embodiment is provided, the forbidden bandwidth can be controlled to a value suitable for the purpose, and the element characteristics can be improved. Further, in the case of having a pn junction including the semiconductor of the present invention, the forbidden band width is controlled to a value suitable for the wavelength of the target light, so that the photoelectric conversion efficiency can be significantly improved.

  In one embodiment of the semiconductor, the forbidden band control element is Zn.

  The inventor tried to control the forbidden bandwidth of iron sulfide by including Zn. As a result, it was discovered that iron sulfide having a desired forbidden band within a wide range of forbidden band widths can be produced.

According to the embodiment, since iron sulfide and Zn are contained, an iron sulfide semiconductor in which the forbidden band is controlled to a desired value can be manufactured. The iron sulfide may have a crystal structure, or may have a structure with a slight deviation from the stoichiometric ratio. Further, the iron sulfide, if has a crystalline structure, the iron sulfide is particularly preferably valence of iron is divalent, it is preferably FeS or FeS _2.

  In one embodiment of the semiconductor, 0.01 ≦ b / a ≦ 0.45, where a is the number of Fe atoms and b is the number of Zn atoms.

  According to the above embodiment, when the number of Fe atoms is a and the number of Zn atoms is b, 0.01 ≦ b / a ≦ 0.45, so that the forbidden band width can be precisely controlled. Can do.

In one embodiment, the iron sulfide includes FeS ₂ having a pyrite type crystal structure.

  According to the above embodiment, a large forbidden bandwidth can be obtained.

  In addition, the semiconductor device of one embodiment includes a group Ia element.

  According to the said embodiment, p-type electroconductivity can be provided.

  In one embodiment, the group Ia element is Na.

  According to the above embodiment, the hole carrier concentration can be particularly increased.

  In addition, the semiconductor device of one embodiment includes a group III element.

  According to the said embodiment, n-type electroconductivity can be provided.

  In one embodiment, the group III element is Al.

  According to the above embodiment, the electron carrier concentration can be particularly increased.

  Moreover, the semiconductor junction element of one Embodiment contains the semiconductor of this invention.

  According to one embodiment, since the semiconductor of the present invention capable of controlling the forbidden band is included, the device characteristics can be appropriately controlled in accordance with the application purpose.

  Moreover, the pn junction element of one Embodiment has a pn junction containing the semiconductor of this invention.

  According to one embodiment, since the pn junction including the semiconductor of the present invention is provided, the forbidden bandwidth can be controlled according to the application purpose, and the rectification characteristics can be improved.

  Moreover, the pn junction element of one embodiment has a pn junction composed of a p-type semiconductor containing iron sulfide and Mg and an n-type semiconductor, and the forbidden band width of the p-type semiconductor is set to Eg1. When the forbidden band width of the n-type semiconductor is Eg2, Eg1 <Eg2.

  According to the embodiment, for example, when the pn junction element is a photoelectric conversion element, the photoelectric conversion efficiency can be increased.

  In one embodiment of the pn junction element, the n-type semiconductor contains Zn.

  According to the embodiment, good rectification characteristics can be obtained between the n-type semiconductor layer and the p-type semiconductor layer obtained by adding Zn to iron sulfide.

  In one embodiment of the present invention, the n-type semiconductor includes a Zn oxide.

  According to the above embodiment, the forbidden bandwidth can be increased and the electrical resistance can be increased.

  Moreover, the photoelectric conversion element of one Embodiment is provided with the semiconductor junction element of one Embodiment, or the pn junction element of one Embodiment.

  According to one embodiment, when the semiconductor junction element according to one embodiment is provided, the forbidden bandwidth can be controlled to a value suitable for the purpose, and the element characteristics can be improved. Further, in the case of having a pn junction including the semiconductor of the present invention, the forbidden band width is controlled to a value suitable for the wavelength of the target light, so that the photoelectric conversion efficiency can be significantly improved.

  In one embodiment, the semiconductor includes a group Ia element.

  According to the said embodiment, p-type electroconductivity can be provided.

  The p-type semiconductor of the present invention is characterized by containing iron sulfide and a group Ia element.

  It has been reported that most of the artificially produced iron sulfides examined so far exhibit p-type conductivity. For this reason, in many cases, undoped iron sulfide is used as p-type iron sulfide. However, atomic deficiencies can be doped, and at the same time have the potential for electrical adverse effects such as recombination centers. The inventor tried to produce p-type iron sulfide by impurity doping using a group Ia element that had not been envisaged until now. As a result, it was discovered that iron sulfide having a high-quality p conductivity type can be produced.

According to the present invention, since iron sulfide and the Group Ia element are included, the conductivity type can be well controlled to the p-type, and the defect density can be reduced. The iron sulfide may have a crystal structure, or may have a structure with a slight deviation from the stoichiometric ratio. Further, the iron sulfide, if has a crystalline structure, the iron sulfide is particularly preferably valence of iron is divalent, it is preferably FeS or FeS _2.

  In one embodiment of the p-type semiconductor, the group Ia element is at least one of Li, Na, and K.

The present inventor has found that the use of at least one of Li, Na, and K as the group Ia element can suppress the generation of an impurity phase. This is presumably because Li, Na, and K have a relatively small difference in ionic radius from Fe ²⁺ among the group Ia elements.

  According to the embodiment, the generation of the impurity phase can be suppressed.

In one embodiment, the group Ia element is Na, and the number density of Na is 4 × 10 ¹⁵ cm ⁻³ or more and 2 × 10 ²⁰ cm ⁻³ or less.

  According to the said embodiment, electroconductivity can be made into favorable p-type electroconductivity, and it can be made the quality excellent.

In one embodiment of the p-type semiconductor, the iron sulfide includes FeS ₂ having a pyrite-type crystal structure.

  According to the embodiment, semiconductor characteristics suitable for application can be obtained.

  The semiconductor junction element of the present invention includes the p-type semiconductor of the present invention.

  According to the present invention, since the p-type semiconductor of the present invention is included, characteristics of the p-type semiconductor such as carrier transport characteristics can be improved, and element characteristics can be improved.

  The pn junction element of the present invention has a pn junction composed of the p-type semiconductor of the present invention and an n-type semiconductor containing iron sulfide.

  According to the present invention, since the pn junction composed of the p-type semiconductor of the present invention and the n-type semiconductor containing iron sulfide is provided, the rectification characteristics of the pn junction can be improved.

  In one embodiment of the pn junction element, the n-type semiconductor includes at least one of Co, Ni, and Mn.

  In one embodiment, the n-type semiconductor includes at least one of Al, Ga, and In.

In one embodiment, the n-type semiconductor includes FeS ₂ having a pyrite type crystal structure.

Further, the p ⁺ pn junction element of the present invention includes the pn junction element of the present invention,
A p ⁺ type semiconductor layer having a higher number density of group Ia elements than a number density of group Ia elements in the p type semiconductor of the pn junction element.

In the p ⁺ pn junction element of one embodiment, the concentration of the group Ia element in the p ⁺ type semiconductor layer is 20 times or more the concentration of the group Ia element in the p type semiconductor.

The photoelectric conversion device of the present invention includes at least one of the semiconductor junction device of the present invention, the pn junction device of the present invention, and the p ⁺ pn junction device of the present invention.

  According to the present invention, the photoelectric conversion efficiency can be significantly improved.

  According to the semiconductor, p-type semiconductor, semiconductor junction element, and pn junction element of the present invention, the forbidden band width can be controlled without any problem, and the conductivity type control (pn control) can be performed without any problem. Can be used as a real product. In addition, according to the p-type semiconductor of the present invention, the conductivity type can be controlled to be p-type with good reproducibility, the defect density can be reduced, and it can be used as a practical product. Moreover, according to the photoelectric conversion element of the present invention, the photoelectric conversion efficiency can be improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view of a photoelectric conversion device according to an embodiment of the present invention.

  This photoelectric conversion device includes a substrate 1, a first electrode layer 2 formed on at least a part of a surface region of the substrate 1, a photoelectric conversion layer 3 formed on the first electrode layer 2, and a photoelectric conversion layer. 2 and a second electrode layer 4 formed on the substrate 3.

  When the substrate 1 is located on the side opposite to the light incidence, whether the substrate 1 is translucent or not is not questioned. On the other hand, when the substrate 1 is located on the light incidence side, the substrate 1 is at least partially It preferably has translucency. As a material of the light-transmitting substrate, there is glass, and there is a light-transmitting resin having a certain heat resistance among polyimide-based, polyvinyl-based, or polysulfide-based materials, and those light-transmitting resins are laminated. There are things. Examples of the material of the non-translucent substrate include stainless steel and non-translucent resin.

  In addition, unevenness may be formed on the surface of the substrate 1, and in this case, various effects such as light confinement and antireflection can be obtained by refraction or scattering of light on the uneven surface. Further, the surface of the substrate 1 may be coated with a metal film, a semiconductor film, an insulating film, or a composite film thereof. The thickness of the substrate 1 is not particularly limited, but needs to have an appropriate strength and weight capable of supporting the structure. For example, the thickness of the substrate 1 can be 0.1 mm to 40 mm.

The first electrode layer 2 may have any form as long as the first electrode layer 2 is formed so as to be substantially in ohmic contact with the photoelectric conversion layer 3. However, the first electrode layer 2 is formed in a film shape on the substrate 1. Is preferred. The material used for the first electrode layer 2 is not particularly limited as long as it is a conductive material, but a metal material such as Mo, Al, Pt, Ti, Fe, Pd, or an alloy thereof is used. , Fluorine doped tin oxide (SnO ₂ : F), antimony doped tin oxide (SnO ₂ : Sb), tin doped indium oxide (In ₂ O ₃ : Sn), Al doped zinc oxide (ZnO: Al) It is preferable to use a transparent conductive electrode material typified by Ga-doped zinc oxide (ZnO: Ga) or B-doped zinc oxide (ZnO: B). In addition, the first electrode layer 2 may be a single layer film made of the above-described material or the like, or may be any one of a laminated film in which a plurality of the above-described materials are stacked.

  When the first electrode layer 2 is located on the light incident side, the first electrode layer 2 preferably has high translucency in the wavelength range of light contributing to photoelectric conversion. The first electrode layer 2 is made of a material such as a vacuum deposition method, a sputtering method, a CVD method, a PVD method, a gas phase method, a sol-gel method, a CBD (chemical bath deposition) method, a spray method, a screen printing method, or the like. Is formed by laminating on the substrate 1.

  As described above, when the substrate 1 is located on the light incident side, the first electrode layer 2 is required to have a high light transmittance. Therefore, in that case, the first electrode layer 2 is a grid-shaped metal electrode that does not cover the surface uniformly, such as a comb, or a transparent conductive layer with high light transmittance, or a combination of these requirements. It is preferable to be formed.

  The first electrode layer 2 preferably has irregularities on the surface thereof. The unevenness present on the surface of the first electrode layer 2 refracts and scatters light that has entered the photoelectric conversion device at the interface between the first electrode layer 2 and the photoelectric conversion layer 3 formed thereon. . As a result, the optical path length of incident light can be increased, the light confinement effect can be improved, and the amount of light that can be used in the photoelectric conversion layer 3 can be increased. As a method for forming the unevenness, a dry etching method, a wet etching method, a mechanical process such as sand blasting, or the like on the surface of the first electrode layer 2 can be used.

As a dry etching method, in addition to physical etching using an inert gas such as Ar, fluorine-based gas such as CF ₄ and SF ₆ , chlorine-based gas such as CCl ₄ and SiCl ₄ , or methane gas is used. Chemical etching, etc. In addition, as the wet etching method, there is a method of immersing the first electrode layer 2 in an acid or alkali solution. Here, examples of the acid solution that can be used in wet etching include one or a mixture of two or more of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, acetic acid, formic acid, perchloric acid, and the like. There are one or a mixture of two or more of sodium, ammonia, potassium hydroxide, calcium hydroxide, aluminum hydroxide, and the like. As a method other than the etching method described above, a method of self-forming surface irregularities by controlling crystal growth of the material itself of the first electrode layer 2 by a CVD method or the like, or depending on a crystal grain shape by a sol-gel method or a spray method. There is a method of forming surface irregularities.

  The photoelectric conversion layer 3 is formed on the first electrode layer 2 so as to be substantially in ohmic contact. The photoelectric conversion layer 3 has a structure including a semiconductor layer formed by adding Mg to iron sulfide. The photoelectric conversion layer 3 has a structure having a pn junction having a p-type semiconductor layer and an n-type semiconductor layer, a pin having a p-type semiconductor layer, an intrinsic (i-type) semiconductor layer, and an n-type semiconductor layer. There are a structure having a junction, a Schottky junction using a semiconductor layer and a metal layer, a structure having a semiconductor junction such as a MIS structure, and the like.

  The i-type semiconductor layer may have a weak p-type or weak n-type conductivity type as long as the photoelectric conversion function is not impaired. Further, the photoelectric conversion device may have a structure in which two or more photoelectric conversion layers are stacked, and the photoelectric conversion device may be a so-called stacked photoelectric conversion device.

  In p. 184 of Non-Patent Document 1, the forbidden band width of iron sulfide is in the range of 0.8 to 0.9 eV in the case of a thin film containing an amorphous component or the like, and in the case of a pyrite type crystal. , 0.9 to 0.95 eV.

  The present inventor is able to obtain a semiconductor layer whose forbidden band width is controlled to a desired value within a range of 0.95 to 1.26 eV by adding Mg to iron sulfide, based on light transmission reflection measurement ( ωα) discovered by performing 2 plots. In detail, when Mg is added to iron sulfide, a semiconductor layer whose forbidden band width is controlled to a desired value within the range of 0.95 to 1.26 eV can be obtained from the appropriate range of the above two plots. It was found from the change in the optical forbidden bandwidth estimated from the x-intercept in the straight line obtained by using the square method.

Here, it has been found that the forbidden band width of iron sulfide changes greatly when the Mg concentration (Mg / Fe) is in the range of 0.1 atomic% to 10 atomic% and then saturates. When it is desired to control the forbidden band width in small increments, a concentration range of 0.1 atomic% to 10 atomic% may be used, and when it is desired to stably obtain a wide forbidden band width, 10 atomic% to 45 atomic%. It has been found that a concentration range of atomic% may be used. The Mg concentration in iron sulfide can be evaluated by a known elemental analysis method such as secondary ion mass spectrometry (SIMS) or Auger electron spectroscopy. Further, in order to further increase the forbidden band width, the iron sulfide includes FeS ₂ having a pyrite type crystal structure. This is because FeS ₂ having a pyrite type crystal structure has a high effect of increasing the forbidden bandwidth by including Mg.

  Control of the carrier concentration is extremely important in considering applications. Here, since the carrier concentration control technique of the semiconductor layer formed by adding Mg to iron sulfide has not been clarified, the present inventor conducted experiments on various elements. And the following carrier concentration control technology was discovered.

  That is, if a group I element is further added to the semiconductor layer obtained by adding Mg to iron sulfide, the hole carrier concentration can be increased. Here, if Na is selected as the group I element to be added, the hole carrier concentration can be particularly increased.

  On the other hand, when a group III element is further added to the semiconductor layer obtained by adding Mg to iron sulfide, the electron carrier concentration can be increased. Here, if Al is selected as the group III element to be added, the electron carrier concentration can be particularly increased. The carrier concentration can be evaluated by hole measurement using, for example, the van der Pauw method.

  According to the photoelectric conversion device of the first embodiment, an iron sulfide semiconductor can be obtained by appropriately adjusting the Mg concentration in iron sulfide or adding an appropriate element to a semiconductor layer formed by adding Mg to iron sulfide. Forbidden band width, carrier type and carrier concentration can be controlled independently, and a semiconductor layer suitable for application can be formed.

  As a manufacturing method of the photoelectric converting layer 3, well-known methods, such as MBE method, CVD method, vapor deposition method, proximity sublimation method, sputtering method, sol-gel method, spray method, CBD (chemical bath deposition) method, screen printing method, etc. A manufacturing method can be used. Examples of the CVD method include atmospheric pressure CVD, reduced pressure CVD, plasma CVD, thermal CVD, hot wire CVD, and MOCVD. The details of the manufacturing method are as detailed in, for example, Non-Patent Document 1 or a cited document described therein.

Here, it is preferable to perform a sulfiding treatment in sulfur vapor or in a hydrogen sulfide atmosphere as necessary. The sulfiding treatment temperature is preferably 200 ° C to 600 ° C. When sulfidation is performed, crystallization of an amorphous component can be promoted, the sulfur content in iron sulfide can be increased, or the proportion of FeS ₂ having a pyrite-type crystal structure can be increased.

Here, the ratio of the amorphous component can be estimated by performing XRD measurement. In detail, the peak intensity of the XRD measurement in the crystallized component detection layer can be estimated by comparing the peak intensity of the crystallized component detection layer with a sufficiently crystallized layer having the same film thickness. The ratio of FeS ₂ having a crystal structure of the pyrite type can be estimated by comparing the XRD peak intensity of FeS ₂ pyrite structure and XRD peak intensity of iron sulfide of the other structure.

  Finally, the second electrode layer 4 is formed on the photoelectric conversion layer 3 to complete the main part of the photoelectric conversion device. Specifically, the second electrode layer 4 is formed on the photoelectric conversion layer 3 so as to be substantially in ohmic contact using the same material and the same manufacturing method as those for the electrode layer 2, and the essential elements of the photoelectric conversion device are thus obtained. Forming part.

  FIG. 2 is a cross-sectional view of a photoelectric conversion device according to another embodiment of the present invention.

  The photoelectric conversion device includes a substrate 21, a first electrode layer 22 formed on at least a part of the surface region of the substrate 21, a photoelectric conversion layer 23 formed on the first electrode layer 22, and a photoelectric conversion layer. The transparent electrode layer 24 formed on the surface 23 and the grid electrode layer 25 formed on a part of the surface region of the transparent electrode layer 24 are provided. The photoelectric conversion layer 23 includes a p-type semiconductor layer 27 formed on the first electrode layer 22 and an n-type semiconductor layer formed on the p-type semiconductor layer 27.

  The first electrode layer 22 is formed on the substrate 21 by the same method as in the first embodiment. The photoelectric conversion layer 23 has a pn junction structure including a p-type semiconductor layer 27 including a semiconductor layer formed by adding Mg to iron sulfide, and an n-type semiconductor layer 28. The p-type semiconductor layer 27 is formed on the first electrode layer 22 so as to be in ohmic contact. As a method of forming the p-type semiconductor layer 27 on the first electrode layer 22, the same method as the method of forming the photoelectric conversion layer 3 on the first electrode layer 2 in the first embodiment may be used. it can.

  The n-type semiconductor layer 28 is formed on the p-type semiconductor layer 27. Here, the n-type semiconductor layer 28 is made to be a p-type semiconductor layer so that the forbidden band width Eg1 of the p-type semiconductor layer 27 and the forbidden band width Eg2 of the n-type semiconductor layer 28 have a relationship of Eg1 <Eg2. 27 is formed. The n-type semiconductor layer 28 is not particularly limited as long as it is an n-type semiconductor layer that satisfies the relationship of Eg1 <Eg2. Typical examples include an iron sulfide semiconductor, an oxidation of Zn or Mg. Products, sulfides or hydroxides. The forbidden band width Eg1 of the p-type semiconductor layer 27 is controlled to have a forbidden band width according to the application purpose because it is used as a photoactive layer. Here, the n-type semiconductor layer 28 preferably has low absorption with respect to light in the target wavelength band. When the relationship of Eg1 <Eg2 is satisfied, the above object can be achieved and high photoelectric conversion efficiency can be realized. The n-type semiconductor layer 28 preferably contains Mg. When the n-type semiconductor layer 28 contains Mg, good rectification characteristics can be obtained between the n-type semiconductor layer 28 and the p-type semiconductor layer 27 formed by adding Mg to iron sulfide.

  As a method for producing the n-type semiconductor layer 28, MBE, CVD, vapor deposition, proximity sublimation, sputtering, sol-gel, spraying, CBD (chemical bath deposition), screen printing, and the like are known. There is a manufacturing method. Examples of the CVD method include atmospheric pressure CVD, reduced pressure CVD, plasma CVD, thermal CVD, hot wire CVD, and MOCVD. Here, if necessary, sulfurization treatment in sulfur vapor or in a hydrogen sulfide atmosphere can be performed. The sulfiding treatment temperature is preferably 200 to 600 ° C. When sulfidation is performed, in the case of an iron sulfide semiconductor, it is possible to improve the crystallization rate or reduce sulfur deficiency. In addition, oxides such as Zn and Mg, sulfides, hydroxides, etc. can be partially sulfided to increase the ratio of sulfides, increasing the forbidden band width and increasing electrical resistance. You can do it.

  The Mg concentration in the p-type semiconductor layer 27 is preferably the highest at the pn interface and decreases as the distance from the interface increases. Since the Mg concentration variation in the p-type semiconductor layer 27 has a concentration gradient that decreases as the distance from the interface increases, high photoelectric conversion efficiency can be obtained. The Mg concentration in the device structure can be evaluated by analyzing the depth direction using a known elemental analysis method such as secondary ion mass spectrometry (SIMS) or Auger electron spectroscopy. As a method for forming the Mg concentration gradient, for example, there is a method in which Mg is contained in the n layer or the p / n interface and then heat treatment is performed at 200 to 500 ° C. In this way, the concentration gradient can be controlled by the heat treatment conditions.

  The transparent electrode layer 24 is formed on the photoelectric conversion layer 23 so as to substantially make ohmic contact. Specifically, in the first embodiment, the transparent electrode layer 24 is formed on the photoelectric conversion layer 23 by using the same material and the same manufacturing method as in the case where the electrode layer 2 has translucency. To do.

  The grid electrode layer 25 is formed on a partial surface region of the transparent electrode layer 24. Specifically, in the first embodiment, the grid electrode layer 25 is formed on a part of the surface region of the transparent electrode layer 24 by using the same material and manufacturing method as the material and manufacturing method performed for the electrode layer 2. To do. In this way, a photoelectric conversion device with high photoelectric conversion efficiency is formed.

  FIG. 3 is a schematic cross-sectional view of the sulfide semiconductor of the first to sixth embodiments of the present invention and the sulfide semiconductor of Comparative Example 1.

  Table 1 below is a table showing the types and concentrations of the compounds of the sulfide semiconductors of the first to sixth embodiments of the present invention and the sulfide semiconductor of Comparative Example 1.

[Table 1]

  Below, based on FIG. 3 and Table 1, the sulfide semiconductor of 1st-6th embodiment is demonstrated.

  The sulfide semiconductors of the first to sixth embodiments are manufactured by forming the iron sulfide layer 32 on the glass substrate 31 having a thickness of 1.1 mm by using the spray pyrolysis method and the sulfide method together. ing.

Specifically, for example, iron chloride (FeCl ₂ ) and thiourea (NH ₂ CSNH ₂ ) are mixed in 500 ml of pure water, the concentration of iron chloride (FeCl ₂ ) is 50 mmol / l, and thio A solution is prepared in which the concentration of urea (NH ₂ CSNH ₂ ) is 100 mmol / l.

Next, magnesium chloride (MgCl ₂ ) having the concentration (mmol / l) shown in Table 1 is further dissolved in the prepared solution to prepare a spray solution. Next, the glass substrate 31 is heated to about 200 ° C. on a hot plate and in the atmosphere, and then the solution is sprayed onto the hot plate to form a thin film.

  The thin film formed by spray coating is subjected to XRD measurement to confirm that no peak of iron oxide or hydroxide is observed, and confirm that the main component of the thin film is FeS.

Next, a sample formed by forming a thin film on the glass substrate 31 is baked at 500 ° C. for 1 hour in a sulfur vapor atmosphere. At this time, sulfur vapor is generated by heating sulfur at a temperature of 150 ° C. using a heater different from the heater for heating the sample, and nitrogen gas is allowed to flow as a carrier gas at a flow rate of 5 l / min. After the sulfiding treatment, XRD measurement is performed to confirm that a single phase of FeS ₂ pyrite is formed. It was 700 nm when the thickness of the iron sulfide layer 32 was measured using the level | step difference film thickness meter. In this way, the iron sulfide semiconductor shown in FIG. 3 is produced.

  The conductivity types shown in Table 1 are determined based on the results of Hall measurement. The conditions for Hall measurement are as follows. Al was used as the electrode material, and the van der Pauw method was used for the electrode structure. The measurement was carried out using RESTEST 8300 manufactured by Toyo Corporation, in a magnetic field maximum amplitude of 0.6 T, a magnetic field frequency of 0.1 Hz, room temperature, and a dry nitrogen atmosphere. Further, the Mg / Fe ratio shown in Table 1 is determined based on the results of Auger electron spectroscopy measurement. Eg (eV) is determined based on optical band gap (Eg) measurement.

Here, Eg obtains the light absorption coefficient α from the light transmittance and reflectance measurements, plots the square of the light absorption coefficient (ω ² α ² ) against the energy of the incident light, It was calculated based on the x-intercept of the straight line obtained from the range using the least square method. That is, the transition band gap is obtained directly from the x intercept.

The concentration (mmol / l) shown in Table 1 indicates the concentration of magnesium chloride (MgCl ₂ ) used for preparing the spray solution.

  As shown in Table 1, the carrier type was p-type in each of Comparative Example 1 not containing Mg and the first to sixth embodiments containing Mg. Further, when the first to sixth embodiments are compared, Eg increases rapidly as the Mg concentration increases until the Mg / Fe ratio is 10%, and then shows a saturation tendency. Therefore, forbidden bandwidth can be controlled by including Mg in iron sulfide.

  Next, the doped semiconductor layer will be described.

  The sulfide semiconductors of the seventh and eighth embodiments of the present invention are doped semiconductor layers. Similarly to the first to sixth embodiments, the sulfide semiconductors of the seventh and eighth embodiments also have the schematic cross-sectional view shown in FIG.

  Table 2 below shows the types and concentrations of the compounds of the sulfide semiconductors of the seventh and eighth embodiments of the present invention and the sulfide semiconductor of Comparative Example 1.

[Table 2]

  Hereinafter, based on FIG. 3 and Table 2, the semiconductor layer of 7th and 8th embodiment and the comparative example 1 is demonstrated.

  The iron sulfide semiconductors of the seventh and eighth embodiments are produced by forming an iron sulfide layer 32 on a glass substrate 31 having a thickness of 1.1 mm by using a spray pyrolysis method and a sulfide method together. Yes.

Specifically, a compound containing impurities for controlling the conductivity type shown in Table 2 (NaCl in the case of p-type and AlCl _{3 in} the case of n-type) is further dissolved in the spray solution used in the fourth embodiment. To prepare a solution for spraying. Next, the glass substrate 31 is heated to about 200 ° C. on a hot plate and in the atmosphere, and then the solution is sprayed onto the hot plate to form a thin film.

  The thin film formed by spray coating is subjected to XRD measurement to confirm that no iron oxide or hydroxide peak is observed. This confirms that the main component of the thin film is FeS.

Next, a sample formed by forming a thin film on the glass substrate 31 in a sulfur vapor atmosphere is baked at 500 ° C. for 1 hour. At this time, sulfur vapor is generated by heating sulfur at a temperature of 150 ° C. using a heater different from the heater for heating the sample, and nitrogen gas is allowed to flow as a carrier gas at a flow rate of 5 l / min. An XRD measurement is performed after the sulfuration treatment to confirm that a single phase of FeS ₂ pyrite is formed. Moreover, it was 700 nm when the thickness of the iron sulfide layer 32 was measured using the level | step difference film thickness meter. In this way, an iron sulfide semiconductor is produced.

  The conductivity types and carrier concentrations shown in Table 2 are determined based on the results of Hall measurement. The conditions for Hall measurement are as follows. Al was used as the electrode material, and the van der Pauw method was used for the electrode structure. The measurement was carried out using RESTEST 8300 manufactured by Toyo Corporation, in a magnetic field maximum amplitude of 0.6 T, a magnetic field frequency of 0.1 Hz, room temperature, and a dry nitrogen atmosphere. Further, the element concentrations in the film shown in Table 2 (Na concentration for p-type and Al concentration for n-type) are determined based on the results of Auger electron spectroscopy measurement.

As shown in Table 2, in Comparative Example 1 in which doping was not performed, the carrier type was p-type and the carrier concentration was 1 × 10 ¹⁷ cm ⁻³ . In the seventh embodiment containing Na, the carrier type was p-type and the carrier concentration was 1 × 10 ¹⁹ cm ⁻³ .

For this reason, the hole carrier concentration can be increased by adding Na to the iron sulfide containing Mg. In the eighth embodiment containing Al, the carrier type was n-type and the carrier concentration was 8 × 10 ¹⁸ cm ⁻³ . From this, in the iron sulfide containing Mg, when Al is included, the electron carrier concentration can be increased. In this way, the forbidden band width, carrier type and carrier concentration of the iron sulfide semiconductor can be independently controlled, and a semiconductor layer suitable for application can be obtained.

  Next, a photoelectric conversion device will be described.

  The photoelectric conversion elements of the ninth to twelfth embodiments of the present invention have a cross-sectional view shown in FIG. Table 3 is a table showing the types of n-type semiconductor layers included in the photoelectric conversion elements of the ninth to twelfth embodiments and the photoelectric conversion efficiency of a photoelectric conversion device using the n-type semiconductor layer.

[Table 3]

  Hereinafter, based on FIG. 2 and Table 3, the photoelectric conversion devices of the ninth to twelfth embodiments will be described.

  The photoelectric conversion devices of the ninth to twelfth embodiments include a substrate 21, a first electrode layer 22 formed on at least a part of the surface region of the substrate 21, and a photoelectric conversion formed on the first electrode layer 22. A layer 23, a transparent electrode layer 24 formed on the photoelectric conversion layer 23, and a grid electrode layer 25 formed on a partial surface region of the transparent electrode layer 24.

  The photoelectric conversion layer 23 includes a p-type semiconductor layer 27 formed on the first electrode layer 22 and an n-type semiconductor layer 28 formed on the p-type semiconductor layer 27. Here, the photoelectric conversion devices of the ninth to twelfth embodiments are the same except that the material and manufacturing method of the n-type semiconductor layer 28 are different.

  The photoelectric conversion device of the ninth embodiment is formed as follows.

First, for example, a Pt film having a thickness of 500 nm is formed on a glass substrate 21 having a plate thickness of 1.1 mm by vacuum deposition, and then n-type gallium-doped zinc oxide (ZnO: Ga) is formed thereon by magnetron sputtering. ) Is deposited to 700 nm to form the first electrode layer 22. Next, a p-type semiconductor layer 27 made of FeS ₂ pyrite containing Mg is formed on the first electrode layer 22 by using a spray pyrolysis method and a sulfurization method in combination. Specifically, when producing p-type FeS ₂ pyrite containing Mg, the same glass substrate 21 on which the first electrode layer 22 is laminated as the p-type spray solution used in the third embodiment of Table 1 is used. Is heated to about 200 ° C. on a hot plate and in the air, and the above solution is spray-coated thereon to form a thin film.

Next, baking is performed at 500 ° C. for 1 hour in a sulfur vapor atmosphere. At this time, sulfur vapor is generated by heating sulfur at a temperature of 150 ° C. using a heater different from the heater for heating the sample, and nitrogen gas is supplied as a carrier gas at a flow rate of 5 l / min. Here, XRD measurement is performed after the sulfurization treatment to confirm that a single phase of FeS ₂ pyrite is formed. still. In one experimental example, the film thickness of the FeS ₂ pyrite film was 2 μm. In this way, the layers up to the p-type semiconductor layer 27 are formed.

Subsequently, in order to produce n-type FeS ₂ pyrite on p-type FeS ₂ pyrite, it performed again spray coating. Specifically, when preparing n-type FeS ₂ pyrite containing Mg and Al, as the n-type spray solution, the same solution as in the eighth embodiment of Table 2 diluted 20 times with pure water, A substrate on which p-type FeS ₂ pyrite is formed is heated to about 100 ° C. in the air on a hot plate, and the solution is sprayed thereon to form a thin film. At this time, after adjusting the number of sprays so that the film thickness becomes 50 nm, the baking is performed at 500 ° C. in the sulfur vapor atmosphere as in the case of the p-type. Here, the firing time was 10 minutes. In this manner, the photoelectric conversion layer 23 including the p-type semiconductor layer 27 formed on the electrode layer 22 and the n-type semiconductor layer 28 formed on the p-type semiconductor layer 27 is formed. Here, the forbidden band width of the p-type semiconductor layer 27 is clearly equal to that of the third embodiment from the spray solution used for the production. The forbidden band width of the n-type semiconductor layer 28 is as follows. FeS ₂ pyrite is produced on a glass substrate in the same manner as described above, and the forbidden band width is measured in the same manner as in the first to sixth embodiments. .29 eV. From this, it was possible to satisfy the relationship of Eg1 <Eg2.

  After that, 700 nm of n-type gallium-doped zinc oxide (ZnO: Ga) is deposited on the photoelectric conversion layer 23 by magnetron sputtering to form a transparent conductive film 24, and then the comb-shaped silver is formed on the transparent conductive film 24. The grid electrode 25 is formed by forming (Ag) by a magnetron sputtering method. In this way, the photoelectric conversion device shown in FIG. 2 is formed.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . And the result shown in the said Table 3 was obtained.

Next, the photoelectric conversion device of the tenth embodiment is formed as follows. Similarly to the ninth embodiment, the layers up to the p-type semiconductor layer 27 are formed. Subsequently, in order to produce n-type FeS ₂ pyrite on p-type FeS ₂ pyrite, it performed again spray coating. More specifically, when preparing n-type Fe _S 2 pyrite containing Mg and Al, AlCl _{3 is set} to 100 mmol / l in the same solution as the first embodiment shown in Table 1 as an n-type spray solution. After the addition, a 20-fold diluted product with pure water is used, and the subsequent steps form the photoelectric conversion device shown in FIG. 2 in the same manner as in the ninth embodiment. Here, the forbidden band width of the p-type semiconductor layer 27 in the tenth embodiment is clearly equal to that in the third embodiment from the spray solution used for the production. The forbidden band width of the n-type semiconductor layer 28 was obtained by preparing FeS ₂ pyrite on a glass substrate in the same manner as described above, and measuring the forbidden band width in the same manner as in the first to sixth embodiments. It was 10 eV. Therefore, there is a relationship of Eg1> Eg2.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . Table 3 shows the measurement results of photoelectric conversion efficiency.

  Next, the photoelectric conversion device of the eleventh embodiment is formed as follows. Similarly to the ninth embodiment, the layers up to the p-type semiconductor layer 27 are formed.

Subsequently, spray coating is performed again to produce n-type ZnO on p-type FeS ₂ pyrite. Specifically, when producing n-type ZnO having oxygen vacancies, zinc chloride (ZnCl ₂ ) is mixed in 500 ml of pure water as an n-type spray solution, and zinc chloride (ZnCl ₂ ) is added at 5 mmol / 1 is prepared and used as a solution for spraying. Next, the substrate on which the p-type FeS ₂ pyrite is formed is heated to about 100 ° C. in the atmosphere on a hot plate, and the solution is sprayed thereon to form a thin film. At this time, after adjusting the number of sprays so that the film thickness becomes 200 nm, it is heated to about 200 ° C. in the air on a hot plate and dried and oxidized for 10 minutes. Then, a photoelectric conversion layer 23 including a p-type semiconductor layer 27 formed on the electrode layer 22 and an n-type semiconductor layer 28 formed on the p-type semiconductor layer 27 is formed. Here, n-type ZnO was produced on a glass substrate in the same manner as described above, and the resistivity and the forbidden band width were measured. The resistivity was 2 × 10 ⁻⁹ Ωcm as a result of laminating comb-shaped Ag electrodes. The forbidden band width was found to be 3.4 eV as determined by the same method as in the case of iron sulfide. Therefore, the relationship of Eg1 <Eg2 is satisfied.

  After that, 700 nm of n-type gallium-doped zinc oxide (ZnO: Ga) is deposited on the photoelectric conversion layer 23 by magnetron sputtering to form a transparent conductive film 24, and then the comb-shaped silver is formed on the transparent conductive film 24. The grid electrode 25 is formed by forming (Ag) by a magnetron sputtering method. In this way, the photoelectric conversion device shown in FIG. 2 is formed.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . Table 3 shows the measurement results of photoelectric conversion efficiency.

  Next, the photoelectric conversion device of the twelfth embodiment is formed as follows. Similarly to the ninth embodiment, the layers up to the p-type semiconductor layer 27 are formed.

Subsequently, spray coating is performed again to produce n-type ZnO on p-type FeS ₂ pyrite. Specifically, when producing n-type ZnO containing Mg and having oxygen vacancies, zinc chloride (ZnCl ₂ ) and magnesium chloride (MgCl ₂ ) are mixed in 500 ml of pure water as an n-type spray solution, A solution in which zinc chloride (ZnCl ₂ ) is 5 mmol / l and magnesium chloride (MgCl ₂ ) is 0.5 mmol / l is prepared as a spray solution. The subsequent steps are the same as in the eleventh embodiment, and the photoelectric conversion device shown in FIG. 2 is formed.

Here, n-type ZnO was produced on a glass substrate in the same manner as described above, and the resistivity and the forbidden band width were measured. The resistivity was 2 × 10 ⁻⁹ Ωcm as a result of laminating comb-shaped Ag electrodes. The forbidden band width was 3.5 eV as a result of obtaining by the same method as in the case of iron sulfide. Therefore, the relationship of Eg1 <Eg2 is satisfied.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . Table 3 shows the measurement results of photoelectric conversion efficiency.

  As shown in Table 3, all the photoelectric conversion devices of the ninth to twelfth embodiments exhibited rectifying properties, and the conversion efficiency of each photoelectric conversion device was a high value exceeding 2%. From this, when an iron sulfide and an iron sulfide semiconductor containing Mg are used, a good pn junction can be formed.

  Further, when the tenth embodiment in which the relationship between the forbidden band width Eg1 of the p-type semiconductor and the forbidden band width Eg2 of the n-type semiconductor is Eg1> Eg2 is compared with the ninth, eleventh and twelfth embodiments in which Eg1 <Eg2. It can be seen that the latter has higher photoelectric conversion efficiency. Therefore, when the forbidden bandwidth has a relationship of Eg1 <Eg2, higher photoelectric conversion efficiency can be realized.

  Further, when comparing the eleventh embodiment using the n-type ZnO semiconductor layer not containing Mg and the twelfth embodiment using the n-type ZnO semiconductor layer containing Mg, the latter is more optoelectronic. It can be seen that the conversion efficiency is high. Therefore, when the n-type semiconductor layer contains Mg, good rectification characteristics can be obtained, and higher photoelectric conversion efficiency can be realized.

  In the ninth to twelfth embodiments, the photoelectric conversion element is manufactured using the pn junction composed of the p-type semiconductor and the n-type semiconductor of the present invention. However, the photoelectric conversion element is composed of the p-type semiconductor and the n-type semiconductor of the present invention. It goes without saying that a pn junction element such as a diode, a transistor (pnp transistor, npn transistor, pnip transistor), or a switch having a pn junction (pnpm switch, pnpn switch) may be manufactured using the pn junction. When a pn junction element is manufactured using a pn junction composed of the p-type semiconductor and the n-type semiconductor of the present invention, the rectification characteristics of the pn junction element can be significantly improved, and the element characteristics of the pn junction element are improved. It can be improved significantly.

  FIG. 4 is a cross-sectional view of a photoelectric conversion device according to an embodiment of the present invention.

  This photoelectric conversion device includes a substrate 101, a first electrode layer 102 formed on at least a part of a surface region of the substrate 101, a photoelectric conversion layer 3 formed on the first electrode layer 102, and a photoelectric conversion layer. And a second electrode layer 104 formed on the substrate 103.

  When the substrate 101 is located on the side opposite to the light incidence, it does not matter whether the substrate 101 is translucent. On the other hand, when the substrate 101 is located on the light incidence side, the substrate 101 is at least partially It preferably has translucency. As a material of the light-transmitting substrate, there is glass, and there is a light-transmitting resin having a certain heat resistance among polyimide-based, polyvinyl-based, or polysulfide-based materials, and those light-transmitting resins are laminated. There are things. Examples of the material of the non-translucent substrate include stainless steel and non-translucent resin.

  Further, unevenness may be formed on the surface of the substrate 101. In this case, various effects such as light confinement and antireflection can be obtained by refraction or scattering of light on the uneven surface. Further, the surface of the substrate 101 may be covered with a metal film, a semiconductor film, an insulating film, or a composite film thereof. The thickness of the substrate 1 is not particularly limited, but needs to have an appropriate strength and weight capable of supporting the structure. For example, the thickness of the substrate 1 can be 0.1 mm to 40 mm.

The first electrode layer 102 may have any form as long as the first electrode layer 102 is formed so as to be substantially in ohmic contact with the photoelectric conversion layer 103. However, the first electrode layer 102 is formed in a film shape on the substrate 1. Is preferred. The material used for the first electrode layer 102 is not particularly limited as long as it is a conductive material, but a metal material such as Mo, Al, Pt, Ti, Fe, Pd, or an alloy thereof is used. , Fluorine doped tin oxide (SnO ₂ : F), antimony doped tin oxide (SnO ₂ : Sb), tin doped indium oxide (In ₂ O ₃ : Sn), Al doped zinc oxide (ZnO: Al) It is preferable to use a transparent conductive electrode material typified by Ga-doped zinc oxide (ZnO: Ga) or B-doped zinc oxide (ZnO: B). In addition, the first electrode layer 2 may be a single layer film made of the above-described material or the like, or may be any one of a laminated film in which a plurality of the above-described materials are stacked.

  When the first electrode layer 2 is located on the light incident side, the first electrode layer 102 preferably has high translucency in the wavelength range of light that contributes to photoelectric conversion. The first electrode layer 102 is made of a material such as a vacuum deposition method, a sputtering method, a CVD method, a PVD method, a gas phase method, a sol-gel method, a CBD (chemical bath deposition) method, a spray method, a screen printing method, or the like. Are formed on the substrate 101.

  As described above, when the substrate 1 is located on the light incident side, the first electrode layer 102 is required to have a high light transmittance. Therefore, in that case, the first electrode layer 102 is a grid-shaped metal electrode that does not cover the surface uniformly, such as a comb, a transparent conductive layer with high light transmittance, or a combination of these requirements. It is preferable to be formed.

  The first electrode layer 102 preferably has irregularities on the surface thereof. The unevenness present on the surface of the first electrode layer 102 refracts and scatters light that has entered the photoelectric conversion device at the interface between the first electrode layer 102 and the photoelectric conversion layer 103 formed thereon. . As a result, the optical path length of incident light can be increased, the light confinement effect can be improved, and the amount of light that can be used in the photoelectric conversion layer 103 can be increased. As a method for forming the unevenness, a dry etching method, a wet etching method, a mechanical process such as sand blasting, or the like on the surface of the first electrode layer 102 can be used.

As a dry etching method, in addition to physical etching using an inert gas such as Ar, fluorine-based gas such as CF ₄ and SF ₆ , chlorine-based gas such as CCl ₄ and SiCl ₄ , or methane gas is used. Chemical etching, etc. Further, as the wet etching method, there is a method of immersing the first electrode layer 102 in an acid or alkali solution. Here, examples of the acid solution that can be used in wet etching include one or a mixture of two or more of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, acetic acid, formic acid, perchloric acid, and the like. There are one or a mixture of two or more of sodium, ammonia, potassium hydroxide, calcium hydroxide, aluminum hydroxide, and the like. As a method other than the etching method described above, a method of self-forming surface irregularities by controlling crystal growth of the material itself of the first electrode layer 2 by a CVD method or the like, or depending on a crystal grain shape by a sol-gel method or a spray method. There is a method of forming surface irregularities.

  The photoelectric conversion layer 103 is formed on the first electrode layer 102 so as to substantially make ohmic contact. The photoelectric conversion layer 103 has a structure including a semiconductor layer formed by adding Zn to iron sulfide. The photoelectric conversion layer 103 has a structure having a pn junction having a p-type semiconductor layer and an n-type semiconductor layer, a pin having a p-type semiconductor layer, an intrinsic (i-type) semiconductor layer, and an n-type semiconductor layer. There are a structure having a junction, a Schottky junction using a semiconductor layer and a metal layer, a structure having a semiconductor junction such as a MIS structure, and the like.

  The i-type semiconductor layer may have a weak p-type or weak n-type conductivity type as long as the photoelectric conversion function is not impaired. Further, the photoelectric conversion device may have a structure in which two or more photoelectric conversion layers are stacked, and the photoelectric conversion device may be a so-called stacked photoelectric conversion device.

  In p. 184 of Non-Patent Document 1, the forbidden band width of iron sulfide is in the range of 0.8 to 0.9 eV in the case of a thin film containing an amorphous component or the like, and in the case of a pyrite type crystal. , 0.9 to 0.95 eV.

  The present inventor is able to obtain a semiconductor layer whose band gap is controlled to a desired value within a range of 0.95 to 1.26 eV when Zn is added to iron sulfide, based on light transmission reflection measurement ( ωα) discovered by performing 2 plots. In detail, when Zn is added to iron sulfide, it is possible to obtain a semiconductor layer whose forbidden band width is controlled to a desired value within the range of 0.95 to 1.26 eV from the appropriate range of the above two plots. It was found from the change in the optical forbidden bandwidth estimated from the x-intercept in the straight line obtained by using the square method.

Here, it has been found that the forbidden band width of iron sulfide changes greatly when the Zn concentration (Zn / Fe) is in the range of 0.1 atomic% to 30 atomic% and then saturates. When it is desired to control the forbidden band width in small increments, a concentration range of 0.1 atomic% to 30 atomic% may be used, and when it is desired to stably obtain a wide forbidden band width, 30 atomic% to 45 atomic%. It has been found that a concentration range of atomic% may be used. The Zn concentration in iron sulfide can be evaluated by a known elemental analysis method such as secondary ion mass spectrometry (SIMS) or Auger electron spectroscopy. Further, in order to further increase the forbidden band width, the iron sulfide includes FeS ₂ having a pyrite type crystal structure. This is because FeS ₂ having a pyrite type crystal structure has a high effect of increasing the forbidden bandwidth by including Zn.

  Control of the carrier concentration is extremely important in considering applications. Here, since the carrier concentration control technique of the semiconductor layer formed by adding Zn to iron sulfide has not been clarified, the present inventor conducted experiments on various elements. And the following carrier concentration control technology was discovered.

  That is, when a group I element is further added to the semiconductor layer obtained by adding Zn to iron sulfide, the hole carrier concentration can be increased. Here, if Na is selected as the group I element to be added, the hole carrier concentration can be particularly increased.

  On the other hand, when a group III element is further added to the semiconductor layer obtained by adding Zn to iron sulfide, the electron carrier concentration can be increased. Here, if Al is selected as the group III element to be added, the electron carrier concentration can be particularly increased. The carrier concentration can be evaluated by hole measurement using, for example, the van der Pauw method.

  According to the photoelectric conversion device of the one embodiment, by appropriately adjusting the Zn concentration in the iron sulfide or adding an appropriate element to the semiconductor layer formed by adding Zn to the iron sulfide, The forbidden band width, carrier type, and carrier concentration can be independently controlled, and a semiconductor layer suitable for application can be formed.

  As a manufacturing method of the photoelectric converting layer 3, well-known methods, such as MBE method, CVD method, vapor deposition method, proximity sublimation method, sputtering method, sol-gel method, spray method, CBD (chemical bath deposition) method, screen printing method, etc. A manufacturing method can be used. Examples of the CVD method include atmospheric pressure CVD, reduced pressure CVD, plasma CVD, thermal CVD, hot wire CVD, and MOCVD. The details of the manufacturing method are as detailed in, for example, Non-Patent Document 1 or a cited document described therein.

Here, it is preferable to perform a sulfiding treatment in sulfur vapor or in a hydrogen sulfide atmosphere as necessary. The sulfiding treatment temperature is preferably 200 ° C to 600 ° C. When sulfidation is performed, crystallization of an amorphous component can be promoted, the sulfur content in iron sulfide can be increased, or the proportion of FeS ₂ having a pyrite-type crystal structure can be increased.

Here, the ratio of the amorphous component can be estimated by performing XRD measurement. In detail, the peak intensity of the XRD measurement in the crystallized component detection layer can be estimated by comparing the peak intensity of the crystallized component detection layer with a sufficiently crystallized layer having the same film thickness. The ratio of FeS ₂ having a crystal structure of the pyrite type can be estimated by comparing the XRD peak intensity of FeS ₂ pyrite structure and XRD peak intensity of iron sulfide of the other structure.

  Finally, the second electrode layer 104 is formed on the photoelectric conversion layer 103, and a main part of the photoelectric conversion device is completed. Specifically, the second electrode layer 4 is formed on the photoelectric conversion layer 3 so as to be substantially in ohmic contact using the same material and the same manufacturing method as those for the electrode layer 2, and the essential elements of the photoelectric conversion device are thus obtained. Forming part.

  FIG. 5 is a cross-sectional view of a photoelectric conversion device according to another embodiment of the present invention.

  This photoelectric conversion device includes a substrate 121, a first electrode layer 122 formed on at least a part of the surface region of the substrate 121, a photoelectric conversion layer 123 formed on the first electrode layer 122, and a photoelectric conversion layer. The transparent electrode layer 124 formed on the surface 23 and the grid electrode layer 125 formed on a part of the surface region of the transparent electrode layer 124 are provided. The photoelectric conversion layer 123 includes a p-type semiconductor layer 127 formed on the first electrode layer 122 and an n-type semiconductor layer formed on the p-type semiconductor layer 127.

  The first electrode layer 122 is formed on the substrate 121 by the same method as in the above embodiment. The photoelectric conversion layer 123 has a pn junction structure including a p-type semiconductor layer 127 including a semiconductor layer formed by adding Zn to iron sulfide, and an n-type semiconductor layer 128. The p-type semiconductor layer 127 is formed on the first electrode layer 122 so as to be in ohmic contact. As a method for forming the p-type semiconductor layer 127 on the first electrode layer 122, the same method as the method for forming the photoelectric conversion layer 103 on the first electrode layer 102 in the above-described embodiment may be used. it can.

  The n-type semiconductor layer 128 is formed on the p-type semiconductor layer 127. Here, the n-type semiconductor layer 128 is made to be a p-type semiconductor layer so that the forbidden band width Eg1 of the p-type semiconductor layer 127 and the forbidden band width Eg2 of the n-type semiconductor layer 128 have a relationship of Eg1 <Eg2. 127 is formed. The n-type semiconductor layer 128 is not particularly limited as long as it is an n-type semiconductor layer that satisfies the relationship of Eg1 <Eg2, but representative examples include an iron sulfide semiconductor, an oxidation of Zn or Mg. Products, sulfides or hydroxides. The forbidden band width Eg1 of the p-type semiconductor layer 127 is controlled to have a forbidden band width according to the application purpose because it is used as a photoactive layer. Here, the n-type semiconductor layer 128 preferably has low absorption with respect to light in the target wavelength band. When the relationship of Eg1 <Eg2 is satisfied, the above object can be achieved and high photoelectric conversion efficiency can be realized. The n-type semiconductor layer 128 preferably contains Zn. When the n-type semiconductor layer 128 contains Zn, good rectification characteristics can be obtained between the n-type semiconductor layer 128 and the p-type semiconductor layer 127 formed by adding Zn to iron sulfide.

  As a method for manufacturing the n-type semiconductor layer 128, MBE method, CVD method, vapor deposition method, proximity sublimation method, sputtering method, sol-gel method, spray method, CBD (chemical bath deposition) method, screen printing method, and the like are known. There is a manufacturing method. Examples of the CVD method include atmospheric pressure CVD, reduced pressure CVD, plasma CVD, thermal CVD, hot wire CVD, and MOCVD. Here, if necessary, sulfurization treatment in sulfur vapor or in a hydrogen sulfide atmosphere can be performed. The sulfiding treatment temperature is preferably 200 to 600 ° C. When sulfidation is performed, in the case of an iron sulfide semiconductor, it is possible to improve the crystallization rate or reduce sulfur deficiency. In addition, oxides such as Zn and Mg, sulfides, hydroxides, etc. can be partially sulfided to increase the ratio of sulfides, increasing the forbidden band width and increasing electrical resistance. You can do it.

  The Zn concentration in the p-type semiconductor layer 127 is preferably the highest at the pn interface and decreases as the distance from the interface increases. High fluctuation in Zn concentration in the p-type semiconductor layer 127 can be obtained by having a concentration gradient that decreases as the distance from the interface increases. The Zn concentration in the device structure can be evaluated by analyzing the depth direction using a known elemental analysis method such as secondary ion mass spectrometry (SIMS) or Auger electron spectroscopy. As a method of forming a Zn concentration gradient, for example, there is a method in which Zn is included in an n layer or a p / n interface and then heat treatment is performed at 200 to 500 ° C. In this way, the concentration gradient can be controlled by the heat treatment conditions.

  The transparent electrode layer 124 is formed on the photoelectric conversion layer 123 so as to substantially make ohmic contact. Specifically, in the above-described embodiment, the transparent electrode layer 124 is formed over the photoelectric conversion layer 123 using the same material and the same manufacturing method as those in the case where the electrode layer 102 has translucency in the description given above. To do.

  The grid electrode layer 125 is formed on a part of the surface region of the transparent electrode layer 124. Specifically, in the one embodiment, the grid electrode layer 125 is formed on a part of the surface region of the transparent electrode layer 124 using the same material and the same manufacturing method as the electrode layer 102 and the manufacturing method. To do. In this way, a photoelectric conversion device with high photoelectric conversion efficiency is formed.

  6 is a schematic cross-sectional view of the sulfide semiconductor of the thirteenth to eighteenth embodiments of the present invention and the sulfide semiconductor of Comparative Example 2. FIG.

  Table 4 below shows the types and concentrations of the compounds of the sulfide semiconductors of the thirteenth to eighteenth embodiments of the present invention and the sulfide semiconductor of Comparative Example 2.

[Table 4]

  Below, based on FIG. 6 and Table 4, the sulfide semiconductor of 13th-18th embodiment is demonstrated.

  The sulfide semiconductors of the thirteenth to eighteenth embodiments are manufactured by forming the iron sulfide layer 132 on the glass substrate 31 having a thickness of 1.1 mm by using the spray pyrolysis method and the sulfide method together. ing.

Specifically, for example, iron chloride (FeCl ₂ ) and thiourea (NH ₂ CSNH ₂ ) are mixed in 500 ml of pure water, the concentration of iron chloride (FeCl ₂ ) is 50 mmol / l, and thio A solution is prepared in which the concentration of urea (NH ₂ CSNH ₂ ) is 100 mmol / l.

Next, zinc chloride (ZnCl ₂ ) having the concentration (mmol / l) shown in Table 4 is further dissolved in the prepared solution to prepare a spray solution. Next, the glass substrate 31 is heated to about 200 ° C. on a hot plate and in the atmosphere, and then the solution is sprayed onto the hot plate to form a thin film.

  The thin film formed by spray coating is subjected to XRD measurement to confirm that no peak of iron oxide or hydroxide is observed, and confirm that the main component of the thin film is FeS.

Next, a sample formed by forming a thin film on the glass substrate 31 is baked at 500 ° C. for 1 hour in a sulfur vapor atmosphere. At this time, sulfur vapor is generated by heating sulfur at a temperature of 150 ° C. using a heater different from the heater for heating the sample, and nitrogen gas is allowed to flow as a carrier gas at a flow rate of 5 l / min. After the sulfiding treatment, XRD measurement is performed to confirm that a single phase of FeS ₂ pyrite is formed. When the thickness of the iron sulfide layer 132 was measured using a step thickness meter, it was 700 nm. In this way, the iron sulfide semiconductor shown in FIG. 6 is manufactured.

  The conductivity types shown in Table 4 are determined based on the results of Hall measurement. The conditions for Hall measurement are as follows. Al was used as the electrode material, and the van der Pauw method was used for the electrode structure. The measurement was carried out using RESTEST 8300 manufactured by Toyo Corporation, in a magnetic field maximum amplitude of 0.6 T, a magnetic field frequency of 0.1 Hz, room temperature, and a dry nitrogen atmosphere. Further, the Zn / Fe ratio shown in Table 4 is determined based on the results of Auger electron spectroscopy measurement. Eg (eV) is determined based on optical band gap (Eg) measurement.

Here, Eg obtains the light absorption coefficient α from the light transmittance and reflectance measurements, plots the square of the light absorption coefficient (ω ² α ² ) against the energy of the incident light, It was calculated based on the x-intercept of the straight line obtained from the range using the least square method. That is, the transition band gap is obtained directly from the x intercept.

The concentration (mmol / l) shown in Table 4 indicates the concentration of zinc chloride (ZnCl ₂ ) used for preparing the spray solution.

  As shown in Table 4, the carrier type was p-type in both cases of Comparative Example 2 not containing Zn and the thirteenth to eighteenth embodiments containing Zn. Further, when the thirteenth to eighteenth embodiments are compared, Eg gradually increases as the Zn concentration increases until the Zn / Fe ratio is 30%, and then shows a saturation tendency. Therefore, the forbidden bandwidth can be precisely controlled by including Zn in iron sulfide.

  Next, the doped semiconductor layer will be described.

  The sulfide semiconductors of the nineteenth and twentieth embodiments of the present invention are doped semiconductor layers. Similarly to the thirteenth to eighteenth embodiments, the sulfide semiconductors of the eighteenth and twentieth embodiments also have the schematic cross-sectional view shown in FIG.

  Table 5 below shows the types and concentrations of the compounds of the sulfide semiconductors of the nineteenth and twentieth embodiments of the present invention and the sulfide semiconductor of Comparative Example 2.

[Table 5]

  Hereinafter, based on FIG. 6 and Table 5, the semiconductor layers of the nineteenth and twentieth embodiments and the comparative example 2 will be described.

  The iron sulfide semiconductors of the nineteenth and twentieth embodiments are produced by forming an iron sulfide layer 132 on a glass substrate 131 having a thickness of 1.1 mm using a spray pyrolysis method and a sulfidation method in combination. Yes.

Specifically, the spray solution used in the sixteenth embodiment (the case of p-type NaCl, the case of n-type AlCl ₃₎ further compound containing an impurity for controlling the conductivity type as shown in Table 5 dissolved To prepare a solution for spraying. Next, the glass substrate 31 is heated to about 200 ° C. on a hot plate and in the atmosphere, and then the solution is sprayed onto the hot plate to form a thin film.

  The thin film formed by spray coating is subjected to XRD measurement to confirm that no iron oxide or hydroxide peak is observed. This confirms that the main component of the thin film is FeS.

Next, a sample in which a thin film is formed on the glass substrate 131 is baked at 500 ° C. for 1 hour in a sulfur vapor atmosphere. At this time, sulfur vapor is generated by heating sulfur at a temperature of 150 ° C. using a heater different from the heater for heating the sample, and nitrogen gas is allowed to flow as a carrier gas at a flow rate of 5 l / min. An XRD measurement is performed after the sulfuration treatment to confirm that a single phase of FeS ₂ pyrite is formed. Moreover, it was 700 nm when the thickness of the iron sulfide layer 132 was measured using the level | step difference film thickness meter. In this way, the iron sulfide semiconductor shown in FIG. 6 is manufactured.

  The conductivity types and carrier concentrations shown in Table 5 are determined based on the results of Hall measurement. The conditions for Hall measurement are as follows. Al was used as the electrode material, and the van der Pauw method was used for the electrode structure. The measurement was carried out using RESTEST 8300 manufactured by Toyo Corporation, in a magnetic field maximum amplitude of 0.6 T, a magnetic field frequency of 0.1 Hz, room temperature, and a dry nitrogen atmosphere. Further, the element concentrations in the film shown in Table 5 (Na concentration in the case of p-type and Al concentration in the case of n-type) are determined based on the results of Auger electron spectroscopy measurement.

As shown in Table 5, in Comparative Example 2 in which doping was not performed, the carrier type was p-type and the carrier concentration was 1 × 10 ¹⁷ cm ⁻³ . In the nineteenth embodiment containing Na, the carrier type was p-type and the carrier concentration was 1 × 10 ¹⁹ cm ⁻³ .

From this, in the iron sulfide containing Zn, the inclusion of Na can increase the hole carrier concentration. In the twentieth embodiment containing Al, the carrier type is n-type and the carrier concentration is 8 × 10 ¹⁸ cm ⁻³ . From this, in the iron sulfide containing Zn, when Al is included, the electron carrier concentration can be increased. In this way, the forbidden band width, carrier type and carrier concentration of the iron sulfide semiconductor can be independently controlled, and a semiconductor layer suitable for application can be obtained.

  Next, a photoelectric conversion device will be described.

  The photoelectric conversion elements of the 21st to 24th embodiments of the present invention have a cross-sectional view shown in FIG. Table 6 is a table showing the types of n-type semiconductor layers included in the photoelectric conversion elements of the 21st to 24th embodiments and the photoelectric conversion efficiency of a photoelectric conversion device using the n-type semiconductor layer.

[Table 6]

  Hereinafter, the photoelectric conversion devices of the 21st to 24th embodiments will be described based on FIG. 5 and Table 6.

  The photoelectric conversion devices of the 21st to 24th embodiments include a substrate 121, a first electrode layer 122 formed on at least a part of the surface region of the substrate 121, and a photoelectric conversion formed on the first electrode layer 122. A layer 123; a transparent electrode layer 124 formed on the photoelectric conversion layer 123; and a grid electrode layer 125 formed on a partial surface region of the transparent electrode layer 124.

  The photoelectric conversion layer 123 includes a p-type semiconductor layer 127 formed on the first electrode layer 122 and an n-type semiconductor layer 128 formed on the p-type semiconductor layer 127. Here, the photoelectric conversion devices of the 21st to 24th embodiments are the same except that the material and manufacturing method of the n-type semiconductor layer 128 are different.

  The photoelectric conversion device of the twenty-first embodiment is formed as follows.

First, for example, a 500 nm-thick Pt film is formed on a glass substrate 121 having a plate thickness of 1.1 mm by vacuum deposition, and then n-type gallium-doped zinc oxide (ZnO: Ga) is formed thereon by magnetron sputtering. ) Is deposited by 700 nm to form the first electrode layer 122. Next, a p-type semiconductor layer 127 made of FeS ₂ pyrite containing Zn is formed on the first electrode layer 122 by using a spray pyrolysis method and a sulfurization method in combination. More specifically, when producing p-type FeS ₂ pyrite containing Zn, the same p-type spray solution as in the fifteenth embodiment of Table 4 is used, and the glass substrate 121 on which the first electrode layer 122 is laminated. Is heated to about 200 ° C. on a hot plate and in the air, and the above solution is spray-coated thereon to form a thin film.

Next, baking is performed at 500 ° C. for 1 hour in a sulfur vapor atmosphere. At this time, sulfur vapor is generated by heating sulfur at a temperature of 150 ° C. using a heater different from the heater for heating the sample, and nitrogen gas is supplied as a carrier gas at a flow rate of 5 l / min. Here, XRD measurement is performed after the sulfurization treatment to confirm that a single phase of FeS ₂ pyrite is formed. still. In one experimental example, the film thickness of the FeS ₂ pyrite film was 2 μm. In this way, the layers up to the p-type semiconductor layer 127 are formed.

Subsequently, in order to produce n-type FeS ₂ pyrite on p-type FeS ₂ pyrite, it performed again spray coating. Specifically, when producing n-type FeS ₂ pyrite containing Zn and Al, as the n-type spray solution, the same solution as in the twentieth embodiment of Table 4 diluted 20 times with pure water was used. A substrate on which p-type FeS ₂ pyrite is formed is heated to about 100 ° C. in the air on a hot plate, and the solution is sprayed thereon to form a thin film. At this time, after adjusting the number of sprays so that the film thickness becomes 50 nm, the baking is performed at 500 ° C. in the sulfur vapor atmosphere as in the case of the p-type. Here, the firing time was 10 minutes. In this way, the photoelectric conversion layer 123 including the p-type semiconductor layer 127 formed on the electrode layer 22 and the n-type semiconductor layer 128 formed on the p-type semiconductor layer 127 is formed. Here, the forbidden band width of the p-type semiconductor layer 127 is clearly equal to that of the fifteenth embodiment from the spray solution used for the production. The forbidden band width of the n-type semiconductor layer 128 is obtained by producing FeS ₂ pyrite on a glass substrate in the same manner as described above, and measuring the forbidden band width in the same manner as in the thirteenth to eighteenth embodiments. .29 eV. From this, it was possible to satisfy the relationship of Eg1 <Eg2.

  After that, 700 nm of n-type gallium-doped zinc oxide (ZnO: Ga) is deposited on the photoelectric conversion layer 123 by magnetron sputtering to form a transparent conductive film 124, and then the comb-shaped silver is formed on the transparent conductive film 124. (Ag) is formed by magnetron sputtering to form the grid electrode 125. In this way, the photoelectric conversion device shown in FIG. 5 is formed.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . And the result shown in the said Table 6 was obtained.

Next, the photoelectric conversion device of the twenty-second embodiment is formed as follows. Similar to the twenty-first embodiment, the layers up to the p-type semiconductor layer 127 are formed. Subsequently, in order to produce n-type FeS ₂ pyrite on p-type FeS ₂ pyrite, it performed again spray coating. Specifically, when preparing n-type Fe _S 2 pyrite containing Zn and Al, AlCl ₃ was added to the same solution as in Example 1 in FIG. 4 so as to be 100 mmol / l as an n-type spray solution. Thereafter, a 20-fold diluted product with pure water is used, and the subsequent steps are performed in the same manner as in the twenty-first embodiment to form the photoelectric conversion device shown in FIG. Here, the forbidden band width of the p-type semiconductor layer 127 in the twenty-second embodiment is clearly equal to that of the fifteenth embodiment from the spray solution used for the production. The forbidden band width of the n-type semiconductor layer 128 is the same as that of the above-described method. FeS ₂ pyrite is produced on a glass substrate and the forbidden band width is measured in the same manner as in the thirteenth to eighteenth embodiments. It was 10 eV. Therefore, there is a relationship of Eg1> Eg2.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . Table 6 shows the measurement results of photoelectric conversion efficiency.

  Next, the photoelectric conversion device of the twenty-third embodiment is formed as follows. Similar to the twenty-first embodiment, the layers up to the p-type semiconductor layer 127 are formed.

Subsequently, in order to produce n-type FeS ₂ pyrite on p-type FeS ₂ pyrite, it performed again spray coating. Specifically, when producing n-type FeS ₂ pyrite containing Zn and Al, AlCl ₃ is 0.5 mmol / l in the same solution as the thirteenth embodiment of Table 4 as a spray solution for n-type. After the addition, a product diluted 20 times with pure water is used, and the subsequent steps are the same as in the twenty-first embodiment to form the photoelectric conversion device shown in FIG. Here, the forbidden band width of the p-type semiconductor layer 27 in Example 10 is clearly equal to that of the fifteenth embodiment from the spray solution used for the production. The forbidden band width of the n-type semiconductor layer 128 is obtained by producing FeS ₂ pyrite on a glass substrate in the same manner as described above, and measuring the forbidden band width in the same manner as in the thirteenth to eighteenth embodiments. 0.000 eV. From this, the relationship of Eg1> Eg2 is established.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . Table 6 shows the measurement results of photoelectric conversion efficiency.

Next, the photoelectric conversion device of the twenty-third embodiment is formed as follows. First, similarly to the twenty-first embodiment, the layers up to the p-type semiconductor layer 127 are formed. Subsequently, in order to produce n-type FeS ₂ pyrite on p-type FeS ₂ pyrite, it performed again spray coating. More specifically, when producing n-type FeS ₂ pyrite containing Zn and Al, AlCl ₃ is added to the same solution as the thirteenth embodiment in Table 4 at 0.5 mmol / l as an n-type spray solution. After that, a 20-fold diluted product with pure water is used, and the subsequent steps are performed in the same manner as the twenty-first embodiment to form the photoelectric conversion device shown in FIG. Here, the forbidden band width of the p-type semiconductor layer 27 in the twenty-second embodiment is clearly equal to that of the fifteenth embodiment from the spray solution used for the production. The forbidden band width of the n-type semiconductor layer 28 is 0 as a result of fabricating FeS ₂ pyrite on a glass substrate in the same manner as described above and measuring the forbidden band width in the same manner as in the thirteenth to eighteenth embodiments. 97 eV. From this, the relationship of Eg1> Eg2 is established.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . Table 6 shows the measurement results of photoelectric conversion efficiency.

Next, the photoelectric conversion device of the twenty-fourth embodiment is formed as follows. First, similarly to the twenty-first embodiment, the layers up to the p-type semiconductor layer 127 are formed. Subsequently, spray coating is performed again to produce n-type ZnO on p-type FeS ₂ pyrite. Specifically, when producing n-type ZnO having oxygen vacancies, zinc chloride (ZnCl ₂ ) is mixed in 500 ml of pure water as an n-type spray solution, and zinc chloride (ZnCl ₂ ) is added at 5 mmol / 1 is prepared and used as a solution for spraying. Next, the substrate on which the p-type FeS ₂ pyrite is formed is heated to about 100 ° C. on a hot plate and in the atmosphere, and the solution is sprayed thereon to form a thin film. At this time, after adjusting the number of sprays so that the film thickness becomes 200 nm, it is heated to about 200 ° C. in the air on a hot plate and dried and oxidized for 10 minutes. A photoelectric conversion layer 123 including a p-type semiconductor layer 127 formed on the electrode layer 22 and an n-type semiconductor layer 128 formed on the p-type semiconductor layer 127 is formed. Here, n-type ZnO was produced on a glass substrate in the same manner as described above, and the resistivity and the forbidden band width were measured. The resistivity was 2 × 10 ⁻⁹ Ωcm as a result of laminating comb-shaped Ag electrodes. The forbidden band width was 3.4 eV as a result of obtaining by the same method as in the case of iron sulfide. Therefore, the relationship of Eg1 <Eg2 is satisfied.

  After that, 700 nm of n-type gallium-doped zinc oxide (ZnO: Ga) is deposited on the photoelectric conversion layer 123 by magnetron sputtering to form a transparent conductive film 124, and then the comb-shaped silver is formed on the transparent conductive film 124. (Ag) is formed by magnetron sputtering to form the grid electrode 125. In this way, the photoelectric conversion device shown in FIG. 5 is formed.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion characteristics were measured under conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . Table 6 shows the measurement results of photoelectric conversion efficiency.

  As shown in Table 6, all of the photoelectric conversion devices of the 21st to 24th embodiments exhibited rectifying properties, and the conversion efficiency of each photoelectric conversion device was a high value exceeding 2%. From this, when an iron sulfide semiconductor containing iron sulfide and Zn is used, a good pn junction can be formed.

  The twenty-second and twenty-third embodiments in which the relationship between the forbidden band width Eg1 of the p-type semiconductor and the forbidden band width Eg2 of the n-type semiconductor is Eg1> Eg2, and the ninth and twenty-fourth embodiments in which Eg1 <Eg2 are satisfied. In comparison, the latter has higher photoelectric conversion efficiency. Therefore, when the forbidden bandwidth has a relationship of Eg1 <Eg2, higher photoelectric conversion efficiency can be obtained.

Further, the first 21 and second 22 embodiment uses a first 23 embodiment uses the n-type FeS ₂ pyrite semiconductor layer which does not contain Zn, the n-type FeS ₂ pyrite semiconductor layer containing Zn Of the latter, the photoelectric conversion efficiency is higher in the latter. Therefore, when the n-type semiconductor layer contains Zn, good rectification characteristics can be obtained, and higher photoelectric conversion efficiency can be obtained.

  The twenty-fourth embodiment in which the n-type semiconductor layer includes a Zn oxide has higher photoelectric conversion efficiency than the twenty-first to twenty-third embodiments in which the n-type semiconductor layer does not include a Zn oxide. It has become. Therefore, higher photoelectric conversion efficiency can be obtained when the n-type semiconductor layer contains an oxide of Zn.

  In the 21st to 24th embodiments described above, the photoelectric conversion element is manufactured using the pn junction composed of the p-type semiconductor and the n-type semiconductor of the present invention. It goes without saying that a pn junction element such as a diode, a transistor (pnp transistor, npn transistor, pnip transistor), or a switch having a pn junction (pnpm switch, pnpn switch) may be manufactured using the pn junction. When a pn junction element is manufactured using a pn junction composed of the p-type semiconductor and the n-type semiconductor of the present invention, the rectification characteristics of the pn junction element can be significantly improved, and the element characteristics of the pn junction element are improved. It can be improved significantly.

  FIG. 7 is a cross-sectional view of a photoelectric conversion device according to an embodiment of the present invention.

  This photoelectric conversion device includes a substrate 201, a first electrode layer 202 formed on at least a part of a surface region of the substrate 201, a photoelectric conversion layer 203 formed on the first electrode layer 202, and a photoelectric conversion layer. And a second electrode layer 204 formed on the substrate 203.

  When the substrate 201 is located on the side opposite to the light incidence, whether or not the substrate 201 is translucent is not questioned. On the other hand, when the substrate 201 is located on the light incidence side, the substrate 201 is at least partially It preferably has translucency. As a material of the light-transmitting substrate, there is glass, and there is a light-transmitting resin having a certain heat resistance among polyimide-based, polyvinyl-based, or polysulfide-based materials, and those light-transmitting resins are laminated. There are things. Examples of the material of the non-translucent substrate include stainless steel and non-translucent resin.

  In addition, unevenness may be formed on the surface of the substrate 1, and in this case, various effects such as light confinement and antireflection can be obtained by refraction or scattering of light on the uneven surface. Further, the surface of the substrate 1 may be coated with a metal film, a semiconductor film, an insulating film, or a composite film thereof. The thickness of the substrate 1 is not particularly limited, but needs to have an appropriate strength and weight capable of supporting the structure. For example, the thickness of the substrate 1 can be 0.1 mm to 40 mm.

The first electrode layer 2 may have any form as long as the first electrode layer 2 is formed so as to be substantially in ohmic contact with the photoelectric conversion layer 3. However, the first electrode layer 2 is formed in a film shape on the substrate 1. Is preferred. The material used for the first electrode layer 2 is not particularly limited as long as it is a conductive material, but a metal material such as Mo, Al, Pt, Ti, Fe, or an alloy thereof is used. Or fluorine-doped tin oxide (SnO ₂ : F), antimony-doped tin oxide (SnO ₂ : Sb), tin-doped indium oxide (In ₂ O ₃ : Sn), Al-doped zinc oxide (ZnO: Al), Ga It is preferable to use a transparent conductive electrode material typified by doped zinc oxide (ZnO: Ga) or B-doped zinc oxide (ZnO: B). In addition, the first electrode layer 2 may be a single layer film made of the above-described material or the like, or may be any one of a laminated film in which a plurality of the above-described materials are stacked.

  When the first electrode layer 2 is located on the light incident side, the first electrode layer 2 preferably has high translucency in the wavelength range of light contributing to photoelectric conversion. The first electrode layer 2 is made of a material such as a vacuum deposition method, a sputtering method, a CVD method, a PVD method, a gas phase method, a sol-gel method, a CBD (chemical bath deposition) method, a spray method, a screen printing method, or the like. Are formed on the substrate 201.

  As described above, when the substrate 1 is located on the light incident side, the first electrode layer 202 is required to have a high light transmittance. Therefore, in that case, the first electrode layer 202 is a grid-shaped metal electrode that does not cover the surface uniformly, such as a comb, or a transparent conductive layer with high light transmittance, or a combination of these requirements. It is preferable to be formed.

  The first electrode layer 202 preferably has irregularities on the surface thereof. The unevenness present on the surface of the first electrode layer 202 refracts and scatters light incident on the photoelectric conversion device at the interface between the first electrode layer 2 and the photoelectric conversion layer 203 formed thereon. . As a result, the optical path length of incident light can be increased, the light confinement effect can be improved, and the amount of light that can be used in the photoelectric conversion layer 203 can be increased. As a method for forming the unevenness, a dry etching method, a wet etching method, a mechanical process such as sand blasting, or the like on the surface of the first electrode layer 202 can be used.

As a dry etching method, in addition to physical etching using an inert gas such as Ar, fluorine-based gas such as CF ₄ and SF ₆ , chlorine-based gas such as CCl ₄ and SiCl ₄ , or methane gas is used. Chemical etching, etc. In addition, as the wet etching method, there is a method of immersing the first electrode layer 2 in an acid or alkali solution. Here, examples of the acid solution that can be used in wet etching include one or a mixture of two or more of hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, acetic acid, formic acid, perchloric acid, and the like. There are one or a mixture of two or more of sodium, ammonia, potassium hydroxide, calcium hydroxide, aluminum hydroxide, and the like. As a method other than the etching method described above, a method of self-forming surface irregularities by controlling crystal growth of the material itself of the first electrode layer 2 by a CVD method or the like, or depending on a crystal grain shape by a sol-gel method or a spray method. There is a method of forming surface irregularities.

The photoelectric conversion layer 203 is formed on the first electrode layer 202 so as to substantially make ohmic contact. The photoelectric conversion layer 203 has a structure including a p-type semiconductor layer obtained by adding a group Ia element to iron sulfide. The structure of the photoelectric conversion layer 203, the structure and having a p-type semiconductor layer and the structure and having a pn junction having an n-type semiconductor layer, p ⁺ pn layer further comprises a p ⁺ -type semiconductor layer, p-type semiconductor layer There are a structure having a pin junction having an intrinsic (i-type) semiconductor layer and an n-type semiconductor layer, a Schottky junction having only a p-type semiconductor layer, a structure having a semiconductor junction such as a MIS structure, and the like. The i-type semiconductor layer may have a weak p-type or weak n-type conductivity type as long as the photoelectric conversion function is not impaired.

The p ⁺ type semiconductor layer only needs to have a relatively higher hole carrier concentration than the p type semiconductor layer, and the hole carrier concentration of the p ⁺ type semiconductor layer is 20 times that of the p type semiconductor layer. It is preferable that it is a grade. Further, the photoelectric conversion device may have a structure in which two or more photoelectric conversion layers are stacked, and the photoelectric conversion device may be a so-called stacked photoelectric conversion device.

  When a group Ia element is added to iron sulfide, a high-quality p-type conductive semiconductor layer having excellent reproducibility can be obtained. This reason is presumed to be as follows. That is, from the result of X-ray diffraction measurement, no impurity crystal phase other than the diffraction pattern of iron sulfide was observed, and a peak shift was observed in the diffraction pattern of iron sulfide. It is presumed to exist in the crystal lattice. From this, for example, when a monovalent group Ia element is substituted with a divalent iron site, the group Ia element is converted to an acceptor, and a p-type conductive semiconductor layer is formed. Further, when the iron sulfide contains a group Ia element, the defect density in the iron sulfide can be reduced. This can be evaluated by photoluminescence measurement. In the measurement, if there is a recombination process via a defect or the like, non-radiative recombination that does not emit light or light emission corresponding to the defect level occurs, and a photoluminescence peak corresponding to interband transition. Strength is lowered. From this, the defect density decreases as the photoluminescence peak intensity corresponding to the interband transition increases.

Here, when the iron sulfide contains a group Ia element, since the peak intensity of the photoluminescence corresponding to the interband transition is higher than when the iron sulfide does not contain the group Ia element, the defect density is reduced. It is thought that it is. Among the group Ia elements, Li, Na, and K have a relatively small difference in ionic radius from Fe ²⁺ . When iron sulfide contains at least one of Li, Na, and K, it is preferable because generation of an impurity crystal phase can be suppressed.

The inventor has experimentally found that when the group Ia element is Na, the concentration is preferably 4 × 10 ¹⁵ cm ⁻³ to 2 × 10 ²⁰ cm ⁻³ . In addition, the kind and density | concentration of the Ia group element in iron sulfide were evaluated by well-known elemental analysis methods, such as secondary ion mass spectrometry (SIMS) and Auger electron spectroscopy.

It was also found that when iron sulfide contains FeS ₂ having a pyrite type crystal structure, semiconductor characteristics suitable for application can be obtained. Since pyrite-type FeS ₂ has a high light absorption coefficient (10 ⁵ cm ⁻¹ or less) with respect to visible light, it is useful as a solar cell material. In addition, pyrite-type FeS ₂ has a band gap close to a wavelength of 1.55 μm or less (photon energy of 0.85 eV or less), which is the lowest loss in an optical fiber, and thus is useful in materials for light receiving and emitting elements for optical communication. is there. Therefore, it is preferable that the iron sulfide has FeS ₂ having a pyrite-type crystal structure because the characteristics of the iron sulfide can be brought close to characteristics useful for the above-mentioned use. In addition, when iron sulfide contains a large amount of FeS ₂ having a pyrite-type crystal structure, relatively high carrier mobility (˜100 cm ² / Vs) can be realized even if it is a polycrystalline body. When used as a material, the semiconductor characteristics can be greatly improved.

  As a manufacturing method of the photoelectric conversion layer 203, MBE method, CVD method, vapor deposition method, proximity sublimation method, sputtering method, sol-gel method, spray method, CBD (chemical bath deposition) method, screen printing method, and the like are known. A manufacturing method can be used. Examples of the CVD method include atmospheric pressure CVD, reduced pressure CVD, plasma CVD, thermal CVD, hot wire CVD, and MOCVD. The details of the manufacturing method are as detailed in, for example, Non-Patent Document 1 or a cited document described therein.

Here, it is preferable to perform a sulfiding treatment in sulfur vapor or in a hydrogen sulfide atmosphere as necessary. The sulfiding treatment temperature is preferably 200 ° C to 600 ° C. When sulfidation is performed, crystallization of an amorphous component can be promoted, the sulfur content in iron sulfide can be increased, or the proportion of FeS ₂ having a pyrite-type crystal structure can be increased.

Here, the ratio of the amorphous component can be estimated by performing XRD measurement. In detail, the peak intensity of the XRD measurement in the crystallized component detection layer can be estimated by comparing the peak intensity of the crystallized component detection layer with a sufficiently crystallized layer having the same film thickness. The ratio of FeS ₂ having a crystal structure of the pyrite type can be estimated by comparing the XRD peak intensity of FeS ₂ pyrite structure and XRD peak intensity of iron sulfide of the other structure.

  Lastly, the second electrode layer 204 is formed over the photoelectric conversion layer 203 to complete the main part of the photoelectric conversion device. Specifically, the second electrode layer 204 is formed on the photoelectric conversion layer 203 so as to be in substantially ohmic contact using the same material and manufacturing method as those of the electrode layer 202, and thus the essential elements of the photoelectric conversion device. Forming part.

  FIG. 8 is a schematic cross-sectional view of the sulfide semiconductor of the 25th to 32nd embodiments of the present invention and Comparative Example 3. Table 7 shown below is a table showing the types and concentrations of the compounds of the 25th to 32nd embodiments of the present invention and Comparative Example 3.

[Table 7]

  Hereinafter, based on FIG. 8 and Table 7, the p-type semiconductor layer of 25th-32nd embodiment is demonstrated.

  The iron sulfide semiconductor of the 25th to 32nd embodiments is fabricated by forming the iron sulfide layer 222 on the glass substrate 221 having a thickness of 1.1 mm by using the spray pyrolysis method and the sulfidation method together. Yes.

Specifically, for example, 500 ml of pure water is mixed with iron chloride (FeCl ₂ ) and thiourea (NH ₂ CSNH ₂ ), so that iron chloride (FeCl ₂ ) is 0.05 mol / l and thio A solution is prepared in which urea (NH ₂ CSNH ₂ ) is 0.1 mol / l.

  Next, a compound containing a doping element indicating the type and concentration of the compound in Table 7 is further dissolved in the prepared solution to prepare a spray solution. Here, when the solute is difficult to dissolve, the solute can be easily dissolved by adding hydrochloric acid. However, hydrochloric acid is not added in the 25th to 31st embodiments and Comparative Example 3.

  Next, the glass substrate 221 is heated to about 300 ° C. on a hot plate and in the atmosphere, and then the solution described in detail in Table 7 is spray-coated on the hot plate to form a thin film. As a result of XRD measurement of the thin film formed by spray coating, no peak of iron oxide or hydroxide was observed. From this, it was confirmed that the main component of the thin film was FeS.

Next, baking is performed at 500 ° C. for 1 hour in a sulfur vapor atmosphere. At this time, sulfur vapor is generated by heating sulfur at a temperature lower than 200 ° C. using a heater different from the heater for heating the sample, and nitrogen gas is allowed to flow as a carrier gas at a flow rate of 5 l / min. An XRD measurement is performed after the sulfuration treatment to confirm that a single phase of FeS ₂ pyrite is formed. In one experimental example, the thickness of the iron sulfide layer 22 was measured using a step thickness meter, and was 700 nm. In this way, the iron sulfide semiconductor shown in FIG. 8 is produced.

  In Table 7, the conductivity type and carrier concentration are the results of hole measurement. The conditions for Hall measurement are as follows. Al was used as the electrode material, and the van der Pauw method was used for the electrode structure. The measurement was carried out using RESTEST 8300 manufactured by Toyo Corporation, in a magnetic field maximum amplitude of 0.6 T, a magnetic field frequency of 0.1 Hz, room temperature, and a dry nitrogen atmosphere. In Table 7, the group Ia element concentration was measured by SIMS measurement in the 25th to 28th, 28th, 31st and 32nd embodiments, and was measured by Auger electron spectroscopy measurement in the 29th and 30th embodiments. In Table 7, the PL emission intensity was measured by photoluminescence measurement. The PL emission intensity was expressed as a relative emission intensity when the peak intensity of photoluminescence corresponding to the interband transition of Comparative Example 3 was 1. Photoluminescence measurement was performed at room temperature using an Ar ion laser (514.5 nm wavelength) with an output of 100 mW as excitation light and an InGaAs detector as a detector. In the case of a sample with low photoluminescence intensity, it is preferable to measure at low temperature using liquid nitrogen or liquid helium.

As shown in Table 7, in Comparative Example 3 in which doping was not performed, the carrier type was p-type and the carrier concentration was 10 ¹⁶ units. In the 25th to 32nd embodiments in which group Ia element doping was performed, the carrier type was p-type. Further, in the 25th to 32nd embodiments in which group Ia element doping was performed, the PL emission intensity was higher than that of Comparative Example 3, and the defect density was reduced. From this, when a group Ia element is contained in the sulfide semiconductor, a high-quality p-type iron sulfide semiconductor can be formed.

  In the 25th to 30th embodiments, the type of the Ia group element is the same, but the concentration of the Ia group element is different. Comparing the 25th to 30th embodiments, the hole carrier concentration increases as the Na concentration increases. However, in the twenty-fifth and twenty-sixth embodiments, the carrier concentration is lower than that in Comparative Example 3 despite doping with an Ia group element that is considered to be an acceptor. The cause of this is not clear, but it is thought that the group Ia element is passivating the Fe deficient site. That is, in Comparative Example 3, it is considered that the atomic deficiency works as an acceptor, but when divalent Fe is deficient, two holes can be supplied, whereas when the monovalent Ia group element fills the deficiency It is thought that the carrier concentration is lowered because only one hole can be supplied.

Moreover, when the comparative example 3 is compared with the 25th to 30th embodiments, as shown in the 25th to 28th embodiments, the PL emission intensity gradually increases with an increase in the group Ia element. Further, when the group Ia element concentration increases, the PL emission intensity decreases as shown in the 28th to 30th embodiments. When the number density of the group Ia element contained in the iron sulfide is in the range of 4 × 10 ¹⁵ cm ⁻³ to 2 × 10 ²⁰ cm ⁻³ due to the change in PL emission intensity, a good p-type semiconductor having a low defect density. Can be earned.

Therefore, when the concentration of the group Ia element contained in the iron sulfide is in the range of 4 × 10 ¹⁵ cm ⁻³ to 2 × 10 ²⁰ cm ⁻³ , the conductivity type of the iron sulfide semiconductor can be made p-type. A carrier concentration corresponding to the doping amount of the group Ia element can be realized, and at the same time, a high-quality p-type semiconductor with a reduced defect density can be produced.

  When a semiconductor junction element such as a diode, a transistor, or a semiconductor laser element is formed using the p-type semiconductor of the present invention, characteristics such as the electron conductivity of the p-type semiconductor of the semiconductor junction element can be improved. Therefore, the element characteristics of the semiconductor junction element can be remarkably improved.

  FIG. 9 is a cross-sectional view of the photoelectric conversion device according to the 33rd to 44th embodiments of the present invention. Table 8 is a table showing the types of spray solutions of the 33rd to 44th embodiments of the present invention.

[Table 8]

  Hereinafter, based on FIG. 9 and Table 8, the photoelectric conversion devices of Examples 9 to 20 will be described.

The photoelectric conversion devices of the 33rd to 44th embodiments are formed as follows. First, for example, a 500 nm Pt film is formed on a glass substrate 241 having a thickness of 1.1 mm by a vacuum deposition method. In this way, the electrode layer 242 is formed on the glass substrate 241. Next, a photoelectric conversion layer 243 having a pn junction of FeS ₂ pyrite is formed on the electrode layer 242 by using a spray pyrolysis method and a sulfurization method in combination. Then, after forming the transparent conductive film 244 on the photoelectric conversion layer 243, the grid electrode 245 is formed on the transparent conductive film 244, and a photoelectric conversion apparatus is formed.

In detail, when preparing p-type FeS ₂ pyrite, as shown in Table 8, the same p-type spray solution as in the 25th to 32nd embodiments of Table 7 was used, and the electrode layer 242 was laminated. The formed glass substrate 241 is heated to about 300 ° C. on a hot plate and in the air, and the solution is sprayed thereon to form a thin film. XRD measurement is performed on the spray-coated thin film, and it is confirmed that the peak of iron oxide or hydroxide is not observed and that it is FeS.

Next, baking is performed at 500 ° C. for 1 hour in a sulfur vapor atmosphere. At this time, sulfur vapor is generated by heating sulfur at a temperature lower than 200 ° C. using a heater different from the heater for heating the sample, and nitrogen gas is supplied as a carrier gas at a flow rate of 5 l / min. XRD measurement is performed after the sulfuration treatment, and a single phase of FeS ₂ pyrite is formed. Here, in one experimental example, the film thickness was 2 μm.

Subsequently, in order to produce n-type FeS ₂ pyrite on p-type FeS ₂ pyrite, it performed again spray coating. In 500 ml of pure water, iron chloride (FeCl ₂ ) and thiourea (NH ₂ CSNH ₂ ) are mixed, and iron chloride (FeCl ₂ ) is 2.5 mmol / l and thiourea (NH ₂ CSNH _2). ) Is 5 mmol / l. And the compound containing the doping element shown in Table 8 is further melt | dissolved with the designated density | concentration in the produced solution, and the solution for spraying is produced. In addition, when the solute is difficult to dissolve, the solute can be easily dissolved by adding hydrochloric acid. Only in the case of the forty-second embodiment, gallium hydroxide (Ga ₂ O ₃ .nH ₂ O) was dissolved by adding 0.15 ml of 35% hydrochloric acid.

A substrate formed up to p-type FeS ₂ pyrite is heated to about 200 ° C. on a hot plate and in the atmosphere, and the above solution is sprayed thereon to form a thin film. At this time, after adjusting the number of sprays so that the film thickness becomes 50 nm, the baking is performed at 500 ° C. in the sulfur vapor atmosphere as in the case of the p-type. Here, the firing time was 10 minutes. In this manner, the photoelectric conversion layer 243 including the p-type semiconductor layer 247 formed on the electrode layer 242 and the n-type semiconductor layer 248 formed on the p-type semiconductor layer 247 is formed.

  Thereafter, 700 nm of n-type gallium-doped zinc oxide (ZnO: Ga) is deposited on the photoelectric conversion layer 243 by magnetron sputtering to form a transparent conductive film 244. Silver (Ag) is formed by magnetron sputtering to form the grid electrode 245. In this way, the photoelectric conversion device shown in FIG. 9 is formed.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion efficiency was measured under the conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ^2. did. Table 8 shows the measurement results of photoelectric conversion efficiency.

  As shown in Table 8, all the photoelectric conversion devices of the 33rd to 44th embodiments exhibited rectifying properties, and the conversion efficiency of each photoelectric conversion device was a high value exceeding 2%. For this reason, when the iron sulfide semiconductor of the present invention is used as the p-type semiconductor, a good pn junction can be formed.

  Further, when the thirty-sixth and forty-first to forty-fourth embodiments having the same manufacturing conditions for the p-type semiconductor layer 247 are compared, the forty-first and forty-second embodiments do not contain Al, Ga, and In as dopants for the n-type semiconductor layer 248. The photoelectric conversion efficiency of the n-type semiconductor layer 48 is lower than the photoelectric conversion efficiency of the thirty-sixth, thirty-fourth, and fourty-fourth embodiments containing at least one element of Al, Ga, and In as the dopant of the n-type semiconductor layer 48. Therefore, when the n-type semiconductor layer 248 contains at least one element of Al, Ga, and In as a dopant, the photoelectric conversion efficiency can be improved.

  In the 33rd to 44th embodiments, the photoelectric conversion element is manufactured using a pn junction including the p-type semiconductor of the present invention and an n-type semiconductor containing iron sulfide. Even if a pn junction structure made of an n-type semiconductor containing iron is used to produce a pn junction element such as a diode, a transistor (pnp transistor, npn transistor, pnip transistor), or a switch (pnpm switch, pnpn switch). Of course it is good. When a pn junction element is manufactured using a pn junction composed of the p-type semiconductor of the present invention and an n-type semiconductor containing iron sulfide, the rectifying characteristics of the pn junction element can be remarkably improved. It is possible to significantly improve the element identification.

  FIG. 10 is a cross-sectional view of the photoelectric conversion device according to the 45th to 50th embodiments of the present invention. Table 9 is a table showing the types of spray solutions of the 45th to 50th embodiments of the present invention.

[Table 9]

  Hereinafter, based on FIG. 10 and Table 9, the photoelectric conversion apparatus of 45th-50th embodiment is demonstrated.

The photoelectric conversion devices of the 45th to 50th embodiments are formed as follows. First, for example, an electrode layer 262 is formed by forming a Pt film of 500 nm on a glass substrate 261 having a thickness of 1.1 mm by a vacuum deposition method. Next, the photoelectric conversion layer 263 having a p ⁺ pn junction of FeS ₂ pyrite is formed on the electrode layer 262 by using a spray pyrolysis method and a sulfurization method in combination. Then, after forming the transparent conductive film 264 on the photoelectric conversion layer 263, the grid electrode 265 is formed on the transparent conductive film 264, and a photoelectric conversion apparatus is formed. About parts other than the photoelectric converting layer 263, it is the same as that of 34th Embodiment.

Details of the method for forming the photoelectric conversion layer 263 are as follows. When preparing p ⁺ type FeS ₂ pyrite, as a p ⁺ type spray solution, as shown in Table 9, a solution obtained by diluting the same solution as in the twenty-seventh to thirty-second embodiments in Table 8 20 times with pure water was used. Each is used, and the glass substrate 261 on which the electrode layer 262 is laminated is heated to about 300 ° C. on a hot plate and in the atmosphere, and the solution is sprayed thereon to form a thin film. The spray-coated thin film is subjected to XRD measurement to confirm that no iron oxide or hydroxide peak is observed, and to confirm that it is FeS.

Next, baking is performed at 500 ° C. for 20 minutes in a sulfur vapor atmosphere. At this time, sulfur vapor is generated by heating the sample at a temperature lower than 200 ° C. using a heater different from the heater for heating, and nitrogen gas is flowed at a flow rate of 5 l / min as a carrier gas. XRD measurement is performed after the sulfurization treatment to confirm that a single phase of FeS ₂ pyrite is formed. Here, in one experimental example, the film thickness was 70 nm.

Then, on the ^{p +} -type FeS ₂ pyrite, sequentially produce FeS ₂ pyrite p-type and n-type like the 34th embodiment. In this manner, the p ⁺ type semiconductor layer 266 formed over the electrode layer 262, the p type semiconductor layer 267 formed over the p ⁺ type semiconductor layer 266, and the n formed over the p type semiconductor layer 267. A photoelectric conversion layer 263 including the type semiconductor layer 268 is formed.

  Thereafter, 700 nm of n-type gallium-doped zinc oxide (ZnO: Ga) is deposited on the photoelectric conversion layer 263 by magnetron sputtering to form a transparent conductive film 264. Silver (Ag) is formed by magnetron sputtering to form the grid electrode 265. In this way, the photoelectric conversion device shown in FIG. 10 is formed.

This inventor investigated the photoelectric conversion efficiency of the photoelectric conversion apparatus produced in this way. Specifically, the photoelectric conversion device thus manufactured was irradiated with AM 1.5 (100 mW / cm ² ) light, and the photoelectric conversion efficiency was measured under the conditions of a cell temperature of 25 ° C. and a cell area of 1 cm ² . . Table 9 shows the measurement results of photoelectric conversion efficiency.

Moreover, the depth direction analysis of the Ia group element density | concentration by SIMS was performed with respect to the photoelectric conversion apparatus produced in this way. As a result, it was confirmed that the group Ia element concentration in the p ⁺ type semiconductor layer and the p type compound semiconductor layer showed substantially the same value as the case where each semiconductor layer shown in Table 7 was evaluated alone.

As shown in Table 9, all of the photoelectric conversion devices of the 45th to 50th embodiments exhibited rectifying properties, and the conversion efficiency of each photoelectric conversion device was a high value exceeding 3%. From this, when the iron sulfide semiconductor of the present invention is used as the p-type and / or p ⁺ -type semiconductor, a good p ⁺ pn junction can be formed.

The photoelectric conversion device having a pn junction of the 34th embodiment, because it can be regarded as a p ⁺ pn junction when p ⁺ -type and p-type Ia group element concentration is equal, a 34th embodiment, the 45th ~ 50 embodiments were compared together. The comparison between the thirty-fourth embodiment and the forty-fifth embodiment shows that high photoelectric conversion efficiency can be obtained when the p ⁺ type semiconductor layer contains more group Ia element concentration than the p type semiconductor layer. . Further, when the concentration of the group Ia element in the p ⁺ type semiconductor layer increases, the photoelectric conversion efficiency increases. In addition, the concentration of the group Ia element in the p ⁺ type semiconductor layer increases particularly rapidly in the case of the 46th embodiment in which the concentration is 20 times that of the p type semiconductor layer. Therefore, when the Ia group element concentration in the p ⁺ type semiconductor layer is 20 times or more the Ia group element concentration in the p type compound semiconductor layer, particularly high photoelectric conversion efficiency can be obtained.

It is a schematic cross section of the photoelectric conversion apparatus of one Embodiment of this invention. It is a schematic cross section of the photoelectric conversion apparatus of one Embodiment of this invention. It is a schematic cross section of the semiconductor of one Embodiment of this invention. It is a schematic cross section of the photoelectric conversion apparatus of one Embodiment of this invention. It is a schematic cross section of the photoelectric conversion apparatus of one Embodiment of this invention. It is a schematic cross section of the semiconductor of one Embodiment of this invention. It is sectional drawing of the photoelectric conversion apparatus of one Embodiment of this invention. It is a schematic cross section of the semiconductor of one Embodiment of this invention. It is a schematic cross section of the photoelectric conversion apparatus of one Embodiment of this invention. It is a schematic cross section of the photoelectric conversion apparatus of one Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Substrate 2 1st electrode layer 3 Photoelectric conversion layer 4 2nd electrode layer 21,31 Glass substrate 22 Electrode layer 23 Photoelectric conversion layer 24 Transparent conductive film 25 Grid electrode 27 P-type semiconductor layer 28 N-type semiconductor layer 32 Iron sulfide layer 101 Substrate 102 First electrode layer 103 Photoelectric conversion layer 104 Second electrode layer 121,131 Glass substrate 122 Electrode layer 123 Photoelectric conversion layer 124 Transparent conductive film 125 Grid electrode 127 P-type semiconductor layer 128 N-type semiconductor layer 132 Iron sulfide layer 201 Substrate 202 First electrode layer 203 Photoelectric conversion layer 204 Second electrode layer 221, 241, 261 Glass substrate 222 Iron sulfide layer 242, 262 Electrode layer 243, 263 Photoelectric conversion layer 244, 264 Transparent conductive film 245, 265 Grid electrode 247, 267 p-type semiconductor layers 248, 268 n-type semiconductor layers 266 p ⁺ -type semiconductor layers

Claims (11)

Including iron sulfide and group Ia elements,
The p-type semiconductor is characterized in that the group Ia element is at least one of Li, K, and Na having a number density of 4 × 10 ¹⁵ cm ⁻³ or more and 2 × 10 ²⁰ cm ⁻³ or less. . The p-type semiconductor according to claim 1,
The p-type semiconductor, wherein the iron sulfide has FeS ₂ having a pyrite type crystal structure.   A semiconductor junction element comprising the p-type semiconductor according to claim 1.   A pn junction element comprising a pn junction comprising the p-type semiconductor according to claim 1 and an n-type semiconductor containing iron sulfide. The pn junction element according to claim 4, wherein
The n-type semiconductor includes at least one of Co, Ni, and Mn. The pn junction element according to claim 4, wherein
The n-type semiconductor includes at least one of Al, Ga, and In. The pn junction element according to claim 4, wherein
The pn junction element, wherein the n-type semiconductor contains FeS ₂ having a pyrite type crystal structure. The pn junction element according to claim 4,
A p ⁺ pn junction element comprising: a p ⁺ type semiconductor layer having a number density of a group Ia element higher than a number density of the group Ia element in the p type semiconductor of the pn junction element. The p ⁺ pn junction element according to claim 8,
The p ⁺ -type number density of Ia group element in the semiconductor layer, p ⁺ pn junction elements, characterized in that at least 20 times the number density of the Ia group elements in the p-type semiconductor. A photoelectric conversion device comprising at least one of the semiconductor junction device according to claim 3, the pn junction device according to claim 4, and the p ⁺ pn junction device according to claim 8. apparatus. Iron sulfide,
Forbidden band control element contained in the iron sulfide,
The forbidden band control element has a property capable of controlling the forbidden band of the iron sulfide based on the number density of the forbidden band control element in the iron sulfide,
A semiconductor comprising a group Ia element.

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