JP2002222975A - THIN FILM CRYSTALLINE Si SOLAR BATTERY AND ITS MANUFACTURING METHOD - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical confinement structure without introducing a decrease in electrical characteristics while realizing optically optimum double- side rugged structure, by eliminating the relationship between optical characteristics and trade-off of the electrical characteristics in association with an introduction of the rugged structure. SOLUTION: A thin film crystalline Si solar battery comprises a metal layer 2 as a rear electrode, a rear transparent conductive film 3, a semiconductor film 4 having a semiconductor junction formed of a crystalline Si in a photoactive layer, a front transparent conductive film 5, and collector electrodes 6 made in a main body of a metal as a surface electrode sequentially laminated on a substrate 1. In the battery, an interface between the layer 2 as the back electrode and the film 3 becomes a rugged shape. A mean height difference of the interface between the film 3 and the film 4 is smaller than that of the rugged shape of the interface between the layer 2 as the rear electrode and the film 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thin-film crystalline Si solar cell and a method for manufacturing the same.

[0002]

2. Description of the Related Art Thin-film crystalline Si solar cells typified by thin-film polycrystalline Si solar cells have attracted attention as next-generation solar cells, but the light absorption coefficient of crystalline Si is sufficiently large relative to the thickness of a thin film. In order to obtain a sufficient photocurrent value, it is particularly important to improve the light use efficiency by introducing a light confinement structure.

As a light confinement technology, a technology for forming an antireflection film on the light incident surface side and a technology for forming a concavo-convex structure have been known, and have been applied to solar cells for a long time.

However, in a thin-film crystalline Si solar cell, since the light absorption coefficient of crystalline Si is small on the long wavelength side, light absorption is sufficiently generated at a film thickness of about several μm or less, and photoelectric conversion is more efficiently performed. It is particularly important that the incident light be reflected and reciprocated a number of times in the crystalline Si film so that the light can be more effectively confined. For this reason, in the thin-film crystalline Si solar cell, in addition to the conventional formation of the concavo-convex structure on the surface of the semiconductor layer on the light incident surface side, the concavo-convex structure is also formed on the semiconductor layer surface opposite to the light incident surface. In order to more effectively confine light, studies have been made on a double-sided uneven structure. These conventional examples include, for example, Japanese Patent No. 2713847 and Japanese Patent No. 2713847.
No. 71414, Japanese Patent No. 2784841, Japanese Patent No. 302
No. 7669, Japanese Patent No. 3029169, JP-A-5-21
No. 8469, JP-A-6-196738, JP-A-10-
No. 117006, Japanese Patent Application Laid-Open No. 11-233800, etc., all show that the photoelectric current increases and the conversion efficiency is improved. Here, as typical element structures, FIGS. 4, 5 and 6 show a substrate type and FIG. 7 shows a superstrate type. FIG.
6, 21 is a substrate, 22 is a back electrode layer,
23 is a back transparent conductive film, 24 is a semiconductor layer, 25 is a front transparent conductive film, 26 is a front electrode, and FIG.
5 shows a structure in which the surface of the back electrode 22 has an uneven structure, and FIG. 5 shows a structure in which the surface of the substrate 21 has an uneven structure. 7, reference numeral 31 denotes a light-transmitting substrate, 32 denotes a front transparent conductive film, 33 denotes a semiconductor layer, 34 denotes a back transparent conductive film, and 35 denotes a back electrode.

[0005]

However, in the conventional double-sided uneven structure in which both surfaces of the semiconductor layers 24 and 33 are uneven, when forming the semiconductor layers 24 and 33, the semiconductor film 24 is formed on the deposition surface already having the uneven structure. , 33 will be grown. This is originally not preferable for growing a high-quality semiconductor film. This is because, when a thin film is grown on a flat surface, the number of unnecessary nucleation sites due to the uneven structure is small, so that it is easy to increase the crystal grain size, and all crystals are oriented in a direction perpendicular to the flat surface. However, there is an advantage that the crystal grains do not collide with each other to form crystal grain boundaries, and the crystal orientation is easily aligned in one direction, and the desired crystal orientation characteristics can be easily controlled. On the other hand, these advantages are lost when the thin film is grown on the uneven surface.

In particular, in a solar cell, an increase in crystal grain boundaries due to a small crystal grain size and generation of crystal grain boundaries due to collision between grown crystal grains are caused by the crystal grain boundary portions serving as a path for generating a leak current. This is a fatal negative factor that causes a decrease in the open-circuit voltage characteristic and a decrease in the curve factor characteristic.

[0007] In fact, regarding the relationship between the concavo-convex shape and the open circuit voltage, the 61st Autumn Meeting of the Japan Society of Applied Physics 6a-C-6,
p. 829 (2000), 6a-C-7, p. 830
(2000), which states that the photocurrent increases but the open-circuit voltage decreases with the increase in the uneven shape.

As described above, in the conventional double-sided concavo-convex structure in which both surfaces of the semiconductor layers 24 and 33 are concavo-convex, there is a trade-off relationship between the photocurrent, the open-circuit voltage, and the fill factor. Despite the fact that the optimal uneven shape is known to exist separately, the open-circuit voltage,
Since the reduction of the fill factor cannot be ignored, the selection of the concave-convex structure is restricted, and it is not always possible to obtain an optically optimal concave-convex structure, and it is not possible to actually obtain a higher conversion efficiency than originally obtained. There were challenges.

In the crystalline Si layer which is the photoactive layer portion, the crystal orientation characteristic is set to be (110) orientation in order to spontaneously form an uneven shape suitable for light confinement on the growth surface. Is important, but when the uneven shape is already formed before the semiconductor layer is formed, the controllability of the orientation is disturbed, and there is a problem that it is difficult to obtain an ideal strong (110) orientation. Was.

The present invention eliminates the trade-off relationship between the photocurrent and the open-circuit voltage and the fill factor associated with the introduction of the double-sided concavo-convex structure, that is, the trade-off relationship between the optical characteristics and the electrical characteristics. It is intended to provide a new light confinement structure that does not cause a decrease in electrical characteristics while realizing a double-sided uneven structure that is optimal for the above.

[0011]

According to a first aspect of the present invention, there is provided a thin-film crystalline Si solar cell in which a metal layer serving as a back electrode, a back transparent conductive film, and a photoactive layer are formed of crystalline Si on a substrate. In a thin-film crystalline Si solar cell in which a semiconductor film having a junction, a front transparent conductive film, and a collector mainly composed of a metal serving as a front electrode are sequentially stacked, the metal layer serving as the back electrode and the back transparent conductive film are formed. The interface has an uneven shape, and the average height difference at the interface between the back transparent conductive film and the semiconductor film is smaller than the average height difference at the interface between the metal layer serving as the back electrode and the back transparent conductive film. It is characterized by the following.

[0012] In the thin-film crystalline Si solar cell, the substrate also serves as a metal layer serving as a back electrode, and the average height difference at the interface between the back transparent conductive film and the semiconductor film is different from the metal layer serving as the back electrode. It is desirable that the average height difference between the irregularities at the interface with the back transparent conductive film is smaller than the average height difference.

Further, in the thin-film crystalline Si solar cell,
The average lateral pitch of the irregularities in the cross-sectional shape of the irregularities at the interface on the back electrode side of the back transparent conductive film according to claim 1 or 2 is 0.01 to 5 μm, and the average height difference in the longitudinal direction is 0.0.
Desirably, it is 1 to 1 μm.

According to a fourth aspect of the present invention, there is provided a thin-film crystalline Si solar cell, comprising: a transparent conductive film serving as a front electrode; a semiconductor film having a semiconductor junction in which a photoactive layer is formed of crystalline Si; In a thin-film crystalline Si solar cell in which a back transparent conductive film and a metal layer serving as a back electrode are sequentially laminated, the interface between the translucent substrate and the front transparent conductive film has an uneven shape, The average height difference at the interface between the film and the semiconductor film is smaller than the average height difference between the irregularities at the interface between the translucent substrate and the front transparent conductive film.

In the above-mentioned thin-film crystalline Si solar cell, the average horizontal uneven pitch in the cross-sectional shape of the unevenness at the interface of the front transparent conductive film on the light-transmitting substrate side is 0.01 to 5 μm, and the vertical unevenness pitch is 0.01 to 5 μm. It is desirable that the average height difference is 0.01 to 1 μm.

Further, in the thin film crystalline Si solar cell,
It is desirable that the crystalline orientation characteristics of the crystalline Si layer be (110) orientation.

Further, in the thin film crystalline Si solar cell,
It is desirable that the surface shape of the crystalline Si layer after the film is formed has a spontaneous irregular shape reflecting the crystal orientation of the crystal grains.

According to a eighth aspect of the present invention, in the method of manufacturing a thin film Si solar cell, a metal layer serving as a back electrode is formed on a substrate so that the surface thereof has an uneven shape, and a back transparent conductive film and a photoactive layer portion are formed. In a method for forming a thin film crystalline Si solar cell, in which a semiconductor film having a semiconductor junction formed of crystalline Si, a front transparent conductive film, and a collector mainly composed of a metal serving as a front electrode are sequentially laminated, the uneven shape is It is characterized in that the surface of the substrate or the surface of the metal layer serving as the back electrode is formed in an uneven shape by RIE.

According to a ninth aspect of the present invention, in the method for manufacturing a thin-film Si solar cell, a front transparent conductive film serving as a front electrode is formed on a translucent substrate so that the surface thereof has an uneven shape, and the photoactive layer portion is further formed. A semiconductor film having a semiconductor junction formed of crystalline Si,
In a method of manufacturing a thin-film crystalline Si solar cell in which a back transparent conductive film and a metal layer serving as a back electrode are sequentially laminated, the irregularities are formed by RIE on the surface of the transparent substrate or the surface of the front transparent conductive film serving as a front electrode. It is characterized in that it is formed in a concave and convex shape.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case of a substrate type solar cell having a light incident surface on the opposite side to a substrate will be described below with reference to FIGS. 1 and 2, 1 is a substrate, 2 is a metal layer serving as a back electrode, 3 is a back transparent conductive film, 4
Reference numeral denotes a semiconductor film having a semiconductor junction in which the photoactive layer portion is formed of crystalline Si, reference numeral 5 denotes a front transparent conductive film, and reference numeral 6 denotes a collector electrode mainly composed of a metal serving as a front electrode.

First, a plate or a film made of glass, metal, plastic or the like is prepared as the substrate 1, and the surface of the substrate 1 is processed into an uneven shape. The processing shape is 0.0
About 1 to 5 μm, and the average height difference in the vertical direction is 0.0
The average unevenness pitch in the horizontal direction is about 0.1 to 2 μm, and the average height difference in the vertical direction is 0.05 to 0.5 μm.
It is good to do. Here, the lateral pitch is 0.01 μm
When the thickness is less than the above range, the surface of the metal layer 2 is substantially flattened when a metal layer 2 serving as a back electrode described later is formed, and a sufficient light confinement effect cannot be obtained. If it is about 5 μm or more, the uneven shape itself becomes substantially flat, and a sufficient light confinement effect cannot be obtained. On the other hand, the average height difference in the vertical direction is 0.01μ
If it is less than m, the surface of the metal layer 2 will be substantially flattened when a metal layer 2 serving as a back electrode described later is formed, and a sufficient light confinement effect cannot be obtained. Setting the average height difference to about 1 μm or more is impractical in terms of cost because the back transparent conductive film 3 is formed with a film thickness larger than that.

Various known techniques such as a sand blast method, a wet etching method, and a dry etching method can be used for forming the uneven shape. ,
Japanese Patent Application No. 2000-30 discloses that a desired fine and random uneven shape can be obtained by etching conditions such as gas pressure.
No. 1419.

It should be noted that, in principle, this uneven shape is
The metal layer 2 may be formed on the metal layer 2 serving as a back electrode, which will be described later, but in this case, the metal layer 2 needs to be formed thicker in anticipation of forming the metal layer 2 into an uneven shape. Since an unfavorable factor occurs, it is desirable that this uneven shape is formed in advance on the substrate 1 side.

Next, a metal layer 2 serving as a back electrode is formed.
As the metal film material, it is desirable to use Al, Ag, or the like which has excellent light reflection characteristics. As a film forming method, a vapor deposition method,
A known technique such as a sputtering method can be used. At this time, the film thickness is set to about 0.1 to 2 μm so that the metal film is formed so as to substantially trace the unevenness of the surface of the substrate 1 already formed. So that it is not flattened.

Next, a back transparent conductive film 3 is formed. Known materials such as SnO ₂ , ITO, and ZnO can be used as the transparent conductive film material.
Since the film is exposed to a hydrogen gas atmosphere due to the use of SiH ₄ and H ₂ when forming the film, the back transparent conductive film 3 is formed with a ZnO film having excellent reduction resistance at least as a final surface. It is desirable to do. As the film forming method,
Known techniques such as a vapor deposition method, an ion plating method, and a sputtering method can be used. At this time, the film thickness may be adjusted up to a maximum of about 1 μm in consideration of the height of the uneven shape of the substrate 1 and the film forming cost. In addition, when the average height difference of the unevenness of the surface after forming the back transparent conductive film 3 is larger than or smaller than the average height difference of the unevenness of the surface of the metal layer 2 to be the back electrode before film formation. However, when it is determined that the average height difference is not suitable for the subsequent formation of the semiconductor film 3, a mechanical polishing method, various etching methods, and CMP (Chemical Mechanical) are used.
The average height difference on the surface of the back transparent conductive film 3 can be reduced by a Polishing method or the like, and can be freely adjusted within a range until the surface becomes substantially flat.

Next, a semiconductor layer 4 serving as a photoelectric conversion layer having a semiconductor junction is formed. The process is roughly divided into formation of a base layer (not shown), formation of a photoactive layer (not shown), and formation of a joint (not shown). In the formation of these semiconductor films 4, as described above, since the semiconductor deposition surface is already substantially flattened, unnecessary nucleation is suppressed, and it is easy to increase the semiconductor crystal grain size. Also, the crystal grains are both on the substrate 1
As the columnar growth grows in parallel to the direction perpendicular to the direction, the generation of crystal grain boundaries due to collisions between crystal grains can be suppressed,
It is possible to form a semiconductor film in which quality deterioration of the semiconductor film 4 due to crystal grain boundaries is suppressed as much as possible. Further, since strong (110) orientation characteristics can be obtained relatively easily, an ideal spontaneous uneven structure suitable for light confinement can be formed on the surface of the semiconductor film 4.

First, as a base layer (not shown), a non-single crystal
Si film is formed by a method such as catalytic CVD or plasma CVD.
Formed. The film thickness is about 10 to 500 nm. Do
1E18-1E21 / cm
^ThreeP as degree⁺Type (or n ⁺Type).

Next, a crystalline Si film is formed as a photoactive layer (not shown) by a method such as a catalytic CVD method or a plasma CVD method. The thickness is about 0.5 to 10 μm. The conductivity type is the same conductivity type having a lower doping concentration than that of the underlayer, or substantially i-type.

Next, in order to form a semiconductor junction (not shown), a non-single-crystal Si film (not shown) is formed by a method such as a catalytic CVD method or a plasma CVD method. The film thickness is 5-500
nm. Doping element concentration is 1E18 ~ 1E
It is set to about 21 / cm ^3, and n ⁺ (or p ⁺ type), which is of the opposite conductivity type to the above-described underlayer. In order to further improve the bonding characteristics, a substantially i-type non-single-crystal Si layer may be inserted between the photoactive layer and the bonding layer. At this time, the thickness of the insertion layer is about 10 to 500 nm in the case of a crystalline Si layer, and about 1 to 20 nm in the case of amorphous Si.

Next, the front transparent conductive film 5 is formed. Known materials such as SnO ₂ , ITO, and ZnO can be used as the transparent conductive film material. As a film forming method, a known technique such as a vapor deposition method, an ion plating method, and a sputtering method can be used. At this time, the film thickness is preferably about 60 to 300 nm in consideration of the optical interference effect.

Finally, a collector electrode 6 mainly composed of a metal serving as a front electrode is formed. As the metal film material, it is desirable to use Al, Ag, or the like having excellent conductivity. Known techniques such as a vapor deposition method, a sputtering method, and a screen printing method can be used as a film forming method. The electrode pattern can be formed into a desired pattern by using a masking method, a lift-off method, or the like. The front transparent conductive film 5
It is effective to insert a metal material having an excellent adhesive strength with an oxide material such as Ti between the front transparent conductive film 5 and the metal having an excellent conductivity in order to enhance the adhesive strength with the metal.

As described above, it is possible to obtain a high-efficiency thin-film crystalline Si solar cell having a double-sided concavo-convex optical confinement structure that does not cause a deterioration in characteristics such as a decrease in open-circuit voltage while realizing a high photocurrent value.

Next, a case of a superstrate type solar cell having a light incident surface on the substrate side will be described with reference to FIG. 3, reference numeral 31 denotes a translucent substrate; 32, a front transparent conductive film serving as a front electrode; 33, a semiconductor film having a semiconductor junction in which a photoactive layer portion is formed of crystalline Si; 34, a back transparent conductive film; Is a metal layer to be a back electrode.

First, a plate material or a film material made of glass, plastic, or the like is prepared as the translucent substrate 31, and the surface of the substrate 31 is processed into an uneven shape as described in the above embodiment.

Next, a front transparent conductive film 32 is formed. Known materials such as SnO ₂ , ITO, and ZnO can be used as the transparent conductive film material.
Since the i-film is exposed to a hydrogen gas atmosphere due to the use of SiH ₄ and H ₂ during the formation of the i-film, it is desirable to form a ZnO film having excellent reduction resistance at least as a final surface. As a film forming method, a known technique such as a vapor deposition method, an ion plating method, and a sputtering method can be used. At this time, the film thickness is 60 to 1000 in consideration of the height of the uneven shape of the substrate, the film formation cost, the optical interference effect, and the like.
It is adjusted in the range of about nm. Even if the average height difference of the unevenness of the surface after film formation is larger or smaller than the average height difference of the unevenness of the substrate surface before film formation, the average height difference is suitable for the subsequent semiconductor film formation. If it is determined that there is no mechanical polishing method, various etching methods, C
MP (Chemical Mechanical Poli)
(Shing) method or the like can reduce the average height difference of the surface, and can be adjusted freely within a range until a substantially flat surface state is obtained.

Next, a semiconductor layer 33 serving as a photoelectric conversion layer having a semiconductor junction is formed. The process is roughly divided into forming a bonding layer (not shown), forming a photoactive layer (not shown), and forming a BSF layer (not shown). In forming these semiconductor films, unnecessary nucleation is suppressed because the semiconductor deposition surface is already substantially flat as described above, so that it is easy to increase the size of semiconductor crystal grains. Since both grains grow in a columnar shape in parallel with the direction perpendicular to the substrate, generation of grain boundaries due to collisions between the grains can be suppressed, and deterioration of the semiconductor film quality due to the grain boundaries is suppressed as much as possible. A semiconductor film can be formed. Since strong (110) orientation characteristics can be obtained relatively easily, an ideal spontaneous uneven structure suitable for optical confinement can be formed on the surface of the semiconductor film.

First, a non-single crystal is used as a bonding layer (not shown).
Si film is formed by a method such as catalytic CVD or plasma CVD.
Formed. The film thickness is about 10 to 500 nm. Do
1E18-1E21 / cm
^ThreeP as degree⁺Type (or n ⁺Type). Here next
A bond will be formed between the photoactive layer to be deposited
However, in order to improve the bonding quality, the bonding layer
An i-type amorphous Si layer having a thickness of 1 to 20 nm
Or an i-type crystalline Si layer having a thickness of 10 to 50
It may be formed with a thickness of about 0 nm.

Next, a crystalline Si film is formed as a photoactive layer (not shown) by a method such as a catalytic CVD method or a plasma CVD method. The thickness is about 0.5 to 10 μm. Note that the conductivity type is opposite to the bonding layer or is substantially i-type.

Next, a non-single-crystal Si film is formed as a BSF layer (not shown) by a method such as a catalytic CVD method or a plasma CVD method. The film thickness is about 10 to 500 nm. The doping element concentration is about 1E18 to 1E21 / cm ^3, and n ⁺ (or p
⁺ Type).

Finally, a metal layer 15 serving as a back electrode is formed. As the metal film material, it is desirable to use Al, Ag, or the like which has excellent light reflection characteristics and conductivity. Known techniques such as a vapor deposition method and a sputtering method can be used as a film forming method. At this time, the film thickness is about 0.1 to 2 μm.

In order to increase the effective light reflectance at the interface between the semiconductor film 33 and the metal layer 35 serving as the back electrode, a back transparent conductive film layer 34 is provided between the semiconductor layer 33 and the back metal layer 35.
Is effective. Known materials such as SnO ₂ , ITO, and ZnO can be used as the material of the back transparent conductive film. As a film forming method, a known technique such as a vapor deposition method, an ion plating method, and a sputtering method can be used. At this time, the film thickness is preferably about 10 to 300 nm in consideration of the optical interference effect.

As described above, it is possible to obtain a high-efficiency thin-film crystalline Si solar cell having a double-sided concavo-convex optical confinement structure that does not cause a deterioration in characteristics such as a decrease in open-circuit voltage while realizing a high photocurrent value.

[0043]

As described above, the thin-film crystalline Si of the present invention
According to the solar cell, the average height difference between the irregularities at the interface between the back transparent conductive film and the semiconductor film is made smaller than the average height difference between the irregular shapes at the interface between the metal layer serving as the back electrode and the back transparent conductive film. Since the average height difference between the irregularities at the interface between the front transparent conductive film and the semiconductor film is smaller than the average height difference between the irregularities at the interface between the translucent substrate and the front transparent conductive film, characteristics such as open-circuit voltage can be reduced. A double-sided concavo-convex optical confinement structure that can obtain a high photocurrent value without causing a decrease can be realized, and a thin-film crystalline Si solar cell with higher efficiency than before can be manufactured.

According to the method of manufacturing a thin-film crystalline Si solar cell of the present invention, the unevenness can be formed on the substrate surface or the metal layer surface serving as the back electrode by the RIE method. Since the surface or the surface of the front transparent conductive film serving as the front electrode is formed to be uneven by the RIE method, a desired fine and random uneven shape can be obtained depending on etching conditions such as a gas type and a gas pressure. That is, for example, in the wet etching of a Si crystal substrate, a regular pyramid-like irregular shape reflecting the crystal structure of crystalline Si is obtained, but a random irregular shape with a disordered regularity is desirable for a more effective light confinement structure. K, R
According to the IE method, a random uneven shape that does not depend on the crystal structure of crystalline Si can be formed.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a thin-film crystalline Si solar cell according to claim 1;

FIG. 2 is a view showing another embodiment of the thin-film crystalline Si solar cell according to claim 1;

FIG. 3 is a view showing one embodiment of a thin-film crystalline Si solar cell according to claim 4;

FIG. 4 is a view showing a conventional substrate-type thin-film crystalline Si solar cell in which the surface of the back transparent conductive film has an uneven structure.

FIG. 5 is a diagram showing a conventional substrate-type thin-film crystalline Si solar cell in which the surface of a metal layer serving as a back electrode has an uneven structure.

FIG. 6 is a view showing a conventional substrate-type thin-film crystalline Si solar cell in which a substrate surface has an uneven structure.

FIG. 7 is a view showing a conventional super straight type thin film crystalline Si solar cell.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Metal layer used as back electrode, 3 ...
Back transparent conductive film, 4 ... a semiconductor film having a semiconductor junction in which the photoactive layer portion is formed of crystalline Si, 5 ... a front transparent conductive film, 6 ... a collection mainly composed of a metal serving as a front electrode Electrodes, 3
DESCRIPTION OF SYMBOLS 1 ... Translucent board | substrate, 32 ... Front transparent conductive film used as a front electrode, 33 ... Semiconductor film which has the semiconductor junction which formed the photoactive layer part by crystalline Si, 34 ... Transparent behind Conductive film,
35 ... Metal layer to be back electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hirofumi Senda 1166, Haseno, Snake-cho, Yokaichi City, Shiga Prefecture F-term in the Kyocera Corporation Shiga Yokaichi Plant F-term (reference) GA03 GA14 GA20

Claims (9)

[Claims] A semiconductor layer having a semiconductor junction in which a photoactive layer portion is formed of crystalline Si, a front transparent conductive film, and a metal serving as a front electrode are provided on a substrate. Thin film crystalline S in which collector electrodes mainly composed of
In the i solar cell, the interface between the metal layer serving as the back electrode and the back transparent conductive film has an uneven shape, and the average height difference at the interface between the back transparent conductive film and the semiconductor film is the metal serving as the back electrode. A thin-film crystalline Si solar cell, characterized in that it is smaller than the average height difference of the irregularities at the interface between the layer and the back transparent conductive film. 2. The substrate also serves as a metal layer serving as a back electrode, and the average height difference between the interface between the back transparent conductive film and the semiconductor film is determined by the interface between the metal layer serving as the back electrode and the back transparent conductive film. 2. The thin-film crystalline Si solar cell according to claim 1, wherein the average height difference of the uneven shape is smaller than the average height difference. 3. An average lateral irregularity pitch in the cross-sectional shape of the irregularity at the interface of the back transparent conductive film on the back electrode side is 0.
01 to 5 μm, and the average height difference in the vertical direction is 0.01 to
The thin-film crystalline Si solar cell according to claim 1, wherein the thickness is 1 μm. 4. A front transparent conductive film serving as a front electrode, a semiconductor film having a semiconductor junction in which a photoactive layer portion is formed of crystalline Si, a back transparent conductive film, and a metal serving as a back electrode are formed on a light transmitting substrate. In a thin-film crystalline Si solar cell in which layers are sequentially stacked, the interface between the light-transmitting substrate and the front transparent conductive film has an uneven shape, and the average height difference at the interface between the front transparent conductive film and the semiconductor film is increased. Is smaller than the average height difference between the irregularities at the interface between the light-transmitting substrate and the front transparent conductive film. 5. An average horizontal unevenness pitch in the cross-sectional shape of the unevenness at the interface of the front transparent conductive film on the light-transmitting substrate side is 0.01 to 5 μm, and the average height difference in the vertical direction is 0.0.
The thin-film crystalline Si solar cell according to claim 4, wherein the thickness is 1 to 1 µm. 6. The crystalline Si layer has a crystal orientation characteristic of (1).
10) The thin-film crystalline Si solar cell according to any one of claims 1 to 5, wherein the solar cell is oriented. 7. The method according to claim 1, wherein the shape of the interface of the crystalline Si layer on the film formation end side has a spontaneous uneven shape reflecting the crystal orientation of the crystal grain. 2. The thin-film crystalline Si solar cell according to 1. 8. A metal layer serving as a back electrode is formed on a substrate so that the surface thereof has an uneven shape.
In a method of forming a thin film crystalline Si solar cell in which a semiconductor film having a semiconductor junction in which a photoactive layer portion is formed of crystalline Si, a front transparent conductive film, and a collector electrode mainly composed of a metal serving as a front electrode are sequentially stacked, A method for manufacturing a thin-film Si solar cell, wherein the unevenness is formed by forming the surface of the substrate or the surface of a metal layer serving as a back electrode by the RIE method. 9. A semiconductor film having a semiconductor junction in which a front transparent conductive film serving as a front electrode is formed on a translucent substrate so that the surface thereof has an uneven shape, and a photoactive layer portion is formed of crystalline Si. , A back transparent conductive film, and a metal layer serving as a back electrode are sequentially laminated. In the method for manufacturing a thin film crystalline Si solar cell, the irregularities are formed by RIE on the surface of the transparent substrate or the surface of the front transparent conductive film serving as the front electrode. A method for manufacturing a thin-film Si solar cell, wherein the thin-film Si solar cell is formed in a concavo-convex shape by a method.