JPH1079523A - Method for manufacturing thin-film solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a thin-film solar cell with high efficiency and large crystal grain size. SOLUTION: A layer 4, which contains a material to be the precursor for forming a chalocopyrite semiconductor layer, is accumulated on a glass substrate 1 with both its sides sandwiched with high-melting point metal films 2 and 3, and these laminated bodies are attached to a heat treatment device 10 which comprises a lower surface-like heater 11, an upper linear heater 12 and a substrate-supporting base 13, and H2 Se gas is made to flow and heat to prevent Se from evaporating/dissipating from the precursor layer 4, so that the precursor layer 4 is grown on a chalcopyrite crystal, having a desired crystal grain and semiconductor characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solar cell comprising a thin film laminated on a substrate.

[0002]

2. Description of the Related Art Due to the recent increase in energy demand and the decrease in reserves of fossil energy such as oil and coal,
The importance of solar cells that make effective use of underutilized solar energy is increasing. In particular, a thin-film solar cell using a chalcopyrite semiconductor or a Si semiconductor which has high conversion efficiency from sunlight to electricity, has stable characteristics even after long use, and consumes less material resources is important.

However, in the conventional chalcopyrite semiconductor solar cells, for example, resulting Group I as represented by CuInSe _2, III-group, it contains many kinds of elements group VI, a solar cell having a desired efficiency In such a case, it is necessary to precisely control the composition ratio distribution of each element in the film thickness direction, thereby controlling the crystal grain size, conduction type, and carrier concentration that can achieve high efficiency in the chalcopyrite semiconductor light absorbing layer. It was done.

However, in the conventional method of forming a chalcopyrite semiconductor, it is difficult to simultaneously achieve (1) increase in crystal grain size and (2) control of conductivity type / carrier concentration. By changing the group / III element ratio in the film thickness direction, the above (1) and (2), which are generally contradictory film formation conditions, are adjusted and compromised, resulting in an efficiency of 10% or more. Was realized.

Further, in the conventional Si thin-film solar cell, the light absorption coefficient of the Si material in the sunlight spectrum is small. Microns were required.

However, there is a concern that the demand for Si, which is a main component of battery materials, will be enormous with the rapid spread of photovoltaic power generation in the future. There is a demand for a solar cell structure that minimizes (ie, most simply minimizes the Si film thickness) and maintains a constant photoelectric conversion efficiency.

As a method of manufacturing such a Si thin-film solar cell, (3) heat treatment is performed on a Si thin-film layer previously deposited on a substrate to cause solid phase growth of Si, thereby forming a polycrystalline film in the film. By promoting the crystal grain growth of Si or (4) melting and recrystallizing a part of the film by scanning with a laser or a heater to cause grain growth to obtain a highly efficient solar cell. was there.

[0008]

In order to satisfy the above-mentioned conditions (1) and (2) to some extent, conventionally, in order to emphasize the controllability of (2), it is necessary to increase the particle size of (1). Is insufficient, and more specifically, only a thin film having a particle size of at most about 4 μm can be formed.
Only a few percent could be obtained.

In the case of the method (3), an inexpensive glass or the like is selected as the substrate without using a crystal substrate that is resistant to heat treatment at a relatively high temperature in order to suppress the manufacturing cost of the solar cell. However, due to the heat resistance problem, a relatively low heat treatment temperature has to be selected. In addition to requiring long-term treatment, the particle size obtained is as small as about 10 microns. Battery efficiency was also unsatisfactory.

In the case of the above method (4), S
Since i is recrystallized after melting, the crystal grains grow larger in a shorter time than the method of (3), but a temperature is required until at least a part of the film is melted.
Inexpensive glass having a problem with heat resistance cannot be used as the substrate, and an expensive Si crystal substrate has been used. In order to reduce the cost, a complicated manufacturing process, such as peeling and reusing the Si substrate, has to be adopted, and there is a problem in productivity as a whole.

An object of the present invention is to satisfy the above condition (2) and increase the particle size of the above (1) as compared with the related art.
It is an object of the present invention to provide a manufacturing method that can provide a dramatic improvement.
A high efficiency of not more than 0% is realized.

Another object of the present invention is to provide a high-efficiency substrate which cannot be used in the method (4) due to the problem of heat resistance, and which can use an inexpensive substrate such as glass, and which cannot be realized in the method (3). An object of the present invention is to provide a manufacturing method capable of growing large Si crystal grains over several tens of microns required for a solar cell.

[0013]

According to the present invention, in order to achieve the above object, to increase the crystal grain size while controlling the conduction type / carrier concentration of the chalcopyrite semiconductor layer, both sides of the chalcopyrite semiconductor layer are controlled. Is sandwiched between at least one of a high melting point metal, boron nitride, aluminum nitride, beryllium oxide and silicon carbide, or one side of a chalcopyrite semiconductor layer is made of a high melting point metal,
High efficiency solar cell can be manufactured by including a step of contacting at least one of boron nitride, aluminum nitride, beryllium oxide, and silicon carbide and contacting at least a part of another surface with a crystalline semiconductor layer. Is working.

Further, in addition to the above-described steps, a step of heating at least a part of the substrate having the above-described layer is included, thereby further increasing the particle diameter and increasing the efficiency of the solar cell. Different from conventional technology.

In general, in order to form a chalcopyrite semiconductor layer, a substance comprising at least a part of the constituent elements of the semiconductor is deposited on a substrate, and evaporation or dissipation of a group VI element substance during or after the deposition is prevented. In order to promote crystallization by heating in an atmosphere and environment containing a group VI element,
A film having characteristics as a semiconductor is manufactured.

In the chalcopyrite semiconductor layer according to the present invention, both surfaces thereof are in contact with at least one of high melting point metal, boron nitride, aluminum nitride, beryllium oxide and silicon carbide, or one side has a high melting point. Metal, boron nitride, aluminum nitride,
By contacting at least one of beryllium oxide and silicon carbide with the boundary and at least part of the other surface with the boundary with the crystalline semiconductor, the wettability and adhesion at the boundary interface are significantly improved, In addition to making it possible to increase the crystal grain size, by appropriately heating the structure, it is possible to promote sufficient crystal grain growth while maintaining wettability and adhesion even at high temperatures. .

The solar cell manufactured through such a process achieves an unprecedented high efficiency by reflecting the effect of increasing the particle size.

In the present invention, first, a step of crystallizing germanium (Ge) having a melting recrystallization temperature lower than that of Si is performed, and then a Si crystal is formed on the obtained Ge crystal.
A crystalline thin film is grown. In the melting and recrystallization of Ge, Ge is prevented from being separated from the substrate during heating.
A configuration in which both sides of the layer are sandwiched between layers made of high melting point metal, etc.
Alternatively, one surface of the Ge layer is in contact with a high melting point metal or the like, and at least a part of the other surface is in contact with the crystalline semiconductor layer, thereby promoting Ge crystal grain growth and taking over the obtained large Ge crystal grains. By growing Si thin-film crystals, it has become possible to manufacture solar cells with high efficiency.

Since the melting point of Ge is about 950 ° C., which is about 500 ° C. lower than that of Si, the temperature of the heater used for melting and recrystallizing Ge can be lowered accordingly. Therefore, a glass substrate which cannot be used at the time of recrystallization of Si can be used, and the advantages of the above methods (3) and (4) are combined, that is, a method capable of growing large crystal grains at a relatively low temperature. Can be provided.

In the normal case where no special measures are taken, the melt-phased Ge has poor wettability with the substrate material, and condenses into a bead to form no film. In order to suppress Ge condensation and sufficiently crystallize the thin film, Ge condensation is prevented above and below the Ge layer or, when one surface of the Ge layer is in contact with the semiconductor crystal layer, on the other surface. It is effective to form in advance a film having a function of performing the following (hereinafter, referred to as a protective film).

Materials suitable for the protective film include (5) Ge
Not significantly react with Ge even at a temperature near the melting point, (6) having a thermal expansion coefficient close to Ge,
(7) It is desirable that the material has a larger surface energy than Ge. In particular, (7) will be briefly described below.

In the state where Ge is present on the protective film material, Ge
When heated to the melting point of (a), Ge is beaded (that is, the surface area of Ge is reduced), and instead the surface of the protective film material is exposed. (B) Ge covers the protective film material. (I.e., Ge is sufficiently wet), and the state where the Ge / protective film interface area is maximized is maintained (Ge surface area is maximized, and the protective film surface area is minimized). Can be

The actual surface or interface is imperfect and contains impurities, and the situation is complicated due to slight reactions and evaporation. However, as a general tendency, the surface energy of the protective film material is Is larger, (a) the maximum surface area of the protective film + the minimum surface area of Ge, and (b) the maximum of the surface area of the Ge + the maximum area of the interface between the Ge and the protective film + the minimum of the surface area of the protective film (substantially 0) are more preferable. Is advantageous in terms of total energy. The magnitude of the surface energy is, in a simplified manner, a quantity indicating the tendency of the surface atoms to seek a bond, and a physical constant that macroscopically reflects the bond strength is cohesive energy. .

Therefore, in the present invention, a material having a large cohesive energy was selected as a material for the protective film in consideration of the above (5) and (6), and sufficient Ge wetting was able to be ensured. By using Si having similarly good crystallinity grown on Ge having good crystallinity obtained through such a process as an active region, a low-cost and high-efficiency solar cell can be manufactured.

[0025]

FIG. 1 shows a first embodiment of the present invention. Here, an example in which a chalcopyrite thin film is used is shown. In the figure, 1 is a glass substrate, 2 and 3 are W
The refractory metal film 4 made of (tungsten) is a layer containing a substance serving as a precursor for forming a chalcopyrite semiconductor layer. In this example, 4 is Cu
This is a layer made of a mixture of Cu, In, Ga, and Se deposited to form an (In _x Ga _1-x ) Se ₂ semiconductor. A refractory metal film 2, a precursor layer 4, and a refractory metal film 3 were sequentially deposited on a glass substrate 1.

The structure having the laminated structure is mounted on a heat treatment apparatus 10 including a lower planar heater 11, an upper linear heater 12, and a substrate support 13, and the temperature of each heater is appropriately set so that the precursor layer is formed. 4 grows into chalcopyrite crystals having desired crystal grain and semiconductor characteristics.
During heating, H ₂ Se gas was flowed into the heat treatment apparatus 10 to prevent evaporation and dissipation of Se from the precursor layer 4.

In the present embodiment, by further moving the substrate support 13 as shown by the arrow 14 in the figure, the region 5 where the temperature becomes the highest immediately below the upper heater 12 and the crystal grain size is increased is moved. Accordingly, it moves in the direction of arrow 15. That is, the chalcopyrite crystal grains grown in the band-like region 5 continue to grow in the direction of the arrow 15 and such movement is performed from one end to the other end of the substrate, thereby obtaining the conventional formation method. Unexpected long grain growth (50 μm × 800 μm or more) was realized.

After the heat treatment, the upper refractory metal layer 3 was removed by etching, and a buffer layer, an upper electrode layer, and the like were appropriately formed on the chalcopyrite semiconductor layer 4 having a large grain size, thereby producing a solar cell. The lower refractory metal layer 2 was used as a lower electrode of a solar cell. A solar cell efficiency of 22% (AM1.
5) was obtained.

In this embodiment, W is used as the refractory metal. However, Mo, BN, AlN, BeO or SiC, which is more general, can be used as a metal for chalcopyrite solar cells. Further, in order to prevent the evaporation and dissipation of Se from the precursor layer 4, it was also effective to use a triethyl selenium bubbling instead of H ₂ Se gas to make the atmosphere and environment around the substrate contain selenium.

Further, in this example, the substrate support 13 was moved to obtain long crystal grains. However, the same effect can be confirmed by moving the upper linear heater 12 instead of the substrate support 13. Was. In addition, instead of using a linear heater for the upper heater, use a planar heater similar to the lower heater, and use a normal heat treatment in which the temperature in the substrate surface is uniform without moving the belt-like region. Growth (particle size of about 5 microns)
Was confirmed. In this case, the heat treatment apparatus is simplified because the substrate moving mechanism or the heater moving mechanism is unnecessary, and a solar cell material that is less expensive than the previous example can be provided. The efficiency of the solar cell in this case was 20% (AM1.5).

As described above, by using the laminated structure described in this example and performing heat treatment by various methods, chalcopyrite crystals having a grain size of 5 μm or more can be formed, and the manufactured solar cell can be made highly Efficiency was obtained.

FIG. 2 shows a second embodiment of the present invention, in which the same components as those in FIG. 1 are denoted by the same reference numerals. That is, 2 and 3 are high melting point metal films made of W, 4 is a layer containing a substance serving as a precursor for forming a chalcopyrite semiconductor layer, 21 is a Si (100) substrate, and 22 is a sputtering method on the substrate 21. Is an SiO ₂ film formed by the method described above.
Portions of the lower refractory metal film 2 and a part of the SiO ₂ film 22 are perforated at appropriate intervals by ordinary optical lithography, so that the precursor layer 4 and the Si substrate 21 are in contact with each other.

As in the case of the first embodiment, the crystal grains in the precursor layer 4 are grown by moving the substrate support (not shown) placed between the upper and lower heaters (not shown). Was. In this example, since a part of the precursor layer 4 is in contact with the Si crystal substrate 21, there is a band-like crystal grain growth region 23 that moves in the same manner as in the first embodiment. When the region 23 reaches the contact region 24, extremely large chalcopyrite crystal grains can be grown while inheriting the crystallinity and crystal habit of the substrate Si.

The belt-like region 23 moves as the contact region 24 moves.
At the point of time 25 on the SiO ₂ film 22, the giant crystal grains grown in the contact region 24 continue to grow, resulting in grain growth (200 μm × 2000 μm) which cannot be achieved by other methods. It was realized.
The efficiency of the solar cell in this case was 25% (AM1.5).

In the case of the present embodiment, the SiO ₂ film 22 can be omitted in view of a request for extracting a current from the lower electrode. Also, from the viewpoint of lowering the price of solar cells,
It is also possible to adopt a method in which the substrate crystal is separated from the chalcopyrite layer by means of etching or the like at a certain stage of the manufacturing process of the solar cell after the grain growth according to this example, and the crystal is reused.

Further, in this example, single-crystal Si was used as the substrate, but even when a less expensive polycrystalline Si substrate was used,
Although the orientation consistency of the growing chalcopyrite crystal grains is inferior to that using a single-crystal substrate, the same size of grain growth is obtained and the solar cell efficiency is comparable to that of a single-crystal substrate. Is obtained.

FIG. 3 shows a third embodiment of the present invention, in which the same components as in FIGS. 1 and 2 are denoted by the same reference numerals. That is, 2 and 3 are high melting point metal films made of W, 4 is a layer containing a substance serving as a precursor for forming a chalcopyrite semiconductor layer, 22 is a SiO ₂ film, 31 is a glass substrate, and 32 is microcrystalline Si. Layer.

Here, first, a microcrystalline Si layer 32 is formed on a glass substrate 31. This microcrystalline Si layer 32 was obtained by heat-treating amorphous Si deposited by a normal plasma vapor deposition method. An SiO ₂ film 22 is formed on the microcrystalline Si layer 32 by a sputtering method.
A precursor layer 4 and a refractory metal film 3 are formed sequentially. Portions of the lower refractory metal film 2 and a part of the SiO ₂ film 22 are perforated at appropriate intervals by ordinary optical lithography, so that the precursor layer 4 and the microcrystalline Si layer 32 are in contact with each other.

As in the case of the first embodiment, the crystal grains in the precursor layer 4 are grown by moving the substrate support (not shown) placed between the upper and lower heaters (not shown). Was. In this example, since a part of the precursor layer 4 is in contact with the microcrystalline Si layer 32, the crystal grain growth region 3 is formed as in the second embodiment.
3 reaches the contact region 34, the crystallinity of the microcrystalline Si
Large chalcopyrite crystal grains could be grown by inheriting the crystal habit.

The belt-shaped region 33 is moved as the contact region 34 moves.
At the point 35 on the SiO ₂ film 22, the crystal grains grown in the contact region 34 continued to grow, and as a result, a grain growth of 80 μm × 1000 μm was realized. The efficiency of the solar cell in this case is 23%
(AM1.5).

In this case, it was possible to omit the SiO ₂ film 22 in the case of this example because of a request for taking out current from the lower electrode. Even if the refractory metal film 2 is sufficiently thin,
Since the effect of the present invention is not impaired even if the entire substrate is not covered, the SiO ₂ film 22 is omitted as a derivative of the present example, and the refractory metal film 2 is configured to be sufficiently thin and partially removed. By forming a pn junction in the microcrystalline Si layer in advance, it was possible to produce a solar cell having a laminated structure integrated with that of the upper chalcopyrite layer.

The method described in the second and third embodiments is a method for promoting the growth of crystal grains of chalcopyrite thin film in the direction of the film surface using a so-called seed crystal. It goes without saying that various modifications are possible in addition to those described in this example.

FIG. 4 shows a fourth embodiment of the present invention, in which the same components as in FIGS. 1 to 3 are denoted by the same reference numerals. That is, 3 is a high melting point metal film made of W, 4 is a layer containing a substance serving as a precursor for forming a chalcopyrite semiconductor layer, and 41 is a Ge (100) substrate. Unlike the examples described above, the precursor layer 4 is in full contact with the crystal substrate 41. By heat treatment with an appropriate heater, large chalcopyrite crystal grains could be grown on a heterogeneous substrate by the mechanism of heteroepitaxy.

In this case, it is not always necessary to arrange heaters above and below, and a cheaper heat treatment apparatus is sufficient. The efficiency of the solar cell in this example is 27% (AM1.
5).

By forming a pn junction or the like in the Ge substrate in advance, a solar cell having a laminated structure can be formed, and further higher photoelectric conversion efficiency can be expected. Although a Ge substrate is used in this example, it goes without saying that a crystal substrate made of a different material capable of performing the same heteroepitaxy can be used.

FIG. 5 shows a fifth embodiment of the present invention. Here, an example in which a Si thin film is used is shown. In the figure, 51 is a glass substrate, 52 and 53 are protective films made of W, and 54 is a Ge layer (100 nm thick). 52, 54 and 53 were sequentially deposited on a glass substrate 51. Before heating,
The Ge layer 54 is composed of amorphous or very small crystal grains. The structure having the stacked structure is mounted in a heat treatment apparatus 60 including a lower planar heater 61, an upper linear heater 62, and a substrate support 63, and the Ge layer 54 is formed by appropriately setting the respective heater temperatures. It grows into a Ge thin film crystal having desired crystal grains and semiconductor characteristics.

Ge has the highest temperature immediately below the upper heater 62 and forms a region 55 in a molten state. By moving the substrate support 63 as shown by the arrow 64 in the figure, the Ge melting region 55 moves in the direction of the arrow 65. With the movement, the portion of the region 55 is solidified again and becomes large crystal grains. The Ge crystal grains grown in the region 55 continue to grow with the movement of the solid-liquid interface in the direction of the arrow 65, and such movement is performed from one end of the substrate to the other end, thereby achieving the conventional formation method. A long Ge grain growth (50 μm × 800 μm or more) that cannot be obtained was realized.

After the above heat treatment, the Ge layer 54 having a large grain size is obtained.
An Si layer (thickness: 10 μm), an upper electrode layer, and the like were appropriately formed thereon to produce a solar cell.

FIG. 6 is a schematic sectional view at the time when a Si layer is grown on the Ge thin film crystal formed as shown in FIG. After the upper protective film 53 in FIG. 5 was removed by etching, a Si layer 56 was grown by a vapor deposition method.
Thereafter, electrodes and the like were formed to form a solar cell. The lower protective film 52 was used as a lower electrode of a solar cell. A solar cell efficiency of 22% (AM 1.5) was obtained.

In this embodiment, W is used as an example of the high melting point metal.
Although Mo was used, Mo or the like, which does not significantly react with Ge, can be used instead. Also, the use of boron nitride or the like instead of the high melting point metal was effective in preventing Ge agglomeration. In addition, the upper and lower protective films do not necessarily have to cover the entire surface of the Ge layer, and may be partially omitted from the viewpoint of a later solar cell manufacturing process. In this case, the step of etching and removing the upper protective film 53 may not be necessary.

Further, in this example, the substrate support 63 was moved in order to obtain long Ge crystal grains. However, the same effect can be confirmed by moving the upper linear heater 62 instead of the substrate support 63. did it. In addition, instead of the Ge layer, S
Similar results were obtained by using a layer made of Geo _0.8 Si _0.2 which is advantageous in terms of the lattice constant difference from the i layer. However, in this case, since the temperature required for melting slightly increases, it is necessary to sufficiently consider the heat resistance range of the glass.

Of course, the same effect can be expected by irradiating and scanning with a laser or an electron beam instead of the upper heater. Irradiation of light during the growth of Si is more preferable because the growth temperature can be reduced. Ge which is advantageous in terms of a lattice constant difference from base Ge instead of Si layer 56
Similar high efficiency was achieved by growing a layer made of _0.2 Si _0.8 and forming a solar cell using this layer as an active layer.

If a pn junction is formed in the underlying Ge layer (this can be done by diffusion of a dopant contained in the lower protective film 52 during heat treatment, etc.), the junction formed in the upper Si can be reduced. In addition, a solar cell having a laminated structure can be manufactured, and in this case, higher efficiency is expected.

FIG. 7 shows a sixth embodiment of the present invention, in which the same components as in FIGS. 5 and 6 are denoted by the same reference numerals. That is, 51 is a glass substrate, 52 is a protective film made of W, 54 is a Ge layer (100 nm thick), 71 is a microcrystalline Si layer, 72 is a SiO ₂ film, and 73 is a silicon carbide film.

First, a microcrystalline Si layer 7 is formed on a glass substrate 51.
Form one. This microcrystalline Si layer 71 was obtained by heat-treating amorphous Si deposited by a normal plasma vapor deposition method. On the microcrystalline Si layer 71, S
An iO ₂ film 72, a refractory metal film 52, a Ge layer 54, and a silicon carbide film 73 are sequentially formed. Lower refractory metal protective film 5
2 and a part of the SiO ₂ film 72 are perforated at appropriate intervals by a normal optical lithography method so that the Ge layer 54 and the microcrystalline Si layer 71 are in contact with each other.

As in the case of the fifth embodiment, the crystal grains in the Ge layer 54 are grown by moving a substrate support (not shown) placed between upper and lower heaters (not shown). Was. In this example, since a part of the Ge layer 54 is in contact with the microcrystalline Si layer 71, the crystallinity of the microcrystalline Si is reached when the crystal grain growth region 74 reaches the contact region 75, as in the fifth embodiment. -Large Ge crystal grains could be grown by inheriting the crystal habit.

The belt-shaped area 74 is moved to the contact area 75 as it moves.
At the point 76 on the SiO ₂ film 72, the crystal grains grown in the contact region 75 continued to grow, and as a result, a grain growth of 80 μm × 1000 μm was realized. The efficiency of the solar cell in this case is 23%
(AM1.5). Note that, in the case of this example, it was possible to omit the SiO ₂ film 72 due to a request for extracting current from the lower electrode.

The method described in the present embodiment is a method of promoting the growth of Ge thin film crystal grains in the film surface direction by using a so-called seed crystal, and the method of adjusting the arrangement of the seed crystal is the same as that described in the present embodiment. Needless to say, various modifications are possible. After the crystallization of the Ge thin film, a solar cell was manufactured through steps such as Si growth as in the fifth embodiment.

[0059]

As described above, according to the present invention,
To promote the crystal grain growth of chalcopyrite or a layer consisting of chalcopyrite, and to prevent exfoliation of the layer from the substrate due to heat treatment of this layer and evaporation of group VI elements, both sides of the layer are made of a high melting point metal. A structure sandwiched by at least one of boron nitride, aluminum nitride, beryllium oxide and silicon carbide, or one surface is in contact with at least one of refractory metal, boron nitride, aluminum nitride, beryllium oxide and silicon carbide,
When at least a part of the other surface is in contact with the crystalline semiconductor layer, a highly efficient solar cell can be manufactured.

According to the present invention, both sides of the layer are made of a high melting point metal or the like in order to promote the crystal grain growth of the layer containing Ge as a main component and to prevent the layer from being peeled off from the substrate by heat treatment. A thin film crystal with a large grain size can be formed by sandwiching it, or by contacting one surface with a high melting point metal or the like, and contacting at least a part of the other surface with the crystalline semiconductor layer, and moving the molten recrystallized portion. This makes it possible to manufacture a highly efficient solar cell.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a third embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a fourth embodiment of the present invention.

FIG. 5 is an explanatory view showing a fifth embodiment of the present invention.

FIG. 6 is an explanatory view showing a fifth embodiment of the present invention.

FIG. 7 is an explanatory view showing a sixth embodiment of the present invention.

[Explanation of symbols]

1, 31, 51: a glass substrate; 2, 3, a high melting point metal film;
4 chalcopyrite semiconductor layer, 5, 23, 33, 5
5, 74: crystal grain growth area, 10, 60: heat treatment apparatus,
11, 61: lower surface heater, 12, 62: upper linear heater, 13, 63: substrate support, 21: Si (100)
Substrate, 22, 72: SiO ₂ film, 24, 34, 75: Contact area, 32, 71: Microcrystalline Si layer, 41: Ge (10
0) Substrate, 52, 53 Protective film, 54 Ge layer, 56
Si layer, 73: silicon carbide film.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takeshi Yamada 3-19-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (4)

[Claims] A step of forming a first layer made of at least one of a refractory metal, boron nitride, aluminum nitride, beryllium oxide and silicon carbide on a substrate; and forming a first layer on the first layer. Forming a second layer made of an element constituting pyrite or chalcopyrite; and forming at least one of a high melting point metal, boron nitride, aluminum nitride, beryllium oxide and silicon carbide on the second layer. A method for manufacturing a thin-film solar cell, comprising: a step of forming a third layer; and a step of heating at least a part of a substrate on which the first, second, and third layers are deposited. Forming a first layer made of chalcopyrite or an element constituting chalcopyrite on a substrate having a semiconductor crystal as at least one of the constituent elements by contacting at least a part of the first layer with the substrate; Forming a second layer made of at least one of a refractory metal, boron nitride, aluminum nitride, beryllium oxide, and silicon carbide on at least a part of the first layer; And heating at least a part of the substrate on which the two layers are deposited. Forming a first layer of at least one of a refractory metal, boron nitride, aluminum nitride, beryllium oxide, and silicon carbide on a substrate; and forming germanium on the first layer. Forming a second layer made of a material containing at least 80% by weight of the second layer, and forming a second layer made of at least one of a refractory metal, boron nitride, aluminum nitride, beryllium oxide, and silicon carbide on the second layer. Forming a third layer, heating at least a part of the substrate on which the first, second, and third layers are deposited; and forming at least a part of silicon on the second layer by 80% or more. Forming a fourth layer made of a substance to be contained. 4. A first layer made of a substance containing at least 80% of germanium is formed over a substrate having a semiconductor crystal as at least one of its constituent elements, at least a part of which is in contact with the semiconductor crystal of the substrate. Forming a second layer made of at least one of a refractory metal, boron nitride, aluminum nitride, beryllium oxide and silicon carbide on at least a part of the first layer; Heating at least a part of the substrate on which the second layer is deposited, and forming a third layer made of a substance containing 80% or more of silicon on at least a part of the first layer. A method for producing a thin-film solar cell, comprising: