JPH1074966A - Method for manufacturing thin-film solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a solar cell which permits composition variation of a CIS Cu(In1-x Gax)y (S1-m Sem )z } based thin film in a wide range, and obtains high-energy conversion efficiency. SOLUTION: In a process for supplying group Ib elements, group III elements and group VIb elements onto a substrate for forming a compound semiconductor thin film as a light-absorbing layer, as the first step, the ratio of the supplying amount of the group Ib elements to that of the group III elements is made higher than the ratio of group Ib elements to group III elements, contained in the compound semiconductor thin film of a target composition. In addition, group Ia elements are supplied onto the substrate. As the second step, the ratio of the supplying amount of group Ib elements to that of group III elements is made lower than the first step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to Cu (In _1-x Ga
a thin film of CIS-based material represented by _{x) y} (S _{1 over m} Se _{m) z} a method of manufacturing a solar cell using the light absorbing layer.

[0002]

2. Description of the Related Art As an inexpensive thin-film solar cell, the composition Cu
In (an In 1 _{over x} Ga _{x) y} (S _{1 over m} Se _{m) z,} crystal structure the development of thin-film solar cell using a thin film having a chalcopyrite structure as the light absorbing layer have been made.

In recent years, among solar cells using CIS-based thin films, those using soda glass as a substrate have been reported to exhibit high energy conversion efficiency.
Studies have been conducted to introduce element a into CIS-based thin films.

[0004] For example, Japanese Patent Application Laid-Open No. Hei 8-102546 discloses a semiconductor thin film in which a compound comprising a group Ia and a group VIa element is simultaneously deposited when depositing a compound semiconductor thin film comprising a group Ib group, a group IIIa and a group VIa element. And a solar cell using a semiconductor thin film formed by alternately depositing at least two or more compound semiconductor thin films composed of a group Ib group, a IIIa group and a VIa element, and a compound thin film composed of a group Ia and a VIa group element. It has been disclosed.

[0005]

In a conventional solar cell using a CIS-based thin film, the conversion efficiency greatly depends on the composition of the CIS-based thin film. It was limited to a very narrow range. for that reason,
Precise composition control is required when forming a CIS-based thin film, and it has been difficult to increase the area and mass production.

Similarly, according to experiments by the inventors, high efficiency can be obtained even for a CIS-based thin film into which Na element has been introduced, when a method such as ordinary simultaneous vapor deposition is used to introduce Na. The range is limited to a very narrow range of the CIS based thin film composition.

It is an object of the present invention to provide a method of manufacturing a solar cell capable of tolerating composition variation of a CIS-based thin film in a wide range and obtaining high energy conversion efficiency.

[0008]

According to the present invention, there is provided a method for manufacturing a solar cell as described below.

That is, a method of manufacturing a solar cell using a compound semiconductor thin film containing a group Ib element, a group III element, and a group VIb element as a light absorbing layer. , A group Ib element on a substrate and a group II
A step of supplying a group I element and a group VIb element, wherein the step comprises controlling the ratio of the supply amount of the group Ib element to the supply amount of the group III element by adjusting the ratio of the Ib group contained in the compound semiconductor thin film having a desired composition. A first step of supplying the group Ia element onto the substrate while increasing the ratio of the element to the group III element, and making the ratio of the supply amount of the group Ib element to the supply amount of the group III element smaller than the first step. And a second step.

[0010]

An embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a thin-film solar cell manufactured by the manufacturing method of this embodiment has a Mo film 11 as a lower electrode and a C-type light absorbing layer on a blue glass substrate 10.
u (an In _{1 over x} Ga x) _y Se _z film 12, i-type or high-resistance n-type CdS film 13 of the buffer layer, n ⁺ -type pin called substrate type of the transparent conductive film 14 are laminated in this order structure of
It is a heterojunction thin-film solar cell. Where 0 ≦ x ≦ 1,
0 <y and 0 <z.

[0012] Incidentally, Cu (In _{1 over x} Ga x) _y Se _z film 12
(Hereinafter referred to as the CIGS film 12), a group Ia element Na is added by a film forming method of the present invention described later.

The thickness of the Mo film 11 is about 0.8 μm, the thickness of the CIGS film 12 is 1 μm to 4 μm, and the thickness of the CdS
The thickness of the film 13 is several nm to 0.3 μm,
Has a thickness of 0.3 μm to 2 μm.

In the substrate type solar cell shown in FIG.
Light is irradiated from the transparent conductive film 14 side as shown in FIG. 1, passes through the transparent conductive film 14 and the CdS film 13, is absorbed by the CIGS film 12, and is converted into a current / voltage.

A manufacturing method of the present embodiment for manufacturing the solar cell of FIG. 1 will be described.

First, a Mo film 11 is formed on a blue glass substrate 10.
Is formed by a sputtering method.

Next, a CIGS film 12 is formed on the Mo film 11 by a vacuum evaporation method. As the deposition source, high-purity Cu, In, Ga, and Se deposition sources, and I
Multi-source evaporation is performed using a group-a element evaporation source. Note that, in this embodiment, Na ₂ S
e is used.

When the CIGS film 12 is formed, a temporal change in the amount of evaporation of each evaporation source is controlled as shown in FIG. 4 to FIG. Thereby, in the present embodiment, CIGS
The wide composition range of the film 12 enables the production of a solar cell with high conversion efficiency. That is, as shown in FIG.
When the CIGS film 12 is formed, the film formation time for obtaining a required film thickness is divided into two stages of a first half and a second half, and in the first half, the excess amount of Cu (Cu / (In + Ga)> 1) and the Na ₂
Se is evaporated. On the other hand, the second half is more C
u is not sufficient, and Na ₂ Se is not evaporated. Se
Is constant throughout the first half. In the present embodiment, Se / (Cu + In + Ga) is set to 2-3.

Specifically, the CIGS film 12, ie, C
u (an In _{1 over x} Ga x) _y Se _z film 12 composition xyz of interest of
The advance determined, Cu evaporation amount required of the composition Cu (an In _{1 over x} Ga x) _y Se _z film 12 in order to obtain by evaporation, I
The amount of n evaporation, the amount of Ga evaporation, and the amount of Se evaporation were measured for the substrate 1 of each element.
It is determined in advance by calculation or experiment according to the adhesion rate to zero.

Then, actually, Cu (In _1−x Ga _x ) _y S
When the _ez film 12 is formed, for example, when the control method shown in FIG. 6 is used, in the first half of the film formation time, Cu is evaporated more than the previously determined Cu evaporation amount, and in the second half, controls the Cu evaporation amount to less evaporation of the Cu than previously obtained Cu evaporation described above, Cu (an in 1 _{over x} Ga _{x) y} Se _z film 12 which is consequently deposited into the substrate 10 is The composition is determined in advance.

In the case of the control method shown in FIG.
The amount of Cu required to make the S film 12 have the desired composition
All the elements are evaporated in the first half of the film formation, and the evaporation of Cu is stopped in the second half.

In the case of the control method shown in FIG. 5, control is performed so that the evaporation amount of Cu is constant throughout the film formation, and the evaporation amounts of In and Ga are reduced in the first half of the film formation and increased in the second half. As a result, the first half of the film formation is excessive in Cu.

In the control methods shown in FIGS. 4 to 6, Se,
In order to accurately control the evaporation amount of In, Ga, Cu, and Na ₂ Se, the shutter of the evaporation apparatus is opened when the evaporation amount from each evaporation source becomes constant.

It is also possible to use a method of starting evaporation of Cu and Na ₂ Se after the shutter is opened, as in the control method of FIG.

In each of the control methods shown in FIGS.
The temperature of the substrate 10 during the formation of the CIGS film 12 is 550 ° C.
I have to. Further, in order to prevent Se from re-evaporating from the surface of the CIGS film 12, the evaporation of Cu, In, and Ga is stopped, and then the evaporation of Cu, In, and Ga is continued until the substrate temperature becomes 350 ° C or lower.
e is continuously evaporated.

After the CIGS film 12 is formed as described above, the CdS film 13 is formed on the
Washing is performed to wash out the alkali metal element and the like existing on the surface of the IGS film 12. In the present embodiment, the cleaning method is C
A method of repeatedly immersing the substrate 10 with the IGS film 12 in pure water for several minutes was used. Then, the substrate 10 taken out of the pure water is directly transferred into a solution for growing a CdS film, and a CdS film 13 is formed by a solution growing method. Thus, the hetero junction between the CdS film 13 and the CIGS film 12 can be formed in a clean state without the surface of the cleaned CIGS film 12 being contaminated by dust and the like in the air. In this embodiment, the solution for growing CdS is as follows.
An aqueous solution in which CdI ₂ , thiourea and ammonia were dissolved was used. When the surface of the CIGS film 12 is immersed in pure water for cleaning, ultrasonic cleaning may be used.

On the CdS film 13 thus formed, a ZnO film to which Al is added is formed as a transparent conductive film 14 by a high-frequency magnetron sputtering method.

As described above, the substrate type solar cell of the present embodiment is manufactured.

Further, in order to measure the characteristics of the above-mentioned Cu (In _{1 -x} Ga _x ) _y Se _z film 12, a plurality of Cu (In _{1 -x} Ga _x ) _y Se with variously changed y compositions are used. A sample of the _z film 12 was formed. For the formation of the sample, the above-mentioned Cu (In _1−x Ga _x ) _y S
used among 7 of the process of the method for forming the e _z film 12, y composition, the sum of the In evaporation and Ga evaporation, it was varied by changing the Cu evaporation and ratios. Further, to produce these Cu (an In 1 _{over x} Ga _x) of the sample having the same composition _y Se _z solar cell sample of the structure 1 using the film 12. The x composition and the z composition were set to be constant throughout each sample.

As a comparative example, no Na was added and y
Cu (In _1−x Ga _x ) _y S with various compositions
A sample of the _ez film was formed. The sample of the comparative example is the Cu
(An In _{1 over x} Ga x) _y Se in the film forming method of the _z film 12, Na
Without evaporating only ₂ Se, other elements Se, In, Ga,
The film was formed by controlling the amount of evaporation of Cu in the same manner as the sample of the present embodiment. A sample of the solar cell having the configuration shown in FIG. 1 was manufactured using a CIGS film having the same composition as the CIGS film samples of these comparative examples.

CIG formed by the manufacturing method of the present embodiment
12 samples of the S film and the CIGS film sample of the comparative example were analyzed in the thickness direction by Auger electron spectroscopy (AES). As a result, both the film of the present embodiment and the film of the comparative example were Cu, In,
Both Ga and Se were detected at a constant concentration in the film thickness direction. Thereby, regardless of whether the film is formed such that the first half of the film is formed with an excessive amount of Cu and the second half is formed with a shortage of Cu,
It was found that the diffusion of the Cu element in the film thickness direction resulted in a CIGS film having a uniform composition in the film thickness direction. In the CIGS film 12 sample of the present embodiment,
Na element was detected on the very surface of the film. This gives N
It was found that the element a was moved to the surface of the film by diffusion. It is considered that Na below the detection limit of AES is incorporated into the crystal grains in the CIGS film 12, but it is unknown at present how much the concentration is. In the CIGS film 12 of the solar cell sample, no Na element was detected even on the surface of the film. This is considered to be because Na was washed away in order to wash the surface of the CIGS film 12 before forming the CdS film 13 when manufacturing the solar cell.

When the size and orientation of crystal grains in the CIGS film 12 of the present embodiment and the CIGS film of the comparative example were observed, the crystal grains of the CIGS film 12 of the present embodiment were observed. Is the CIG of the comparative example without adding Na.
The grains were larger than the crystal grains of the S film, and the orientation was excellent. Also, when the surface roughness of the film was measured,
The IGS film 12 was flatter than the CIGS film of the comparative example. This is considered to be the effect of adding Na.

Further, the carrier concentrations of the CIGS film 12 formed by the manufacturing method of the present embodiment and the CIGS film of the comparative example to which Na was not added were measured. The result is shown in FIG.
Shown in

As can be seen from FIG. 8, the CIGS film of the comparative example without addition of Na has a group III element (Ga + I) with Cu / (Ga + In) = 1.0, that is, with a composition y = 1.0.
The carrier concentration rapidly decreases on the side where n) becomes excessive, and C
In the vicinity of u / (Ga + In) = 0.7, that is, y = 1.4, the carrier concentration becomes lower than 10 ¹⁶ cm ⁻³ .
In contrast, the CIGS film 12 formed by the manufacturing method of the present embodiment has a carrier concentration of 10 ¹⁶ to 10 ¹⁷ even if Cu / (Ga + In) ≦ 0.7, that is, y composition ≧ 1.4.
cm ^-3 , which is a completely different result from the comparative example.

Further, the open-circuit voltage V _oc , the short-circuit current _Isc , and the fill factor FF of the solar cell sample of the present embodiment and the solar cell sample using the CIGS film without addition of Na of the comparative example were measured. Open circuit voltage V _oc of the solar cell of the present embodiment, the short-circuit current I _sc, respectively the measurement results of fill factor FF Figure 3 (a),
(B) and (c) show.

Further, the conversion efficiency η was obtained by η = (output at the optimum operating point) / (input energy to the solar cell) = (V _oc × J _sc × FF) / (input energy to the solar cell). . The result is shown in FIG.

As can be seen from FIGS. 3 (a), 3 (b) and 3 (c), the solar cell of this embodiment has an open-circuit voltage V _{oc over} the entire range of Cu / (Ga + In) where the measurement was performed. , Short-circuit current _Isc , and fill factor FF indicate high levels, respectively.
As a result, as can be seen from FIG. 9, the conversion efficiency η is in the entire range where the measurement was performed, and 0.5 ≦ Cu / (Ga + In) ≦
1.0, that is, high conversion efficiency was obtained in a very wide composition range of 1 ≦ y ≦ 2. This is because the CIGS film 12 of the present embodiment can obtain a high carrier concentration in a wide composition range.

On the other hand, in the comparative example, CI without addition of Na was used.
In a solar cell using a GS film, Cu / (Ga + In) =
High conversion efficiency can be obtained only in a very narrow composition range of 0.85 to 0.95.

[0039] Thus, a solar cell was fabricated by the manufacturing method of this embodiment, it is possible to obtain a high conversion efficiency in a very wide y composition range of Cu (an In 1 _{over x} Ga _{x) y} Se _z film 12 it can. Therefore, the composition variation of the CIGS film 12 during manufacture can be tolerated in a very wide range of at least about five times that in the related art, so that a large-area solar cell can be easily manufactured. Further, since precise control of the composition is not required, it is suitable for mass production.

[0040] Incidentally, while the Cu excess in the first half of the time of forming the Cu (an In _{1 over x} Ga x) _y Se _z film 12, the solar cell manufacturing method of the embodiment of adding Na element, wide Although the reason for the high conversion efficiency in the composition range is not clear at present, it is considered to be related to the timing of adding Na to the CIGS film 12.

Therefore, in order to investigate the relationship between the timing of adding Na to the CIGS film and the conversion efficiency, the following comparative samples were prepared and the conversion efficiency was measured.

That is, as a second comparative example, CIGS
When forming the film, while controlling the amount of evaporation of Cu, In, Ga, Se in the same manner as in the present embodiment, using a method of evaporating Na ₂ Se during all the time during the film formation, A solar cell sample was prepared.

Further, as a third comparative example, CIG
In forming the S film, a method of evaporating Na ₂ Se only in the second half without evaporating in the first half of the film formation while controlling the evaporation amounts of Cu, In, Ga, and Se in the same manner as in the present embodiment. Thus, a solar cell sample was prepared.

When the conversion efficiencies of the solar cells of the second and third comparative examples were measured, as in the case of the solar cell of the first comparative example in FIG.
It was found that the composition Cu / (Ga + In) was only in a very narrow region of 0.85 to 0.95.

From this, it has been confirmed that it is desirable to add Na at the same time as Cu vapor deposition in the first half of film formation.

As described above, in the present embodiment, CIGS
When the film 12 is formed, Na is added together with Cu vapor deposition in the first half of the film formation, and Cu is not vapor-deposited or Cu-deficient in the latter half of the film formation.
By not adding Na, a solar cell having excellent conversion efficiency can be obtained.

In the above embodiment, the Na element is added to the CIGS film 12, but instead of Na, K or Li is used.
It has been confirmed by experiments that a solar cell with high efficiency can be obtained in a wide range of the composition of the CIGS film 12 by the manufacturing method of adding another group Ia element as described above. Further, at present, experiments have shown that K is more suitable than Na and Li is more suitable than K to obtain a highly efficient solar cell in a wider composition range.

In this embodiment, Na ₂ Se is used as the Na vapor deposition source.
Group a metal element or alloy of Cu and Group Ia element, or Group Ia element such as Na ₂ O, Na ₂ S, Na ₂ Te—
A Group VIb element compound or a Group Ia element-Group VIIb element compound such as NaCl or NaBr can be used as an evaporation source. When using these Ia group element -VIb group element compound, VIb group elements, Cu (In _{1 over x} Ga x) _y S
Since the e _z film 12 is the same group as group VIb element contained originally, be included as an impurity in the crystal, it does not adversely affect the membrane. When using a Ia group element -VIIb group element compound, VIIb group element is evaporated by high temperature of the substrate temperature above 500 ℃, Cu (In _{1 over} x Ga _x) is not taken into _y Se _z film 12.

Similarly, as a deposition source when adding a Group Ia element such as Li or K, a Li-VIb group element compound or K
A -VIb group element compound, a Li-VIIb group element compound, or a K-VIIb group element compound can be used.

Further, in the control methods shown in FIGS.
Although the film formation time of the S film 12 is divided in half, it is not always necessary to divide the time into the first half and the second half, and the film may be divided into a first stage in which Cu is excessive and a second stage in which Cu is insufficient. Therefore, the time distribution at each stage can be set freely.

Further, it is not necessary to completely match the timing for terminating the evaporation of the Na element with the timing for switching Cu from excess to insufficient as shown in FIGS. Na
The element evaporation time can be shorter or longer than the Cu excess time.

[0052] Further, in this embodiment, although the composition of the light absorbing layer is a Cu (an In _{1 over x} Ga x) _y Se _z film 12 is not limited thereto, CuIn _y Se _z film, CuGa _y Se _z membrane, C
UIN _y S _z film, CuIn _y (S _m Se _{1 over} m) _z film, Cu (I
n _1−x Ga _x ) _y (S _m Se _1−m ) _z film.
However, 0 <y, 0 <z, and 0 ≦ m ≦ 1. When films having these compositions are used, Cu is excessively added in the first half of film formation, and a Group Ia element such as Na is added, and Cu is added in the second half.
By making it insufficient, a solar cell with high conversion efficiency in a wide composition range can be obtained.

In the present embodiment, the transparent conductive film 14
Is a ZnO film to which Al is added, but n ⁺
Any other type of transparent conductive film may be used. For example, a ZnO film to which an element such as B, Ga, or In is added;
A so-called ITO film obtained by adding 10% of SnO ₂ to ₂ O ₃ , a SnO ₂ film obtained by adding an element such as F, and the like can be used.

Further, in this embodiment, the substrate type solar cell shown in FIG. 1 is used as the thin film solar cell, but the form of the solar cell is not limited to this form. For example, as shown in FIG. 2, a transparent conductive film 21, a CdS film 22,
The IGS film 23 and the Au film 24 may be sequentially stacked to form a super-straight solar cell in which light is emitted from the substrate 20 side. Also in this case, by using the method of forming the CIGS film 12 as the method of forming the CIGS film 23, high conversion efficiency can be obtained in a wide composition range.

In the structure of the solar cell shown in FIG. 1, the Na element contained in the
Blue glass substrate 10 and M
An SiO ₂ film or the like can be arranged between the o-film 11 and a block layer of an alkali metal such as Na.

Further, in this embodiment, the CIGS film 12 is formed by the multi-source vacuum evaporation method, but a method other than the multi-source vacuum evaporation method can be used. For example, a Cu film, an In-Ga film, and a Se film are sequentially stacked on a substrate, and then heated and diffused to form a CIGS film by a solid phase selenization method, or a Cu film and an In-Ga film are formed on the substrate. It is also possible to use a vapor-phase selenization method in which the layers are sequentially stacked and diffused with each other and selenized with Se vapor or H ₂ Se gas, a sputtering method, or the like. In the case of the selenization method, it is considered that by adding Na to the Cu film, high efficiency can be obtained in a wide composition range as in the present embodiment. In the case of the sputtering method, similarly to the present embodiment, by adding Cu and adding Na in the first half of the film formation, high efficiency can be obtained in a wide composition range as in the present embodiment. It is thought that it is possible.

[0057]

As described above, according to the present invention,
It is possible to provide a method for manufacturing a solar cell that can tolerate composition fluctuation of a CIS-based material thin film in a wide range and can obtain high energy conversion efficiency.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a substrate type solar cell manufactured by a manufacturing method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a superstrate type solar cell manufactured by the manufacturing method according to one embodiment of the present invention.

3 shows a (a) fill factor and (b) of a solar cell having the configuration of FIG. 1 using a CIGS film 12 formed by controlling the time change of the amount of evaporation from an evaporation source as shown in FIG. Short-circuit current,
(C) Graph showing the relationship between the open circuit voltage and the composition of the CIGS film, respectively.

FIG. 4 is a diagram illustrating a manufacturing method according to an embodiment of the present invention;
5 is a graph showing a temporal change in the evaporation amount of each evaporation source when the CIGS film 12 is formed.

FIG. 5 is a diagram illustrating a manufacturing method according to an embodiment of the present invention;
5 is a graph showing a temporal change in the evaporation amount of each evaporation source when the CIGS film 12 is formed.

FIG. 6 is a diagram illustrating a manufacturing method according to an embodiment of the present invention;
5 is a graph showing a temporal change in the evaporation amount of each evaporation source when the CIGS film 12 is formed.

FIG. 7 is a view showing a manufacturing method according to an embodiment of the present invention;
5 is a graph showing a temporal change in the evaporation amount of each evaporation source when the CIGS film 12 is formed.

FIG. 8 is a graph showing the relationship between the carrier concentration and the composition of the CIGS film 12 formed by the method of FIG.

9 is a graph showing the relationship between the conversion efficiency of the solar cell of FIG. 1 using the CIGS film 12 formed by the method of FIG. 3 and the composition of the CIGS film 12.

[Explanation of symbols]

10, 20 ... Blue glass substrate, 11 ... Mo film,
12,23 ··· Cu (In _{1 over x} Ga x) _y Se _z film (CIG
S film), 13, 22,... CdS film, 14, 21,.
Transparent conductive film, 24 ... Au film.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 17, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3 shows the time change of the evaporation amount from the evaporation source as shown in FIG.
Configuration of FIG. 1 using CIGS film 12 formed by control
Each of the solar cell's fill factor, short-circuit current, and open-circuit voltage,
4 is a graph showing a relationship with the composition of a CIGS film.

Claims (12)

[Claims] 1. A method for manufacturing a solar cell using a compound semiconductor thin film containing a group Ib element, a group III element, and a group VIb element as a light absorbing layer, the method comprising: , Ib on the substrate
A step of supplying a group III element, a group III element, and a group VIb element, wherein the step comprises: supplying a group Ib element supply amount to a group III element supply amount;
Ib contained in the compound semiconductor thin film having a desired composition
A first step of supplying the group Ia element onto the substrate while increasing the ratio of the group III element to the group III element, and the step of supplying the group Ib element supply amount to the group III element supply amount,
A second step of making the solar cell smaller than the first step. 2. The method for manufacturing a solar cell according to claim 1, wherein the supply amount of the group Ib element in the second step is set to zero. 3. The method according to claim 1, wherein the supply amount of the group III element in the first step is set to zero. 4. The method for manufacturing a solar cell according to claim 1, wherein a VIb group element is supplied onto the substrate through the first step and the second step. 5. The semiconductor device according to claim 1, wherein Cu is supplied as said group Ib element, at least one of In and Ga is supplied as said group III element, and S and Se are provided as said group VIb element. A method for manufacturing a solar cell, comprising supplying at least one of the following. 6. The method for manufacturing a solar cell according to claim 1, wherein at least one of Na, Li, K and Rb is supplied as said Group Ia element. 7. The method according to claim 1, wherein at least one of a group Ia element, a compound containing a group Ia element, and an alloy containing a group Ia element is supplied to supply the group Ia element in the first step. A method for manufacturing a solar cell. 8. The compound according to claim 7, wherein the compound of a group Ia element and a group VIb element, a compound of a group Ia element and a group VIIb element, and Ia are supplied to supply the group Ia element in the first step. A method for manufacturing a solar cell, comprising supplying at least one of an alloy of a group III element and Cu. 9. The method according to claim 8, wherein said group Ia element and VI
The group VIb element of the compound with the group b element is O, S, Se,
Or Te, and the group Ia element and VII
A method for manufacturing a solar cell, wherein the Group VIIb element of the compound with a Group b element is any of F, Cl, and Br. 10. The method according to claim 1, wherein:
A method for manufacturing a solar cell, wherein a method of supplying a group Ib element, a group III element, a group VIb element, and a group Ia element to a substrate is a vapor phase growth method. 11. The method of manufacturing a solar cell according to claim 1, further comprising a step of cleaning the surface of the formed compound semiconductor thin film after the step of forming the compound semiconductor thin film. Method. 12. The method according to claim 11, wherein after the cleaning step, a solution growth method is performed on the compound semiconductor thin film.
A method for manufacturing a solar cell, further comprising a step of forming a CdS film.