JPH07226410A - Method for manufacturing thin film made of chalcopyrite type compound, and solar cell having the thin film - Google Patents

Abstract

PURPOSE:To form easily a thin film made of CuInSe based chalcopyrite type compound which has a good crystal quality and a strong adhesive force, and to realize a highly efficient solar cell using this thin film. CONSTITUTION:First, the raw materials (Cu, In, Ge, Se, S, etc.) of a film are filled respectively into respective enclosed type crucibles (step S1), and the raw materials are jetted respectively into a high vacuum from respective jetting nozzles provided in the respective crucibles (step S2), and further, by the supercooling phenomenon (action) caused by the adiabatic expanding of the raw materials in the high vacuum, block-like atomic groups (cluster) in each of which the 5X10<2>-2X10<3> atoms of the foregoing raw materials are combined loosely with each other are formed (step S3). Subsequently, the block-like atomic groups are ionized respectively, and they are accelerated, and thereby, on a substrate, the thin film made of CuInSe2, CuInxGa1-xSe2, CuInSySe2-y and CuInxGa1-xSySe2-y is formed (step S4).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to CuInSe ₂ , CuIn _x Ga _{1 -x} Se by the cluster ion beam method.
₂ , CuInS _y Se _2-y and CuIn _x Ga _1-x S _y
The present invention relates to a method for producing a thin film of an Se _2-y chalcopyrite type compound and a solar cell having the thin film.

[0002]

_2. Description of the Related Art CuInSe ₂ is a zinc blende structure II-
In the Group VI semiconductor ZnSe, Zn is regularly added to Cu and I.
It is a compound semiconductor having a chalcopyrite type crystal structure in which n is replaced by n, and CuIn _x Ga _1-x Se ₂ , C
uInS _y Se _2-y and CuIn _x Ga _1-x S _y Se
_2-y (0 ≦ x <1, 0 <y ≦) is also a compound semiconductor having a similar crystal structure.

The characteristics of CuInSe ₂ are that it is a direct transition type semiconductor with a forbidden band width of 1.04 eV, that it has the highest light absorption coefficient among existing semiconductors, and photodegradation that is a problem with amorphous Si. It is possible to control the forbidden band width by selecting various elements, and research is being conducted as a polycrystalline thin film solar cell material.

Conventionally, the above CuInSe ₂ film and CuIn
_x Ga _1-x Se ₂ film, CuInS _y Se _2-y film, CuI
_{n x Ga 1-x S y} Se 2-y film, vapor deposition, sputtering,
It is produced by a method such as selenization, and the substrate temperature is set to 450 ° C. in order to improve the crystallinity of the film during film formation.
Required above ℃.

6A and 6B are views showing the structure of a solar cell having a general CuInSe ₂ -based thin film. FIG. 6A shows a substrate type structure, and FIG. 6B shows a superstrate type structure.

In the substrate type shown in FIG. 6 (a), a Mo electrode 2 is vapor-deposited on a glass substrate (Glass) 1, a CuInSe ₂ -based thin film 3 is deposited, and a window layer II-VI is formed thereon. A CdS film 4 and a ZnO film 5 of a group compound semiconductor are deposited to form a solar cell.

The superstrate type shown in FIG. 6 (b) has a structure opposite to that of the above substrate type.
ITO, ZnO, SnO on a glass substrate (Glass)
_A TCO film 7 made of ₂ or the like is formed, a CdS film 4 is deposited thereon as a window layer, a CuInSe ₂ -based thin film 3 is deposited thereon, and a metal (Metal) electrode 6 is further provided thereon. ing. This super straight type is
Since light (hν) can be incident from the glass substrate 1 side, it is excellent in hermeticity and mass productivity.

In the solar cell having the above structure, it is necessary that the Mo electrode 2 and the metal electrode 6 have low resistance and stable ohmic contact. In particular, the Mo electrode 2 and the CuInSe ₂ system are used. A Te film or a Ga film may be provided between the thin film 3 and the thin film 3 in order to improve adhesion. Further, it is effective to suppress mutual diffusion at the boundary surface between the CuInSe ₂ -based thin film 3 and the CdS film 4 to achieve a high open circuit voltage.

[0009]

However, conventionally, a CuInSe ₂ thin film is produced by the vapor deposition method, the sputtering method, the selenization method or the like as described above, and the substrate temperature is increased in order to improve the crystallinity of the film. While a high temperature of 450 ° C or higher is required, in the case of a superstrate type structure excellent in airtightness and mass productivity, C is added on a II-VI group compound (for example, CdS).
Since a uInSe ₂ -based thin film is deposited, it does not affect II-VI group compounds (Cu does not diffuse into CdS etc.)
In order to do so, low temperature film formation with a substrate temperature of 300 ° C. or lower is required.

Therefore, conventionally, when a super straight type solar cell is manufactured, CuInSe _{2 having} good crystallinity is used.
There is a problem that it is difficult to form a thin film of a system, and it is difficult to obtain a solar cell with high performance and high efficiency.

Further, when depositing a CuInSe ₂ -based thin film on a glass substrate, conventionally, there is a problem in that a gap is formed between the film and the substrate due to a difference in thermal expansion coefficient and the adhesive force of the film is weakened. there were.

The present invention has been made in view of the above problems, and CuInSe _{2 having} a good crystallinity can be easily obtained.
_{Film, CuIn x Ga 1-x Se} 2 film, CuInS _y Se
_2-y layer and _{CuIn x Ga 1-x S y} Se 2-y film can be prepared, also adhesion strong film can be obtained CuIn
Se ₂ film, CuIn _x Ga _1-x Se ₂ film, CuInS _y
And its object is to provide a Se _2-y layer and _{CuIn x Ga 1-x S y} Se 2-y film highly efficient solar cell manufacturing method and had the thin film.

[0013]

CuInSe _{2 of the} present invention
The method for producing the thin film of the chalcopyrite type compound is
Raw materials of u, In and Se are put in a closed container having a spray nozzle, respectively, and sprayed into a vacuum from the spray nozzle, and the atoms of the raw materials are loosely bonded to each other by a supercooling action by adiabatic expansion in the vacuum. To form a CuInSe ₂ film on the substrate by ionizing and accelerating the lumped atomic populations, and the Cu ionization current is higher than the In ionization current. It was made larger and accelerated.

The method for producing a thin film of the chalcopyrite type compound of CuIn _x Ga _{1 -x} Se ₂ of the present invention is Cu, I.
The raw materials of n, Ga, and Se are put in a sealed container each having a spray nozzle, sprayed from the spray nozzle into a vacuum, and the atoms of the raw material are loosely bonded to each other by a supercooling action by adiabatic expansion in the vacuum. To form a CuIn _x Ga _{1 -x} Se ₂ film on the substrate by ionizing and accelerating this massive atomic population. I
The ionization currents of n and Ga are set to be larger than the ionization currents of n and Ga for acceleration. The value of x at this time is 0 ≦ x <1.

The method for producing a thin film of the chalcopyrite type compound of CuInS _y Se _2-y of the present invention is as follows.
The raw materials of S and Se are put into a closed container having a spray nozzle, respectively, and sprayed into a vacuum from the spray nozzle, and the atom of the raw material is loosely bonded to each other by a supercooling action by adiabatic expansion in the vacuum. A CuInS _y Se _2-y film is formed on a substrate by forming an atomic population and ionizing and accelerating this massive atomic population. Further, the Cu ionization current is the In ionization current. It is designed to be bigger than the above to accelerate.
At this time, the value of y is 0 <y ≦ 2.

The CuIn _x Ga _1-x S _y Se _{2-y of the} present invention
The method for producing the thin film of the chalcopyrite type compound is
The raw materials of u, In, Ga, S, and Se are put into a sealed container having an injection nozzle, respectively, and injected into a vacuum from the injection nozzle, and the atoms of the raw material are atomized by a supercooling action by adiabatic expansion in the vacuum. Form a lumpy atomic population that is loosely bonded to each other and ionize and accelerate the lumpy atomic population to form CuIn _x Ga _1-x S _y Se _2-y on the substrate.
A film is formed, and the ionization current of Cu is made larger than the ionization currents of In and Ga to accelerate the film. X, y at this time
The values of 0 are respectively 0 ≦ x <1 and 0 <y ≦ 2.

The solar cell having a CuInSe ₂ thin film on the substrate of the present invention is a CuInSe ₂ thin film containing Cu, I
It is a film formed by ionizing and accelerating a massive atomic group in which the atoms are loosely bound to each other and formed when the raw materials of n and Se are jetted in a vacuum.

Further, CuIn _x Ga may be formed on the substrate of the present invention.
A solar cell having a thin film of _1-x Se ₂ is CuIn _x Ga
A thin film of _1-x Se ₂ was formed by ionizing and accelerating a massive atomic group in which atoms of each of which are loosely bound to each other and which are formed when a raw material of Cu, In, Ga, and Se is injected in a vacuum. It is a thing.

Further, CuInS _y Se may be formed on the substrate of the present invention.
A solar cell having a thin film of _2-y is CuInS _y Se _2-y
Is a thin film formed by ionizing and accelerating a massive atomic group in which atoms of each of which are loosely bonded and formed when the raw materials of Cu, In, S, and Se are jetted in a vacuum.

Further, CuIn _x Ga may be formed on the substrate of the present invention.
Solar cell having a thin film of _{1-x S y Se 2-} y is, CuIn
A thin film of _x Ga _1-x S _y Se _2-y is formed of Cu, In, Ga,
This is a film formed by ionizing and accelerating a massive atom population in which atoms of each other are loosely bonded and formed when the raw materials of S and Se are injected into a vacuum. At this time, the value of x is 0 <x <1, and the value of y is 0 <y <2.

[0021]

Function _: CuInSe ₂ , CuIn _x Ga _{1-x of the} present invention
Se ₂ , CuInS _y Se _2-y , and CuIn _x Ga _1-x
In the method for producing a thin film of S _y Se _2-y , the raw materials of the film are sprayed from a nozzle into a vacuum, respectively, and expansion and cooling action in the vacuum form a massive atomic group in which the atoms are loosely bonded to each other. , This massive atomic population is ionized,
Since the film is formed on the substrate by being accelerated, the film can be formed at a low temperature, and the adhesion of the film becomes strong due to the ionization.

Further, in the solar cell of the present invention, the CuInSe ₂ film and CuInGaS film formed as described above are used.
e ₂ film, CuInS _y Se _2-y film or CuIn _x G
Since _{a 1-x S y Se 2} -y film is used, without affecting the group II-VI compound to be a window layer, a high efficiency is obtained.

[0023]

EXAMPLE FIG. 1 shows a CuInSe ₂ film, Cu according to the present invention.
In _x Ga _1-x Se ₂ film is a diagram illustrating a manufacturing process of the CuInS _y Se _2-y layer and _{CuIn x Ga 1-x S y} Se 2-y film. A method for producing these thin films is called a cluster ion beam method (ICB method). First, raw materials (Cu, In, Se, etc.) for the films are put into each closed crucible (step S1), and then the crucible is provided. 5 × 1 by the supercooling phenomenon (action) by adiabatic expansion in the high vacuum (step S2).
A mass atomic cluster (cluster) in which 0 ^{2 to} 2 × 10 ³ atoms of the above-mentioned raw material are loosely bonded to each other is formed (step S3). Then, by ionizing and accelerating this massive atomic population, CuInSe ₂ and CuIn _{x are} deposited on the substrate.
Ga _1-x Se ₂ or CuInS _y Se _2-y or CuIn _x G
a _1-x S _y Se _2-y thin film is formed (step S
4).

In this way, the CuInSe ₂ film and the Cu
In _x Ga _1-x Se ₂ film, CuInS _y Se _2-y film and C
Although _{uIn x Ga 1-x S y} Se 2-y film is obtained, and by utilizing the kinetic energy due to ionization in place of the Sainetsu energy to control the kinetic energy, and chemically to activate To get a thin film. For this reason,
As a film forming condition, the substrate temperature may be about 300 ° C., and a good quality thin film can be formed at a low temperature. Further, the acceleration voltage of ions is about 0 to 3 KV, and the ionization current is C
The ionization current I _Cu of u is made larger than the ionization currents I _In and I _Ga of In and Ga (I _Cu > I _In , I _Ga > 0 m
A) It is desirable to accelerate.

FIG. 2 is a diagram showing a schematic configuration of an ICB device used for the above film formation. This device is a vacuum device (V
ACUUM SYSTEM 11 and a vacuum container 12 that can be sealed and connected thereto, and the vacuum container 12 is a crucible 13, which is a closed container having the above-mentioned injection nozzle.
14 and 15 are arranged as sources (SOURCE) of the respective raw materials (Cu, In, Se). Further, in the vacuum container 12, a substrate 16, a substrate heating lamp 17, and a device for ionization are arranged.

FIG. 3 shows a surface SEM image of the CuInSe ₂ film formed by changing the ionization conditions of Cu and In. FIG. 3A shows a case where Cu, In co-ionization is not performed (I _Cu = I _In = 0 mA). In this case, the particle size of the film was small and the film was rough and non-uniform. FIG. 3B shows a case where only Cu is ionized (I _Cu = 50 mA,
I _In = 0 mA), and an increase in particle size was observed at this time, but the film was still non-uniform.

Further, FIG. 3C shows the case where Cu and In are ionized to the same degree (I _Cu = I _In = 50 mA),
At this time, the uniformity of the film was improved, but the particle size was rather small (about 0.3 μm). FIG. 3D shows the case where the ionization current of Cu is larger than that of In as described above (I _Cu = 100 mA, I _In = 50 mA),
At this time, a uniform film having a particle size increased to about 1 μm was obtained. At this time, the acceleration voltage is 1 to 2 KV, and the substrate temperature is 300.
It was ℃. FIG. 4 shows an enlarged SEM image of FIG. Further, FIG. 5 shows an X-ray diffraction pattern of the CuInSe ₂ film at that time.

As shown in FIG. 5, the C obtained in this embodiment was obtained.
The X-ray diffraction of the uInSe ₂ film is strongly oriented in (a: (112)), and the full width at half maximum is narrow at 0.3 °, indicating that the crystallinity is good. Furthermore, diffraction lines (b: (101)), (c: (103)), (d: peculiar to the chalcopyrite structure)
(211)) and the like were also found, and it was found that the film was a high quality polycrystalline film. The difference between the ionization currents of Cu and In is preferably I _Cu −I _In ≧ 30 mA, and good results were obtained at this time.

From the above, in the low temperature film formation at the substrate temperature of 300 ° C., the Cu ionization current is made larger than the In ionization current (preferably I _Cu −I _In ≧ 30 m).
By A), there are no different phases and the particle size is about 1 μm.
C with good crystallinity such that facets of crystals are also observed
It was found that a uInSe ₂ film was obtained. Also, In
Some were the same experiment for CuIn _x Ga _1-x Se ₂ film was replaced by Ga, I _Cu -I _In ≧ 30m of
When A and I _Cu −I _Ga ≧ 30 mA, good results similar to those of the CIS film were obtained.

Here, the range of x in each of the above chemical formulas is preferably 0.1 <x <0.5, and the optimum value is around 0.25.

A similar experiment was conducted on a CuInS _y Se _2-y film in which a part of Se in CuInSe ₂ was replaced with S. As a result, the difference in ionization current between Cu and In was preferably I _Cu. Good results were obtained when -I _In ≧ 30 mA and y range was 0.3 <y <1. This y
The optimum value of was about 0.5.

Further, when the same experiment was conducted for the CuIn _x Ga _1-x S _y Se _2-y film, good results were obtained in the same range as above.

The ionization of Cu, In and Ga at this time is as follows.
It is considered that during film formation, it promotes nucleation and nucleation of vapor-deposited atoms and contributes to the formation of a high-quality film due to the action of crystal nucleus aggregation.

Next, the CIS formed by the above-mentioned ICB method
A superstrate type solar cell made of a film will be described. The structure of this battery is similar to that shown in FIG. 6B, and ZnO is formed on a non-alkali glass substrate.
(1 μm), CdS (1000 Å), CuInSe ₂
(1.5 μm) and Au (1 μm) films are sequentially formed. The characteristics of this solar cell are AM
Under the irradiation conditions of 1.5 and 100 mW / cm ² , a conversion efficiency of about 2% was obtained.

As described above, when a CIS film is formed at a low temperature by the ICB method at a substrate temperature of 300 ° C. or less, when a super straight solar cell is produced, the underlying window layer (II- C to Group VI compound CdS)
The diffusion of u is suppressed, a good CdS-CuInSe ₂ interface is obtained, and a high-performance and high-efficiency solar cell is obtained.

Further, CuInSe ₂ produced by the ICB method
The film has a strong adhesive force due to the effect of ionization and the like, so that film peeling does not occur even when a tape test is performed.

The film obtained by the above film forming method is Cu
For both the InSe ₂ film and the CuIn _x Ga _1-x Se ₂ film, C
Even with the uInS _y Se _2-y film, CuIn _x Ga _1-x S _y S
Similar quality is guaranteed for e2 _-y films. Further, these films can be applied not only to the solar cell but also to an image pickup tube and the like.

[0038]

As described above, according to the present invention, a CuInSe ₂ film and a CuIn _x Ga _{1 -x} S film having good crystallinity can be easily obtained.
e ₂ film, CuInS _y Se _2-y film, and CuIn _x Ga
There is an effect that a _{1-x Sy} Se _2-y film can be formed and a strong adhesive force of the film can be obtained.

In addition, the above-mentioned CuInSe ₂ film, CuIn
_x Ga _1-x Se ₂ film, the CuInS _y Se _2-y film or _{CuIn x Ga 1-x S y} Se 2-y film, there is an effect that it is possible to realize a high efficiency solar cells.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of a film according to the present invention.

FIG. 2 is a schematic configuration diagram of an apparatus used for film formation in FIG.

FIG. 3 Surface SE of CuInSe ₂ film by ionization
Figure showing M image (photo)

FIG. 4 is an enlarged view (photograph) of FIG.

5 is a diagram showing an X-ray diffraction pattern of the CuInSe ₂ film of FIG.

FIG. 6 is a diagram showing a structure of a general solar cell.

[Explanation of symbols]

 11 Vacuum Equipment 12 Vacuum Container 13 Crucible (Sealed Container) 14 Crucible (Sealed Container) 15 Crucible (Sealed Container) 16 Substrate 17 Substrate Heating Lamp

[Procedure amendment]

[Submission date] November 30, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 8

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

_2. Description of the Related Art CuInSe ₂ is a zinc blende structure II-
In the Group VI semiconductor ZnSe, Zn is regularly added to Cu and I.
It is a compound semiconductor having a chalcopyrite type crystal structure in which n is replaced by n, and CuIn _x Ga _1-x Se ₂ , C
uInS _y Se _2-y and CuIn _x Ga _1-x S _y Se
_2-y (0 ≦ x ≦ 1, 0 <y ≦ 2 ) is also a compound semiconductor having a similar crystal structure.

Claims (12)

[Claims] 1. A method for producing a thin film of a chalcopyrite-type compound of CuInSe ₂ , wherein raw materials of Cu, In, and Se are put in a sealed container each having a spray nozzle and sprayed from the spray nozzle into a vacuum. Due to the supercooling effect of adiabatic expansion in vacuum, the atoms of the raw material are loosely bound to each other to form a cluster of massive atoms, which is ionized and accelerated to form CuIn on the substrate.
CuInSe ₂ characterized by forming a Se ₂ film
Method for producing thin film of chalcopyrite type compound of. 2. The Cu ionization current is made larger than the In ionization current to accelerate.
A method for producing a thin film of the chalcopyrite type compound of CuInSe ₂ described. 3. CuIn _x Ga _1-x Se ₂ (where 0 ≦ x
In the method for producing a thin film of a chalcopyrite type compound according to <1), Cu, In, Ga, and Se raw materials are placed in a sealed container each having a spray nozzle and sprayed from the spray nozzle into a vacuum. By the supercooling effect due to adiabatic expansion at 1, the atoms of the raw material are loosely bound to each other to form a cluster of atomic clusters, and the cluster of atomic clusters is ionized and accelerated to form CuIn _x Ga _{1 -x} Se ₂ on the substrate.
CuIn _x Ga _1-x S characterized by forming a film
e ₂ A method for producing a thin film of a chalcopyrite compound. 4. The thin film of the chalcopyrite type compound of CuIn _x Ga _{1 -x} Se _{2 according} to claim 3, characterized in that the ionization current of Cu is made larger than the ionization currents of In and Ga to accelerate it. Method. 5. CuInS _y Se _2-y (where 0 <y ≦
In the method for producing a thin film of a chalcopyrite type compound according to 2), Cu, In, S and Se raw materials are placed in a sealed container having an injection nozzle and injected into a vacuum from the injection nozzle. By the supercooling action due to the adiabatic expansion of the above, the atoms of the raw material are loosely bound to each other to form a lumped atomic group, and the lumped atomic group is ionized and accelerated to form a CuInS _y Se _2-y film on the substrate. A method for producing a thin film of a chalcopyrite type compound of CuInS _y Se _2-y , characterized in that 6. The ionization current of Cu is made larger than that of In to accelerate the ionization current.
A method for producing a thin film of the chalcopyrite type compound of CuInS _y Se _{2 -y} described. 7. A method for producing a thin film of a chalcopyrite type compound of CuIn _x Ga _1-x S _y Se _2-y (where 0 ≦ x <1,0 <y ≦ 2), wherein Cu, In, Ga, S, Se
Each of the raw materials is put in a closed container having a spray nozzle and sprayed into the vacuum from the spray nozzle, and a massive atomic group in which the atoms of the raw material are loosely bonded to each other by a supercooling action by adiabatic expansion in the vacuum is generated. Cu is formed on the substrate by ionizing and accelerating this massive atomic population.
_{In x Ga 1-x S y} Se 2-y film _{CuIn x Ga 1-x S y} Se 2-y method for manufacturing a thin film of the chalcopyrite-type compound, which is characterized in that for forming the. 8. The thin film of the chalcopyrite type compound of CuIn _x Ga _{1 -x} Se _{2-y according} to claim 7, wherein the ionization current of Cu is made larger than the ionization currents of In and Ga to accelerate. Of manufacturing. 9. A solar cell having a CuInSe ₂ thin film on a substrate, wherein the CuInSe ₂ thin film is C
A superstrate type solar cell characterized in that a film is formed by ionizing and accelerating a lumpy atomic group in which atoms of each of which are loosely bonded and formed when the raw materials of u, In, and Se are jetted in a vacuum. . 10. CuIn _x Ga _{1 -x} Se ₂ on a substrate
In a solar cell having a thin film (where 0 ≦ x <1),
The CuIn _x Ga _1-x Se ₂ thin film is made of Cu, In,
A super straight solar cell, wherein a film is formed by ionizing and accelerating a massive atomic group in which atoms of each Ga and Se are loosely bonded and formed when the raw materials of Ga and Se are injected into a vacuum. 11. A solar cell having a thin film of CuInS _y Se _2-y (where 0 <y ≦ 2) on a substrate, wherein C
The thin film of uInS _y Se _2-y is formed by ionizing and accelerating a massive atomic population in which atoms of each of the Cu, In, S, and Se formed when the raw materials are loosely bonded are formed. A super straight type solar cell that is characterized. 12. CuIn _x Ga _{1 -x} S _y Se on a substrate
In _2-y (where 0 ≦ x <1,0 <y ≦ 2) solar cell having a thin film of the _{CuIn x Ga 1-x S y} Se 2-y
The thin film of is characterized by being formed by ionizing and accelerating a massive atomic population in which atoms of each of which are formed by spraying the raw materials of Cu, In, Ga, S, and Se into each other are loosely bound to each other. A super straight solar cell.