JPH104206A - Compound semiconductor thin film forming method and optoelectric transducer using the thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film forming method with which a high quality large area compound semiconductor thin film, which is uniformly thinned off, can be obtained at low cost in the formation of a compound semiconductor thin film, especially in the manufacture of a sulfide thin film. SOLUTION: A metal organic compound, which is obtained by sublimating or evaporating by heating a substrate 1 where a metal organic compound 2, containing at least one or more metal and sulfur, is deposited by heating to sublimate or evaporate, is adhered to a thin film forming substrate 3 having a transparent conductive film 4 which is arranged in an interval with the substrate 1 on which heated metal organic compound is applied. By thermally decomposing the adhered metal organic compound simultaneously with the adhesion or after adhesion, a metal sulfide thin film is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a compound semiconductor thin film used for a photoelectric conversion element, and more particularly to a method for forming a metal sulfide thin film and a method for forming a photoelectric conversion element using the same.

[0002]

2. Description of the Related Art Conventionally, compound semiconductors, particularly sulfide thin films such as cadmium sulfide, zinc sulfide, copper sulfide, lead sulfide, and mercury sulfide, have been widely used as photoelectric conversion element materials. Many of these compounds have been conventionally produced by a sputtering method, an evaporation method, a CVD method, or the like. By these methods, a thin film having a desired film quality can be obtained as a photoelectric conversion element material, but all require extremely expensive film forming equipment such as a vacuum apparatus, so that large-area uniform film forming and high-speed continuous film forming are required. Etc. were difficult.

There is also a solution method as a method for forming a large-area thin film at a lower cost. In this case, the cost required for a film-forming apparatus and a process is relatively inexpensive. It was very difficult to obtain uniformity and reproducibility.

Therefore, a coating and sintering method has been proposed as a technique for producing a large area of a compound semiconductor thin film with good reproducibility using an inexpensive apparatus. In this method, a fine powder dispersion paste of a compound semiconductor is screen-printed on a substrate and sintered in a continuous belt furnace, and a cadmium telluride sintered film is also formed on the cadmium sulfide sintered film by the same method. A method for producing a cadmium telluride photoelectric conversion element has been disclosed (Japanese Patent Publication No. 56-28386).

This method uses an inexpensive device as described above,
There is an excellent feature that a large area of a compound semiconductor thin film can be continuously formed uniformly and with good reproducibility, and patterning can be performed simultaneously with the film formation. However, since the sintering temperature is as high as about 700 ° C., it is necessary to use expensive special glass (eg, barium borosilicate glass) having excellent heat resistance as a substrate. Unsuitable for high-speed, mass-production due to the need for sintering reaction,
An expensive ceramic sintering case is required to control the evaporation of the melting point depressant during sintering, an inert atmosphere such as nitrogen is required during sintering, 4 μm) cannot be formed,
There are problems such as formation of a large number of voids in the film and uneven film quality.

[0006]

Recently, as a method for solving these problems by making use of the characteristics of the coating and sintering method, a solution containing a metal organic compound having at least one metal-sulfur bond inside is coated on a substrate. And a thermal decomposition of the metal organic compound in an oxidizing atmosphere to form a metal sulfide thin film has been proposed (Japanese Patent Publication No. Hei 6-99809).
No.).

In this method, it is a general method to apply a solution by a spinner method to form a film. However, it is difficult to apply the solution uniformly and thinly to a large-area substrate. To form a large area metal sulfide thin film with a uniform thickness
Making this possible is a major challenge.

The present invention solves the above-mentioned problems of the prior art with respect to a method for forming a compound semiconductor thin film, and provides a film forming means for obtaining a high quality, inexpensive, large-area compound semiconductor thin film uniformly thinned. The purpose is to provide. Another object is to provide a photoelectric conversion element having high conversion efficiency using the compound semiconductor thin film.

[0009]

In order to solve the above-mentioned problems, the present invention heats a metal-organic compound containing at least one metal and sulfur, and sublimates, vaporizes or evaporates the metal-organic compound by this heating. This method is characterized in that a metal sulfide thin film is formed by causing the metal organic compound to be attached to a thin film forming substrate and thermally decomposing the attached metal organic compound simultaneously with or after the attachment. Thereby, a high-quality and inexpensive compound semiconductor thin film can be industrially formed.

Further, according to the present invention, a thin film forming substrate is disposed at a predetermined interval on a substrate coated with a metal organic compound containing at least one metal and sulfur, and the coated substrate is heated to a predetermined temperature. The metal organic compound sublimated, vaporized or evaporated by heating is attached to the thin film forming substrate heated to a predetermined temperature, and the attached metal organic compound is thermally decomposed simultaneously with or after the attachment to form a metal sulfide thin film. This is a method for forming a compound semiconductor thin film characterized in that it is obtained. Thus, a high-quality and inexpensive large-area compound semiconductor thin film can be industrially formed.

The present invention further provides a method for heating a metal-organic compound containing at least one of a metal and sulfur, and transporting the metal-organic compound sublimated, vaporized or evaporated by the heating to the surface of the thin-film forming substrate. A method for forming a compound semiconductor thin film, characterized in that a metal sulfide thin film is obtained by thermally decomposing the metal organic compound attached simultaneously with or after the attachment. Thus, a high-quality and inexpensive large-area compound semiconductor thin film can be industrially formed.

Further, the present invention is a photoelectric conversion element characterized in that a compound semiconductor thin film formed by any one of the above-described methods for forming a compound semiconductor thin film is used as a window layer. By using this high-quality semiconductor film, a high-performance photoelectric conversion element can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a method of heating a metal organic compound containing at least one metal and sulfur, and attaching the metal organic compound sublimated, vaporized or evaporated by the heating to a thin film forming substrate. The formation method is characterized in that a metal sulfide thin film is formed by thermally decomposing the formed metal organic compound simultaneously with or after the adhesion. By this method, the organic matter generated by the thermal decomposition of the metal organic compound attached to the thin film forming substrate is scattered, and the metal sulfides separated into molecules are regularly arranged on the substrate, and a simple method is used. An extremely dense high-quality thin film can be formed.

According to a second aspect of the present invention, a thin film forming substrate is disposed at a predetermined interval on a substrate coated with a metal organic compound containing at least one metal and sulfur, and the coated substrate is heated at a predetermined temperature. The metal organic compound which has sublimated, vaporized or evaporated by heating is attached to the thin film forming substrate heated to a predetermined temperature, and the attached metal organic compound is thermally decomposed simultaneously with or after the attachment. This is a method for forming a compound semiconductor thin film, characterized by obtaining a sulfide thin film. According to this method, the metal organic compound evaporated or sublimated from the metal organic compound coated substrate can be uniformly attached to the thin film forming substrate in a shorter time to form a thinner dense metal sulfide thin film. it can.

According to a third aspect of the present invention, there is provided a method of forming a compound semiconductor thin film according to the second aspect, wherein a metal organic compound containing cadmium, zinc, copper, lead or mercury is used. , Zinc sulfide, copper sulfide, lead sulfide, or mercury sulfide can be obtained.

The invention according to claim 4 is characterized in that the metal organic compound is a metal mercaptide, a metal thioate, a metal dithioate, a metal thiocarbonate, a metal dithiocarbonate, a metal trithiocarbonate. 3. The method for forming a compound semiconductor thin film according to claim 2, which is a salt of a salt, a metal thiocarbamate or a metal dithiocarbamate, and a high-quality thin film of various metal sulfides is obtained.

According to a fifth aspect of the present invention, there is provided the method of forming a compound semiconductor thin film according to the second aspect, wherein the substrate coated with the metal organic compound is heated at a temperature of 100 ° C. or more and 600 ° C. or less. A high-quality semiconductor thin film can be formed in a shorter time, and a thin film forming substrate having a relatively low heat-resistant temperature can be used.

The invention according to claim 6 is the method for forming a compound semiconductor thin film according to claim 2, wherein the substrate for forming a thin film is a glass plate, a metal plate or a resin film. As described above, it is possible to form photoelectric conversion elements having various structures from the viewpoint of increasing the degree of freedom in selecting a substrate material for forming a thin film.

Further, since the substrate for forming a thin film having a relatively low heat-resistant temperature according to claim 5 can be used and the degree of freedom in selecting the substrate material for forming a thin film according to claim 6 can be increased, the substrate for forming a thin film can be manufactured at a low cost. For example, materials such as soda lime glass and polyamide resin film, which are generally available, can be used, so that they can be widely used as inexpensive photoelectric conversion element materials for solar cells and the like.

According to a seventh aspect of the present invention, there is provided the method of forming a compound semiconductor thin film according to the second aspect, wherein the substrate temperature for forming a thin film is 300 ° C. or higher, and a dense high-quality film can be obtained.

The invention according to claim 8 is the method for forming a compound semiconductor thin film according to claim 2, wherein the distance between the substrate coated with the metal organic compound and the substrate for thin film formation is 0.1 mm or more. In addition, film formation defects due to distortion are reduced, and stable film formation can be performed.

According to a ninth aspect of the present invention, there is provided the method for forming a compound semiconductor thin film according to the second aspect, wherein the thickness of the metal sulfide thin film is 700 nm or less, and the film contains almost no organic component such as carbon. No high quality film can be obtained.
Further, by setting the thickness to 30 nm or more, an extremely good compound semiconductor thin film free from defects such as pinholes can be obtained.

According to a tenth aspect of the present invention, a metal-organic compound containing at least one metal and sulfur is heated, and the sublimated, vaporized or evaporated metal-organic compound is conveyed to the surface of the thin film forming substrate by this heating. A compound semiconductor thin film forming method characterized in that a metal sulfide thin film is obtained by causing the metal organic compound to adhere to a thin film forming substrate and thermally decomposing the metal organic compound simultaneously with or after the attachment. An extremely dense high-quality metal sulfide thin film can be formed over a large area by a simple method.

The invention according to claim 11 is the method for forming a compound semiconductor thin film according to claim 10, wherein the metal contained is a metal organic compound containing cadmium, zinc, copper, lead or mercury. , Zinc sulfide,
Various high-quality semiconductor thin films of copper sulfide, lead sulfide, or mercury sulfide can be obtained.

According to a twelfth aspect of the present invention, the metal organic compound is a metal mercaptide, a metal thioate, a metal dithioate, a metal thiocarbonate, a metal dithiocarbonate, or a metal trithiocarbonate. The method for forming a compound semiconductor thin film according to claim 10, wherein the thin film is a salt of a salt, a metal thiocarbamate or a metal dithiocarbamate, and a high-quality metal sulfide thin film can be obtained.

According to a thirteenth aspect of the present invention, there is provided the method of forming a compound semiconductor thin film according to the tenth aspect, wherein the heating temperature of the metal organic compound is set to 100 ° C. or more and 600 ° C. or less. A high-quality semiconductor thin film can be formed, and a thin-film formation substrate having a relatively low heat-resistant temperature can be used.

The invention according to claim 14 is the method for forming a compound semiconductor thin film according to claim 10, wherein the substrate temperature for forming a thin film is 300 ° C. or higher, and a dense high-quality film can be obtained.

The invention according to claim 15 is the first or second invention.
Alternatively, a photoelectric conversion element using a compound semiconductor thin film formed by the method for forming a compound semiconductor thin film according to 10 as a window layer. By using a large-area dense thin film formed by a simple method, a highly efficient photoelectric conversion element with good short-wavelength sensitivity can be formed.

According to a sixteenth aspect of the present invention, the light absorption layer of the photoelectric conversion element is made of a cadmium telluride film.
It is a photoelectric conversion element of description, It can form a highly efficient cadmium telluride photoelectric conversion element.

The invention according to claim 17 is the method for forming a photoelectric conversion element according to claim 15, wherein the light absorption layer of the photoelectric conversion element is made of I-III-VI type ₂ chalcopyrite. A highly efficient I-III-VI _2- type chalcopyrite photoelectric conversion element, for example, a CuIn _x Ga _{1 -x} Se ₂ photoelectric conversion element or a CuIn _x Ga _{1 -x} S ₂ photoelectric conversion element can be formed.

An embodiment of the present invention will be described below with reference to FIGS. (Embodiment 1) The present invention is a forming method in which a metal organic compound coated substrate and a thin film forming substrate are arranged at a predetermined interval, and will be described with reference to FIG. In FIG. 1, the prepared paste of the metal-organic compound 2 is uniformly applied onto the metal-organic compound-coated substrate 1 by using a screen printing method. The coated substrate is dried, and the solvent is volatilized to prepare a metal organic compound coated substrate.

On the other hand, a transparent conductive film 4 is formed on the thin film forming substrate 3, preheated in the air by a heater 6, and metal is disposed at predetermined intervals by using a spacer 5 so as to face the thin film forming substrate 3 in parallel. An organic compound coated substrate is arranged. The metal organic compound coated substrate is heated by radiant heat from the thin film forming substrate 3 which has been heated in advance, and the temperature is increased.
This temperature state is maintained for several seconds, and the metal organic compound 2 is sublimated, vaporized or evaporated to obtain a uniform metal sulfide film on the thin film forming substrate.

In this embodiment, the method of heating the substrate for forming the thin film in advance and heating the metal organic compound by the radiant heat is described. However, the substrate for coating the metal organic compound or the substrate for forming the thin film and the substrate for coating the metal organic compound is described. Are heated together, temperature control can be performed more accurately.

(Embodiment 2) The present invention relates to a method of forming a sublimated, vaporized or evaporated metal organic compound on a thin film forming substrate by heating a container containing the metal organic compound. It will be described using FIG. In FIG.
A transparent conductive film 4 is formed on a thin film forming substrate 3 and a heater 6
In advance in the atmosphere.

The metal organic compound is placed in a sealable metal container 9 having an inlet 7 and an outlet 8 and heated by a heater 10 to sublimate, vaporize or evaporate. By introducing a nitrogen gas heated from the inlet 7 into the metal container at a predetermined flow rate, the gas of the generated organometallic compound is transported from the outlet 8 to the thin film forming substrate 3 by using the pipe 11 and is used for forming a thin film. It is sprayed on the substrate 3 to obtain a uniform metal sulfide film on the substrate 3 for forming a thin film.

It is to be noted that the temperature of the outlet or the pipe can be accurately controlled by heating the pipe, and that the metal organic compound can be prevented from adhering to the outlet or the pipe.

[0037]

Embodiments will be described below with reference to embodiments.

[0038]

Example 1 Cadmium diethyldithiocarbamate, which is a metal organic compound, was added to a propylene glycol solvent.
A paste was prepared by dissolving at a rate of 75 mol / liter. The paste is uniformly applied to a glass substrate at 6.4 mg / cm ² by a screen printing method. The coated substrate was dried at 120 ° C., and the solvent was volatilized to prepare a metal organic compound coated substrate.

On the other hand, an indium oxide film (ITO film) having a thickness of 200 nm was formed as a thin film forming substrate.
mm soda lime glass is heated to 450 ° C. in the air in advance, and 1 m so as to face the thin film forming substrate in parallel.
The metal organic compound coated substrates are arranged at intervals of m. The metal-organic compound-coated substrate is heated by radiant heat from a previously heated substrate for forming a thin film, and the temperature is increased to about 300 ° C. This temperature state was maintained for 40 seconds, and the metal organic compound was sublimated or evaporated, whereby a uniform film having a thickness of 70 nm was obtained on the thin film forming substrate.

It has been confirmed that this film formation can be performed similarly under an inert atmosphere such as nitrogen, argon or helium.

The optical band gap of this film was measured and found to be 2.42 eV, which was in agreement with the generally known standard value of the band gap of cadmium sulfide. From this, it was confirmed that a cadmium sulfide thin film having few lattice defects was formed. In addition, from the results of photoelectron spectroscopy analysis, it was confirmed that almost no organic matter such as carbon causing a decrease in optical transmittance remained on the surface of the cadmium sulfide thin film and in the film.

Using the cadmium sulfide thin film produced by the above method as a window layer, a cadmium telluride film is formed on the cadmium sulfide film to form a photoelectric conversion element. FIG. 3 shows a structural sectional view of a photoelectric conversion element prepared as an example.

A 200 nm indium oxide film 17 is formed on a glass substrate 16, and a cadmium sulfide film 12 is formed on a part of the film in the same manner as in the first embodiment.

The substrate on which the cadmium sulfide film 12 was formed was opposed to an alumina board on which cadmium telluride powder was laid at a distance of 3.0 mm, and the pressure was 200 Pa.
Under argon atmosphere, the former is 600 ° C, the latter is 630 ° C
For 1 minute to form a cadmium telluride film 13 having a thickness of 5.0 μm.

The substrate with the cadmium telluride film 13 is
It is immersed in a saturated solution of cadmium chloride, heat-treated at 400 ° C. for 30 minutes, and then the surface is washed with pure water.

A carbon paste is applied on the cadmium telluride film 13 using a screen printing method. The coated substrate is dried at 150 ° C. for 60 minutes using a hot air drier to obtain a carbon electrode 14.

An AgIn electrode 15 is formed on the carbon electrode 14 and the indium oxide film 17 as a current collecting electrode. Thus, a cadmium sulfide / cadmium telluride photoelectric conversion device having the structure shown in FIG. 3 was formed.

FIG. 5 shows, as a conventional example, a cross-sectional structure of a photoelectric conversion element using a cadmium sulfide thin film (thickness: 20 μm) produced by a coating and sintering method as a window layer. A cadmium sulfide film 18 and a cadmium telluride film 19 having a thickness of 20 μm are formed on a glass substrate 22, and a carbon electrode 20 and an AgIn electrode 21 are formed thereon.

FIGS. 4 and 6 show the voltage-current characteristics of the photoelectric conversion device of the embodiment and the conventional photoelectric conversion device, respectively.
4, the conversion efficiency of the photoelectric conversion element (area: 1 cm ² ) of the example is 14.9%, which is much higher than 11.3% of the conventional photoelectric conversion element shown in FIG. Was.
This is because the photoelectric conversion device prototyped using the present invention has a thin cadmium sulfide layer and a dense film quality, so that short-wavelength sensitivity is increased, and as a result, the short-circuit current density is 21.1 mA / c.
The main factor is considered to be the increase from m ² to 25.3 mA / cm ² .

The photoelectric conversion element manufactured by the same method as in the above embodiment using borosilicate glass or barium borosilicate glass as the thin film forming substrate, and the above-described embodiment using soda lime glass. It was confirmed that characteristics completely consistent with those of the photoelectric conversion element were obtained.

Conventionally, in the sintering method, since the temperature for forming a film is as high as about 700 ° C., it is necessary to select a substrate material for forming a thin film which has a small thermal expansion coefficient and is hardly softened or deteriorated even at a high temperature. Expensive materials such as borosilicate glass or barium borosilicate glass have to be used. However, if the present invention is applied by the above confirmation, a film can be formed at a relatively low temperature, so that an inexpensive and commonly available glass substrate material such as soda lime glass can be used, and the degree of freedom in material selection is increased. It has been proved that it has expanded significantly.

[0052]

Example 2 Cadmium dimethyldithiocarbamate was used as the metal organic compound, the heating temperature of the substrate for forming the thin film was 440 ° C., and the distance between the two substrates was adjusted so that the temperature of the metal organic compound coated substrate was 330 ° C. Other than
A cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1. The measurement results of the optical band gap of the obtained film showed a value close to 2.42 eV as shown in (Table 1), and it was found that this thin film was a good quality cadmium sulfide film.

[0053]

[Table 1]

[0054]

Example 3 Cadmium dibutyldithiocarbamate was used as the metal organic compound, the heating temperature of the thin film forming substrate was 440 ° C., and the distance between the two substrates was adjusted so that the temperature of the metal organic compound coated substrate was 270 ° C. Other than
A cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1. The measurement results of the optical band gap of the obtained film almost agreed with 2.42 eV as shown in (Table 1).
This thin film was found to be a good cadmium sulfide film.

[0055]

Example 4 Cadmium dibenzyldithiocarbamate was used as the metal-organic compound, the heating temperature of the substrate for forming a thin film was 440 ° C., and the distance between the two substrates was adjusted so that the temperature of the substrate coated with the metal-organic compound became 320 ° C. Except for the adjustment, a cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1. The measurement results of the optical band gap of the obtained film almost coincided with 2.42 eV as shown in (Table 1), and it was found that this thin film was a good quality cadmium sulfide film.

[0056]

Embodiment 5 Zinc diethyldithiocarbamate was used as the metal organic compound, the heating temperature of the substrate for forming the thin film was 500 ° C., and the temperature of the substrate coated with the metal organic compound was 305.
A zinc sulfide semiconductor thin film was formed in the same manner as in Example 1 except that the distance between the two substrates was adjusted so as to be ° C. The measurement results of the optical band gap of the obtained film were as shown in (Table 1), and the band gap standard value of zinc sulfide (3.5) was obtained.
eV), which indicates that this thin film is a good quality zinc sulfide film.

[0057]

Embodiment 6 Copper diethyldithiocarbamate was used as the metal organic compound, and the heating temperature of the thin film forming substrate was 3
80 ° C. and the temperature of the substrate coated with the metal organic compound is 310 ° C.
Example 1 except that the distance between both substrates was adjusted so that
In the same manner as described above, a copper sulfide semiconductor thin film was formed. The measurement results of the optical band gap of the obtained film are shown in (Table 1), and the standard value of the band gap of copper sulfide (1.2 e) was obtained.
V), and it was found that this thin film was a high-quality copper sulfide film.

[0058]

Embodiment 7 As the metal organic compound, lead diethyl dithiocarbamate was used, and the heating temperature of the substrate for forming a thin film was 5
50 ° C, and the temperature of the substrate coated with the metal organic compound is 330 ° C
Example 1 except that the distance between both substrates was adjusted so that
A lead sulfide semiconductor thin film was formed in the same manner as described above. The measurement results of the optical band gap of the obtained film are shown in Table 1, and the band gap standard value of lead sulfide (0.37e) was obtained.
V), which indicates that the thin film is a good quality lead sulfide film.

[0059]

Example 8 Mercury diethyldithiocarbamate was used as the metal organic compound, the heating temperature of the thin film forming substrate was set to 330 ° C., and the temperature of the metal organic compound coated substrate was set to 250 ° C.
A mercury sulfide semiconductor thin film was formed in the same manner as in Example 1 except that the distance between the two substrates was adjusted so as to be ° C. The measurement results of the optical band gap of the obtained film were as shown in Table 1 and the band gap standard value of mercury sulfide (1.9) was obtained.
eV), which indicates that this thin film is a good-quality mercury sulfide film.

[0060]

Example 9 Cadmium ethyl mercaptide, which is cadmium mercaptide, was used as a metal organic compound.
A cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1 except that the heating temperature of the thin film forming substrate was 440 ° C., and the distance between the two substrates was adjusted so that the temperature of the metal organic compound coated substrate was 360 ° C. . The measurement result of the optical band gap of the obtained film was 2.4 as shown in (Table 1).
The value almost coincided with 2 eV, indicating that this thin film was a good-quality cadmium sulfide film.

[0061]

Example 10 Cadmium ethyl thioate, which is cadmium thioate, was used as the metal organic compound, the heating temperature of the thin film forming substrate was set to 440 ° C., and the temperature of the metal organic compound coated substrate was set to 320 ° C. Adjust the spacing of
A cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1 except for performing the above. The measurement results of the optical band gap of the obtained film almost coincided with 2.42 eV as shown in (Table 1), and it was found that this thin film was a good quality cadmium sulfide film.

[0062]

EXAMPLE 11 Cadmium ethyldithioate, which is cadmium dithioate, was used as the metal organic compound, the heating temperature of the substrate for forming the thin film was 440 ° C., and the temperature of the substrate coated with the metal organic compound was 270 ° C. A cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1 except that the interval was adjusted. The measurement result of the optical band gap of the obtained film was 2.42 eV as shown in (Table 1).
, Indicating that this thin film was a good-quality cadmium sulfide film.

[0063]

Example 12 Ethyl thiocarbonate cadmium, which is thiocarbonate cadmium, was used as the metal organic compound, and the heating temperature of the substrate for forming a thin film was 440 ° C.
A cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1, except that the distance between the two substrates was adjusted so that the temperature of the metal-organic compound-coated substrate was 240 ° C. The measurement results of the optical band gap of the obtained film showed a value close to 2.42 eV as shown in (Table 1), and it was found that this thin film was a good quality cadmium sulfide film.

[0064]

Example 13 Ethyl dithiocarbonate cadmium, which is dithiocarbonate cadmium, was used as the metal organic compound, the heating temperature of the thin film forming substrate was set to 440 ° C., and the temperature of the metal organic compound coated substrate was set to 300 ° C. A cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1 except that the distance between the two substrates was adjusted. The measurement results of the optical band gap of the obtained film showed a value close to 2.42 eV as shown in (Table 1), and it was found that this thin film was a good quality cadmium sulfide film.

[0065]

Embodiment 14 Ethyl trithiocarbonate cadmium, which is trithiocarbonate cadmium, was used as the metal organic compound, and the heating temperature of the substrate for forming a thin film was 440.
° C, and a cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1 except that the distance between the two substrates was adjusted so that the temperature of the substrate coated with the metal organic compound became 320 ° C. The measurement results of the optical band gap of the obtained film showed a value close to 2.42 eV as shown in (Table 1), and it was found that this thin film was a good quality cadmium sulfide film.

[0066]

Example 15 Cadmium diethylthiocarbamate, which is cadmium thiocarbamate, was used as the metal organic compound, the heating temperature of the thin film forming substrate was 440 ° C., and the temperature of the metal organic compound coated substrate was 310 ° C. A cadmium sulfide semiconductor thin film was formed in the same manner as in Example 1 except that the distance between the two substrates was adjusted. The measurement results of the optical band gap of the obtained film showed a value close to 2.42 eV as shown in (Table 1), and it was found that this thin film was a good quality cadmium sulfide film.

[0067]

Embodiment 16 A substrate for forming a thin film heated to 440 ° C.
The same procedure as in Example 1 was carried out except that a metal-organic compound coated substrate heated or cooled at a predetermined temperature in the range of 50 ° C. to 630 ° C. was arranged in parallel at an interval of 1 mm and a film was formed for 5 seconds. To form a cadmium sulfide thin film. FIG. 7 shows the relationship between the resulting cadmium sulfide film formation rates. As can be seen from FIG. 7, 100
It was found that the film formation rate was high at ~ 600 ° C and the productivity was remarkably excellent.

[0068]

Embodiment 17 A copper plate (10 cm square) having a thickness of 1 mm was used as a substrate for forming a thin film.
A 0 μm molybdenum film is formed, a cadmium telluride film is formed on the molybdenum film by a vapor deposition method to a thickness of 5.0 μm, and a cadmium sulfide thin film is formed on the cadmium telluride film by the method of Example 1. A transparent conductive film mainly composed of indium oxide was formed, and then a silicon oxide thin film was formed for cell sealing, thereby producing a photoelectric conversion element having a cadmium sulfide / cadmium telluride structure. As a result, a photoelectric conversion element having an open-circuit voltage of 0.77 V and a short-circuit current density of 24.5 mA / cm ^{2 having a} conversion efficiency of 12.3% was obtained.

The substrate for forming the thin film is an iron plate,
It has been confirmed that an aluminum plate or a stainless plate can be similarly used.

[0070]

Embodiment 18 A soda lime moth was used as a thin film forming substrate.
A molybdenum film is deposited on glass using a lath plate by evaporation.
Formed on the molybdenum film using a quaternary vapor deposition method,
3.0 μm thick CuIn_xGa_1-xSe_Two(0 ≦ x ≦
1) Form a film. CuIn_xGa _1-xSe_Two(0 ≦ x ≦
1) A substrate with a film is used as a substrate for film formation, and thereafter the same as in Example 1
To form a cadmium sulfide film having a thickness of 50 nm. Sulfuric acid
Magnetron sputtering on cadmium fluoride film
Is used to form a 100 nm-thick zinc oxide film. Oxidation
Using RF magnetron sputtering method on zinc film
An indium oxide film having a thickness of 200 nm is formed. Morib
As a current collecting electrode on the den film and the indium oxide film,
Form a silver electrode. As a result, the open circuit voltage is 0.55 V,
Fault current density 39.5 mA / cm^Two, Conversion efficiency 11.6%
Was obtained.

[0071]

Example 19 A cadmium sulfide thin film was formed in the same manner as in Example 1 except that a 1 mm-thick polyimide substrate having an indium oxide film formed thereon as a transparent conductive film was used as a thin film forming substrate. After forming cadmium telluride, a carbon film was formed as a back electrode, and a photoelectric conversion element having a cadmium sulfide / cadmium telluride structure was manufactured. As a result, a photoelectric conversion element having an open-circuit voltage of 0.75 V, a short-circuit current density of 25.5 mA / cm ² , and a conversion efficiency of 12.2% was obtained.

When a resin film other than polyimide was used as a substrate for forming a thin film, it was necessary to lower the temperature of the substrate for forming a thin film, but a photoelectric conversion element could be formed in the same manner.

[0073]

Example 20 A cadmium sulfide thin film was formed in the same manner as in Example 1, except that the holding time of the metal organic compound coated substrate was changed to 10 to 405 seconds. As a result, the thickness of the obtained cadmium sulfide film was 20 to 710 nm.

FIG. 8 shows the results of analysis of the amount of carbon in the thin film using photoelectron spectroscopy. As can be seen from FIG. 8, it can be seen that when the film is formed to a thickness of 700 nm or more, the amount of carbon in the film is extremely increased.
It has been found that a film thickness of less than m is desirable.

The film leak test shown in FIG.
The leak current was measured. In FIG. 9, the transparent conductive film 24
An Ag electrode 26 having no ohmic contact with cadmium sulfide is formed on the cadmium sulfide film 25 formed on the glass substrate 23 provided with the above. The current value between the Ag electrodes 26 was measured by the probe 27, and the density of the cadmium sulfide film was evaluated by calculating the leak resistance between the Ag electrodes. FIG. 10 shows the results of the film leak test as resistance values with respect to the film thickness. As a result, the resistance was large when the cadmium sulfide film was 30 nm or more. From this, it was confirmed that when the cadmium sulfide film thickness was 30 nm or more, a good quality cadmium sulfide thin film without pinholes could be formed. Furthermore, it shows a constant large resistance value at 50 nm or more, and it has been confirmed that a higher quality cadmium sulfide thin film can be formed.

[0076]

Embodiment 21 The temperature of the substrate coated with the metal organic compound was 330 ° C.
A cadmium sulfide thin film was formed in the same manner as in Example 1 except that the substrate temperature for forming a thin film was 100 to 600 ° C. The formed cadmium sulfide film was evaluated in the same manner as in Example 20 by a film leak test shown in FIG. FIG.
FIG. 1 shows the results of the film leak test as resistance values with respect to the temperature of the substrate for forming a thin film. As a result, as can be seen from FIG. 11, the resistance value calculated from the current value showed a constant large resistance value when the temperature of the thin film forming substrate was 300 ° C. or higher when the cadmium sulfide thin film was manufactured. From this, it has been found that when a cadmium sulfide thin film is prepared, if the substrate temperature for forming the thin film is 300 ° C. or higher, the cadmium sulfide film can be formed with high density and high quality.

[0077]

Example 22 A cadmium sulfide thin film was formed in the same manner as in Example 1 except that the distance between the substrate coated with the metal organic compound and the substrate for forming the thin film was 0 to 50 mm. As a result, poor appearance was caused by contact between the substrates due to the size of the gap. FIG. 12 shows the yield rate of the obtained cadmium sulfide film by an appearance inspection. As can be seen from FIG. 12, defects can be reduced when the distance between the metal organic compound coated substrate and the thin film forming substrate is set to 0.2 mm or more in the production of the present film.

[0078]

Embodiment 23 A soda-lime glass having a thickness of 1.1 mm on which an indium oxide film (ITO film) having a thickness of 200 nm is formed as a substrate for forming a thin film is previously heated to 450 ° C. in the atmosphere.

100 g of cadmium dimethyldithiocarbamate, which is an organometallic compound, is placed in a sealable metal container having an inlet and an outlet having an inner volume of 0.5 liter,
Heat at 350 ° C. By introducing nitrogen gas heated to 350 ° C. from the inflow port into the metal container at a flow rate of 1 liter / minute, the generated cadmium dimethyldithiocarbamate vapor was discharged from the outlet port onto the thin film forming substrate using a pipe heated to 350 ° C. And sprayed on the substrate for thin film formation. By spraying for 100 seconds, a uniform cadmium sulfide thin film was obtained. The band gap of the obtained film showed a value close to 2.42 eV, and it was found that this film was a cadmium sulfide film.

In this example, cadmium diethyldithiocarbamate, cadmium dimethyldithiocarbamate, etc. were used as the metal organic compound. However, other metal mercaptides, metal thioates, metal dithioates, metal thiolates, etc. Carbonate salts, metal dithiocarbonate salts,
It is also possible to use metal trithiocarbonate, metal thiocarbamate or metal dithiocarbamate.

In Example 23, cadmium dimethyldithiocarbamate was used as the metal organic compound, but other metal dithiocarbamates or metal mercaptides, metal thioates, metal dithioates, metal thiocarbonates It is also possible to use a salt, a metal dithiocarbonate, a metal trithiocarbonate or a metal thiocarbamate.

In this example, CuIn _x Ga _{1 -x} Se ₂ was used as the I-III-VI _2- type chalcopyrite.
It is also possible to use CuIn _x Ga _1-x S ₂ .

Although a solar cell is used as a photoelectric conversion element in this embodiment, it can be used as a sensor or the like.

[0084]

As described above, according to the present invention, a high quality metal sulfide thin film can be formed very easily.

Further, by implementing the present invention, a thin film can be formed at a relatively low heating temperature.
It is possible to use a low-cost substrate for forming a thin film such as a resin film, and thereby it is possible to significantly reduce the cost of the photoelectric conversion element and expand the degree of freedom in design.

Further, since a large-area film can be formed in a short time in the atmosphere, it is extremely effective as a means for high-speed and mass production. At the same time, effects such as the ability to form a thin film of uniform film quality without voids in the film are obtained.

Further, by applying the technology for forming a compound semiconductor thin film according to the present invention to the production of a thin film photoelectric conversion device having a cadmium sulfide / cadmium telluride structure, the conversion efficiency can be greatly improved, and at the same time, environmental pollution is reduced. The amount of cadmium used as a heavy metal, which has become a topic of concern, can also be significantly reduced as compared with cadmium sulfide / cadmium telluride photoelectric conversion elements manufactured by a conventional coating / sintering method.

[Brief description of the drawings]

FIG. 1 is a diagram showing a film forming method according to an embodiment of the present invention.

FIG. 2 is a view showing a film forming method according to another embodiment of the present invention.

FIG. 3 is a structural diagram of a cadmium sulfide / cadmium telluride thin-film photoelectric conversion element manufactured by using the film forming method of the present invention.

FIG. 4 is a voltage-current characteristic diagram of a cadmium sulfide / cadmium telluride thin-film photoelectric conversion device manufactured by using the film forming method of the present invention.

FIG. 5 is a structural diagram of a cadmium sulfide / cadmium telluride photoelectric conversion element manufactured by a conventional coating / sintering method.

FIG. 6 is a voltage-current characteristic diagram of a cadmium sulfide / cadmium telluride photoelectric conversion element manufactured by a conventional coating / sintering method.

FIG. 7 is a diagram showing the relationship between the heating temperature of the metal organic compound coated substrate and the deposition rate of the cadmium sulfide film.

FIG. 8 is a diagram showing the relationship between cadmium sulfide film thickness and carbon content in the film.

FIG. 9 is a schematic diagram of a film leak test.

FIG. 10 is a relationship diagram between a film thickness and a resistance value obtained by a leak test.

FIG. 11 is a diagram showing a relationship between a substrate temperature for forming a thin film and a resistance value obtained by a leak test.

FIG. 12 is a graph showing the relationship between the interval between the metal organic compound coated substrate and the thin film forming substrate and the yield rate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Metal-organic compound coated substrate 2 Metal-organic compound 3 Thin film forming substrate 4 Transparent conductive film 5 Spacer 6 Heater 7 Inflow port 8 Outlet 9 Metal container 10 Heater 11 Glass substrate 12 Cadmium sulfide 13 Cadmium telluride 14 Carbon electrode 15 AgIn electrode Reference Signs List 16 glass substrate 17 indium oxide film 18 cadmium sulfide 19 cadmium telluride 20 carbon electrode 21 AgIn electrode 22 glass substrate 23 glass substrate 24 transparent conductive film 25 cadmium sulfide film 26 Ag electrode 27 probe

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Mikio Murosono 1-1 Matsushita-cho, Moriguchi-shi, Osaka Matsushita Battery Industry Co., Ltd.

Claims (17)

[Claims] 1. A metal-organic compound containing at least one metal and sulfur is heated, and the sublimated, vaporized or evaporated metal-organic compound is adhered to a substrate for forming a thin film by this heating, and the adhered metal-organic compound is adhered. A method for forming a compound semiconductor thin film, characterized in that a metal sulfide thin film is obtained by performing thermal decomposition simultaneously or after adhesion. 2. A thin film forming substrate is disposed at a predetermined interval on a substrate coated with a metal organic compound containing at least one metal and sulfur, and the coated substrate is heated to a predetermined temperature, and sublimated by heating. A metal sulfide thin film of a metal is obtained by depositing the vaporized or evaporated metal organic compound on a thin film forming substrate heated to a predetermined temperature and simultaneously decomposing the deposited metal organic compound simultaneously or after the deposition. Characterized method of forming compound semiconductor thin film. 3. The method for forming a compound semiconductor thin film according to claim 2, wherein a metal organic compound containing cadmium, zinc, copper, lead or mercury is used. 4. The metal organic compound is a metal mercaptide, a metal thioate, a metal dithioate, a metal thiocarbonate, a metal dithiocarbonate, a metal trithiocarbonate, or a metal thiocarbamine. 3. The method for forming a compound semiconductor thin film according to claim 2, wherein the compound semiconductor is a dithiocarbamate or a metal dithiocarbamate. 5. The method according to claim 2, wherein the heating temperature of the substrate coated with the metal organic compound is 100 ° C. or more and 600 ° C. or less. 6. The method for forming a compound semiconductor thin film according to claim 2, wherein the thin film forming substrate is a glass plate, a metal plate or a resin film. 7. The method for forming a compound semiconductor thin film according to claim 2, wherein the substrate temperature for forming the thin film is 300 ° C. or higher. 8. The method for forming a compound semiconductor thin film according to claim 2, wherein a distance between the substrate coated with the metal organic compound and the substrate for forming the thin film is 0.2 mm or more. 9. The method according to claim 2, wherein the thickness of the metal sulfide thin film is 700 nm or less. 10. A metal-organic compound containing at least one metal and sulfur is heated, and the sublimated, vaporized or evaporated metal-organic compound is conveyed to the surface of the substrate for thin film formation and adhered to the substrate for thin film formation by heating. A method for forming a compound semiconductor thin film, wherein a metal sulfide thin film is obtained by thermally decomposing the attached metal organic compound simultaneously with or after the attachment. 11. The metal contained is cadmium, zinc, copper,
The method for forming a compound semiconductor thin film according to claim 10, wherein a metal organic compound which is lead or mercury is used. 12. The metal organic compound is a metal mercaptide, a metal thioate, a metal dithioate, a metal thiocarbonate, a metal dithiocarbonate, a metal trithiocarbonate, or a metal thiocarbamine. 11. The method for forming a compound semiconductor thin film according to claim 10, wherein the compound semiconductor is a metal salt or a metal dithiocarbamate. 13. The method according to claim 10, wherein the heating temperature of the substrate coated with the metal organic compound is 100 ° C. or more and 600 ° C. or less. 14. The method for forming a compound semiconductor thin film according to claim 10, wherein the substrate temperature for forming the thin film is 300 ° C. or higher. 15. A photoelectric conversion element, wherein a compound semiconductor thin film formed by the method for forming a compound semiconductor thin film according to claim 1, 2 or 3 is used as a window layer. 16. The photoelectric conversion device according to claim 15, wherein the light absorption layer of the photoelectric conversion device is made of a cadmium telluride film. 17. The light-absorbing layer of the photoelectric conversion element may be made of I-III-VI ₂
2. The method according to claim 1, wherein the chalcopyrite is formed.
6. The photoelectric conversion element according to 5.