JPWO2011068197A1 - Photoelectric conversion device and method of manufacturing photoelectric conversion device - Google Patents

Abstract

This photoelectric conversion device includes a substrate (1), a transparent conductive film (2) formed on the substrate (1), a first p-type semiconductor layer (31), and a first i comprising an amorphous silicon thin film. A first semiconductor layer (32), a first n-type semiconductor layer (33) made of a crystalline silicon-based thin film, and an n-type semiconductor made of an amorphous silicon-based thin film, the first i-type semiconductor layer (32) A first photoelectric conversion unit (3) including a buffer layer (35) disposed between the first n-type semiconductor layer (33) and formed on the transparent conductive film (2); A second photoelectric conversion unit (4) formed on the photoelectric conversion unit (3).

Description

The present invention relates to a photoelectric conversion device using a thin film and a method for manufacturing the photoelectric conversion device.
This application claims priority based on Japanese Patent Application No. 2009-276320 for which it applied on December 4, 2009, and uses the content here.

In recent years, photoelectric conversion devices are generally used for solar cells, optical sensors, and the like, and in particular, solar cells have begun to spread widely from the viewpoint of efficient use of energy.
In particular, a photoelectric conversion device using single crystal silicon is excellent in energy conversion efficiency per unit area.
However, on the other hand, since a photoelectric conversion device using single crystal silicon uses a silicon wafer obtained by slicing a single crystal silicon ingot, a large amount of energy is consumed for manufacturing the ingot and the manufacturing cost is high.
For example, if a large-area photoelectric conversion device installed outdoors or the like is manufactured using single crystal silicon, it is considerably expensive at present.
Therefore, a photoelectric conversion device using an amorphous (amorphous) silicon thin film (hereinafter also referred to as an “a-Si thin film”) that can be manufactured at a lower cost is widely used as a low-cost photoelectric conversion device.

However, a photoelectric conversion device using this amorphous (amorphous) silicon thin film has a lower conversion efficiency than a crystalline photoelectric conversion device using single crystal silicon or polycrystalline silicon.
Therefore, as a structure for improving the conversion efficiency of the photoelectric conversion device, a tandem structure in which two photoelectric conversion units are stacked has been proposed.
For example, a tandem photoelectric conversion device 200 as shown in FIG. 11 is known (see, for example, Patent Document 1).
In this photoelectric conversion device 200, an insulating transparent substrate 201 on which a transparent conductive film 202 is disposed is used. A p-type semiconductor layer 231 (p layer), an i-type silicon layer 232 (amorphous silicon layer, i layer), and an n-type semiconductor layer 233 (n layer) are sequentially stacked on the transparent conductive film 202. A pin-type first photoelectric conversion unit 203 is formed. A p-type semiconductor layer 241 (p layer), an i-type silicon layer 242 (crystalline silicon layer, i layer), and an n-type semiconductor layer 243 (n layer) are sequentially stacked on the first photoelectric conversion unit 203. The obtained pin-type second photoelectric conversion unit 204 is formed. Further, a back electrode 205 is formed on the second photoelectric conversion unit 204.

FIG. 12 shows the relationship between the wavelength and the power generation efficiency in the photoelectric conversion device having such a conventional tandem structure. In FIG. 12, the relationship between the wavelength and the power generation efficiency of each of the pin-type first photoelectric conversion unit made of an amorphous silicon-based thin film and the pin-type second photoelectric conversion unit made of a crystalline silicon-based thin film. It is shown.
FIG. 13 shows the relationship between current density and voltage for the first photoelectric conversion unit and the second photoelectric conversion unit.
As shown in FIG. 12, the pin-type second photoelectric conversion unit made of a crystalline silicon thin film has low power generation efficiency in the long wavelength region. For this reason, it was difficult to improve the photoelectric conversion efficiency in the whole photoelectric conversion apparatus including the first photoelectric conversion unit and the second photoelectric conversion unit.
Further, as shown in FIG. 13, a photoelectric conversion device constituted by a single pin-type first photoelectric conversion unit made of an amorphous silicon-based thin film, and a pin-type first made of a crystalline silicon-based thin film. In a photoelectric conversion device constituted by a single photoelectric conversion unit, the battery characteristics are deteriorated in a photoelectric conversion device having a tandem structure in which both are stacked despite having good characteristics. There was a problem.

  In order to solve such a problem, in the pin type first photoelectric conversion unit made of an amorphous silicon thin film, the battery characteristics could be improved by forming the n layer with a crystalline silicon thin film. However, the performance inherent to the pin-type first photoelectric conversion unit made of an amorphous silicon-based thin film cannot be sufficiently obtained.

Japanese Patent No. 3589581

The present invention has been made in consideration of such circumstances, and has improved the power generation efficiency in the pin-type first photoelectric conversion unit made of an amorphous silicon thin film, and improved the photoelectric conversion efficiency. It is a first object to provide a photoelectric conversion device having the following.
A second object of the present invention is to provide a method for manufacturing a photoelectric conversion device capable of manufacturing a photoelectric conversion device having a tandem structure with improved photoelectric conversion efficiency by a simple method.
The present invention also provides a photoelectric conversion device that improves power generation efficiency and improves photoelectric conversion efficiency in a photoelectric conversion device having a single structure including a pin-type photoelectric conversion unit made of an amorphous silicon thin film. The third purpose is to do.
Moreover, this invention makes it the 4th objective to provide the manufacturing method of the photoelectric conversion apparatus which can manufacture the photoelectric conversion apparatus which has the single structure which improved the photoelectric conversion efficiency by a simple method.

  The photoelectric conversion device according to the first aspect of the present invention includes a substrate, a transparent conductive film formed on the substrate, a first p-type semiconductor layer, a first i-type semiconductor layer comprising an amorphous silicon-based thin film, a crystalline material A first n-type semiconductor layer comprising a silicon-based thin film, and an n-type semiconductor comprising an amorphous silicon-based thin film, the buffer being disposed between the first i-type semiconductor layer and the first n-type semiconductor layer A first photoelectric conversion unit formed on the transparent conductive film and a second photoelectric conversion unit formed on the first photoelectric conversion unit.

  In the photoelectric conversion device according to the first aspect of the present invention, the second photoelectric conversion unit includes a second p-type semiconductor layer and a second i-type semiconductor layer, and the second p-type semiconductor layer and the second i-type semiconductor layer. The semiconductor layer is preferably made of a crystalline silicon-based thin film.

  In the photoelectric conversion device of the first aspect of the present invention, the buffer layer preferably has a thickness in the range of 20 to 200 mm.

  In the photoelectric conversion device according to the first aspect of the present invention, the intensity of Raman scattered light attributed to the amorphous phase dispersed in the buffer layer observed with a laser Raman microscope is defined as Ia, and is dispersed in the buffer layer. When the intensity of Raman scattered light resulting from the microcrystalline phase is defined as Ic, it is preferable that Ic / Ia is less than 1.0.

  According to a second aspect of the present invention, there is provided a method for manufacturing a photoelectric conversion device, comprising: preparing a substrate on which a transparent conductive film is formed; and forming a first p-type semiconductor layer constituting the first photoelectric conversion unit and an amorphous layer on the transparent conductive film. A first i-type semiconductor layer made of a silicon-based thin film, and a buffer layer made of an amorphous silicon-based thin film formed on the first i-type semiconductor layer. And forming a first n-type semiconductor layer comprising the crystalline silicon-based thin film and constituting the first photoelectric conversion unit, and forming a second photoelectric conversion unit on the first n-type semiconductor layer. A type semiconductor layer, a second i-type semiconductor layer, and a second n-type semiconductor layer are sequentially formed.

  In the method for manufacturing a photoelectric conversion device according to the second aspect of the present invention, the second p-type semiconductor layer and the second i-type semiconductor layer are preferably made of a crystalline silicon-based thin film.

  The photoelectric conversion device according to the third aspect of the present invention includes a substrate, a transparent conductive film formed on the substrate, a third p-type semiconductor layer composed of an amorphous silicon-based thin film, and a third composed of an amorphous silicon-based thin film. an i-type semiconductor layer, a third n-type semiconductor layer made of a crystalline silicon-based thin film, and an n-type semiconductor made of an amorphous silicon-based thin film, wherein the third i-type semiconductor layer and the third n-type semiconductor layer are And a third photoelectric conversion unit formed on the transparent conductive film.

  In the photoelectric conversion device according to the third aspect of the present invention, the thickness of the buffer layer is preferably in the range of 20 to 200 mm.

  In the photoelectric conversion device according to the third aspect of the present invention, the intensity of the Raman scattered light attributed to the amorphous phase dispersed in the buffer layer, which is observed with a laser Raman microscope, is defined as Ia, and is dispersed in the buffer layer. When the intensity of Raman scattered light resulting from the microcrystalline phase is defined as Ic, Ic / Ia is preferably less than 1.0.

  The manufacturing method of the photoelectric conversion apparatus of the 4th aspect of this invention prepares the board | substrate with which the transparent conductive film was formed, and consists of an amorphous silicon-type thin film which comprises a 3rd photoelectric conversion unit on the said transparent conductive film. A third p-type semiconductor layer and a third i-type semiconductor layer made of an amorphous silicon-based thin film are sequentially formed, and a buffer layer that is an n-type semiconductor made of an amorphous silicon-based thin film is formed on the third i-type semiconductor layer. And a third n-type semiconductor layer made of a crystalline silicon-based thin film and constituting the third photoelectric conversion unit is formed on the buffer layer.

In the photoelectric conversion device according to the first aspect of the present invention (hereinafter also referred to as “first photoelectric conversion device”), in the first photoelectric conversion unit, an i layer (first i-type semiconductor layer) made of an amorphous silicon-based thin film. And a buffer layer, which is an n layer (n-type semiconductor) made of an amorphous silicon-based thin film, is disposed between the n-layer (first n-type semiconductor layer) made of a crystalline silicon-based thin film. According to this configuration, mismatch at the interface between the i layer made of an amorphous silicon thin film and the n layer made of a crystalline silicon thin film can be alleviated.
Thereby, the function of the n layer made of the crystalline silicon-based thin film can be effectively utilized in the first photoelectric conversion unit. The n-layer and the second photoelectric conversion unit constitute the crystalline silicon-based thin film. Lattice matching at the interface with the p layer (second p-type semiconductor layer) made of can be obtained. Furthermore, the open circuit voltage (Voc) in the first photoelectric conversion unit can be improved, the power generation efficiency of the first photoelectric conversion unit is improved, and the entire photoelectric conversion device including the first photoelectric conversion unit and the second photoelectric conversion unit The photoelectric conversion efficiency of can be improved.
As a result, according to the present invention, it is possible to provide a photoelectric conversion device having a tandem structure with improved photoelectric conversion efficiency.
Moreover, the manufacturing method of the photoelectric conversion device according to the second aspect of the present invention (hereinafter also referred to as “the manufacturing method of the first photoelectric conversion device”) is a p layer (first p-type semiconductor layer) constituting the first photoelectric conversion unit. And forming an i layer (first i-type semiconductor layer) in sequence, forming the buffer layer on the i layer of the first photoelectric conversion unit, and configuring the first photoelectric conversion unit on the buffer layer A step of forming an n layer (first n-type semiconductor layer), a step of sequentially forming a p layer, an i layer, and an n layer constituting the second photoelectric conversion unit on the n layer of the first photoelectric conversion unit , At least in order. For this reason, the obtained photoelectric conversion device can improve the open circuit voltage (Voc) in the first photoelectric conversion unit, improve the power generation efficiency of the first photoelectric conversion unit, and the first photoelectric conversion unit and the second photoelectric conversion unit. The photoelectric conversion efficiency as the whole photoelectric conversion apparatus including the unit can be improved.
As a result, according to the present invention, it is possible to provide a method for manufacturing a photoelectric conversion device that can easily manufacture a photoelectric conversion device having a tandem structure with improved photoelectric conversion efficiency.

In the photoelectric conversion device according to the third aspect of the present invention (hereinafter also referred to as “second photoelectric conversion device”), the p layer (third p-type semiconductor layer) and the i layer (first layer) constituting the third photoelectric conversion unit. The third i-type semiconductor layer) is made of an amorphous silicon thin film, the n layer (third n-type semiconductor layer) constituting the third photoelectric conversion unit is made of a crystalline silicon thin film, and the i layer and the n layer A buffer layer that is an n layer (n-type semiconductor) made of an amorphous silicon-based thin film is disposed between the two. According to this configuration, mismatch at the interface between the i layer made of an amorphous silicon thin film and the n layer made of a crystalline silicon thin film can be alleviated.
Thereby, the function of the n layer made of a crystalline silicon-based thin film can be effectively utilized, and the open circuit voltage (Voc) can be improved.
As a result, according to the present invention, it is possible to provide a photoelectric conversion device having a single structure with improved photoelectric conversion efficiency.
In addition, the method for manufacturing a photoelectric conversion device according to the fourth aspect of the present invention (hereinafter also referred to as “method for manufacturing a second photoelectric conversion device”) is a p layer (third p-type semiconductor layer) constituting the third photoelectric conversion unit. And i layer (third i-type semiconductor layer) in order, forming the buffer layer on the i layer constituting the third photoelectric conversion unit, and third photoelectric conversion on the buffer layer Forming n layers (third n-type semiconductor layers) constituting the unit at least in order. For this reason, the obtained photoelectric conversion device can improve the open circuit voltage (Voc).
As a result, according to the present invention, it is possible to provide a method for manufacturing a photoelectric conversion device that can easily manufacture a photoelectric conversion device having a single structure with improved photoelectric conversion efficiency.

It is sectional drawing which shows the layer structure of the photoelectric conversion apparatus (1st photoelectric conversion apparatus) of 1st embodiment of this invention. It is a figure explaining the manufacturing method of the photoelectric conversion apparatus shown in FIG. It is a figure explaining the manufacturing method of the photoelectric conversion apparatus shown in FIG. It is a figure explaining the manufacturing method of the photoelectric conversion apparatus shown in FIG. It is the schematic which shows the manufacturing system which manufactures the photoelectric conversion apparatus of 1st embodiment of this invention. It is sectional drawing which shows the layer structure of the photoelectric conversion apparatus (2nd photoelectric conversion apparatus) of 2nd embodiment of this invention. It is a figure which shows a discharge curve about the photoelectric conversion apparatus produced in Example 1 and Comparative Example 1. FIG. It is a figure which shows the relationship between a wavelength and electric power generation efficiency about the photoelectric conversion apparatus produced in Example 1 and Comparative Example 1. FIG. It is a figure which shows the relationship between the thickness of a buffer layer, and photoelectric conversion efficiency (eta) about the photoelectric conversion apparatus produced in Examples 2-4 and Comparative Example 1. FIG. It is a figure which shows the relationship between the thickness of a buffer layer, and the fill factor FF about the photoelectric conversion apparatus produced in Examples 2-4 and the comparative example 1. FIG. It is a figure which shows the relationship between the thickness of a buffer layer, and the short circuit current Jsc about the photoelectric conversion apparatus produced in Examples 2-4 and the comparative example 1. FIG. It is a figure which shows the relationship between the thickness of a buffer layer, and the open circuit voltage Voc about the photoelectric conversion apparatus produced in Examples 2-4 and the comparative example 1. FIG. It is sectional drawing which shows an example of the conventional photoelectric conversion apparatus. It is a figure which shows the relationship between a wavelength and power generation efficiency in the conventional photoelectric conversion apparatus. It is a figure which shows the relationship between a current density and a voltage in the conventional photoelectric conversion apparatus.

Hereinafter, embodiments of a photoelectric conversion device and a method for manufacturing the photoelectric conversion device according to the present invention will be described with reference to the drawings.
In the drawings used for the following description, the scale of each member is appropriately changed in order to make each member a recognizable size.

<First embodiment>
In the first embodiment, a photoelectric conversion device having a tandem structure in which a first photoelectric conversion unit that is an amorphous silicon photoelectric conversion device and a second photoelectric conversion unit that is a microcrystalline silicon photoelectric conversion device are stacked. Is described based on the drawings.
FIG. 1 is a structural cross-sectional view showing the layer structure of the photoelectric conversion device according to the first embodiment of the present invention.
In the photoelectric conversion device 10A (10) of the first embodiment, a substrate 1 on which a transparent conductive film is formed is used, and the transparent conductive film 2 is formed on the first surface 1a of the substrate 1. . On the transparent conductive film 2, the 1st photoelectric conversion unit 3 and the 2nd photoelectric conversion unit 4 are piled up in order. The first photoelectric conversion unit 3 and the second photoelectric conversion unit 4 have a pin-type semiconductor stacked structure in which a p-type semiconductor layer, a substantially intrinsic i-type semiconductor layer, and an n-type semiconductor layer are stacked. A back electrode 5 is formed on the second photoelectric conversion unit 4.

The board | substrate 1 is an insulating board | substrate which has a light transmittance, for example, consists of insulating materials which are excellent in the transmittance | permeability of sunlight, such as glass or transparent resin, and have durability. The substrate 1 includes a transparent conductive film 2. As the material of the transparent conductive film 2, for example, a light-transmitting metal oxide such as ITO (indium tin oxide), SnO ₂ , ZnO or the like is employed. The transparent conductive film 2 is formed on the substrate 1 by vacuum evaporation or sputtering. In this photoelectric conversion device 10 </ b> A (10), sunlight S is incident on the second surface 1 b of the substrate 1 as indicated by the white arrow in FIG. 1.

The first photoelectric conversion unit 3 includes a p-type semiconductor layer 31 (p layer, first p-type semiconductor layer), a substantially intrinsic i-type semiconductor layer 32 (i layer, first i-type semiconductor layer), and It has a pin structure in which an n-type semiconductor layer 33 (n layer, first n-type semiconductor layer) is stacked.
That is, the first photoelectric conversion unit 3 is formed by stacking the p layer 31, the i layer 32, and the n layer 33 in this order.
The first photoelectric conversion unit 3 is made of, for example, an amorphous (amorphous) silicon-based material. The p layer 31 and the i layer 32 constituting the first photoelectric conversion unit 3 are made of an amorphous silicon thin film, and the n layer 33 is made of a crystalline silicon thin film.
In the first photoelectric conversion unit 3, the thickness of the p layer 31 is, for example, 80 mm, the thickness of the i layer 32 is, for example, 1800 mm, and the thickness of the n layer 33 is, for example, 100 mm.
The p layer 31, i layer 32, and n layer 33 of the first photoelectric conversion unit 3 are formed in a plurality of plasma CVD reaction chambers. That is, in each of a plurality of plasma CVD reaction chambers different from each other, one layer constituting the first photoelectric conversion unit 3 is formed.

The second photoelectric conversion unit 4 includes a p-type semiconductor layer 41 (p layer, second p-type semiconductor layer), a substantially intrinsic i-type semiconductor layer 42 (i layer, second i-type semiconductor layer), and an n-type. It has a pin structure in which semiconductor layers 43 (n layers and second n-type semiconductor layers) are stacked.
That is, the second photoelectric conversion unit 4 is formed by stacking the p layer 41, the i layer 42, and the n layer 43 in this order.
The second photoelectric conversion unit 4 is made of a silicon-based material containing a crystalline material.
In the second photoelectric conversion unit 4, the thickness of the p layer 41 is, for example, 150 mm, the thickness of the i layer 42 is, for example, 15000 mm, and the thickness of the n layer 43 is, for example, 300 mm.
Here, the silicon containing crystal is a material containing so-called microcrystalline silicon, silicon in which microcrystals are dispersed in amorphous, and so-called microcrystalline silicon.
The n layer 43 of the second photoelectric conversion unit 4 can also include an amorphous silicon layer.
In the second photoelectric conversion unit 4, if the i layer 42, which is a substantially intrinsic i-type semiconductor layer, includes a silicon-based material including a crystalline material, the configuration of the other layers is a silicon-based material including a crystalline material. It is not limited.

In particular, in the photoelectric conversion device 10 </ b> A (10) of the first embodiment, in the first photoelectric conversion unit 3, an n layer made of an amorphous silicon thin film is interposed between the i layer 32 and the n layer 33 in the buffer layer 35. Is arranged as.
In the photoelectric conversion device 10 </ b> A (10) of the first embodiment, in the first photoelectric conversion unit 3, an amorphous layer is formed between the i layer 32 made of an amorphous silicon thin film and the n layer 33 made of a crystalline silicon thin film. Since the buffer layer 35, which is an n layer made of a silicon-based thin film, is disposed, mismatch at the interface between the i layer 32 made of an amorphous silicon-based thin film and the n layer 33 made of a crystalline silicon-based thin film is prevented. Can be relaxed.
Thereby, the function of the n layer 33 made of a crystalline silicon-based thin film can be effectively utilized in the first photoelectric conversion unit 3, and this n layer and the second photoelectric conversion unit 4 constitute the crystalline silicon. It is possible to obtain lattice matching at the interface with the p-layer 41 made of a system thin film. Furthermore, the open circuit voltage (Voc) in the first photoelectric conversion unit 3 can be improved.
Thus, in the photoelectric conversion device 10A (10) of the first embodiment, Voc can be improved by inserting the buffer layer 35 between the i layer 32 and the n layer 33, and the first photoelectric conversion is performed. The power generation efficiency of the unit 34 can be improved.
As a result, it is possible to improve the photoelectric conversion efficiency of the entire photoelectric conversion device including the first photoelectric conversion unit and the second photoelectric conversion unit.

The thickness of the buffer layer 35 is preferably in the range of 20 to 200 mm, for example, and can be 50 mm, for example.
It has been confirmed that when the thickness of the buffer layer 35 is in the range of 20 to 50 mm, the fill factor (FF) and the open circuit voltage (Voc) increase, and the photoelectric conversion efficiency increases.
When the thickness of the buffer layer 35 is 200 mm or more, Jsc and Voc are lowered. This is presumably because the buffer layer 35 absorbed light and the Jsc of the second photoelectric conversion unit 4 made of a crystalline silicon thin film was lowered.

Next, the intensity of Raman scattered light observed with a laser Raman microscope will be described. When the intensity of Raman scattered light attributed to the amorphous phase dispersed in the buffer layer 35 is defined as Ia, and the intensity of Raman scattered light attributed to the microcrystalline phase dispersed in the buffer layer 35 is defined as Ic, The crystallization rate in the buffer layer 35 constituting the conversion device 10A (10) is less than 1.0. The crystallization rate means a value obtained by dividing Ic by Ia (hereinafter referred to as (Ic / Ia)).
The crystallization rate of the buffer layer 35 can be controlled independently of the crystallization rate (Ic / Ia) of the i layer 32.
That is, by adopting such a layer structure, it becomes possible to improve the photoelectric conversion efficiency of the photoelectric conversion device 10 of the first embodiment.
The layer structure of the first embodiment of the present invention improves the open circuit voltage (Voc) and fill factor (FF), and can improve the photoelectric conversion efficiency by about 0.6% in the microcrystalline tandem thin film solar cell. It is.

The back electrode 5 is made of, for example, a conductive light reflecting film such as Ag (silver) or Al (aluminum). The back electrode 5 is formed, for example, by sputtering or vapor deposition. Moreover, as a structure of the back surface electrode 5, a laminated structure in which a layer made of a conductive oxide such as ITO, SnO ₂ , or ZnO is formed between the n layer 43 of the second photoelectric conversion unit 4 and the back surface electrode 5 is used. It can also be used.

Next, a manufacturing method for manufacturing the photoelectric conversion device 10A (10) having the above configuration will be described.
The photoelectric conversion device manufacturing method of the first embodiment includes a step of sequentially forming a p layer 31 and an i layer 32 of the first photoelectric conversion unit 3, and an n layer (on the i layer 32 of the first photoelectric conversion unit 3). Forming the buffer layer 35), forming the n layer 33 of the first photoelectric conversion unit 3 on the buffer layer 35, and forming the second photoelectric conversion unit 4 on the n layer 33 of the first photoelectric conversion unit 3. Forming at least a p layer 41, an i layer 42, and an n layer 43 in order.

Therefore, according to the method for manufacturing the photoelectric conversion device of the first embodiment, the step of sequentially forming the p layer 31 and the i layer 32 made of an amorphous silicon thin film, and the amorphous silicon thin film on the i layer 32. a step of forming an n layer (buffer layer 35), a step of forming an n layer 33 made of a crystalline silicon thin film on the buffer layer 35, and the second photoelectric conversion on the n layer of the first photoelectric conversion unit 3. Since the step of forming the p layer 41, the i layer 42, and the n layer 43 made of a crystalline silicon-based thin film constituting the unit 4 at least in order is provided, the obtained photoelectric conversion device 10 includes the first photoelectric The open circuit voltage (Voc) in the conversion unit 3 can be improved, the power generation efficiency of the first photoelectric conversion unit 3 is improved, and the first photoelectric conversion unit and the second light are improved. It is possible to improve the photoelectric conversion efficiency of the entire photoelectric conversion device including a conversion unit.
As a result, according to the manufacturing method of the first embodiment, the photoelectric conversion device 10 with improved photoelectric conversion efficiency can be easily manufactured.
Hereinafter, a method for manufacturing a photoelectric conversion device having a tandem structure will be described in the order of steps.

First, as shown in FIG. 2A, an insulating transparent substrate 1 on which a transparent conductive film 2 is formed is prepared.
Next, as shown in FIG. 2B, the p layer 31, i layer 32, n-type semiconductor layer (buffer layer 35), n layer 33, and second photoelectric conversion of the first photoelectric conversion unit 3 are formed on the transparent conductive film 2. The p layer 41 of the unit 4 is formed.
Here, a plurality of plasma CVD reaction chambers in which the p layer 31, the i layer 32, the buffer layer 35, the n layer 33, and the p layer 41 are formed are different from each other. Further, in one plasma CVD reaction chamber, one layer of p layer 31, i layer 32, buffer layer 35, n layer 33, and p layer 41 is formed, and a plurality of plasma CVD reaction chambers connected in a row are used. A p layer 31, an i layer 32, a buffer layer 35, an n layer 33, and a p layer 41 are sequentially formed.
That is, the photoelectric conversion device first intermediate product 10a in which the p layer 41 constituting the second photoelectric conversion unit 4 is provided on the n layer 33 of the first photoelectric conversion unit 3 is obtained.

The p layer 31 (amorphous silicon layer) is formed using a plasma CVD method in a separate reaction chamber. For example, a p-layer made of amorphous silicon (a-Si), a substrate temperature of 180 to 200 ° C., a power supply frequency of 13.56 MHz, a reaction chamber pressure of 70 to 120 Pa, a reaction gas flow rate of monosilane (SiH ₄ ) of 300 sccm, A film can be formed under conditions where hydrogen (H ₂ ) is 2300 sccm, diborane (B ₂ H ₆ / H ₂ ) using hydrogen as a diluent gas is 180 sccm, and methane (CH ₄ ) is 500 sccm.
The i layer 32 (amorphous silicon layer) is formed using a plasma CVD method in a separate reaction chamber. For example, an i layer made of amorphous silicon (a-Si) has a substrate temperature of 180 to 200 ° C., a power supply frequency of 13.56 MHz, a reaction chamber pressure of 70 to 120 Pa, and a reaction gas flow rate of monosilane (SiH ₄ ) of 1200 sccm. The film can be formed under certain conditions.

The buffer layer 35 (amorphous silicon layer) is formed using a plasma CVD method in a separate reaction chamber. For example, an n layer made of amorphous silicon (a-Si) is used in which the substrate temperature is 180 to 200 ° C., the power supply frequency is 13.56 MHz, the reaction chamber pressure is 70 to 120 Pa, the reaction gas flow rate is hydrogen as a diluent gas. The film can be formed under the condition that the phosphine (PH ₃ / H ₂ ) is 200 sccm.

The n layer 33 (crystalline silicon layer) is formed using a plasma CVD method in a separate reaction chamber. For example, an n-layer of microcrystalline silicon (μc-Si), a substrate temperature of 180 to 200 ° C., a power supply frequency of 13.56 MHz, a reaction chamber pressure of 500 to 900 Pa, a reaction gas flow rate of monosilane (SiH ₄ ) of 180 sccm, A film can be formed under conditions where hydrogen (H ₂ ) is 27000 sccm and phosphine (PH ₃ / H ₂ ) using hydrogen as a diluent gas is 200 sccm.

The p layer 41 is formed using a plasma CVD method in a separate reaction chamber. For example, a p-layer of microcrystalline silicon (μc-Si) has a substrate temperature of 180 to 200 ° C., a power supply frequency of 13.56 MHz, a reaction chamber pressure of 500 to 900 Pa, a reaction gas flow rate of monosilane (SiH ₄ ) of 100 sccm, A film can be formed under conditions where hydrogen (H ₂ ) is 25000 sccm and diborane (B ₂ H ₆ / H ₂ ) using hydrogen as a diluent gas is 50 sccm.

Next, the substrate 1 on which the p layer 31, i layer 32, buffer layer 35, n layer 33, and p layer 41 are formed as described above is taken out of the reaction chamber, and the p layer 41 is exposed to the atmosphere.
Subsequently, after the p layer 41 of the second photoelectric conversion unit 4 is exposed to the atmosphere, as shown in FIG. 2C, the second photoelectric conversion unit 4 is formed on the p layer 41 exposed to the atmosphere. A type silicon layer 42 (crystalline silicon layer) and an n layer 43 are formed in the same plasma CVD reaction chamber.
That is, the photoelectric conversion device second intermediate product 10 b in which the second photoelectric conversion unit 4 is provided on the first photoelectric conversion unit 3 is formed. Then, the back surface electrode 5 is formed on the n layer 43 of the second photoelectric conversion unit 4 to obtain a photoelectric conversion device 10A (10) as shown in FIG.

The i layer 42 is formed using a plasma CVD method in a reaction chamber in which the n layer 43 is formed. For example, an i-layer of microcrystalline silicon (μc-Si) is formed using a substrate temperature of 180 to 200 ° C., a power supply frequency of 13.56 MHz, a reaction chamber pressure of 500 to 900 Pa, and a reaction gas flow rate of monosilane (SiH ₄ ) of 180 sccm, A film can be formed under a condition where hydrogen (H ₂ ) is 27000 sccm.
The n layer 43 is formed using a plasma CVD method in a reaction chamber in which the i layer 42 is formed. For example, an n-layer of microcrystalline silicon (μc-Si), a substrate temperature of 180 to 200 ° C., a power supply frequency of 13.56 MHz, a reaction chamber pressure of 500 to 900 Pa, a reaction gas flow rate of monosilane (SiH ₄ ) of 180 sccm, A film can be formed under conditions where hydrogen (H ₂ ) is 27000 sccm and phosphine (PH ₃ / H ₂ ) using hydrogen as a diluent gas is 200 sccm.

Next, a manufacturing system of the photoelectric conversion device 10A (10) will be described with reference to FIG.
The manufacturing system of the photoelectric conversion device 10 according to the first embodiment includes a so-called in-line type first film forming device 60, an exposure device 80 that exposes the p layer 41 to the atmosphere, and a so-called batch type second film forming device 70. Are arranged in order.
The in-line type first film forming apparatus 60 has a configuration in which a plurality of film forming reaction chambers called chambers are arranged in a straight line. In the first film forming apparatus 60, the p layer 31, the i layer 32, the buffer layer 35, the n layer 33 of the first photoelectric conversion unit 3, and the p layer 41 of the second photoelectric conversion unit 4 are formed separately. The Since a plurality of film formation reaction chambers are connected in a row, five layers including a p layer 31, an i layer 32, a buffer layer 35, an n layer 33, and a p layer 41 are arranged in the order of the plurality of film formation reaction chambers. Are stacked on the substrate 1.
The exposure apparatus 80 exposes the substrate processed in the first film forming apparatus 60 to the atmosphere, and then moves the substrate to the second film forming apparatus 70.
In the second film forming apparatus 70, the i layer 42 and the n layer 43 of the second photoelectric conversion unit 4 are stacked in this order in the same film forming reaction chamber. Further, in such a film formation reaction chamber, a plurality of substrates are collectively transferred, and an i layer 42 and an n layer 43 are sequentially formed on each of the plurality of substrates in the film formation reaction chamber (batch processing). .

In the first film forming apparatus 60 in the manufacturing system, a loading chamber 61 (L: Lord) is disposed in which the substrate is first carried in and the internal space is decompressed. A heating chamber that heats the substrate so that the substrate temperature reaches a certain temperature may be provided in the subsequent stage of the preparation chamber 61 according to the process.
A P layer deposition reaction chamber 62 for forming the p layer 31 is connected to the preparation chamber 61. An I layer deposition reaction chamber 63 for forming the i layer 32 is connected to the P layer deposition reaction chamber 62. An N layer deposition reaction chamber 64 for forming the buffer layer 35 (n layer) is connected to the I layer deposition reaction chamber 63. An N layer deposition reaction chamber 65 for forming the n layer 33 is connected to the N layer deposition reaction chamber 64. A P layer film formation reaction chamber 66 for forming the p layer 41 of the second photoelectric conversion unit 4 is connected to the N layer film formation reaction chamber 65. The P-layer film formation reaction chamber 66 is connected to an extraction chamber 67 (UL: United) for returning the internal space from the reduced pressure atmosphere to the air atmosphere and carrying out the substrate from the first film formation apparatus 60. The plurality of reaction chambers 62, 63, 64, 65, 66 described above are arranged in a straight line between the preparation chamber 61 and the take-out chamber 67. In a state where the reduced-pressure atmosphere is maintained, the substrate is sequentially transferred to the reaction chambers 62, 63, 64, 65, and 66, and a film forming process is performed in each reaction chamber.
FIG. 3 shows an example in which the N layer film formation reaction chamber 64 for forming the buffer layer 35 (n layer) and the N layer film formation reaction chamber 65 for forming the n layer 33 are constituted by individual reaction chambers. However, the present invention does not limit the configuration in which the N layer deposition reaction chambers 64 and 65 are separate. For example, a configuration in which the N layer deposition reaction chambers 64 and 65 are included in one reaction chamber may be adopted as necessary.
At point A shown in FIG. 3, an insulating transparent substrate 1 on which a transparent conductive film 2 is formed is prepared as shown in FIG. 2A. Further, at the point B shown in FIG. 3, as shown in FIG. 2B, the p layer 31, the i layer 32, the buffer layer 35, the n layer 33, and the first layer of the first photoelectric conversion unit 3 are formed on the transparent conductive film 2. The first intermediate product 10a of the photoelectric conversion device 10 provided with the p layer 41 of the two photoelectric conversion unit 4 is disposed.

The second film forming apparatus 70 in the manufacturing system includes a preparation / removal chamber 71 (L / UL) and an IN layer film formation reaction chamber 72 connected to the preparation / removal chamber 71.
The preparation / removal chamber 71 carries the first intermediate product 10 a of the photoelectric conversion device processed in the first film formation apparatus 60 into the IN layer film formation reaction chamber 72. The loading / unloading chamber 71 reduces the internal space of the loading / unloading chamber 71 after the substrates have been loaded into the loading / unloading chamber 71, or reduces the internal space when the substrates are unloaded from the loading / unloading chamber 71. Or return to the atmosphere.
In the IN layer deposition reaction chamber 72, the i layer 42 and the n layer 43 of the second photoelectric conversion unit 4 are stacked in this order in the same deposition reaction chamber. Further, in such a film formation reaction chamber, a plurality of substrates are collectively transferred, and an i layer 42 and an n layer 43 are sequentially formed on each of the plurality of substrates in the film formation reaction chamber (batch processing). . Accordingly, the film formation process in the IN layer film formation reaction chamber 72 is simultaneously performed on a plurality of substrates.
At the point C shown in FIG. 3, as shown in FIG. 2C, the second intermediate product 10 b of the photoelectric conversion device 10 in which the second photoelectric conversion unit 4 is provided is disposed on the first photoelectric conversion unit 3.

In addition, in the inline-type first film forming apparatus 60 shown in FIG. 3, film forming processes are simultaneously performed on two substrates. The I layer deposition reaction chamber 63 is composed of four reaction chambers 63a, 63b, 63c, and 63d.
In the batch-type second film forming apparatus 70 shown in FIG. 3, film forming processes are simultaneously performed on six substrates.

According to the manufacturing method of the photoelectric conversion device as described above, the second photoelectric conversion unit 4 that is a crystalline photoelectric conversion device is formed on the n layer 33 of the first photoelectric conversion unit 3 that is an amorphous photoelectric conversion device. The p layer 41 is formed in advance, and the i layer 42 and the n layer 43 of the second photoelectric conversion unit 4 are formed on the p layer 41. By forming the film in this way, it is possible to easily control the crystallization rate distribution of the i layer 42 of the second photoelectric conversion unit 4.
In particular, in the present invention, the buffer layer 35 is formed in a separate film formation chamber between the i layer 32 and the n layer 33 of the first photoelectric conversion unit 3, thereby providing the photoelectric conversion device 10 having good characteristics. Can be obtained.

In the first embodiment, the i layer 42 and the n layer 43 constituting the second photoelectric conversion unit 4 are formed on the p layer 41 exposed to the atmosphere. In this case, before forming the i layer 42, it is desirable to expose the p layer 41 exposed to the atmosphere to plasma in an atmosphere containing OH radicals (OH radical plasma treatment). In addition, before forming the i layer 42, it is desirable to expose the p layer 41 exposed in the atmosphere to plasma in an atmosphere containing hydrogen gas (hydrogen plasma treatment).
As the OH radical plasma treatment, an OH radical plasma treatment chamber is prepared in advance, and the substrate on which the p layer 31, i layer 32, buffer layer 35, n layer 33, and p layer 41 are formed is transported to the plasma treatment chamber. A method of exposing the p layer 41 to plasma is employed. Further, after the OH radical plasma treatment, the i layer 42 and the n layer 43 constituting the second photoelectric conversion unit 4 are formed in a reaction chamber different from the OH radical plasma treatment chamber.
On the other hand, as the OH radical plasma treatment, the OH radical plasma treatment and the treatment for forming the i layer 42 and the n layer 43 constituting the second photoelectric conversion unit 4 may be continuously performed in the same reaction chamber.

Here, in the case where the OH radical plasma treatment and the treatment for forming the i layer 42 and the n layer 43 of the second photoelectric conversion unit 4 are continuously performed in the same processing chamber, the OH radicals are contained before each layer is formed. By exposing the inner wall of the processing chamber to plasma, the impurity gas PH ₃ remaining in the processing chamber can be decomposed and removed.
Therefore, even when the film formation process of the i layer 42 and the n layer 43 of the second photoelectric conversion unit 4 is repeated in the same processing chamber, a good impurity profile can be obtained and the laminated thin film having good power generation efficiency can be obtained. The photoelectric conversion apparatus 10 which becomes can be obtained.

In the OH radical-containing plasma treatment applied to the p layer 41 of the second photoelectric conversion unit 4, CO ₂ , CH ₂ O ₂ or a mixed gas composed of H ₂ O and H ₂ is used as a process gas. Is desirable.
That is, in order to generate OH radical-containing plasma, (CO ₂ + H ₂ ), (CH ₂ O ₂ + H ₂ ), or (H ₂ O + H ₂ ) is allowed to flow between the electrodes in the processing chamber while flowing into the processing chamber. For example, plasma can be effectively generated by applying a high frequency such as 13.5 MHz, 27 MHz, or 40 MHz.
In the generation of this OH radical-containing plasma, alcohols such as (HCOOCH ₃ + H ₂ ) and (CH ₃ OH + H ₂ ), and oxygen-containing hydrocarbons such as formate esters may be used. However, in a system having a problem that the amount of C impurity increases, it is preferable to use (CO ₂ + H ₂ ), (CH ₂ O ₂ + H ₂ ) or (H ₂ O + H ₂ ).

When CO ₂ is used as a plasma generation gas in the generation of this OH radical-containing plasma, the presence of H ₂ is necessary in the system. However, in addition to (CH ₂ O ₂ + H ₂ ), (H ₂ O + H ₂ ), alcohols such as (HCOOCH ₃ + H ₂ ) and (CH ₃ OH + H ₂ ), and hydrocarbons containing oxygen such as formate esters when using the no presence of H ₂ is required necessarily to the system.

When the OH radical plasma treatment is performed in this way, a mild reaction occurs as compared with the O radical treatment. Therefore, the n layer in which the microcrystalline phase formed on the p layer 31, the i layer 32, and the buffer layer 35 of the first photoelectric conversion unit 3 is dispersed in the amorphous crystalline phase without damaging the lower layer. 33 is obtained. As a result, an effect of activating the surface of the p layer 41 formed on the n layer 33 is obtained.
Therefore, it is possible to activate the surface of the p layer 41 of the second photoelectric conversion unit 4, and to effectively generate crystals of the i layer 42 of the second photoelectric conversion unit 4 stacked on the p layer 41. Can do. Therefore, even when the second photoelectric conversion unit 4 is formed on a large-area substrate, a uniform crystallization rate distribution can be obtained.
Even if hydrogen plasma treatment is performed instead of the OH radical plasma treatment, the same effect as the OH radical plasma treatment can be obtained.

Further, as the crystalline n layer 33 formed on the buffer layer 35 and the p layer 41 of the second photoelectric conversion unit 4, microcrystalline silicon (μc-Si) is formed on an amorphous amorphous silicon (a-Si) layer. May be used, or a film in which microcrystalline silicon (μc-Si) is dispersed in an amorphous silicon oxide (a-SiO) layer may be used.
However, in order to obtain a uniform crystallization distribution rate necessary for a film formed on a large-area substrate, that is, uniform crystallization by generating crystal growth nuclei of the crystalline photoelectric conversion layer i and n layers. In order to obtain the distribution rate, it is preferable to employ a film in which microcrystalline silicon (μc-Si) is dispersed in an amorphous silicon oxide (a-SiO) layer.

As described above, a film in which microcrystalline silicon (μc-Si) is dispersed in an amorphous amorphous silicon oxide (a-SiO) layer has a lower refractive index than an amorphous silicon (a-Si) semiconductor layer. Can be adjusted. It is possible to improve conversion efficiency by making this layer function as a wavelength selective reflection film and confining short wavelength light on the top cell side.
Regardless of the presence or absence of this optical confinement effect, a film in which microcrystalline silicon (μc-Si) is dispersed in an amorphous amorphous silicon oxide (a-SiO) layer is subjected to OH radical-containing plasma treatment. Crystal growth nuclei of the i layer 42 and the n layer 43 of the photoelectric conversion unit 4 are effectively generated. Therefore, a uniform crystallization rate distribution can be obtained even on a large-area substrate.

In particular, in the present invention, a crystalline silicon-based thin film is formed as the n layer 33 constituting the first photoelectric conversion unit 3. That is, the crystalline n layer 33 and the p layer 41 of the crystalline second photoelectric conversion unit 4 are formed above the buffer layer 35 of the amorphous first photoelectric conversion unit 3.
At this time, the crystalline n layer 33 and the p layer 41 of the second photoelectric conversion unit 4 formed above the p layer 31, the i layer 32, and the buffer layer 35 of the amorphous first photoelectric conversion unit 3, After the p layer 31, the i layer 32, and the buffer layer 35 of the first photoelectric conversion unit 3 are formed in the individual film forming chambers, it is desirable that the film forming chambers be continuously formed without opening them to the atmosphere.

That is, after forming the p layer 31, i layer 32, buffer layer 35, and n layer 33 of the first photoelectric conversion unit 3, the film formation chamber is opened to the atmosphere, and the second photoelectric conversion unit 4 is opened in another film formation chamber. In the method of forming the p layer 41, the i layer 42, and the n layer 43, the i layer 32 of the first photoelectric conversion unit 3 is caused by the time, temperature, atmosphere, and the like that the substrate is exposed to the air atmosphere. It deteriorates and the device performance decreases.
Therefore, after the p layer 31 and the i layer 32 buffer layer 35 of the first photoelectric conversion unit 3 are formed, the crystalline n layer 33 and the second photoelectric conversion unit 4 are continuously formed without opening the film formation chamber to the atmosphere. The p layer 41 is formed.

  As described above, by performing OH radical plasma treatment on the substrate on which the crystalline n layer 33 and the p layer 41 of the second photoelectric conversion unit 4 are formed in separate reaction chambers or the same reaction chamber, the p layer 41 is obtained. The surface of is activated and crystal nuclei are generated. Subsequently, the i-layer 42 of the crystalline second photoelectric conversion unit 4 is laminated on the p-layer 41, thereby comprising a laminated thin film having a uniform crystallization rate distribution over a large area and good power generation efficiency. A photoelectric conversion device 10A (10) can be obtained.

<Second embodiment>
Next, a second embodiment of the present invention will be described.
In the following description, the same members as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified. In the second embodiment, a configuration or method different from the first embodiment described above will be mainly described.
FIG. 4 is a structural cross-sectional view showing the layer configuration of the photoelectric conversion device 10B (10) according to the second embodiment.

In the first embodiment described above, the photoelectric conversion device having a tandem structure has been described. However, the present invention is not limited to the tandem structure, and can also be applied to a photoelectric conversion device having a single structure.
As shown in FIG. 4, in the photoelectric conversion device 10B (10), a p-type semiconductor layer 81 (p layer, third p-type semiconductor layer), a substantially intrinsic i-type semiconductor layer 82 (i layer, third i). A pin type third photoelectric conversion unit 8 in which an n type semiconductor layer 83 and an n type semiconductor layer 83 (n layer, third n type semiconductor layer) are stacked is formed on the transparent conductive film 2.

  In the photoelectric conversion device 10B (10) of the second embodiment, the p layer 81 and the i layer 82 constituting the third photoelectric conversion unit 8 are made of an amorphous silicon thin film, and n constituting the third photoelectric conversion unit 8 is formed. The layer 83 is made of a crystalline silicon-based thin film. Further, an n layer made of an amorphous silicon thin film is disposed as a buffer layer 85 between the i layer 81 and the n layer 83.

Also in the photoelectric conversion device 10B (10) having such a structure, an amorphous silicon thin film is interposed between an i layer 82 made of an amorphous silicon thin film and an n layer 83 made of a crystalline silicon thin film. Since the n-layer buffer layer 85 is arranged, mismatch at the interface between the i layer 82 made of an amorphous silicon thin film and the n layer 83 made of a crystalline silicon thin film can be alleviated. .
Thereby, the function of the n layer 83 made of a crystalline silicon-based thin film can be effectively utilized, and the open circuit voltage (Voc) can be improved.
As a result, the photoelectric conversion device 10B (10) can improve the photoelectric conversion efficiency.

And the manufacturing method of photoelectric conversion apparatus 10B (10) of 2nd embodiment forms the p layer 81 and i layer 82 of the 3rd photoelectric conversion unit 8 in order, i layer which comprises the 3rd photoelectric conversion unit 8 At least a step of forming a buffer layer 85 on 82, and a step of forming an n layer of the third photoelectric conversion unit 8 on the buffer layer 85.
The formation method of the p layer 81, i layer 82, n layer 83, and buffer layer 85 constituting the third photoelectric conversion unit 8 is the p layer 31 constituting the first photoelectric conversion unit 3 in the first embodiment described above. This is the same as the formation method of the i layer 32, the n layer 33, and the buffer layer 35.
The photoelectric conversion device 10 </ b> B (10) thus obtained can improve the open circuit voltage (Voc) by the function of the buffer layer 85.
As a result, according to the manufacturing method of the present invention, it is possible to easily manufacture the photoelectric conversion device 10B (10) having a single structure with improved photoelectric conversion efficiency.

Next, the result of conducting the following experiment on the photoelectric conversion device manufactured by the method for manufacturing a photoelectric conversion device according to the present invention will be described. The photoelectric conversion device manufactured by each example and its manufacturing conditions are shown below.
In Example 1 and Comparative Example 1, a photoelectric conversion device having a tandem structure was manufactured.
In any of the examples and comparative examples, a photoelectric conversion device was manufactured using a substrate having a size of 1100 mm × 1400 mm.

<Example 1>
In Example 1, a photoelectric conversion device having a structure in which a first photoelectric conversion unit was formed on a substrate and a second photoelectric conversion unit was formed on the first photoelectric conversion unit was produced. Specifically, in Example 1, the p layer made of an amorphous amorphous silicon thin film constituting the first photoelectric conversion unit, the buffer layer, the i layer made of an amorphous amorphous silicon thin film, and the i layer An n layer (buffer layer) made of amorphous amorphous silicon (a-Si) thin film, an n layer containing microcrystalline silicon formed on the buffer layer, and a microcrystal constituting the second photoelectric conversion unit A p-layer containing silicon was sequentially stacked on the substrate using a plurality of different deposition chambers. Thereafter, the p layer of the second photoelectric conversion unit was exposed to the atmosphere. Next, hydrogen plasma treatment was performed on the p layer of the second photoelectric conversion unit using hydrogen (H ₂ ) as a process gas. Thereafter, an i layer made of microcrystalline silicon and an n layer made of microcrystalline silicon constituting the second photoelectric conversion unit were formed on the p layer.

In Example 1, the p layer, i layer, buffer layer, n layer, and p layer of the second photoelectric conversion unit constituting the first photoelectric conversion unit are formed by plasma CVD in individual reaction chambers. did. The i layer and the n layer of the second photoelectric conversion unit and the p layer formed on the n layer of the second photoelectric conversion unit were formed using the plasma CVD method in the same film formation chamber.
Regarding the p layer constituting the first photoelectric conversion unit, the substrate temperature is 190 ° C., the power supply frequency is 13.56 MHz, the pressure in the reaction chamber is 110 Pa, the reaction gas flow rate is 300 sccm for monosilane (SiH ₄ ), and 2300 sccm for hydrogen (H ₂ ). Then, a p-layer having a thickness of 80 cm was formed under the condition that diborane (B ₂ H ₆ / H ₂ ) using hydrogen as a diluent gas was 180 sccm and methane (CH ₄ ) was 500 sccm.
Regarding the buffer layer, the substrate temperature is 190 ° C., the power supply frequency is 13.56 MHz, the pressure in the reaction chamber is 110 Pa, the reaction gas flow rates are 300 sccm for monosilane (SiH ₄ ), 2300 sccm for hydrogen (H ₂ ), and methane (CH ₄ ). A buffer layer having a film thickness of 60 mm was formed under the condition of 100 sccm.

In addition, regarding the i layer of the first photoelectric conversion unit, a film of 1800 mm is obtained under the conditions that the substrate temperature is 190 ° C., the power supply frequency is 13.56 MHz, the pressure in the reaction chamber is 80 Pa, and the reaction gas flow rate is 1200 sccm of monosilane (SiH ₄ ). An i layer having a thickness was formed.
Regarding the buffer layer (n layer), the substrate temperature is 170 ° C., the power supply frequency is 13.56 MHz, the pressure in the reaction chamber is 80 Pa, the reaction gas flow rate is 150 sccm for monosilane (SiH ₄ ), 550 sccm for hydrogen (H ₂ ), and dilution. A buffer layer (n layer) having a thickness of 20 mm was formed under the condition that phosphine (PH ₃ / H ₂ ) using hydrogen as a gas was 60 sccm.
Further, regarding the n layer of the first photoelectric conversion unit, the substrate temperature is 170 ° C., the power supply frequency is 13.56 MHz, the pressure in the reaction chamber is 800 Pa, the reaction gas flow rate is 20 sccm for monosilane (SiH ₄ ), and 2000 sccm for hydrogen (H ₂ ). Then, an n layer having a thickness of 300 mm was formed under the condition that phosphine (PH ₃ / H ₂ ) using hydrogen as a diluent gas was 15 sccm.

Next, regarding the p layer of the second photoelectric conversion unit, the substrate temperature is 180 ° C., the power supply frequency is 13.56 MHz, the reaction chamber pressure is 700 Pa, the reaction gas flow rate is 100 sccm of monosilane (SiH ₄ ), and hydrogen (H ₂ ). A p-layer having a thickness of 150 mm was formed under the conditions of 25000 sccm and diborane (B ₂ H ₆ / H ₂ ) using hydrogen as a diluent gas at 50 sccm.
Further, the p layer of the second photoelectric conversion unit is exposed to the atmosphere, and the substrate temperature is 190 ° C., the power supply frequency is 13.56 MHz, the pressure in the reaction chamber is 700 Pa, and H ₂ which is a process gas is exposed to the p layer. Plasma treatment was performed under the condition of 1000 sccm.

Subsequently, regarding the i layer of the second photoelectric conversion unit, the substrate temperature is 170 ° C., the applied RF power is 550 W, the pressure in the reaction chamber is 1200 Pa, the reaction gas flow rate is 40 sccm for monosilane (SiH ₄ ), and 2800 sccm for hydrogen (H ₂ ). Under certain conditions, an i layer having a thickness of 15000 mm was formed. At this time, the film formation rate was 262 Km / min.
Regarding the n layer of the second photoelectric conversion unit, the substrate temperature is 170 ° C., the applied RF power is 1000 W, the reaction chamber pressure is 800 Pa, the reaction gas flow rate is 20 sccm for monosilane (SiH ₄ ), 2000 sccm for hydrogen (H ₂ ), Under the condition that phosphine (PH ₃ / H ₂ ) using hydrogen as a diluent gas was 15 sccm, an n layer having a thickness of 300 mm was formed. At this time, the film formation rate was 174 K / min.

<Example 2 to Example 4>
In Example 2, instead of the buffer layer (n layer) having a thickness of 20 mm in Example 1, a photoelectric conversion device including a buffer layer (n layer) having a thickness of 50 mm was manufactured.
In Example 3, instead of the buffer layer (n layer) having a thickness of 20 mm in Example 1, a photoelectric conversion device including a buffer layer (n layer) having a thickness of 100 mm was manufactured.
In Example 4, instead of the buffer layer (n layer) having a thickness of 20 mm in Example 1, a photoelectric conversion device including a buffer layer (n layer) having a thickness of 200 mm was manufactured.
Except for the buffer layer whose film thickness is adjusted as described above, the structures of the photoelectric conversion devices of Examples 2 to 4 are the same as the structure of the photoelectric conversion device having the tandem structure described in Example 1.

<Comparative Example 1>
In Comparative Example 1, no buffer layer was formed between the i layer and the n layer in the first photoelectric conversion unit. Except for the point that this buffer layer is not formed, the structure of the photoelectric conversion device of Comparative Example 1 is the same as the structure of the photoelectric conversion device having the tandem structure described in Example 1.
That is, the p layer, i layer, and n layer that constitute the first photoelectric conversion unit on the substrate, the p layer that constitutes the second photoelectric conversion unit, and a plurality of film formation chambers different from each other are sequentially formed on the substrate. Laminated. Thereafter, the p layer of the second photoelectric conversion unit was exposed to the atmosphere. Next, hydrogen plasma treatment was performed on the p layer of the second photoelectric conversion unit. Then, i layer and n layer which comprise a 2nd photoelectric conversion unit were formed.

Each of the photoelectric conversion devices of Examples 1 to 4 and Comparative Example 1 manufactured as described above was irradiated with AM 1.5 light at a light amount of 100 mW / cm ² , and the photoelectric conversion efficiency as output characteristics at 25 ° C. (Η), short circuit current (Jsc), open circuit voltage (Voc), and fill factor (FF) were measured. The results are shown in Table 1.

Moreover, about the photoelectric conversion apparatus of Example 2 and Comparative Example 1, a discharge curve is shown in FIG. 5, and the relationship between a wavelength and power generation efficiency is shown in FIG.
As shown in Table 1, FIG. 5 and FIG. 6, the photoelectric conversion device (Example 2) of the present invention in which the buffer layer composed of the amorphous n layer is arranged is compared with the conventional photoelectric conversion device (Comparative Example 1). In particular, the photoelectric conversion efficiency was improved by nearly 0.6%.
In particular, as is apparent from FIG. 5, it is understood that the power generation efficiency is improved in the pin type first photoelectric conversion unit made of an amorphous silicon-based thin film, and the photoelectric conversion efficiency of the entire photoelectric conversion device can be improved. It was.

Moreover, about the photoelectric conversion apparatus of Examples 1-4 and the comparative example 1, when changing the thickness of a buffer layer (n layer), photoelectric conversion efficiency ((eta)), a fill factor (FF), a short circuit current (Jsc), The measurement results of the open circuit voltage (Voc) are shown in FIGS.
Each of FIGS. 7 to 10 is a graph in which values of η, FF, Jsc, and Voc (vertical axis) are plotted with respect to the thickness of the buffer layer (horizontal axis).
As shown in Table 1 and FIGS. 7 to 10, when the thickness of the buffer layer is in the range of 20 to 200 mm, the fill factor (FF) and the open circuit voltage (Voc) increase, and the photoelectric conversion efficiency increases. Admitted.
When the thickness of the buffer layer was 200 mm or more, it was confirmed that Jsc and Voc would decrease. This is presumably because the buffer layer absorbed light and Jsc in the second photoelectric conversion unit made of a crystalline silicon-based thin film was lowered. Further, it is considered that the Voc improvement effect by the buffer layer was hindered by the n layer made of an amorphous silicon thin film having a large film thickness. The thickness of the buffer layer is preferably 20 to 200 mm, and particularly preferably 20 to 100 mm.

The present invention can be used for a photoelectric conversion device having a single structure including a photoelectric conversion unit having an i-layer of amorphous silicon, and a photoelectric conversion device having a multilayer structure such as a tandem structure or a triple structure.
At this time, as a structure of another photoelectric conversion unit, a structure in which a microcrystal silicon system, an amorphous SiGe system, a SiGe system including a crystal, or the like can be used.
As described above, the photoelectric conversion device and the method for manufacturing the photoelectric conversion device of the present invention have been described. However, the technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Can be added.

  The present invention is widely applicable to a photoelectric conversion device having a tandem structure or a single structure that functions as a solar cell and a method for manufacturing the photoelectric conversion device.

  1 substrate (transparent substrate), 2 transparent conductive film, 3 first photoelectric conversion unit, 4 second photoelectric conversion unit, 5 back electrode, 10A, 10B, (10) photoelectric conversion device, 31 p-type semiconductor layer, 32 i-type Semiconductor layer, 33 n-type semiconductor layer, 35 buffer layer, 41 p-type semiconductor layer, 42 i-type silicon layer, 43 n-type semiconductor layer, 8 third photoelectric conversion unit, 81 p-type semiconductor layer, 82 i-type silicon layer, 83 n-type semiconductor layer, 85 buffer layer, 60 first deposition apparatus, 61 preparation chamber, 62 P layer deposition reaction chamber, 63 (63a, 63b, 63c, 63d) I layer deposition reaction chamber, 64 buffer layer ( n layer) film formation reaction chamber, 65 N layer film formation reaction chamber, 66 P layer film formation reaction chamber, 67 take-out chamber, 70 second film formation apparatus, 71 preparation / removal chamber, 72 IN layer film formation reaction chamber, 80 Exposure device.

Claims (10)

A photoelectric conversion device,
A substrate,
A transparent conductive film formed on the substrate;
A first p-type semiconductor layer, a first i-type semiconductor layer composed of an amorphous silicon-based thin film, a first n-type semiconductor layer composed of a crystalline silicon-based thin film, and an n-type semiconductor composed of an amorphous silicon-based thin film. A first photoelectric conversion unit formed on the transparent conductive film, including a buffer layer disposed between the first i-type semiconductor layer and the first n-type semiconductor layer;
A photoelectric conversion device comprising: a second photoelectric conversion unit formed on the first photoelectric conversion unit. The photoelectric conversion device according to claim 1,
The second photoelectric conversion unit includes a second p-type semiconductor layer and a second i-type semiconductor layer,
The second p-type semiconductor layer and the second i-type semiconductor layer are made of a crystalline silicon-based thin film. The photoelectric conversion device according to claim 1 or 2, wherein
The thickness of the said buffer layer is the range of 20-200 mm. The photoelectric conversion apparatus characterized by the above-mentioned. It is a photoelectric conversion device according to any one of claims 1 to 3,
The intensity of Raman scattered light attributed to the amorphous phase dispersed in the buffer layer observed with a laser Raman microscope is defined as Ia, and the intensity of Raman scattered light attributed to the microcrystalline phase dispersed in the buffer layer is defined as Ic. Ic / Ia is less than 1.0 when defined as: A photoelectric conversion device. A method for manufacturing a photoelectric conversion device, comprising:
Prepare a substrate on which a transparent conductive film is formed,
On the transparent conductive film, a first p-type semiconductor layer constituting the first photoelectric conversion unit and a first i-type semiconductor layer made of an amorphous silicon-based thin film are sequentially formed.
Forming a buffer layer, which is an n-type semiconductor composed of an amorphous silicon-based thin film, on the first i-type semiconductor layer;
On the buffer layer, a first n-type semiconductor layer made of a crystalline silicon-based thin film and constituting the first photoelectric conversion unit is formed,
A second p-type semiconductor layer, a second i-type semiconductor layer, and a second n-type semiconductor layer constituting a second photoelectric conversion unit are sequentially formed on the first n-type semiconductor layer. Device manufacturing method. It is a manufacturing method of the photoelectric conversion device according to claim 5,
Said 2nd p-type semiconductor layer and said 2nd i-type semiconductor layer consist of a crystalline silicon-type thin film. The manufacturing method of the photoelectric conversion apparatus characterized by the above-mentioned. A photoelectric conversion device,
A substrate,
A transparent conductive film formed on the substrate;
From a third p-type semiconductor layer composed of an amorphous silicon-based thin film, a third i-type semiconductor layer composed of an amorphous silicon-based thin film, a third n-type semiconductor layer composed of a crystalline silicon-based thin film, and an amorphous silicon-based thin film A third photoelectric conversion unit formed on the transparent conductive film, including a buffer layer disposed between the third i-type semiconductor layer and the third n-type semiconductor layer.
A photoelectric conversion device comprising: The photoelectric conversion device according to claim 7,
The thickness of the said buffer layer is the range of 20-200 mm. The photoelectric conversion apparatus characterized by the above-mentioned. The photoelectric conversion device according to claim 7 or 8,
The intensity of Raman scattered light attributed to the amorphous phase dispersed in the buffer layer, observed with a laser Raman microscope, is defined as Ia, and the intensity of Raman scattered light attributed to the microcrystalline phase dispersed in the buffer layer is defined as Ia. A photoelectric conversion device characterized in that, when defined as Ic, Ic / Ia is less than 1.0. A method for manufacturing a photoelectric conversion device, comprising:
Prepare a substrate on which a transparent conductive film is formed,
On the transparent conductive film, a third p-type semiconductor layer made of an amorphous silicon-based thin film and a third i-type semiconductor layer made of an amorphous silicon-based thin film, which constitute a third photoelectric conversion unit, are formed in order.
Forming a buffer layer, which is an n-type semiconductor composed of an amorphous silicon-based thin film, on the third i-type semiconductor layer;
A method of manufacturing a photoelectric conversion device, comprising: forming a third n-type semiconductor layer comprising the crystalline silicon-based thin film and constituting the third photoelectric conversion unit on the buffer layer.

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