JPH0685291A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To suppress the light deterioration of photoelectric conversion efficiency for high efficiency and improved stability as a solar cell. CONSTITUTION:In a pin (or nip) type semiconductor device. an i-type semiconductor layer 5 is constituted of a first layer 51 and a second layer 52, the first layer 51 is laid out at a light-reception surface side, at the same time the film- formation speed is made slower than that of the second layer 52 for forming a film. Also, when forming a pin (or nip) type semiconductor device, an i-type semiconductor layer 5 is constituted of the first layer 51 and the second layer 52, the first layer 51 is formed at the light-reception surface side, and at the same time, the film-formation speed is made slower than that of the second layer 52. Since the film-formation speed of the first layer 51 is slower than that of the second layer 52, it is desirable that the film thickness of the first layer 51 should be thinner than that of the second layer 52.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device. More specifically, it relates to a method for manufacturing a semiconductor device for photoelectric conversion elements.

[0002]

2. Description of the Related Art It is generally well known that non-single-crystal photovoltaic devices lack stability. Particularly in the case of amorphous silicon, there is a phenomenon called the Steebler-Wronski effect in which the conductivity is lowered by irradiation light and the conductivity is restored again by a heat treatment at about 150 ° C. Therefore, when a solar cell is created using such an element, its photoelectric conversion efficiency (hereinafter referred to as conversion efficiency) is reduced.

Therefore, in order to obtain a relatively stable photovoltaic element, a photovoltaic element constructed so that the i-type semiconductor layer is thinned to increase the electric field strength applied to the active layer and thereby enhance the transporting ability. Proposed.

FIG. 2 is a schematic view of a solar cell using such amorphous silicon as a photovoltaic element. In the figure,
1 is a glass substrate, 2 transparent electrodes, 3 is a p-type semiconductor layer, 4 is a buffer layer, 5 is an i-type semiconductor layer, 6 is an n-type semiconductor layer,
Reference numeral 7 indicates a back surface electrode. In the example shown in FIG. 2, a wide bandgap semiconductor layer such as hydrogenated amorphous silicon (a-SiC: H) is used on the light-receiving surface side. The buffer layer 4 is provided at the interface between the p-type semiconductor layer 3 and the i-type semiconductor layer 5 as shown in the drawing, and the impurity concentration thereof is reduced toward the i-type semiconductor layer 5. The film formation of the i-type semiconductor layer 5 here is performed at a film formation rate of 0.2 nm / sec.

However, when the solar cell shown in FIG. 2 was actually manufactured and a deterioration acceleration test was carried out, when the film thickness of the i-type semiconductor layer 5 was 500 nm, a decrease in conversion efficiency of about 30% was recognized. When the film thickness of the i-type semiconductor layer 5 was 100 nm, a decrease in conversion efficiency of about 20% was recognized.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is suitable for use in a solar cell because it suppresses photodegradation of conversion efficiency, has high efficiency, and is excellent in stability. An object of the present invention is to provide a semiconductor device that can be manufactured and a manufacturing method thereof.

[0007]

The semiconductor device of the present invention comprises:
A semiconductor device for a photovoltaic element, wherein the semiconductor has at least a p-type non-single-crystal silicon-based semiconductor layer, an i-type non-single-crystal silicon-based semiconductor layer, and an n-type non-single-crystal silicon-based semiconductor layer, The i-type non-single-crystal silicon-based semiconductor layer comprises at least a first layer formed on the semiconductor layer side used on the light-receiving surface side and a second layer formed adjacent to the first layer, It is characterized in that the first layer is formed at a film formation rate lower than the film formation rate of the second layer.

In the semiconductor device of the present invention, it is preferable that the semiconductor layer used on the light receiving surface side is a p-type non-single crystal silicon semiconductor layer or an n-type non-single crystal silicon semiconductor layer.

Further, in the semiconductor device of the present invention, the film thickness of the first layer is 10 nm or more and 30 nm or less, and the film formation rate of the first layer is 0.03 nm / sec or more and 0.1 nm or more.
/ Sec or less is preferable.

Further, in the semiconductor device of the present invention,
It is preferable that the semiconductor layer used on the light receiving surface side is made of hydrogenated amorphous silicon.

The manufacturing method of the present invention is a method for manufacturing a semiconductor device for a photovoltaic element, wherein the semiconductor is at least a p-type non-single-crystal silicon-based semiconductor layer, an i-type non-single-crystal silicon-based semiconductor layer, and an n-type. Type non-single-crystal silicon-based semiconductor layer, the i-type non-single-crystal silicon-based semiconductor layer is adjacent to the first layer formed on at least the semiconductor layer side used on the light-receiving surface side. And a second layer formed as described above, and the film forming rate of the first layer is slower than the film forming rate of the second layer.

In the manufacturing method of the present invention, it is preferable that the semiconductor layer used on the light-receiving surface side is a p-type or n-type non-single-crystal silicon semiconductor layer.

In the manufacturing method of the present invention, the film thickness of the first layer is 10 nm or more and 30 nm or less, and the film forming rate of the first layer is 0.03 nm / sec or more and 0.1 nm / sec or less. Preferably.

Further, in the manufacturing method of the present invention, it is preferable that the semiconductor layer used on the light-receiving surface side is made of hydrogenated amorphous silicon.

[0015]

In the semiconductor device of the present invention, as described above, the i-type semiconductor layer is composed of at least the first layer on the light-receiving surface side and the second layer adjacent thereto, and the first layer has a first film formation rate. Since it is slower than that of the two layers, p on the light-receiving surface side
The film quality near the / i (n / i in the case of nip type) interface is stably maintained. Therefore, the semiconductor device of the present invention is suppressed from photodegradation and is highly efficient and excellent in stability. Moreover, according to the manufacturing method of the present invention, a semiconductor device having such characteristics can be manufactured.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to such embodiments.

FIG. 1 is a schematic view of a solar cell using the semiconductor device of the present invention. In the figure, 1 is a transparent substrate, 2 is a transparent electrode, 3 is a p-type non-single-crystal silicon-based semiconductor layer, 4 is a buffer layer, 5 is an i-type non-single-crystal silicon-based semiconductor layer,
Reference numeral 6 indicates a microcrystallized n-type non-single-crystal silicon semiconductor layer, and 7 indicates a back surface electrode.

Examples of the non-single-crystal silicon semiconductor in the present invention include Si, SiC, SiN, SiGe,
Examples include hydrogenated alloys such as SiSn, fluorinated alloys, and other amorphous semiconductors generally used in photovoltaic devices, and amorphous or polycrystalline semiconductors including microcrystals.

A wide bandgap semiconductor is used as the window layer material for the non-single crystal silicon semiconductor, and is a pin-type or nip-type photovoltaic element. The thickness of each non-single-crystal silicon-based semiconductor forming the photovoltaic element is not particularly limited and may be in the range normally used for photovoltaic elements.

In the present invention, when the initial film (first layer) is formed when the i-type semiconductor layer is formed on the p-type semiconductor layer 3 (n-type semiconductor layer 6 in the case of nip type) side on the light-receiving surface side. The film forming speed of (2) is slowed down, and the film forming speed of the second layer after the initial film (first layer) is formed is increased. As a method of adjusting the film forming speed, RF is used.
Examples include a method of increasing / decreasing the power, a method of increasing / decreasing the pressure, a method of increasing / decreasing the film forming temperature, and a method of increasing / decreasing the amount of diluted hydrogen. It is also possible to combine these methods.

The film thickness of the initial film (first layer) is preferably as thin as possible because the film forming speed is slow, but the stability of the p / i (n / i in the case of nip type, the same applies below) interface is maintained. In order to keep it, a film thickness of 10 nm or more is preferable. However, it is desirable not to exceed 30 nm.

The film formation rate of the initial film (first layer) should be as slow as possible in consideration of the stability of the p / i interface, but if the operability of the manufacturing apparatus is taken into consideration, the film formation rate should be minimized. 0.0
It is preferably 3 nm / sec. On the other hand, if the film formation rate is too fast, the p / i interface is roughened, so it is necessary to keep the maximum at 0.1 nm / sec.

As the window layer on the light-receiving surface side (corresponding to the p-type semiconductor layer 3 in the embodiment shown in FIG. 1), wide bandgap SiC, SiN or the like is preferable in view of the doping characteristics. In this embodiment, SnO is used as the transparent electrode 2.
_{Although 2} is used, ITO, ZnO or the like or a multilayer film of these may be used.

Since the remaining structure of the p-type semiconductor layer 3 and the n-type semiconductor layer 6 and the structures of the transparent substrate 1, the buffer layer 4 and the back electrode 8 are the same as those of the conventional solar cell, Detailed description of the configuration is omitted.

The method for manufacturing the semiconductor device of the present invention will be described below based on specific examples.

Examples and Comparative Examples Using a parallel plate capacitively coupled glow discharge device, each semiconductor layer was formed and formed into a solar cell having an effective area of 1.0 cm ² . The film formation was performed as follows. On the glass substrate 1 on which the SnO ₂ transparent electrode 2 is formed, a p film having a thickness of 25 nm is formed.
The gas flow rate of SiH ₄ (50 sccm), C
H ₄ (35 sccm), B ₂ H ₆ (1000 ppm H ₂
Diluted product) (100sccm), H ₂ (500sccm)
At a reaction pressure of 1.0 Torr and a heater temperature of 200
A film was formed at a temperature of 50 ° C. and RF power of 50 mW / cm ² . Next, the buffer layer 4 having a film thickness of 10 nm is subjected to a gas flow rate SiH ₄ (50
sccm), CH ₄ (35 sccm), H ₂ (500s
ccm), the reaction pressure was 1.0 Torr, the heater temperature was 200 ° C., and the RF power was 50 mW / cm ² . Then, the i-type semiconductor layer (first layer) 51 having a film thickness of 30 nm is formed.
At a gas flow rate of SiH ₄ (50 sccm), reaction pressure of 0.3 Torr, heater temperature of 200 ° C., RF power of 3
The i-type semiconductor layer (second layer) 52 having a film thickness of 400 nm is continuously formed at 0 mW / cm ² , and the gas flow rate is SiH ₄ (50 sc).
cm), reaction pressure 0.3 Torr, heater temperature 2
The i-type semiconductor layer 5 was formed by increasing the film formation rate at 00 ° C. and RF power of 50 mW / cm ² . Next, the film thickness 3
The gas flow rate SiH is applied to the microcrystallized n-type semiconductor layer 6 of 00Å
_{4 (5sccm), PH 3 (} 1000ppmH 2 diluted mixture) (100 sccm), with H ₂ (200sccm), reaction pressure 1.0 Torr, a heater temperature of 200 ° C.,
A film was formed with an RF power of 500 mW / cm ² . Furthermore, the back surface electrode 7 was produced, and the solar cell was completed (Example).

For comparison, a solar cell was manufactured by a conventional manufacturing method (comparative example).

Regarding the obtained solar cells of Examples and Comparative Examples, AM1.5 100 mW under a temperature condition of 48 ° C.
A deterioration acceleration test was carried out for 500 hours by using artificial sunlight of / cm ² . As a result, in the solar cell of the comparative example, 1
While a decrease in efficiency of 8 to 20% was observed, only a decrease in efficiency of 10 to 15% was observed in the solar cells of the examples.

[0029]

As described above, in the semiconductor device of the present invention, when the i-type semiconductor layer is formed on the light-receiving surface side of the p-type semiconductor layer or the n-type semiconductor layer side, the first layer is formed. The speed is slower than that of the second layer, and p / i or n /
Since the stability at the i interface is maintained, photodegradation is suppressed, high efficiency and excellent stability are achieved. Therefore, it can be suitably used for a solar cell.

According to the manufacturing method of the present invention, a semiconductor device having such characteristics can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic view of an example of a solar cell using a semiconductor device manufactured by the manufacturing method of the present invention.

FIG. 2 is a schematic view of a conventional solar cell.

[Explanation of symbols]

1 translucent substrate (glass substrate) 2 transparent electrode 3 p-type non-single-crystal silicon semiconductor layer (p-type semiconductor layer) 4 buffer layer 5 i-type non-single-crystal silicon semiconductor layer (i-type semiconductor layer) 51 first layer ( Initial layer) 52 Second layer 6 Microcrystallized n-type non-single-crystal silicon semiconductor layer (n-type semiconductor layer) 7 Back electrode

[Procedure amendment]

[Submission date] March 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

Claims (1)

1. A semiconductor device for a photovoltaic element, wherein the semiconductor is at least a p-type non-single-crystal silicon semiconductor layer, an i-type non-single-crystal silicon semiconductor layer, and an n-type non-single crystal silicon semiconductor layer. A single crystal silicon-based semiconductor layer, wherein the i-type non-single crystal silicon-based semiconductor layer is adjacent to the first layer formed on at least the semiconductor layer side used on the light-receiving surface side; A semiconductor device comprising a formed second layer, wherein the first layer is formed at a film formation rate slower than a film formation rate of the second layer. 2. The semiconductor layer used on the light-receiving surface side is p
The semiconductor device according to claim 1, wherein the semiconductor device is a non-single-crystal silicon semiconductor layer. 3. The semiconductor layer used on the light-receiving surface side is n
The semiconductor device according to claim 1, wherein the semiconductor device is a non-single-crystal silicon semiconductor layer. 4. The film thickness of the first layer is 10 nm or more and 30.
nm or less, Claim 1, 2 or 3 characterized by the above-mentioned.
The semiconductor device described. 5. The film forming rate of the first layer is 0.03 nm.
/ Second or more and 0.1 nm / second or less, The semiconductor device according to claim 1, 2 or 3. 6. The semiconductor device according to claim 1, wherein the semiconductor layer used on the light-receiving surface side is made of hydrogenated amorphous silicon. 7. A method for manufacturing a semiconductor device for a photovoltaic element, wherein the semiconductor is at least a p-type non-single crystal silicon semiconductor layer, an i-type non-single crystal silicon semiconductor layer and an n-type non-single crystal silicon. A semiconductor layer, and the i-type non-single-crystal silicon semiconductor layer is formed adjacent to the first layer formed at least on the semiconductor layer side used on the light-receiving surface side. A second layer which is present, wherein the film forming rate of the first layer is slower than the film forming rate of the second layer. 8. The semiconductor layer used on the light receiving surface side is p
8. The method of manufacturing a semiconductor device according to claim 7, wherein the semiconductor device is a non-single crystal silicon semiconductor layer. 9. The semiconductor layer used on the light-receiving surface side is n
8. The method of manufacturing a semiconductor device according to claim 7, wherein the semiconductor device is a non-single crystal silicon semiconductor layer. 10. The film thickness of the first layer is 10 nm or more and 3
The method for manufacturing a semiconductor device according to claim 7, 8 or 9, wherein the thickness is 0 nm or less. 11. The deposition rate of the first layer is 0.03 n
The method for manufacturing a semiconductor device according to claim 7, 8 or 9, wherein the value is m / sec or more and 0.1 nm / sec or less. 12. The method of manufacturing a semiconductor device according to claim 7, wherein the semiconductor layer used on the light-receiving surface side is made of hydrogenated amorphous silicon.