JPS61111586A - Manufacture of amorphous silicon solar cell - Google Patents

Abstract

PURPOSE:To prevent the deterioration in characteristic of the solar cell by a method wherein the clear conductive film of a solar cell having amorphous Si layers is adhered by sputtering at low temperature. CONSTITUTION:Using a stainless steel substrate 1 as the substrate of a solar cell, an amorphous Si P-layer 2 is formed by a plasma CVD apparatus in a mixed atmosphere of SiH4, B2H6, and H2 at a substrate temperature of 150-250 deg.C. Next, an amorphous Si I-layer 3 is formed in a mixed atmosphere of SiH4 and H2, and an amorphous Si N-layer 4 is formed in a mixed atmosphre of SiH4, PH3, and H2. Finally, a clear conductive film 5 is adhered by using a magnetron sputtering apparatus. Since the substrate temperature at the time of adhering the clear conductive film is thus kept at low temperature, the photoelectric conversion efficiency of the solar cell can be markedly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for manufacturing an amorphous silicon solar cell.

<Technical background of the invention and its problems> Various methods for producing amorphous silicon solar cells have been proposed in the past. , a method of stacking an I-type amorphous (non-crystalline T) silicon layer and an N-type amorphous (non-crystalline) silicon layer in this order and attaching a transparent conductive film thereon; Conductive film, P-type amorphous silicon layer,
A method has been proposed in which an Ig amorphous silicon layer and an N-type amorphous silicon layer are stacked in this order, and an aluminum layer is deposited thereon.

Conventionally, when producing an amorphous silicon solar cell using a conductive substrate, a transparent conductive film CITO (indium tin oxide) is mainly formed by an electron beam evaporation method. However, in order to obtain a transparent conductive film with good transmittance and specific resistance using electron beam evaporation, the substrate temperature must be increased to 3.
It is necessary to keep the temperature around 00°C. However, when a solar cell is normally fabricated by plasma CVD using SiH4 gas, the substrate temperature is maintained at about 200°C; After depositing the amorphous silicon layer, the temperature must be increased to deposit the transparent conductive film, which could result in deterioration of the solar cell properties.

<Object of the Invention> The present invention has been made in view of the above points, and provides a method for manufacturing an amorphous solar cell in which the step of attaching a transparent conductive film after depositing an amorphous silicon layer does not deteriorate solar cell characteristics. It is intended to.

<Structure of the Invention> In order to achieve the above object, the method for manufacturing an amorphous solar cell of the present invention is such that the substrate temperature during the transparent conductive film deposition step is 150°C.
The temperature is maintained between 250°C and 250°C.

<Embodiments of the Invention> Prior to detailed description of the present invention, the characteristics of the present invention will be described as follows.

That is, 1. When producing an amorphous solar cell, the substrate temperature when attaching a transparent conductive film is set at 150°C to 250°C, preferably 200°C, thereby making it possible to produce a solar cell with higher efficiency. More specifically, as will be clear from the description of the examples below, the transparent conductive film can be deposited by using sputtering instead of electron beam evaporation, for example. The transparent conductive film is attached at a lower temperature.

The sputtering method has advantages over the electron beam evaporation method in that it allows continuous discharge for a long time and is highly suitable for mass production. When producing a transparent conductive film, a sintered body of ITOC (indium tin oxide) was used as a sputtering target, and as shown in Figure 2, the substrate temperature was 20.
At temperatures above 0° C., the transmittance was almost constant, and although the resistivity decreased as the substrate temperature increased, a transparent conductive film was obtained that exhibited relatively good resistivity at temperatures above 200° C. When an amorphous silicon solar cell was fabricated at 200°C using this transparent conductive film, the photoelectric conversion efficiency was significantly improved compared to when it was fabricated at 300°C using the conventional electron beam evaporation method. The present invention will be described in detail below with reference to Examples.

Example 1 A mirror-finished stainless steel substrate was used as a substrate for an amorphous silicon solar cell. 72 layers of amorphous silicon were formed on the substrate using a plasma CVD apparatus in a mixed atmosphere of SiH4°B, H6, and H2 at a substrate temperature of 200°C. Next, amorphous silicon I was deposited at a substrate temperature of 200°C in a mixed atmosphere of 5iH, H2.
Form i, t, ri.

Finally, an amorphous silicon N layer was formed at a substrate temperature of 200° C. in a mixed atmosphere of S i Ha , PH3, and H2. A transparent conductive film was deposited on the thus produced material using a magnetron sputtering device. Figure 1 shows the structure of the solar cell fabricated in this way. 1 is a stainless steel base i, 2 is a 72-layer amorphous silicon layer, 3 is a 71-layer amorphous silicon layer, 4 is an amorphous silicon N layer, and 5 is a sputtering method. This is a transparent conductive film made with.

Hereinafter, the change in photoelectric conversion efficiency depending on the substrate temperature when attaching a transparent conductive film to this solar cell will be explained.

Figure 3 is a graph showing the temperature dependence of the photoelectric conversion efficiency obtained with a 130 lux (Ix) white fluorescent plate.As is clear from this figure, when the substrate temperature is 200°C
The charging conversion efficiency is maximum at around 300℃, and at 300℃
It turns out that it only shows the charge conversion efficiency of Section 4. The example shown in FIG. 3 is the result when the transparent conductive film 5 was formed by sputtering method, but the substrate temperature was 300°C.
The photoelectric conversion efficiency in this case is almost equivalent to that in the case of electron beam evaporation. .

FIG. 4 shows the dependence of photoelectric conversion efficiency on substrate temperature under AMl , l OQgW, /+2.

Although it is somewhat different from the case of a white fluorescent light, it is similar in that the photoelectric conversion efficiency reaches its maximum value when the substrate temperature is around 200°C.

Example 2 As in Example 1, a mirror-finished stainless steel substrate was used as the substrate. A plasma CVD device was used to deposit 5i2Hs, B2Hs, and Hz on the substrate.

An amorphous silicon P layer was formed at a substrate temperature of 290° C. in a mixed He atmosphere. Next, 5izHs,
An amorphous silicon I layer was formed at a substrate temperature of 250° C. in a mixed atmosphere of Hz.

Finally, SiF4. A microcrystalline silicon N layer was formed at a substrate temperature of 250° C. in a mixed atmosphere of PHa 1H 21Ar. A transparent conductive film was deposited on the thus produced material using a magnetron sputtering device.

FIG. 5 shows the substrate temperature dependence of the charge conversion efficiency obtained with a 130 lux (Ix) white fluorescent knife. As can be seen from FIG. 5, the photoelectric conversion efficiency reaches its maximum at around 200° C., as in the case of the solar cell fabricated using SiH4 in Example 1.

In an amorphous silicon solar cell using Si2H6, the manufacturing temperature of the amorphous silicon is SiH.

Although it is higher than when using , it shows a similar trend.

FIG. 6 shows the dependence of photoelectric conversion efficiency on substrate temperature under AMI of 100 mW/2. In this case 250
Although the photoelectric conversion efficiency at 200° C. is almost the same as that at 200° C., the tendency is the same as in other cases. The board temperature is 2
It is thought that the decrease in photoelectric conversion efficiency at temperatures below 00°C is mainly due to a decrease in the transmittance of the transparent conductive film.
The cause of the decrease in charge conversion efficiency at temperatures above °C is not clear.

Example 3 In Example 1 and Example 2 described above, after depositing a transparent conductive film using a magnetron sputtering device,
Annealing treatment was performed at a temperature range of 150°C to 250°C for 1 minute to 60 minutes.

As a result, the transparency of the transparent conductive film increased, the sheet resistance decreased, and the charge conversion efficiency further improved.

<Effects of the Invention> As described above, the method for manufacturing an amorphous silicon solar cell of the present invention can reduce the substrate temperature from 150°C to 2°C during the transparent conductive film deposition step.
Since the temperature is maintained between 50° C., the photoelectric conversion efficiency of the amorphous silicon solar cell can be significantly improved.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the structure of an amorphous silicon solar cell, Figure 2 is a diagram showing the substrate temperature dependence of the specific resistance and transmittance of a transparent conductive film produced by sputtering, and Figure 3 is a diagram showing the substrate temperature dependence of a transparent conductive film fabricated by a sputtering method. Solar cell white fluorescent lamp 130 made by
Figure 4 shows the dependence of photoelectric conversion efficiency on substrate temperature when a transparent conductive film is attached under lux (Ix).
A M l of the solar cell produced using
Figure 5 shows the dependence of the photoelectric conversion efficiency on the substrate temperature when a transparent conductive film is attached under mW'/2.
Figure 6 shows the dependence of the photoelectric conversion efficiency on the substrate temperature when a transparent conductive film is attached under a white fluorescent lamp of 130 lux (Ix) for a solar cell fabricated using Si2H6. Battery AMI. FIG. 3 is a diagram showing the dependence of photoelectric conversion efficiency on substrate temperature at the time of attachment of a transparent conductive film under 100 rnW/b. DESCRIPTION OF SYMBOLS 1... Stainless steel substrate, 2... Amorphous silicon P layer, 3... Amorphous silicon I layer, 4...
Amorphous silicon N layer, 5... Transparent qsti agent Patent attorney Aihiko Fukushi (and 2 others) Fig. 1 & aLH)

Claims (1)

[Claims] 1. In an amorphous silicon solar cell, the substrate temperature during the process of attaching a transparent conductive film is adjusted from 150°C to 250°C.
A method for manufacturing an amorphous silicon solar cell characterized by maintaining the cell at between ℃. 2. The method of manufacturing an amorphous silicon solar cell according to claim 1, wherein the step of attaching the transparent conductive film is performed using a sputtering method. 3. The transparent conductive film adhesion step is carried out at 150°C after the transparent conductive film is attached.
2. The method for manufacturing an amorphous silicon solar cell according to claim 1, further comprising the step of annealing at a temperature in the range from 1 to 60 minutes.