JPH02168677A - Semiconductor device - Google Patents

Abstract

PURPOSE:To weld an inter-connector to a metallic electrode without lowering the characteristics of the electrode by forming a reflection preventing film and the electrode on an insulating film by extending a p-n junction section and the connecting section of the electrode with GaAs in the GaAs layer of an area which is formed on the side nearer to an Si substrate and has a p-n junction. CONSTITUTION:A p-n junction is formed on the surface of an Si substrate 1 by forming an insulating film 9 at part of the surface and selectively forming a GaAs layer 2 at the other part of the surface and, at the same time, a reflection preventing film 6 and metallic electrode 7 are formed by forming the part of the p-n junction section near the insulating film 9 near the substrate 1 and extending the p-n junction section onto the film 9. The electrode 7 is brought into contact with a p-type GaAs layer 4 through a contact hole opened in the film 6 and a p-type AlGaAs layer 5 and, at the same time, extended onto the film 9 formed on the substrate 1. The extended section of the electrode 7 becomes a welding section to which an inter-connector is welded. Therefore, the GaAs solar cell section of the electrode 7 is not destroyed by the thermal damage given at the time of welding.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a lightweight and high-performance semiconductor device,
In particular, it relates to the electrode structure of solar cells.

[Conventional technology]

Figure 2 shows, for example, the conventional Ga
FIG. 1 is a cross-sectional view showing an As on Si solar cell. In this figure, 1 is a Si substrate, 2 is an n-type GaAs layer epitaxially grown on this Si substrate 1, and 3 is a superlattice layer of GaAs and AlGaAs (hereinafter referred to as GaAs/AlGaAs, S, L ), 2′
4 is an n-type GaAs layer as an active layer of the solar cell, and 4 is formed on the n-type GaAs layer formed on the GaAs/AnGaAs, S, L3. An n-type GaAs layer 5 for forming a p-n junction that absorbs and generates electricity is formed on this n-type GaAs layer 4 and serves as a window layer of the solar cell.
s layer, 6 is an anti-reflection film (hereinafter referred to as ARC) to allow as much light as possible to enter the inside of the solar cell, and 7 is a hole made in this ARC 6 and the p-type AJ2GaAs layer 5 so as to contact the n-type GaAs layer 4. A p-side metal electrode 8 is formed by patterning on the Si substrate 1 for effectively collecting and extracting photocurrent generated by light irradiation to the outside.
This is an n-side metal electrode formed on the back side of the .

Next, the operation will be explained.

p-type G through ARC6 and p-type AflGaAs layer 5
The light incident on the aAs layer 4 and the n-type GaAs layer 2' is
In this region, it is absorbed and converted into electron and hole carriers,
Electrons generated in the p-type GaAs layer 4 pass through the p-n junction and
The holes generated in the GaAs layer 2' diffuse into the p-type GaAs layer 4 through the p-n junction, and the positive charges are collected on the p-side metal electrode 8i7 and the negative charges are collected on the n-side metal electrode 8. A voltage is generated between these terminals, and current can be extracted from between these terminals.

(Problems to be Solved by the Invention) Conventional GaAs on Si solar cells are configured as described above, so in principle there seems to be no problem in extracting current, but when actually used as a solar cell, there are It is necessary to connect an interconnector for current extraction to the p-side metal electrode 7 and the n-side metal electrode 8. For this connection, GaAs on GaAs thick
A highly reliable parallel gap welding method is generally used for batteries, etc., but if this method is applied to a GaAs on Si solar cell with the structure shown in Figure 2, the p-side metal electrode 7 will be damaged due to thermal damage. There was a practical problem in that the underlying GaAs layer 4 was destroyed and the solar cell characteristics were significantly degraded.

This invention was made in order to solve the above-mentioned problems, and the purpose is to obtain a semiconductor device in which an interconnector can be welded to a metal electrode without deteriorating the characteristics (in order to solve the problem) Means) In the semiconductor device according to the present invention, an insulating film is formed on a part of a Si substrate, a GaAs layer is selectively grown on the other part to form a pn junction, and a part of the Si substrate near the insulating film is grown. A pn junction is formed on the side closer to the Si substrate, and is extended onto the insulating film to form an antireflection film and a metal 'fH,
A contact portion of this metal electrode with the GaAs layer is formed in the GaAs layer in a region having a pn junction formed on the side closer to the Si substrate.

(Function) In this invention, the welded portion of the metal electrode interconnector is formed not on the active layer of the semiconductor device but on the insulating film on the Si substrate, which is functionally just a holding material. Welding the interconnector does not reduce the characteristics.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, 1 is a Si substrate, S is an insulating film formed on this Si substrate 1, 2 is an n-type GaAs layer selectively grown on the Si substrate 1 on which this insulating film 9 is formed, and 3 is this n-type GaAs layer. GaAs/GaAs for strain relaxation formed on the type GaAs layer 2
AlGaAs,S.

L12' is an n-type GaAs layer, and a part of it, that is, a part near the extension of the p-side metal electrode 7 onto the insulating film 9, is made p-type. 4 is a p-type GaAs layer formed on the n-type GaAs layer 2', 5 is a p-type AuGaAs layer as a window layer of the solar cell, and 6 is an ARC (anti-reflection coating), which is insulating in this embodiment. 5t3N4 is assumed, and the GaAs crystal end face including the pn junction and the insulating film 9
is also passivated. 7 is the ARC6 and p
Contact is made with the p-type GaAs layer 4 through the contact hole made in the type AA GaAi 9 layer 5, and the extension thereof extends onto the insulating film 9 formed on the Si substrate 1, thereby forming a welding part to which the interconnector is welded. The p-side metal electrode 8 is an n-side metal electrode formed on the back surface of the Si substrate 1.

Since the basic operating principle of the solar cell of this invention is the same as that of the conventional example, its explanation will be omitted, and the effect exerted by the structure of this embodiment will be described.

First, by forming the interconnector weld on the Si substrate 1, the GaAs solar cell part will not be destroyed by heat damage during welding, and therefore the solar cell characteristics will not deteriorate. .

Second, since the insulating film 9 on the Si substrate 1 conducts heat less easily than GaAs or the like, the energy input during welding can be reduced, further reducing damage to the solar cell.

This makes it possible to weld interconnectors, which is currently impossible in practice, at a practical level.

Thirdly, if an insulating film such as SiO2 is first formed on the Si substrate 1 and GaAs is grown, the subsequent etching process can be simplified due to the selectivity that GaAs does not grow on the 5in2. In a manufacturing method in which the thick part of the GaAs battery is first formed and the insulating film is formed later, the G
Productivity was an issue, as the insulating film had to be formed at a temperature of 200°C to prevent thermal damage to the aAs solar cells, and a process for etching several types of GaAs films was required. Become.

Fourth, since the p-side metal electrode 7 is extended on the insulating film 9, the p-side metal electrode 7 is
If it comes into contact with the solar cell, the characteristics of the solar cell will become short-circuited and it will no longer function. To avoid this, the n-type GaAs layer 2' in the region below the p-side metal electrode 7 that does not contribute to power generation is made p-type, and the p-n junction is lowered to a position as far away from the p-side metal electrode 7 as possible, and then insulated. It was passivated with a reflective anti-reflection film 6.

In addition, although the solar cell was explained in the above example, G
Other semiconductor devices having an aAs on Si structure may also be used, and the same effects as in the above embodiments can be achieved.

〔Effect of the invention〕

As explained above, the present invention forms a pn junction by forming an insulating film on a part of a Si substrate and selectively growing a GaAs layer on other parts, and also forms a pn junction on a part of the Si substrate near the insulating film. A bonding portion is formed on the side closer to the Si substrate,
An anti-reflection film and a metal electrode are formed by extending it onto the insulating film, and the connection portion of this metal electrode with the GaAs is made of S.
G of the region with the pn junction formed on the side closer to the i-substrate
Since it is formed in an aAs layer, if this is applied to a solar cell, a practical GaAs on Si solar cell can be manufactured at high yield and at low cost.

[Brief explanation of the drawing]

FIG. 1 shows a GaAson S according to an embodiment of the present invention.
A cross-sectional structural diagram showing an i solar cell, Figure 2 is a conventional GaAs
FIG. 2 is a cross-sectional structural diagram showing an on-Si solar cell. In the figure, 1 is a Si substrate, 2 is an n-type GaAs layer, 2'
3 is an n-type GaAs layer with a part of it being p-type, and 3 is a GaAs/A layer.
JZGaAs, S, L, 4 is a p-type GaAs layer, 5 is a p-type AJ2GaAs layer, 6 is an insulating antireflection film, 7 is a p-side metal electrode, 8 is an n-side metal electrode, and 9 is an insulating film. Note that the same reference numerals in each figure indicate the same or corresponding parts. Figure 1 Figure 2 Agent Masuo Oiwa (2 others) 1. Indication of the case 29. Title of the invention 3. Authorized letter of the person making the amendment (spontaneous) Japanese Patent Application No. 1988-324235 Semiconductor device Representative 5, detailed description of the invention column 2 of the specification subject to amendment, brief description of the drawings column 6, contents of the amendment (1) 1i111J detailed description, page 2, lines 6-7, line 29,
rGaAs/AlGaAs, S, on page 5, lines 16-17;
LJ is rGaAs/AjGaAs S, L
Correct with J. (2) Similarly, on page 3, line 8, “through the pn junction” is changed to r
to the n-type GaAs layer 2 through the p-n junction.'' (3) Similarly, on page 7, line 17, "on the insulating film 9" is corrected to "up to the insulating film 9". (4) rGaAs/AlGaAs on page 9, line 10
, S, LJ, [Ga'As/A, 1'GaAs5. L
Correct with J. that's all

Claims (1)

[Claims] An insulating film is formed on a negative part of the Si substrate, and a GaAs layer is selectively grown on other parts to form a pn junction, and a part of the pn junction near the insulating film is formed on the Si substrate. An antireflection film and a metal electrode are formed on the side closer to the Si substrate and extended to the top of the insulating film, and a connection portion of the metal electrode with the GaAs layer has a pn junction formed on the side closer to the Si substrate. A semiconductor device characterized in that it is formed on a GaAs layer in a region.