JPS6253958B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to an optical semiconductor device including a thin optical semiconductor layer that produces a photoelectric effect upon irradiation with light.

(B) Background Art There are optical semiconductor devices that utilize the so-called photoelectric effect, which is a phenomenon in which photovoltaic force is generated or electrical conductivity is reduced by light irradiation. Conventionally, this type of optical semiconductor device has been formed from a single crystal material, but in recent years, new materials such as amorphous semiconductors have been attracting attention because they are easy to manufacture and are advantageous in terms of cost, and are being actively researched.

The present inventors have also developed solar cells and photo sensors made of PIN junction type amorphous silicon.

Figure 1 shows the basic structure of the above-mentioned PIN junction type amorphous silicon solar cell, where 1 is a glass plate. A transparent substrate made of heat-resistant plastic or the like with a thickness of about 1 to 3 mm,
2, tin oxide (Sno ₂ ), indium oxide (In ₂ O ₃ ), indium oxide. A transparent electrode layer with a thickness of about 2000 to 5000 Å made of tin (In ₂ O ₃ -Sno ₂ ), etc.; 3 is a silicon compound such as silane (SiH ₄ ); appropriate impurities are added to the atmosphere to cause a plasma reaction; thickness formed by
An optical semiconductor layer made of PIN junction type amorphous silicon with a thickness of about 5000 to 7000 Å, and 4 a back electrode layer with a thickness of about 2000 to 10000 Å, which is made by vapor-depositing a metal such as aluminum (Al) on the optical semiconductor layer 3; When light is irradiated from the other main surface of the transparent substrate 1, electrons and hole pairs are generated mainly in the I layer, and these move to the transparent electrode layer 2 and the back electrode layer 4 to emit light. Generates electromotive force.

However, as mentioned above, amorphous semiconductors such as amorphous silicon are formed by plasma reactions, etc., and the film thickness is usually about 5000 Å to 1 μm (in some cases, several μm), so it is a thin film on the order of microns. In particular, during the manufacturing process, there may be areas on the transparent electrode layer 2 where the amorphous semiconductor material is not adhered due to the surface conditions of the substrate 1 and the transparent electrode layer 2, adhesion of dust, etc. A pinhole 5 may be formed penetrating the optical semiconductor layer 3 made of an amorphous semiconductor material. Then, when the back electrode layer 4 is formed as described above on the optical semiconductor layer 3 having the pinholes 5, the pinholes 5
The back electrode material penetrates through the back electrode material, and the light-transmitting electrode layer 2 and the back electrode layer 4 are electrically short-circuited by the back electrode material.

(C) Disclosure of the Invention The present invention has been made in order to avoid short-circuit accidents between the light-transmitting electrode layer that sandwiches the optical semiconductor layer and the back electrode layer, which is applied after the optical semiconductor layer is formed. The present invention provides an optical semiconductor device in which pinholes are also formed in the electrode layer, the pinholes in the electrode layer communicate with the pinholes in the optical semiconductor layer, and the pinholes are electrically insulated. In the next section, an embodiment in which the present invention is applied to a PIN junction type amorphous silicon solar cell as in the conventional example described above will be described in detail. Needless to say, the optical semiconductor layer is not limited to amorphous silicon.

(d) Best Mode for Carrying Out the Invention FIG. 2 is a sectional view showing an embodiment of the present invention, and the same parts as in FIG. 1 are given the same numbers.
1 is a transparent substrate, 2 is a transparent electrode layer, 3 is a thin film-like optical semiconductor layer, 4 is a back electrode layer, and 5 is a layer that penetrates the optical semiconductor layer 3 when forming the optical semiconductor layer 3 on the thin film. The difference is that a pinhole 6 is also made in the back electrode layer 4, which is an electrode layer deposited after the formation of the optical semiconductor layer 3, and the pinholes 5 and 6 are made to communicate with each other. The holes 5 and 6 are electrically insulated.

A method for forming the pinholes 6 in the back electrode layer 4 will be explained below.

First, as described above, by plasma reaction in a silicon compound atmosphere, a thin optical semiconductor layer 3 made of amorphous silicon and having a thickness of approximately micron order or less is formed on a transparent electrode disposed on one main surface of a transparent substrate 1. A back electrode layer 4 is laminated by depositing on layer 2 and depositing a metal such as Al. At this point, the optical semiconductor layer 3
If a pinhole 5 is formed in the back electrode layer 4, the back electrode material penetrates through the pinhole 5 in the next step of vapor deposition of the back electrode layer 4, and the back electrode layer 4 and the transparent electrode layer 2 are electrically connected. It becomes a short circuit condition. On the other hand, optical semiconductor devices without pinholes 5 are formed that operate normally.

Next, defective products due to the short circuit are sorted out from non-defective products, and as shown in FIG. 3, the light beam 7 is irradiated from the other main surface of the transparent substrate 1 while scanning the plane with the light beam 7. When the short-circuit current of the optical semiconductor device is measured during plane scanning with this beam light 7, it is found that even if the beam light 7 is irradiated to the short-circuited pinhole 5, the short-circuit current does not flow, and the short-circuit current does not flow at a point separated from the pinhole 5. In this case, a short circuit current flows due to the movement of electron and hole pairs generated in the optical semiconductor layer 3. Therefore, the location of the pinhole 5 can be determined by scanning the plane of the beam 7 and measuring the short circuit current.

Finally, connect the pinhole 5 with a YAG with a peak output of 5×10 ⁶ W/cm ² from the back electrode layer 4 side as shown by arrow 8.
The output beam of the pulsed laser is radiated to dissipate and remove the back electrode material that has entered the back electrode layer 4 and the pinhole 5. That is, as shown in FIG. 2, the optical semiconductor layer 3 is coaxial with the pinhole 5 that is formed by penetrating the optical semiconductor layer 3 during the formation of the thin film optical semiconductor layer 3.
A pinhole 6 is formed in the back electrode layer 4 deposited after formation.
The pinholes 5 and 6 are made to communicate with each other, and the insides of the pinholes 5 and 6 are electrically insulated. At this time, even if the laser beam 8 reaches the transparent electrode layer 2 and dissipates the transparent electrode layer 2, it will not have any adverse effect on the characteristics of the device, and the transparent substrate 1
is thick enough that it will not penetrate.

Preferably, after forming the pinholes 5 and 6, the surface of the back electrode layer 4 is coated with a passivation film such as an insulating resin, and the pinholes 5 and 6 are filled with the passivation material.

Note that the substrate 1 in the above embodiment is made of glass. The case where the back electrode layer 4 is made of a transparent material such as heat-resistant plastic has been described, but when it is made of a metal material such as stainless steel, the metal material constitutes the back electrode layer 4, and the transparent electrode layer is formed after the optical semiconductor layer 3 is formed. 2 is applied,
A pinhole 6 communicating with the pinhole 5 of the optical semiconductor layer 3 is bored in the transparent electrode layer 2 . Further, the means for making the pinhole 6 in the electrode layer is not limited to the laser beam as described above, but may also be an energy beam such as an electron beam or a molecular beam. Furthermore, beam light 7
The radiation position of the energy beam may be scanned in conjunction with the scanning of the energy beam, and the radiation of the energy beam may be triggered by a sharp decrease in the short-circuit current by inputting the short-circuit current.

(E) Effect As is clear from the above description, the present invention provides a method in which a pinhole is formed in the electrode layer that is deposited after the formation of the optical semiconductor layer, coaxially with the pinhole that was formed through the formation of the optical semiconductor layer. Since both pinholes are connected and the insides of both pinholes are electrically insulated, the penetration of the electrode material into the pinhole of the optical semiconductor layer is eliminated, and the transparent electrode layer and the back electrode layer are Short circuit accidents can be avoided. Therefore, with a simple configuration, products that were previously considered defective due to short-circuit accidents can be treated as good products, improving yields during manufacturing, and reducing costs by using a thin optical semiconductor layer. Together, it becomes possible to further reduce the cost.

[Brief explanation of the drawing]

FIG. 1 shows a conventional example, FIG. FIG. 2 is a cross-sectional view schematically showing a main part of the manufacturing process. DESCRIPTION OF SYMBOLS 1... Transparent substrate, 2... Transparent electrode layer, 3... Thin film optical semiconductor layer, 4... Back electrode layer, 5, 6... Pinhole.

Claims (1)

[Claims] 1. A thin-film photosemiconductor layer that produces a photoelectric effect when irradiated with light, a transparent electrode layer provided on the light incident surface of the photosemiconductor layer, a back electrode layer that sandwiches the photosemiconductor layer together with the transparent electrode layer, A pinhole is formed in one of the electrode layers to be deposited after the formation of the optical semiconductor layer, coaxially with the pinhole that is formed through the optical semiconductor layer during the formation of the thin optical semiconductor layer. An optical semiconductor device characterized in that a pinhole in the optical semiconductor layer is made to communicate with a pinhole in one of the electrode layers, and the inside of the pinhole is electrically insulated.