JPS6246278Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an amorphous semiconductor light receiving device.

2. Description of the Related Art As the use of optoelectronic technology becomes more active, demand for light receiving devices that electrically detect light, so-called optical sensors, is expanding in various fields. Conventionally, this type of photodetector has formed a PN junction or PIN junction by diffusion on a semiconductor substrate made of single crystal silicon, but in recent years, (hydrogenated) amorphous silicon, amorphous silicon, etc. have been used to realize low-cost solar cells. Amorphous semiconductors such as silicon carbide and fluorinated amorphous silicon have been in the spotlight, and the inventors of the present invention are attempting to use such amorphous semiconductors in light receiving devices.

FIG. 1 is a cross-sectional view of a light receiving device equipped with the amorphous semiconductor described above, in which 1 is a transparent substrate made of a heat-resistant insulating material such as glass or acrylic resin, and 2 is a main body of the transparent substrate 1. The photoreceptor 2 has a light-transmitting first electrode film 3 made of tin oxide, indium oxide, indium tin oxide, etc., a P-type layer, a non-doped (I-type) layer, It consists of a laminate in which an amorphous semiconductor film 4 having a three-layer structure of N-type layers and a second electrode film 5 made of a conductive metal such as aluminum, chromium, silver, etc. are laminated in sequence. The periphery of the amorphous semiconductor film 4 of the photoreceptor 2 extends outward from the effective light receiving area defined by the first electrode film 3 and the second electrode film 5 facing each other. There is.

Conventionally, in manufacturing this type of light receiving device, a plurality of light receiving devices are formed on a large transparent substrate 1 at the same time. At this time, the amorphous semiconductor film 4 is deposited over the entire area of the large transparent substrate 1 on which the first electrode film 3 is selectively formed by a well-known plasma discharge method, or by using a mask. and selectively deposited in a desired pattern. When using a normal mask, it is difficult to process it into a fine shape compared to the case where the amorphous semiconductor film 4 is deposited over the entire area and then patterned using photolithography technology. Photolithography technology is generally applied during manufacturing.

However, the P-type, I-type, and N-type layers are exposed at the peripheral edge portion 4e of the amorphous semiconductor film 4 patterned by this photolithography technique, and a second electrode film is formed on this edge portion 4e. When 5 touches,
Dark current flows in the low illuminance region, causing an undesirable phenomenon for a light receiving device that lacks linearity in the light amount vs. photocurrent characteristics.

Therefore, as shown in FIG. 1, the peripheral edge portion 4e of the amorphous semiconductor film 4 is prevented from coming into contact with the second electrode film 5, which defines the effective light receiving area.
The periphery extends further outward.

However, according to such a structure, the amorphous semiconductor film 4
Although we were able to improve the linearity of the light intensity vs. photocurrent characteristic caused by the peripheral edge portion 4e, the gamma γ value, which represents the slope of the light intensity vs. photocurrent characteristic, was as shown by the broken line in Figure 2. It had the disadvantage that it becomes smaller in the low illuminance area (approximately 10 Lux or less) than 1. In particular, light receiving devices for cameras that measure reflected light from a subject are required to have a γ value of 1 even in a low illuminance region of 10 Lux or less, with the development of highly sensitive films.

In order to make the γ value 1 even in such a low illuminance area, the present invention conducted an experiment to investigate the cause. That is, the beam spot 6 as shown by the arrow in FIG.
After passing through the effective light-receiving areas B to C defined by the first and second electrode films 3 and 5 facing each other from the peripheral edge A of the amorphous semiconductor film 4, the area extending from the peripheral edge D to the peripheral edge D was irradiated. The relative sensitivity characteristics shown in FIG. 3 were obtained. As a result, it was found that the γ value becomes smaller than 1 in the low illuminance region because a photocurrent flows due to light reception at the peripheral edge of the amorphous semiconductor film 4 located at A to B and C to D. Although the photocurrent at the periphery is observed even in the high irradiation area, the photocurrent at the effective light receiving area is so large that it can be ignored, and the γ value becomes substantially 1 in the high irradiation area.

The present invention was developed in consideration of the γ value in such a low illuminance area, and is shown in Figures 4 and 5 below.
Embodiments of the present invention will be described in detail based on the drawings.

FIG. 4 is a sectional view of one embodiment of the present invention, and FIG. 5 is a sectional view of another embodiment, which corresponds to the conventional example shown in FIG. 3 is a first electrode film, 4 is an amorphous semiconductor film, and 5 is a second electrode film. It is at the point that I have set. That is, in the embodiment shown in FIG. 4, the light shielding body 7 is provided on the light-receiving side surface of the light-transmitting substrate 1, and a small-area window is provided inward from the periphery of the amorphous semiconductor film 4 in the center thereof. It has a transparent portion 8 having a shape. Since the light-transmitting portion 8 having such a small area regulates the light irradiated to the amorphous semiconductor film 4, basically the light-receiving body divided by the first and second electrode films facing each other is divided. It is preferable that it coincides with the effective light receiving area. On the other hand, in the other embodiment shown in FIG. 5, the light shielding body 7 is provided on the same surface as the light receiving body 2 of the light-transmitting substrate 1, and the first electrode film 3 is located in the light-transmitting part 8. That is, in this embodiment, since the outer circumferential wall of the first electrode film 3 and the inner circumferential wall of the light shielding body 7 are in contact with each other, the effective light-receiving area and the light-transmitting portion 8 coincide. The light shielding body 7 is made of black resin such as silicone resin mixed with carbon black, black paint, photoresist, or metal especially on the light receiving side surface as shown in FIG. 4, and a light receiving device is incorporated therein. A frame such as a package may also be used.

When the light-transmitting portion 8 and the effective light-receiving area coincide, the light irradiated onto the amorphous semiconductor film 4 is blocked by the light-shielding body 7 at the periphery where it has an adverse effect, and the effective light-receiving area is reach only. Therefore,
The generation of photocurrent in the photoreceptor 2 occurs only in the effective light-receiving area that is irradiated with light, and approximately γ = 1 depending on the amount of light irradiation.
photocurrent flows.

The light shielding body 7 is an inverted pattern of the first electrode film 3, and when forming the first electrode film 3 by photolithography, the photomask can be changed depending on whether the photoresist used is positive or negative. It can also be used in common, and is particularly useful in the embodiment of FIG. 4 when metal is used as the light shielding body 7.

As is clear from the above description, the light-receiving device of the present invention is provided with a light-shielding body having a light-transmitting part of a small area inward from the periphery of the amorphous semiconductor film on the light-receiving side of the light-receiving body. It is possible to block light irradiated to the periphery of the amorphous semiconductor film and suppress photocurrent generated at the periphery. Therefore, the photocurrent which cannot be ignored in the low illuminance region generated at the periphery is reduced, and the γ value can be made approximately 1.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the conventional device, Fig. 2 is a characteristic diagram showing the light amount versus photocurrent characteristics of the conventional device, and Fig. 3 is a curve diagram showing the relative sensitivity depending on the position of the conventional device.
FIG. 4 shows a sectional view of one embodiment of the device of the present invention, and FIG. 5 shows a sectional view of another embodiment of the device of the present invention. 2... Photoreceptor, 3... First electrode film, 4... Amorphous semiconductor film, 5... Second electrode film, 7... Light shielding body, 8... Light transmitting portion.

Claims (1)

[Scope of utility model registration request] The first electrode film or the second electrode film is placed on the light receiving side of a photoreceptor in which a first electrode film and a second electrode film of a small area are arranged inward from the periphery of both the front and back surfaces of a thin film-like amorphous semiconductor film. An amorphous semiconductor light-receiving device characterized in that a light-shielding body is provided, the light-transmitting part having approximately the same area as the electrode film and blocking light irradiated onto the periphery of the amorphous semiconductor film.