JPH01220473A - light sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical sensor having an amorphous semiconductor layer used in optical measuring devices, optical switching elements, and the like.

(Prior Art) The present inventor has developed a method of applying a transparent conductive film onto a transparent substrate.
An optical sensor is constructed by forming a plurality of stacked bodies of an amorphous semiconductor layer in which a first conductivity type, a second conductivity type, and a third conductivity type are bonded, and a metal electrode to which a bias voltage is applied. Proposed.

FIG. 4 is a structural diagram of the optical sensor.

This optical sensor has a structure in which two laminates a and b, each consisting of a transparent conductive film 2 and a metal electrode 4 sandwiching an amorphous semiconductor layer 3 bonded to each other by P-1-N, are joined together.

The transparent substrate 1 is made of glass, translucent ceramic, etc.
A transparent conductive film 2 is adhered to the entire surface of the transparent substrate 1.

The transparent conductive film 2 is formed of a metal oxide film such as tin oxide, indium oxide, or indium tin oxide, and is formed to be a film common to at least the laminates a and b on the entire surface of the transparent substrate 1.

The amorphous semiconductor layer 3 has a first conductivity type, a second conductivity type, and a second conductivity type, at least in the laminated body parts a and b where the metal electrodes 4a and 4b are formed.
conductivity type and the third conductivity type are joined, that is, a P-1-N junction is formed.

The metal electrodes 4a and 4b are formed on the amorphous semiconductor layer 3 at predetermined intervals.

An external circuit (not shown) is provided between the metal electrodes 4a and 4b.
For example, a constant bias voltage is applied to the metal electrode 4a of the stacked body A, and - to the metal electrode 4b of the stacked body A.
If a bias voltage is applied at , a reverse bias will be applied to the stacked body a side, and a forward bias will be applied to the stacked body side.

In the dark state, the resistance between the metal electrodes 4a and 4b is the sum of the reverse resistance of the laminate a and the forward resistance of the laminate A.

In a bright state in which light is irradiated from the transparent insulating substrate 1 side of the photosensor, a current flows between the metal electrode 4a of the laminate a - the N layer 33 - 1 of the amorphous semiconductor layer 32 - 2 layer 31 - the transparent conductive film 2 - Two layers of amorphous semiconductor layers in the laminate 31-1 layer 32-N layer 3
3- Flows to metal electrode 4b. That is, the resistance between the metal electrodes 4a and 4b is the sum of the reverse resistance of the laminate a and the forward resistance of the laminate A, but a reverse photocurrent is generated in the laminate a, and the laminate is forward biased. So it acts as a resistance.

Therefore, the resistance of the entire optical sensor appears to decrease due to light irradiation, and it functions like a photoconductive sensor. As a result, the illuminance-resistance value characteristic becomes linear, and the T value becomes approximately 1.

[Problems with conventional technology]

However, the above-mentioned optical sensor has metal electrodes 4a, 4b.
Since the amorphous semiconductor layer 3 sandwiched between the transparent conductive film 2 and the amorphous semiconductor layer 3 has a low breakdown voltage, the externally applied bias voltage had to be kept low.

Also, the dark current becomes too high, 1xlO-12A/cm
I couldn't get it below 2.

[Object of the present invention]

The present invention was devised in view of the above-mentioned problems with optical sensors, and its purpose is to reduce dark current even under strong irradiation light, to be easily usable even with alternating current, and to have high voltage reliability. The present invention provides an improved optical sensor.

[Specific means for solving the problems] According to the present invention, in order to solve the above problems, an amorphous semiconductor layer is formed on a transparent substrate on which a plurality of transparent conductive films are formed. ,
An optical sensor in which a conductive film is formed on an amorphous semiconductor layer corresponding to the interval between at least two adjacent transparent conductive films (INI) so as to overlap a part of both transparent conductive films via the amorphous semiconductor layer. is provided.

〔Example〕

Hereinafter, the optical sensor of the present invention will be explained in detail based on the drawings.

FIG. 1 is a sectional view showing the structure of an optical sensor according to the present invention.

In the optical sensor of the present invention, a plurality of, for example, three, transparent conductive films 2a to 2c are formed on a transparent substrate 1, an amorphous semiconductor layer 3 is formed continuously to the transparent conductive films 2a to 2c, and further Electrodes 4a and 4b to which a bias voltage is applied on the amorphous semiconductor layer 3 and two adjacent transparent conductive films 2a and 2
A conductive film 5a at a position corresponding to the gap between b, 2b, and 2C,
5b is formed.

The transparent substrate 1 is made of glass, translucent ceramic, etc.
Transparent conductive films 2a to 2c are attached to the entire surface of the transparent substrate 1.

The transparent conductive films 2a to 2c are formed of metal oxide films such as tin oxide, indium oxide, and indium tin oxide. Specifically, a mask is attached to the entire surface of the transparent substrate 1 and the metal oxide film described above is deposited, or after a metal oxide film is deposited on the entire surface of the transparent substrate 1, resist etching is performed. It is formed by processing.

The amorphous semiconductor layer 3 is formed so as to continuously cover the transparent conductive films 2a to 2c, and a P-I-N junction is formed. Specifically, the amorphous semiconductor layer 3 is made of amorphous silicon deposited by a plasma CVD method or a photo CVD method in which silicon compound gas such as silane is decomposed by glow discharge, and the second layer 31 is made of silane gas. 17m32 is formed with a reactive gas mixed with P-type doping gas such as diborane, 17m32 is formed with silane gas as a reactive gas, and N)'633 is formed with a reactive gas mixed with silane gas with an N-type doping gas such as phosphine. .

The metal electrodes 4a, 4b are formed so as to partially overlap the transparent conductive films 2a, 2C with the amorphous semiconductor layer 3 in between.

The conductive films 5a and 5b are two adjacent transparent conductive films 2a.
, 2b and 2b, 2c so that they overlap with each other with the amorphous semiconductor layer 3 in between. It is formed. The shapes of the conductive films 5a and 5b are two adjacent transparent conductive films 2a, 2b and 2b.

Two transparent conductive films 2 with the same width as the interval of 2C or adjacent to each other
The width is set wider than the distance so that it partially overlaps a, 2b, 2b, and 2c.

Specifically, metal electrodes 4a, 4b and conductive film 5a.

5b is formed in the same process, and a mask of a predetermined shape is attached on the amorphous semiconductor layer 3, and metals such as nickel, alumium, titanium, and chromium are deposited on the amorphous semiconductor layer 3. After depositing a metal film of aluminum, titanium, chromium, etc., a resist etching process is performed to form a predetermined pattern. Preferred metals include metal electrode 4a,
4b and the external lead are made of nickel which can be easily soldered.

Finally, in order to prevent unnecessary light from entering from sources other than the transparent substrate 1 and to enable accurate light detection, only the part where the solder layer 6 will be formed is opened, and the back side is covered with an insulating layer containing a light-shielding pigment. It is covered with a membrane 7. If the insulating protective film 7 is made of an epoxy resin that is heat resistant and cannot be soldered, for example containing a light-shielding pigment, the solder layer 6 can be formed very easily by applying solder after forming the insulating protective film 7. be done.

FIG. 2 is an equivalent circuit diagram in which a constant bias voltage is applied from an external circuit to the metal electrode 4a of the optical sensor shown in FIG. 1 and to the metal electrode 4b of the laminated body.

For the sake of explanation, the part where the amorphous semiconductor layer 3 is sandwiched between the metal electrode 4a and the transparent conductive film 2a is referred to as the laminate U, and the part where the amorphous semiconductor layer 3 is sandwiched between the conductive film 5a and the transparent conductive film 2a. A laminate ■, a part where the amorphous semiconductor layer 3 is sandwiched between the conductive film 5a and the transparent conductive film 2b are a laminate W, a part where the amorphous semiconductor layer 3 is sandwiched between the conductive film 5b and the transparent conductive film 2b. The laminate
, the part where the amorphous semiconductor layer 3 is sandwiched between the conductive film 5b and the transparent conductive film 2c is a laminate y, the metal electrode 4b and the transparent conductive film 2
The part in which the amorphous semiconductor layer 3 is sandwiched between the two layers is called a laminate 2, and the amorphous semiconductor layer 3 is laminated with a P layer, a 1 layer, and an N stone from the substrate side, and each gold electrode 4a, 4b, and a conductive layer. The distance between the films 5a, 5b and the transparent conductive films 2a to 20 is greater than the thickness of the amorphous semiconductor layer 3.

In the equivalent circuit diagram shown in FIG. 2, in the dark state, although a bias voltage is applied between the metal electrodes 4a and 4b, the resistance Rab between the metal electrodes 4a and 4b is
It is the sum of the reverse resistance of w and y and the forward resistance of the stacked body V+X+Z. The resistor Rab is Ru+Rv+Rw+Rx+R since each stacked body u-Z is connected in series.
It is equivalent to y+Rz.

In the bright state, although holes and electrons are generated in each stack u-Z, reverse photocurrents are generated in the stacks u, w, y, and forward photocurrents are generated in the stacks v, x, z. occurs. That is, the stacked bodies v, x, z are the forward diodes Dv, Dx, Dz, and the stacked bodies u, w, y
are the resistances Ru, Rw, and Ry, and the resistance Rab between the metal electrodes 4a and 4b is equivalent to Ru+Rw+Ry.

As described above, even in an optical sensor having a P-1-N junction amorphous semiconductor layer 3 whose resistance value is difficult to control due to an increase in film thickness, two adjacent transparent conductive films 2a
, 2b and the conductive film 5 at a position corresponding to the spacing between 2b and 2c.
By forming elements a and 5b, the resistance values in the dark state and bright state can be tripled in relative value. That is, a plurality of transparent conductive films 2a.

At least two transparent conductive films 2a, 2b, 2c, .
If conductive films 5a, 5b, 5c, + are formed on the amorphous semiconductor layer 3 with intervals of 2b, 2b, 2c, . . . , conductive films 5a, 5b, 5c, . The resistance value can be set to an arbitrary value of 2.3.4 times, and the dark current can be set freely.

In addition, this increase in resistance value allows the external bias voltage to be distributed to a plurality of resistors, so that even if the bias voltage becomes relatively high, it can be sufficiently withstood, and high voltage reliability is improved.

Furthermore, when the polarity of the bias voltage is reversed so that one layer is applied to the metal electrode 4a and the other is applied to the metal electrode 4b, the functions of the layers u, w, y and the layers v, x, z are reversed. Therefore, it is an optical sensor that can be used without any problems and can be easily used even with alternating current. FIG. 3 is an equivalent circuit diagram showing another method of using the present invention.

The optical sensor of the present invention includes metal electrodes 4a, 4b and a conductive film 5.
Since conductive films 5a, 5b, 5c, . . . are formed simultaneously, one or two of the conductive films 5a, 5b, 5co, .

Metal electrodes 4a, 4b or conductive films 5a, 5b, 5
C01, transparent conductive films 2a, 2b, 2c, .
b, 5c, . . . are used as electrodes to which a bias voltage is applied, a large number of resistance characteristics can be obtained from the -(II) optical sensor. In Fig. 3, the relationship between metal electrode 4a and metal electrode 4b A first resistance component Rab is obtained between the metal electrode 4a and the conductive film 5c, and a second resistance component Rac is obtained between the metal electrode 4a and the conductive film 5c.

In the above embodiment, the amorphous semiconductor layer is formed so as to continuously cover the transparent conductive layer, and a P-I-N junction is formed. An amorphous semiconductor layer may be used, and during the assembly process, part or all of the amorphous semiconductor layer between the metal electrode and the conductive film or between the adjacent conductive layers may be removed by laser irradiation or etching. I don't mind.

Further, although the γ value is approximately 0.5, the amorphous semiconductor layer may be formed as a single layer.

〔Effect of the invention〕

As described above, the present invention includes forming a plurality of transparent conductive films on a transparent substrate, forming an amorphous semiconductor layer continuously on the transparent conductive films, and furthermore forming a non-crystalline semiconductor layer between at least two transparent conductive films. Since a conductive film is formed on the crystalline semiconductor layer, the structure has a series-connected layered structure whose resistance value characteristics change with light irradiation. can be set to a predetermined value.

In addition, since the electrode to which bias is applied has no polarity, it can be easily used even with alternating current.Furthermore, the bias voltage can be increased depending on the number of conductive ++g formed, and high voltage resistance reliability is improved.

Furthermore, if the output is taken between any two of the metal electrodes or the plurality of conductive films, a plurality of types of resistance characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an optical sensor according to the present invention. FIG. 2 is an equivalent circuit diagram of the optical sensor shown in FIG. 1. FIG. 3 is an equivalent circuit diagram showing another method of using the optical sensor of the present invention. FIG. 4 is a structural diagram of a conventional optical sensor. 1...Retired substrates 2a, 2b, 2c...Transparent conductive film 3...Amorphous semiconductor layer 4a, 4b...
... Metal electrodes 5a, 5b, 5c... Conductive film

Claims (1)

[Claims] An amorphous semiconductor layer is formed on a transparent substrate on which a plurality of transparent conductive films are formed, and the amorphous semiconductor layer is placed on the amorphous semiconductor layer corresponding to the space between at least two adjacent transparent conductive films. An optical sensor in which a conductive film is formed so as to overlap part of both transparent conductive films through the transparent conductive film.