JPH0262921A - Optical sensor - Google Patents

Abstract

PURPOSE:To accurately detect the intensity of incident light for the position shift of spot light by connecting adjacent lamination bodies about one point on a transparent conductive film so that the junction directions of P-I-N for bias voltages are opposite to each other. CONSTITUTION:For example, the lamination bodies (a)-(d) are formed divided as shown in a figure. Exposed parts 41a-41d are formed at parts of metallic electrodes 4a-4d and the electrodes 4a-4d are connected by conductive layers 5a and 5b through the exposed parts so that adjacent electrodes are not connected mutually. Terminals 6a and 6b to which the bias voltages are applied are formed at parts of the conductive layers 5a and 5b. Then if the incident light shifts in spot position and only the lamination bodies (a) and (b) operate as a sensor, the lamination bodies (a) and (b) are opposite in potential but the plus and minus bias voltages are applied to the terminals 6a and 6b, so opposite-directional photoelectric currents are generated in the lamination body (+a) and an output corresponding to the spot light incident on the lamination body (a) appears between the terminals 6a and 6b. Thus, the intensity detection with a small error can be performed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an optical sensor used in an optical measuring device, an optical switching element, etc., and particularly relates to a P-I-
This is an optical sensor using an N-junction amorphous semiconductor layer.

[Background of the invention]

The present inventor has developed a laminate consisting of an amorphous semiconductor layer and a metal electrode on a transparent substrate coated with a transparent conductive film as an optical sensor using a P-I-N bonded amorphous semiconductor layer. We proposed an optical sensor that is connected in opposite directions and applies a bias voltage to both stacked bodies (Japanese Patent Application No. 62-331620).

FIGS. 3(a) and 3(b) are a sectional view and a plan view showing the structure of the optical sensor.

The transparent substrate 31 is made of glass, translucent ceramic, or the like, and a transparent conductive film 32 is adhered to one main surface of the transparent substrate 31 .

The transparent conductive film 32 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 x and y on one main surface of the transparent substrate 31. .

The amorphous semiconductor layer 33 has at least metal electrodes 34X, 3
P-I-
An N junction is formed.

The metal electrodes 34x, 34y are formed on the amorphous semiconductor layer 33 with a rectangular interval.

As described above, the optical sensor has a structure in which diodes of the laminated body x and y, which are connected by P-I-N, are tied together.

Then, a constant bias voltage is applied between the metal electrodes 34x and 34y from an external circuit (not shown). Now, + to the metal electrode 34x of the laminate X, and the metal electrode 34y of the laminate y.
If a bias voltage is applied at -, a reverse bias will be applied to the amorphous semiconductor layer 33x on the side of the stacked body X, and a forward bias will be applied to the amorphous semiconductor layer 33y on the side of the stacked body Y.

In the dark state, the resistance between the metal electrodes 34x and 34y is the sum of the reverse resistance Rx of the laminate X and the forward resistance Ry of the laminate y, and the current flowing between the metal electrodes 34x and 34y is
This corresponds to the resistance (Rx+Ry).

In the bright state where light is irradiated from the transparent substrate 31 side of the above-mentioned photosensor, photovoltaic force is generated in the laminates X and y, but since they have opposite potentials, they cancel each other out, and in reality, the photovoltaic current does not flow. Although not present, since a + bias voltage is applied to the metal electrode 4X and a - bias voltage is applied to the metal electrode 4y, a reverse photocurrent (bright current) is generated in the laminated body a. Note that the diode of the stacked body y can be regarded as a resistor consisting of forward resistance.

The current between the two metal electrodes 34x and 34y is the metal electrode 4X of the stacked body X-NN-1 of the amorphous semiconductor layer 33X.
It flows into the layer-P layer-transparent conductive film 32-layer P layer-1 layer-N layer metal electrode 34y of the amorphous semiconductor layer 33Y of the stacked body y.

Here, the resistance (bias voltage/bright current) of the entire optical sensor appears to have decreased due to light irradiation, and it functions like a photoconductive type sensor. This results in
The illuminance-resistance value characteristic becomes linear, and the T value becomes approximately 1.

However, since the above-mentioned optical sensor has a structure in which diodes, which are P-IN junctioned stacked bodies x and y, are tied together, both stacked bodies x and y must be irradiated with light. For example, when the light-receiving surface of a photosensor is illuminated with the incident light that you want to detect as a spot, such as when adjusting the exposure of a camera, if you narrow down the incident light, the spot illumination position will shift slightly, and the laminated X
It is conceivable that only one of the laminates y and y will be irradiated. In such a case, the resistance value that is the same as that in the dark state or the bright resistance value that is less than a certain value is obtained, and there is a problem that the intensity of the incident light cannot be detected accurately. It was difficult to use it for this purpose.

[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 detect a spot even when the incident light to be detected is irradiated as a spot or when narrowing down the incident light. To provide an optical sensor in which incident light is irradiated onto a laminate X and a laminate y at the same time even if the irradiation position is slightly shifted, and there is no detection error due to the position of the spot incident light or the irradiation area.

[Specific means for solving the problem] According to the present invention, in order to solve the above-mentioned problem, an amorphous semiconductor layer P-IN bonded is formed on a transparent substrate coated with a transparent conductive film. In an optical sensor in which a plurality of stacked bodies are formed, each stacked body is formed of a plurality of stacked bodies each consisting of a metal electrode to which a bias voltage is applied. An optical sensor is provided in which the optical sensors are arranged such that the bonding directions of the optical sensors are connected in opposite directions.

〔Example〕

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

FIG. 1(a) is a plan view showing the structure of the optical sensor according to the present invention, FIG. 1(b) is a cross-sectional view taken along line x-X in FIG. 1(a), and FIG. 1(c) is a sectional view taken along the line y-y in FIG.

The optical sensor of the present invention is a laminate consisting of a transparent substrate 1 coated with a transparent conductive film 2, an amorphous semiconductor layer 3 bonded by P-I-N, and metal electrodes 4a to 4d to which a bias voltage is applied. A plurality of laminates a=d, for example four, are formed, and adjacent laminates a-d are arranged around one point on the transparent conductive film 2 so that the bonding directions of P-I-H with respect to the bias voltage are opposite to each other. They are arranged so that they are connected, that is, they have a structure that is divided into a square shape.

A transparent substrate 1 is made of glass or the like, and a transparent conductive film 2 is adhered to one main surface of the transparent substrate 1.

The transparent conductive film 2 is formed of a metal oxide film such as tin oxide, indium oxide, indium tin oxide, etc., and is formed to be a film common to at least the laminate a=d on one main surface of the transparent substrate 1. . Specifically, a mask is attached to one main surface of the transparent substrate 1, and the above-mentioned metal oxide film is deposited, or after a metal oxide film is deposited on one main surface of the transparent substrate 1, a resist is applied.・It is formed by etching.

The amorphous semiconductor layer 3 has a first conductivity type,
The second conductivity type and the third conductivity type are joined together, that is, they are formed by a P-I-N junction. Specifically, the amorphous semiconductor layer 3 is made of amorphous silicon deposited by a plasma CVD method or a photo CVD method in which a silicon compound gas such as silane or disilane is decomposed by glow discharge. is formed from a reactive gas containing silane gas mixed with a P-type doping gas such as diporane, 153I is formed using silane gas as a reactive gas, and NFi3N is formed from a reactive gas containing silane gas mixed with an N-type doping gas such as phosphine. .

The metal electrodes 4a to 4d are arranged radially on the amorphous semiconductor layer 3,
In other words, it is formed by being divided into a rice field shape. Specifically, in the photoetching method, the metal electrodes 4a to 4d are formed by depositing a metal film of nickel, aluminum, titanium, chromium, etc. on the amorphous semiconductor N3, and then depositing a metal film on the metal film using a spin code method or the like. Apply photoresist and pre-bake (~100
°C), exposure pattern, development, post-bake (120~
150° C.), immersion in an etching solution, peeling off the photoresist, and cleaning to form a predetermined pattern.

In addition, in the lift-off method, a photoresist is formed on the amorphous semiconductor layer 3 in a predetermined pattern in which the metal films of the metal electrodes 4a to 4d are not deposited, and a metal film of nickel, alumium, titanium, chromium, etc. is deposited. Then, at the same time as the photoresist is peeled off, unnecessary metal films are removed to form metal electrodes 4a to 4d in predetermined patterns.

In this way, a plurality of laminates a to d were formed by being divided into a square shape.Next, the connection of each laminate with the metal electrodes 4a to 4d and the application of bias voltage were performed. I will explain about it.

Metal electrodes 4 of the laminate a-d formed on the transparent substrate 1
Exposed portions 41a to 41d are formed in parts of a to 4d, and a protective film 5 made of insulating resin or the like is formed to cover the entire surface.

Then, the exposed portions 41a to 41
They are connected by conductive layers 5a and 5b via d. That is, the metal electrode 4a of the laminate a is not connected to the metal electrodes 4b and 4d of the adjacent laminates A and d (the metal electrode 4a of the laminate A is not connected to the metal electrodes 4b and 4d of the adjacent laminates A and D (i.e., the metal electrode 4a of the laminate A is not connected to the metal electrodes 4b and 4d of the adjacent laminates A and D). The metal electrode 4b of the laminate is connected to the metal electrode 4c of the laminate.
is connected to the metal electrode 4d of the stacked body d via the conductive layer 5b.

Thereby, the laminate a and the laminate C are connected to the laminates 1 and d through the transparent conductive film 2 in opposite directions.

Furthermore, a second insulating protective film 6 is coated on the stacked bodies a to d and the conductive layers 5a and 5b so as to form terminals 6a and 6b for applying a bias voltage to parts of the conductive layers 5a and 5b.

Specifically, the conductive layers 5a and 5b are formed by screen printing or the like using a material in which metal powder particles are mixed into a base material such as epoxy resin, acrylic resin, or phenol resin, and the second insulating protective film 6 is It is formed by screen printing a material in which a light-shielding pigment and a black colored pigment are added to a base material such as epoxy resin, acrylic resin, or phenol resin.

An external circuit (not shown) is connected between these terminals 6a and 6b.
A constant bias voltage is applied from .

Now, if a bias voltage of "+" is applied to the terminal 6a and a bias voltage of "-" is applied to the terminal 6b, the laminate a and the laminate.

A reverse bias is applied to the amorphous semiconductor layers 3a and 3C, and a forward bias is applied to the amorphous semiconductor layers 3b and 3d of the laminate d.

The operation of the optical sensor will be explained using the state in which the incident light is spotted as shown in FIG.

When the optical sensor is not irradiated with any incident light, each of the laminated bodies a''d functions as a resistor as described above.

The spot of incident light irradiated on the optical sensor is the laminate a
-d intersection point (spot 1), a photovoltaic force is generated for each stack a = d, but each stack a - d
Since they are at opposite potentials, they cancel each other out, and no current flow corresponding to the photovoltaic force occurs between the terminal 6a and the 6th layer. However, since a "+" bias voltage is applied to the terminal 6a and a "-" bias voltage is applied to the terminal 6b, a reverse photocurrent is generated in the laminates a and C, and the spot light is incident on the laminates a and C. An output corresponding to 1 is derived between the terminal 6a and the 6th layer. Note that the laminated bodies S and D can be regarded as resistors consisting of forward-directed diodes.

Next, when the spot irradiation position is slightly shifted and the light sensor is irradiated (spot 2) to narrow down the incident light, such as when adjusting the exposure of a camera, the laminate a that acts as a sensor is and b only. and,
Although a photovoltaic force is generated in the laminate a and the laminate 2 due to the light irradiation, each laminate a and the laminate 2 are at opposite potentials, so they cancel each other out, and the photovoltaic force is generated between the terminal 6a and the 6th layer. No current flow occurs. However, there is a "+" on terminal 6a.
Since a negative bias voltage is applied to the terminal 6b, a reverse photocurrent is generated in the laminate a, and an output corresponding to the spot light incident on the laminate a is output between the terminal 6a and the 6th layer. be done.

Next, when only the three stacked bodies bXc and d are irradiated with the spotlight (spot 3), only the stacked bodies S, c, and d function as sensors. Although photovoltaic force is generated in the laminate b, laminate C, and laminate d by the light irradiation, the laminate C is at an opposite potential to the laminates 1 and d, so it is canceled out, and the photovoltaic force is canceled out by the terminal 6a. , no current flow corresponding to the photovoltaic force occurs between the six layers. However, there is a "+" on terminal 6a.
Since a negative bias voltage is applied to the terminal 6b, a reverse photocurrent is generated in the laminate C, and an output corresponding to the spot light incident on the laminate C is derived between the terminal 6a and the 6th layer. be done. Note that the laminated body b11 and the laminated body d serve as forward diode, and can be regarded as a resistor connected in parallel through the conduction layer 5b.

In the present invention, in particular, the laminates a to d are divided and arranged, for example, in the shape of a square, centering on one center point of the substrate 1, and the adjacent laminates a = d are arranged. Because they are connected in opposite directions through the transparent conductive film 2, the incident light that you want to detect with the optical sensor is illuminated as a spot on a part of the optical sensor.Even in the case of an optical sensor used for adjusting the exposure of a camera, the incident light is a spot. Even if a slight positional shift occurs, the detection error is small and the intensity of the incident light can be detected accurately.

In the above-mentioned optical sensor, the laminate a to d is divided into four parts in a square shape, but 6.8
...It may be divided. In addition, the amorphous semiconductor layer is a P-T-
Although it is N-junction, from the glass substrate side, the N layer, IEt,
An amorphous semiconductor layer in which P layers are sequentially laminated may also be used.

〔Effect of the invention〕

As described above, the present invention forms a plurality of laminates each consisting of a P-I-N bonded amorphous semiconductor layer and a metal electrode to which a bias voltage is applied, on a transparent substrate coated with a transparent conductive film. In the optical sensor, adjacent stacked bodies are arranged around one point on the transparent conductive film at a P level relative to a bias voltage.
-1-H are arranged so that the bonding directions are opposite to each other, so even if the incident light that you want to detect with the optical sensor is irradiated as a spot on a part of the optical sensor, at least the adjacent laminates will be connected at the same time. The intensity of the incident light can be accurately detected even if the position of the spot light is shifted to the extent that the incident light can be irradiated, and the applications of the optical sensor can be expanded.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view showing the structure of the optical sensor according to the present invention, FIG. 1(b) is a cross-sectional view taken along line x-X in FIG. 1(a), and FIG. 1(c) is a sectional view taken along the line y-y in FIG. FIG. 2 is a plan view for explaining the operation of the optical sensor according to the state of the spot light incident on the optical sensor according to the present invention. FIGS. 3(a) and 3(b) are a sectional view and a plan view showing the structure of a conventional optical sensor. 1.31 ・ ・ 2.32 ・ ・ 3.33 ・ ・ 4a, 4b, 4c, 4d a, b, c, d ・ ・ Transparent substrate Transparent conductive film Amorphous semiconductor layer Metal electrode/laminate

Claims (1)

[Claims] An optical sensor in which a plurality of laminates each consisting of a P-I-N bonded amorphous semiconductor layer and a metal electrode for applying a bias voltage are formed on a transparent substrate coated with a transparent conductive film. An optical sensor, characterized in that adjacent laminates are arranged around one point on the transparent conductive film so that the P-I-N bonding directions relative to the bias voltage are connected in opposite directions.