JPH0294670A - Photosensor - Google Patents

Abstract

PURPOSE:To detect infrared rays accurately and with good sensitivity by a method wherein a filter layer used to cut off light in a visible-ray region from the incident side of light and a fluorescent substance layer are formed on one main face of a transparent substrate. CONSTITUTION:Light of a wavelength in a visible-ray region, e.g., light (region B) of 700nm or lower, is cut off by a visible-ray cutoff filter layer 3. Accordingly, this sensor does not react at all to the light of the wavelength in the visible- ray region by direct irradiation. Then, light of a wavelength other than light of the wavelength in the visible-ray region, e.g., light (region A) in a long- wavelength region of 700nm or higher, reaches a fluorescent-substance layer 6; the fluorescent substance layer 6 is excited; a light energy of the wavelength (region A) according to a spectroscopic sensisivity of an amorphous silicon semiconductor layer 3 is radiated toward the amorphous silicon semiconductor layer 3. That is to say, the light in the long-wavelength region is converted into a wavelength according to the spectroscopic sensitivity of the amorphous silicon semiconductor layer 3. Thereby, only infrared rays are detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an infrared region sensitive optical sensor used in optical measuring devices, optical switching elements, etc.

[Background of the invention]

Conventionally, a stacked diode having an amorphous silicon semiconductor layer with a P-T-N junction is tied together in opposite directions,
There was a combined type optical sensor that applied a bias voltage between both laminates (Japanese Patent Application No. 331620/1982).
.

FIG. 4 is a sectional view showing the structure of the optical sensor.

The transparent substrate 41 is made of glass, translucent ceramic, or the like, and a transparent conductive film 42 is adhered to one main surface of the transparent substrate 41 . The transparent conductive film 42 is made of tin oxide, indium oxide,
An amorphous silicon semiconductor layer 43 is formed of a metal oxide film such as indium oxide or tin oxide, and is formed on one main surface of the transparent substrate 41 (both are formed as a film common to the stacked bodies x and y). is formed in a P-1-N junction at least in the portion where the metal electrodes 44x and 44y are formed.

The metal bridges 44x and 44y are made of amorphous silicon semiconductor layer 4.
3 are formed in a rectangular shape at predetermined intervals.

That is, the above-mentioned optical sensor has a structure in which diodes, which are PIN-junctioned stacked bodies x and y, are tied together.

A constant bias voltage is applied to the metal electrodes 44x and 44y from an external circuit (not shown).

Now, if a + bias voltage is applied to the metal electrode 44x of the laminate X and a - bias voltage is applied to the metal electrode 44y of the laminate y, the laminate
A reverse bias is applied to the y side of the stack, and a forward bias is applied to the y side of the stack. A current due to bias application flows between the metal electrode 44x of the stacked body X - the N layer 43N of the amorphous silicon semiconductor layer -
I layer 431-2 layer 43P-transparent conductive film 42-2 layers 43P-I layer 43I-N of amorphous silicon semiconductor layer of laminate y
F! 43N--flows to the metal electrode 44y. That is, metal electrode 4
The resistance between 4x and 44y is the sum of the reverse resistance of the laminate X and the forward resistance of the laminate y.In the bright state, photovoltaic force is generated in the laminates Since it is at a subpotential, it is canceled out and no photovoltaic current actually flows.

However, since a + bias voltage is applied to the conductive film X and a - bias voltage is applied to the conductive film y, a reverse photocurrent (bright current) is generated in the stack acts as a resistance change (bias voltage/bright current) of the optical sensor. Therefore, the resistance of the entire optical sensor is reduced by the apparent principal light irradiation, and it functions like a photoconductive sensor. This makes the illuminance-resistance value characteristic linear.

That is, in the bright state, among the stacked bodies XtY, only the stacked body X in the reverse bias direction contributes to a change in the resistance (bright current) of the photosensor, and the thick stacked body (y) does not contribute.

The above-mentioned optical sensor uses an amorphous silicon semiconductor layer with a P-I-N junction in the photoelectric part, but the spectral sensitivity characteristics of the amorphous silicon semiconductor are as shown in the characteristic diagram in Figure 2. Conforms to visible light range.

For this reason, it is used for color correction in visual equipment. In this way, although the above-mentioned optical sensor is suitable as a color sensor in the visible light range, it is suitable as a color sensor in the visible light range, but it is suitable for use in the infrared range, for example, 700
Due to spectral sensitivity, it was not possible to detect light having a wavelength of rtn+ or higher.

[Object of the present invention]

The present invention was devised in view of the above background,
The purpose is to provide an optical sensor that can accurately detect light on the long wavelength side using a P-1-N junction amorphous silicon semiconductor layer.

[Specific Means for Achieving the Object] According to the present invention, in order to achieve the above-mentioned object, a transparent conductive film, a P-I-N junction amorphous semiconductor layer, and a bias voltage are provided on a transparent substrate. An optical sensor is provided in which two conductive films are formed to apply the irradiation, and a phosphor layer and a filter for cutting visible light from the light incident side are formed on one main surface of the transparent substrate.

[Effect]

In the specific means described above, the light that enters the amorphous silicon semiconductor layer from the transparent substrate side is blocked by the visible light cut filter layer, and the amorphous silicon semiconductor layer absorbs light in the wavelength region to which it is most sensitive. cut off. Thereby, light in a wavelength range that can pass through the visible light cut filter layer becomes light on the shorter wavelength side or longer wavelength side with respect to light in the visible light range.

Next, the light in the long wavelength side of the wavelength range that has passed through the filter is incident on the phosphor layer, the phosphor layer is excited, and the amorphous silicon semiconductor layer is exposed to the wavelength range in which it is most sensitive. The converted light is converted into light, and the converted light is incident on the amorphous silicon semiconductor layer.

As a result, only the light in the long wavelength range (infrared light) that is incident on the optical sensor is accurately detected.

〔Example〕

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

FIG. 1 is a cross-sectional structural diagram showing the structure of an optical sensor according to the present invention.

In the optical sensor of the present invention, a visible light cut filter layer 5 and a phosphor layer 6 are provided on a transparent substrate 1 from the light incident side. A transparent conductive film 2 is placed on the visible light cut filter layer 5 and the phosphor layer 6 of the transparent substrate 1, an amorphous silicon semiconductor layer 3 with P-1-N junction, and a conductive film 4a to which a bias voltage is applied. 4b are sequentially formed.

The transparent substrate 1 is made of glass, translucent ceramic, etc.
A visible light cut filter layer 5 is provided on one main surface of the transparent substrate 1.
, a phosphor layer 6 is deposited.

The visible light cut filter layer 5 cuts off wavelength light in the visible light range of the light incident on the amorphous silicon semiconductor layer 3, for example, 70 nm.
It cuts light of 0 nm or less, such as color glass filter RG9 (manufactured by Nippon Melles Griot).

The phosphor layer 6 is provided at a predetermined interface between the visible light cut filter layer 5 and the amorphous silicon semiconductor layer 3, and the phosphor layer 6 is provided at a predetermined interface between the visible light cut filter layer 5 and the amorphous silicon semiconductor layer 3.
It is excited by light in a long wavelength region of nm or more, and emits light in a wavelength region corresponding to the spectral sensitivity of the amorphous silicon semiconductor layer 3.

The material used is a transition metal such as yttrium (Y) to which an alkaline earth metal such as calcium (Ca), strontium (Sr), or barium (Ba) is added. Specifically, the above-described metal powder is kneaded using yttrium (Y) as a base material, and is formed with a thickness of about 0.511II11 by a screen printing method.

For example, in the strontium (Sr)/selenium (Se)/thallium (TI) system, infrared light with a wavelength of around 2 μm is generated in the visible light range. Also, strontium (Sr)
・For sulfur (S) and europium (Eu) systems, the wavelength is 1μ
Generates infrared light in the visible range around m.

The transparent conductive film 2 is formed of a metal oxide film such as tin oxide, indium oxide, and indium tin oxide.

Specifically, after attaching a mask to one main surface of the phosphor layer 6 of the transparent substrate 1, the above-mentioned metal oxide film is deposited, or a metal oxide film is deposited on one main surface of the phosphor layer 6. After depositing the material, it is formed into a predetermined shape by photo-etching.

The amorphous silicon semiconductor layer 3 connects the first conductivity type, the second conductivity type, and the third conductivity type from the substrate side, that is, P-I-N.
A junction is formed. Specifically, the amorphous silicon semiconductor layer 3 is formed using a plasma CVD method in which a silicon compound gas such as silane or disilane is decomposed by glow discharge, or by a photochemical vapor deposition method.
It is deposited using a VD method, etc., and the P layer is formed using a reactive gas containing silane gas mixed with a P-type doping gas such as diborane.
The first layer is formed using silane gas as a reactive gas, and the N layer is formed using a reactive gas obtained by mixing silane gas with an N-type doping gas such as phosphine.

The conductive films 4a and 4b are formed on the amorphous silicon semiconductor layer 3 in a predetermined shape and at a predetermined interval. Specifically, the conductive films 4a and 4b are formed using nickel, aluminum, titanium,
After depositing a metal such as chromium or depositing a metal film such as nickel, aluminum, titanium, or chromium on the amorphous silicon semiconductor layer 3, photoetching treatment, YA
It is formed into a predetermined pattern by laser fusing treatment using a G laser.

The above-mentioned optical sensor includes a P-I-N bonded laminate a,
It has a structure in which the diodes b are tied together in opposite directions.

Next, the operation of the optical sensor will be explained using the spectral sensitivity characteristic diagram of the amorphous silicon semiconductor layer 3 shown in FIG. The amorphous silicon semiconductor layer 3 is hardly sensitive to light having a wavelength in the infrared region of 700 nm or more (region A).

Now, the optical sensor is irradiated with light having various wavelength components from the transparent substrate 1 side. First, the visible light cut filter layer 5 absorbs light having a wavelength in the visible light range, for example, 700 nn.
+ or less light (area B) is blocked. As a result, it does not react at all to visible wavelength light that is directly irradiated.

Next, light with a wavelength other than the visible light region, for example, 700
Light in a long wavelength region of nm or more (region A) reaches the phosphor layer 6. Then, the phosphor layer 6 is excited and emits light energy of a wavelength (region B) corresponding to the spectral sensitivity of the amorphous silicon semiconductor layer 3 toward the amorphous silicon semiconductor layer 3 . That is, light in a long wavelength region is converted into a wavelength corresponding to the spectral sensitivity of the amorphous silicon semiconductor layer 3. As a result, a bright current is generated in the amorphous silicon semiconductor layer 3 by the light in the long wavelength range that has passed through the visible light cut filter layer 5 and is incident from the transparent substrate 1 side. That is, only light in the long wavelength region (infrared light) of the light incident on the optical sensor is detected.

In particular, since the visible light cut filter layer 5 is provided on the phosphor layer 6, it is possible to completely block the visible light of noise components incident from the outside.
Since the generated light energy does not leak to the outside through the transparent substrate 1, a lossless (highly sensitive) optical sensor sensitive to long wavelength region (infrared light) can be achieved.

Note that the light on the short wavelength side that has passed through the visible light cut filter layer 5 is converted into optical energy by the phosphor layer 6, and is directly irradiated onto the amorphous silicon semiconductor layer 3, but due to the difference in spectral sensitivity, the amorphous It is not detected in the silicon semiconductor layer 3.

FIG. 3 is a cross-sectional view of another embodiment of the invention.

In this embodiment, a visible light cut filter layer 51 and a phosphor layer 61 are formed on the outer surface of the transparent substrate 1. As a result, the visible light cut filter layer 51 is removed from the harsh amorphous silicon semiconductor layer 3 and the transparent conductive l! 12. Formation of the conductive film 4 prevents deterioration and facilitates the manufacturing process.

Although not shown in the above embodiments, if a transparent protective film is formed on the interface between the phosphor layer and the transparent conductive film, or on the interface between the visible light cut filter layer and the phosphor layer, visible light can be removed. Impurities can be prevented from diffusing into the cut filter layer, phosphor layer, and transparent conductive film.

The above-mentioned optical sensor has a structure in which the diodes of the laminated bodies a and b which are P-1-N joined are tied together, but the laminated body may be a single photodiode type optical sensor. do not have.

〔Effect of the invention〕

As described above, the present invention provides a transparent conductive film, a P
In an optical sensor formed with a -1-N-junctioned amorphous silicon semiconductor layer and two conductive films to which a bias voltage is applied, light in the visible light region is cut from the light incidence side on one main surface of the transparent substrate. Since a filter layer and a phosphor layer are formed, it is possible to accurately and sensitively detect light in the long wavelength range, that is, infrared rays, using an optical sensor with a simple structure that includes an amorphous silicon semiconductor.

[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 a characteristic diagram showing the spectral sensitivity of the amorphous silicon semiconductor layer of the optical sensor according to the present invention. FIG. 3 is a sectional view showing another structure of the optical sensor according to the present invention. FIG. 4 is a sectional view showing the structure of a conventional optical sensor. 1 ・ ・ 2 ・ 3 ・ 4a. 5゜6゜a. b 51 ・ 61 ・ b ・ ・ ... Transparent substrate ... Transparent conductive film ... Amorphous silicon semiconductor layer ... Conductive film ... Visible light film ... Phosphor layer ... Laminate filter layers

Claims (1)

[Claims] In an optical sensor, a transparent conductive film, a P-I-N bonded amorphous semiconductor layer, and two conductive films for applying a bias voltage are formed on a transparent substrate. An optical sensor comprising a filter layer and a phosphor layer that cut out light in the visible light range.