JPH0298976A - Photoelectric conversion device - Google Patents

Abstract

PURPOSE:To obtain a photoelectric conversion device whose output has a linearity in a wide range of illumination by forming a light shield in one of two laminates and providing the device with a metal terminal electrically connected with a transparent conductive film outside the laminates. CONSTITUTION:After a transparent conductive film 2 is formed, a light shield 5 is formed in a part where a laminate (a) is to be formed. A resistance component 7 is connected between a metal terminal 6 and a metal electrode 4a of the laminate (a). Further, a DC bias voltage 8 is applied across the resistance component 7 and the metal electrode 4a in the forward direction of the laminate (a). When a bias voltage is applied in the forward direction to the laminate (a), with the metal electrode 4a negative and with the transparent conductive film 2 positive via the resistance component 7, a voltage Vab of the sum of an open voltage of a laminate (b) and a voltage output from the laminate (a) appears at the output (between points A and B). That is, the open voltage of the laminate (b) caused by the light with which a photoelectric conversion device is irradiated changes logarithmically with the change of the amount of the incident light, and derived from between output contact points A and B. The linearity of the output Vab in respect to the logarithmic change of illumination can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photoelectric conversion device used in cameras and the like, and particularly to a photoelectric conversion device that detects illuminance based on changes in open-circuit voltage.

[Background of the invention]

Currently, CdS is used as a photometric method for optical equipment such as cameras.
(Cadmium sulfide) light-receiving elements and photodiode-type silicon light-receiving elements are used.

Light receiving elements used in photometric means of optical equipment are strongly required to have excellent linearity in output characteristics with respect to illuminance, and to eliminate the need for complex peripheral circuits.

The resistance value of the CdS light-receiving element changes with light irradiation, and the peripheral circuitry for processing the output from the GdS into a predetermined signal is simple and inexpensive, and furthermore, the light-receiving element itself is inexpensive. However, the output change due to the change in illuminance is
Poor linearity, usable illuminance range is 10-100Q
After all, CdS light receiving elements were used in inexpensive cameras for the general public.

On the other hand, a photodiode type silicon light receiving element (PBS)
uses a change in short-circuit current with respect to a change in illuminance as an output, and its output characteristic is proportional to a change in illuminance, and has almost linearity over a wide illuminance range of o, ooi to 100,000 Lux.

However, PBS uses single-crystal silicon as the light-receiving material, and it cannot be used with processing circuits unless a logarithmic compression circuit is used to logarithmically compress outputs that are proportional to changes in illuminance. This results in high costs, and in the end, it is only used in high-end camera equipment.

The output of currently used PBSs is the change in short-circuit current as described above, but if we talk about PBSs that output changes in open-circuit voltage, changes in open-circuit voltage with respect to changes in illuminance are logarithmically related outputs. is obtained, a logarithmic compression circuit for logarithmic compression becomes unnecessary, and it seems that the peripheral circuit becomes a surface element. However, the change in open circuit voltage varies greatly depending on the ambient temperature, approximately -2.7mV/"C
It has such a large temperature coefficient that it is difficult to use it directly in a wide temperature operating range.

Ultimately, such a PBS has not been put into practical use because it requires a temperature detection circuit or a temperature correction circuit that uses a thermistor for temperature compensation.

[Object of the present invention]

The present invention has been devised based on the above-mentioned background, and its purpose is to make the output whose open circuit voltage changes with respect to changes in illuminance have linearity over a wide illuminance range and have a small temperature coefficient. The object of the present invention is to provide an inexpensive photoelectric conversion device.

[Specific Means for Achieving the Object] According to the present invention, in order to achieve the above-mentioned object, an amorphous semiconductor layer bonded to P-r-N is formed on a transparent substrate coated with a transparent conductive film. In a photoelectric conversion device in which two laminates are formed by overlapping a metal electrode and a metal electrode and are connected in opposite directions to each other via the transparent conductive film, light is applied to an amorphous semiconductor layer in one of the laminates. A photoelectric conversion device is provided in which a light shielding body is formed to block the light incident thereon, and a metal terminal that is electrically connected to the transparent conductive film is provided outside the two laminates.

Further, between the transparent conductive film and the metal electrode of one of the laminates,
A photoelectric conversion device is provided that includes a power source that applies a constant bias voltage and a bypass resistance component (hereinafter referred to as a resistance).

〔Example〕

Hereinafter, the photoelectric conversion device 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 a photoelectric conversion device according to the present invention, and FIG. 2 is an equivalent electric circuit diagram of the photoelectric conversion device shown in FIG.

In the photoelectric conversion device of the present invention, laminates a and b each consisting of a transparent conductive film 2, a P-1-N bonded amorphous semiconductor layer 3, and metal electrodes 4a and 4b are formed on a transparent substrate 1. The two laminates a and b are connected in opposite directions to each other via the transparent conductive F42, and
A light shielding body 5 that blocks the incidence of ambient light is formed on one of the laminates a.

Furthermore, as shown in FIG.
A metal terminal 6 is formed to communicate with the transparent conductive film 2 so that a bias voltage is applied therebetween.

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. Specifically, after a mask is attached to the whole surface of the transparent substrate 1, the above-mentioned metal oxide film is attached, or after a metal oxide film is deposited on the whole surface of the transparent substrate 1, a photo-etching process is performed. It is formed by

The amorphous semiconductor layer 3 has a first conductivity type, a second conductivity type, and a third conductivity type bonded, that is, P- An 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 a silicon compound gas such as silane or disilane is decomposed by glow discharge, and the PI3 is made of silane gas. NI'5 is formed with a reactive gas mixed with P-type doping gas such as diborane, the first layer is formed with silane gas as the reactive gas, and NI'5 is formed with a reactive gas mixed with silane gas and N-type doping gas such as phosphine. .

The metal electrodes 4a and 4b are placed on the amorphous semiconductor layer 3 at a predetermined interval, for example, through the amorphous semiconductor layer 3.
They are formed with a sufficient distance between them to prevent leakage current. Specifically, for the gold M electrodes 4a and 4b, a mask is attached on the amorphous semiconductor layer 3, and a metal such as nickel, aluminum, titanium, or chromium is 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. Through this process,
Stone stacks a and b having the transparent conductive film 2 as a common crotch are formed.

Note that during the resist etching process for the metal electrodes 4a and 4b, the metal electrodes 4. a, 4. b and amorphous semiconductor layer 3
The metal electrodes 4a, 4b are formed by immersing the amorphous semiconductor layer 3 in a solution that etches the amorphous semiconductor layer 3, or by immersing it in a solution that etches only the amorphous semiconductor layer 3 without attacking the metal electrodes 4a, 4b following resist etching treatment. A part (NFt in the figure) of the amorphous semiconductor N3 that is not removed may be partially or completely removed.

The light shielding body 5 is formed on one of the stone stacks a and b, for example, the stone stack a, so that the amorphous semiconductor layer 3 of the stack a is not irradiated with light from the surroundings. Light shielding body 5
It is conceivable to simply form a light-shielding film on the outer surface of the transparent substrate 1, but since there are leakage light incident from the end surface of the transparent substrate 1 and light that reaches the thickness of the transparent substrate 1 while being diffusely reflected, Preferably, it is interposed between the transparent conductive film 2 and the amorphous semiconductor layer 3 corresponding to the laminate a.

Specifically, after forming the above-described transparent conductive film 2, the light shielding body 5 is formed in the portion that will become the laminate a.

The light shielding member 5 can be formed using a screen printing method using an opaque resin or an inorganic material, or using a physical vapor deposition method such as sputtering to form a metal such as nickel, chromium, titanium, or nickel-chromium to a thickness of 500 Å or more. Form. This makes it possible to completely block out ambient light. In particular, when the latter metal is deposited, the transparent conductive film 2 can act as a buffer substance, so that peeling of the metal layer of the light shield 5 from the substrate can be prevented. Furthermore, if metal is deposited on the light shielding body 5, a eutectic layer of silicide or silicon may be formed with silicon, which is the material of the amorphous semiconductor layer 3, and this may adversely affect the characteristics of the amorphous semiconductor layer 3. be. At this time, after forming the above-mentioned light shield 5, silicon oxide or silicon nitride may be formed on the metal layer so that the metal layer of the light shield 5 and the amorphous semiconductor layer 3 do not come into direct contact.

The metal terminal 6 is formed to be electrically connected to the transparent conductive film 2 at a portion where the two viN bodies a and b are not present. When the amorphous semiconductor layer 3 completely covers the transparent conductive film 2 as shown in the figure, an opening 61 is formed in the amorphous semiconductor layer 3,
The opening 61 may be formed so as to be electrically connected to the transparent conductive film 2 by communicating with it.

Specifically, the metal terminal 6 is formed from the same metal, such as nickel, aluminum, titanium, or chromium, when forming the metal electrodes 4a and 4b.

Application of a bias voltage will be explained based on the photoelectric conversion device configured as described above.

A resistance component 7 is connected between the metal terminal 6 and the metal electrode 4a of the stone stack a. Furthermore, a DC bias voltage 8 is applied between the resistance component 7 and the metal electrode 4a of the laminate a.
It is applied in the forward direction to the two layers.

Now, if a forward bias voltage is applied to the metal electrode 4a of the laminate a and the transparent conductive film 2 through the resistance component 7, then an output (between points A and B) is applied. ) Vab appears as the sum of the open circuit voltage of the laminated body and the voltage coming out of the laminated stone body a.

In the bright state, as the ambient temperature rises, the voltage output from the light-shielded laminate a (the voltage between numbers 4a and 6 in FIG. 2) increases as the temperature rises. Furthermore, the open circuit voltage of the laminate decreases as the temperature rises. Therefore, the changes in open circuit voltage due to temperature changes cancel each other out, and the output change of this device due to changes in illuminance is only the change in open circuit voltage of the laminated body, which appears as the output Vab.

As described above, the change in the open circuit voltage of the laminated body caused by the amount of light irradiated to the photoelectric conversion device has a logarithmic relationship with respect to the change in the amount of incident light, and is derived from between the output contacts A and B.

Now, a resistance element of 1.5MΩ is set as the resistance component 7, a voltage of 1V is set as the bias voltage 8, and a light receiving area of the stacked body ASB is set to 1.
When the temperature coefficient of the output Vab was measured with each set at 1cm2, it was +0.1mV/"C ~ +0.17mV
/℃.

This result shows that the conventional P
It is more than 1/10 of the temperature coefficient of -2.7 mV/''C of the BS optical sensor, that is, the optical sensor that detects the output between a single laminate transparent conductive film and a metal electrode. This makes it possible to accurately detect the amount of light even in environments with large temperature changes.

Also, regarding the output Vab change with respect to illuminance, when the receiving surface precision is 1.1 cm2 and the resistance component 7 is 109Ω, it is 0.5
In the range of Lux to 50,000 Lux, linearity proportional to the logarithm of illuminance was obtained. In addition, 0°5 Lux or less and 5
0000 Lux or more, which is a practically negligible range, and the output was only slightly reduced.

As described above, according to the photoelectric conversion device of the present invention, the linearity of the output Vab, which is a change in open-circuit voltage in response to a logarithmic change in illuminance, is achieved, so that a logarithmic compression circuit is not required in the peripheral circuit as in the conventional case. Since the temperature coefficient is extremely small, there is no need for peripheral circuitry to correct the output in response to changes in ambient temperature.

Furthermore, since an amorphous semiconductor layer is used as the photoconductive material of the photoelectric conversion device of the present invention, mass production and cost reduction can be easily achieved.

Now, considering the temperature coefficient +0.17 mV/''C, the unit for illuminance used in cameras is E. When the EV value increases by 1, the illuminance doubles.

In other words, the change in open circuit voltage due to a change in IEV is 30.1 mV.
becomes. The temperature coefficient of a normal photoelectric conversion device is -2°7mV
/'C, the temperature change corresponding to the change in light amount IEV is 11.2°C. As a result, for example, there is a large temperature difference between outdoors and indoors. Illuminance correction more than equivalent to EV is required.

However, when the temperature coefficient +0.17 mV/'C is converted into a temperature change corresponding to IEV, it is approximately 177°C.

This means that in the temperature range in which a normal photoelectric conversion device is used, there is no need to make any correction equivalent to IEV.

FIGS. 3(a) and 3(b) are a plan view and a sectional view of the non-light receiving surface side showing another embodiment of the present invention.

In this embodiment, the resistive layer 71 is formed on the metal terminal 6 by screen printing or the like with a paste prepared by kneading a predetermined amount of a metal oxide such as ruthenium oxide so as to have a predetermined resistance value.

Then, the insulating film 9 is formed by exposing parts of the metal electrodes 4a, 4b and the resistive layer 71 of the laminates a, b.

According to this embodiment, the metal electrodes 4a, 4b and the metal terminal 6
Since the shaped resistance layer 71 appears on the non-light-receiving surface side of the photoelectric conversion device, a chip-shaped element can be easily achieved, and for example, a lead-off component can be easily achieved by immersing it in a solder bath or the like. .

Furthermore, when forming the metal terminal 6, a predetermined resistance material may be kneaded into the conductive paste for the metal terminal, and the metal terminal 6 itself may also be used as the resistance component 7.

〔Effect of the invention〕

As described above, the present invention forms two laminates consisting of a P-I-N bonded amorphous semiconductor layer and a metal electrode on a transparent substrate covered with a transparent conductive film, and They are connected in opposite directions to each other through the film, and a light shielding body is formed on one of the stacked bodies to block light from entering the amorphous semiconductor layer, and a light shield is formed between the transparent conductive film and the full-voltage electrode of one stacked body. Due to the simple structure and easy connection of interposing a resistance component and applying a forward bias voltage between the resistance component and the full voltage electrode of one VI layer, the open circuit voltage output from the other layer A photoelectric conversion device with excellent temperature compensation is achieved in which a linear output in which the change in the added output is proportional to the logarithm of the illuminance and in which the change in output with respect to changes in ambient temperature is almost negligible.

Further, peripheral circuits such as a logarithmic compression circuit, a temperature compensation circuit, and a dedicated IC become unnecessary, and furthermore, a photoelectric conversion device made of amorphous silicon that is inexpensive and easy to mass-produce can be achieved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of a photoelectric conversion device according to the present invention. FIG. 2 is an isometric electric circuit surface of the photoelectric conversion device, and FIG. 3(a) is a plan view of the non-light-receiving surface side showing the structure of another embodiment of the photoelectric conversion device according to the present invention. Yes, 3rd
FIG. 3(b) is a sectional view of the photoelectric conversion device shown in FIG. 3(a). 1 ・ ・ ・ ・ 2 ・ ・ ・ ・ 3 ・ ・ ・ ・ 4a, 4b ・ 5 ・ ・ ・ ・ 6 ・ ・ ・ ・ 7 ・ ・ ・ ・ ・ Transparent substrate Transparent conductive film Amorphous semiconductor layer・・・Metal electrode, light shielding layer, fully bent terminal, resistance component

Claims (2)

[Claims] (1) P-I-N on a transparent substrate coated with a transparent conductive film
2 formed by superimposing a bonded amorphous semiconductor layer and a metal electrode
In a photoelectric conversion device in which two laminates are formed and connected in opposite directions to each other via the transparent conductive film, one of the laminates is provided with a light shielding member that blocks light from entering the amorphous semiconductor layer of the laminate. A photoelectric conversion device characterized in that a metal terminal is provided outside the two laminates to be electrically connected to the transparent conductive film. (2) P-I-N on a transparent substrate coated with a transparent conductive film
Two laminates are formed by overlapping the bonded amorphous semiconductor layer and the metal electrode, and are connected in opposite directions to each other via the transparent conductive film to form a light shielding body in one of the laminates. A photoelectric conversion device further comprising a power source for applying a constant bias voltage and a resistance component for adjusting the bias voltage between the transparent conductive film and the metal electrode of one of the laminates.