JP2706953B2 - Photoelectric conversion device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device used for a camera or the like, and more particularly to a photoelectric conversion device that detects illuminance by a change in an open circuit voltage.

[Conventional background]

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

There is a strong demand for light receiving elements used in photometric means of optical instruments to have excellent linearity in output characteristics with respect to illuminance and to eliminate the need for complicated peripheral circuits.

The resistance value of the CdS light receiving element changes due to light irradiation, the peripheral circuit for processing the output from the CdS into a predetermined signal is simple and inexpensive, and the light receiving element itself is inexpensive. However, the change in output with respect to the change in illuminance is poor in linearity, the usable illuminance range is about 10 to 10,000 Lux, and as a result, the CdS light receiving element has been used in inexpensive cameras for ordinary people.

On the other hand, photodiode type silicon photo detector (SPD)
Uses a change in short-circuit current with respect to a change in illuminance as an output, and its output characteristic is proportional to the change in illuminance, and has almost linearity in a wide illuminance range of 0.001 to 100000 Lux.

However, SPD uses single-crystal silicon as the light-receiving material, and cannot respond to the processing circuit without using a logarithmic compression circuit to logarithmically compress the output proportional to changes in illuminance. In the end, the camera is used only for high-end devices.

The output of the currently used SPD uses the change in short-circuit current as described above.However, if the SPD that outputs the change in open-circuit voltage is mentioned, the change in open-circuit voltage with respect to the change in illuminance is an output that is logarithmic. It seems that the logarithmic compression circuit for logarithmic compression becomes unnecessary, and the peripheral circuit is simplified. However, the change in the open-circuit voltage greatly varies depending on the ambient temperature. That is, it has a large temperature coefficient of about -2.7 mV / ° C., and it is difficult to directly use it in a wide temperature operation region.

As a result, such SPDs have not been put to practical use because a temperature detection circuit or a temperature correction circuit using a thermistor for temperature compensation is required.

(Object of the present invention)

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

[Specific means to achieve the purpose]

According to the present invention, in order to achieve the above object, a two-layer structure in which an amorphous semiconductor layer and a metal electrode having a PIN junction are superimposed on a transparent substrate on which a transparent conductive film is applied is provided. A photoelectric conversion device connected to the opposite direction through the transparent conductive film, wherein a light-shielding body for preventing light from entering the amorphous semiconductor layer is formed on the one of the stacked bodies; There is provided a photoelectric conversion device in which a metal terminal that is electrically connected to the transparent conductive film is provided outside one of the laminates.

Further, there is provided a photoelectric conversion device provided with a power supply for applying a constant bias voltage and a bypass resistance component (hereinafter, referred to as a resistance) between the transparent conductive film and a metal electrode of one of the laminates.

〔Example〕

Hereinafter, a photoelectric conversion device of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional structural view showing a 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, on a transparent substrate 1, a laminate a, b composed of a transparent conductive film 2, an amorphous semiconductor layer 3 joined by a PIN junction, and metal electrodes 4a, 4b is formed. The two laminates a and b are formed so as to be connected to each other in the opposite directions via the transparent conductive film 2, and one of the laminates a has a light-shielding body 5 that blocks incidence of ambient light. It is formed.
Further, as shown in FIG. 2, the transparent conductive film 2 is applied so that a bias voltage is applied between the transparent conductive film 2 and the metal electrode 4a of the laminate a having the light shielding body 5 with a resistance component 7 interposed therebetween. A metal terminal 6 is formed which communicates with the terminal.

The transparent substrate 1 is made of glass, translucent ceramic, or the like, and a transparent conductive film 2 is attached 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, or indium tin oxide, and is formed to be a film common to at least the stacked bodies a and b on one main surface of the transparent substrate 1. . Specifically, after mounting a mask on one main surface of the transparent substrate 1, the above-described metal oxide film is deposited, or after a metal oxide film is deposited on one main surface of the transparent substrate 1, -It is formed by etching or the like.

The amorphous semiconductor layer 3 has a first conductivity type, a second conductivity type, and a third conductivity type joined to at least portions where the metal electrodes 4a and 4b are formed to become the laminates a and b, that is, P-type. An IN junction is formed. Specifically, the amorphous semiconductor layer 3 is made of amorphous silicon or the like 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. The silane gas is formed with a reaction gas in which a P-type doping gas such as diborane is mixed, the I layer is formed with silane gas as a reaction gas, and the N layer is formed with a reaction gas in which silane gas is mixed with an N-type doping gas such as phosphine. .

The metal electrodes 4a and 4b are provided on the amorphous semiconductor layer 3 at predetermined intervals,
For example, it is formed with a sufficient distance through the amorphous semiconductor layer 3 between the metal electrodes 4a and 4b so that no leak current occurs. Specifically, for the metal electrodes 4a and 4b, a mask is mounted on the amorphous semiconductor layer 3 to deposit a metal such as nickel, aluminum, titanium, chromium, or the like.
A metal film of nickel, aluminum, titanium, chromium, or the like is applied thereon, followed by a resist etching process to form a predetermined pattern. By this step, the laminates a and b using the transparent conductive film 2 as a common film are formed.

During the resist etching process of the metal electrodes 4a and 4b, the metal electrodes 4a and 4b and the metal electrodes 4a and 4B are immersed in a solution for etching the amorphous semiconductor layer 3 or the metal electrodes 4a and 4B are successively etched after the resist etching process. Non-invasive, amorphous semiconductor layer 3
By immersing the amorphous semiconductor layer 3 in a solution in which only the metal electrodes 4a and 4b are not formed, a part (the N layer in the drawing) or all of the amorphous semiconductor layer 3 where the metal electrodes 4a and 4b are not formed may be removed.

The light shield 5 is formed on one of the laminates a and b, for example, on the laminate a so that light from the surroundings is not irradiated on the amorphous semiconductor layer 3 of the laminate a. It is conceivable that the light-shielding body 5 simply forms a light-shielding film on the outer surface of the transparent substrate 1. However, light leaked from the end face of the transparent substrate 1 and light that reaches the thickness of the transparent substrate 1 while being diffusely reflected are considered. Therefore, it is preferably provided between the transparent conductive film 2 corresponding to the stacked body a and the amorphous semiconductor layer 3.

Specifically, after the above-described transparent conductive film 2 is formed, the light shielding body 5 is formed in a portion to be the stacked body a. As a method for forming the light-shielding member 5, a light-opaque resin or an inorganic material is formed by a screen printing method, or a metal such as nickel, chromium, titanium, or nickel-chromium is formed to a thickness of 500 mm or more by a physical vapor deposition method such as sputtering. Form. Thus, ambient light can be completely blocked. In particular, when the latter metal is applied, the transparent conductive film 2 can act as a buffer substance, so that the metal layer of the light shield 5 can be prevented from peeling off the substrate. In addition, when a metal is applied to the light shielding body 5, a eutectic layer of silicon and silicide or silicon, which is a material of the amorphous semiconductor layer 3, may be formed, which may adversely affect the characteristics of the amorphous semiconductor layer 3. is there. At this time, after forming the above-described 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 does not directly contact the amorphous semiconductor layer 3.

The metal terminal 6 is formed so as to be electrically connected to the transparent conductive film 2 at a portion where the two stacked bodies a and b are not provided. 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 and communicates with the transparent conductive film 2 through the opening 61. What is necessary is just to form so that it may be electrically connected.

Specifically, the metal terminal 6 is formed of the same material, such as nickel, aluminum, titanium, and chromium, when the metal electrodes 4a and 4b are formed.

The application of the bias voltage will be described 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 laminate a. Further, a DC bias voltage 8 is applied between the resistance component 7 and the metal electrode 4a of the laminate a in the forward direction with respect to the laminate a.

Now, when a bias voltage is applied to the laminate a in the forward direction with − to the metal electrode 4a of the laminate a and + through the resistance component 7 between the transparent conductive films 2, the output (between points A and B) ) Vab appears as the sum of the open voltage of the stacked body b and the voltage emerging from the stacked body a.

When the ambient temperature rises in the bright state, the voltage (the voltage between No. 4a and No. 6 in FIG. 2) output from the light-shielded stacked body a increases as the temperature rises. Also, the laminate b
Open-circuit voltage decreases with increasing temperature. Therefore, the change in the open-circuit voltage with respect to the temperature change cancels each other, and the change in the output of the present apparatus with respect to the change in the illuminance is only the change in the open-circuit voltage of the laminate b, which appears as the output Vab.

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

Now, a resistance element of 1.5 MΩ and a bias voltage of 8
The voltage coefficient of 1 V and the light receiving area of the laminates a and b were set to 1.1 cm ^{2, respectively,} and the temperature coefficient of the output Vab was measured.
0.1 mV / ° C to +0.17 mV / ° C.

This result uses the conventional open-circuit voltage change as the output.
SPD optical sensor, that is, the temperature coefficient of the optical sensor that detects the output between the transparent conductive film and the metal electrode of a single laminated body, compared with -2.7 mV / ℃, 1/10 or more This makes it possible to accurately detect the amount of light even in an environment with a large temperature change. Also, the output Vab change with respect to the illuminance is 0.5% when the light receiving area is 1.1 cm ² and the resistance component 7 is 10 ⁹ Ω.
In the range of Lux to 50,000 Lux, linearity proportional to the logarithm of the illuminance was obtained. The output slightly decreased in a practically negligible range of 0.5 Lux or less and 50000 Lux or more.

As described above, according to the photoelectric conversion device of the present invention, the output Vab, which is a change in open-circuit voltage, corresponding to a logarithmic change in illuminance can be obtained in a linear manner. Is unnecessary, and since the temperature coefficient is extremely small, a peripheral circuit for correcting an output in response to a change in ambient temperature is not required.

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

Considering the temperature coefficient + 0.17mV / ° C,
The unit for illuminance used in cameras is EV. When the EV value increases by 1, the illuminance doubles.

That is, the change of the open circuit voltage by 1EV is 30.1 mV. Since the temperature coefficient of a normal photoelectric conversion device is −2.7 mV / ° C., the temperature change corresponding to a change in light amount of 1 EV is 11.2 ° C. Thus, for example, between outdoors and indoors where the temperature difference is large, illuminance correction of 1 EV or more is required.

However, if the temperature coefficient + 0.17mV / ° C is converted into a temperature change corresponding to 1EV, it will be about 177 ° C. This means that there is no need to make a correction equivalent to 1 EV in a temperature range in which a normal photoelectric conversion device is used.

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

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

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

According to this embodiment, since the metal electrodes 4a and 4b and the metal terminal 6-shaped resistive layer 71 appear on the non-light-receiving surface side of the photoelectric conversion device, a chip-shaped element can be easily achieved, for example, immersion in a solder bath or the like. By doing so, a lead-off component is easily achieved.

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

〔The invention's effect〕

As described above, the present invention forms two laminates each composed of an amorphous semiconductor layer and a metal electrode joined by a PIN junction on a transparent substrate on which a transparent conductive film is adhered. Connected in the opposite directions via the film, and forming a light-shielding body that blocks light from entering the amorphous semiconductor layer in one of the laminates,
With a simple structure and easy connection of applying a forward bias voltage between the transparent conductive film and the metal electrode of one of the laminates, and applying a forward bias voltage between the resistance component and the metal electrode of the one of the laminates, A photoelectric output excellent in temperature compensation in which a change in output obtained by adding the open-circuit voltage output from the other laminated body and the output is linear in proportion to the logarithm of illuminance, and the output change with respect to a change in ambient temperature is almost negligible. A conversion device is achieved.

Further, peripheral circuits such as a logarithmic compression circuit and a temperature compensation circuit and dedicated ICs are simplified or unnecessary, and an inexpensive and mass-produced photoelectric conversion device made of amorphous silicon is achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of the photoelectric conversion device according to the present invention. FIG. 2 is an equivalent electric circuit diagram of the photoelectric conversion device, and FIG. 3 (a) is a plan view on the non-light receiving surface side showing the structure of another embodiment of the photoelectric conversion device according to the present invention. , Third
FIG. 3B is a cross-sectional view of the photoelectric conversion device shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Transparent substrate 2 ... Transparent conductive film 3 ... Amorphous semiconductor layer 4a, 4b ... Metal electrode 5 ... Light shielding layer 6 ... Metal terminal 7 ... Resistance component

Claims (2)

(57) [Claims] 1. A method according to claim 1, wherein a transparent conductive film is provided on a transparent substrate.
In a photoelectric conversion device in which two stacked bodies formed by overlapping an amorphous semiconductor layer and a metal electrode that have been subjected to an IN junction are connected to each other in opposite directions via the transparent conductive film, A photoelectric conversion device, further comprising: forming a light-shielding body for preventing light from being incident on the amorphous semiconductor layer of the stacked body; and providing a metal terminal that is electrically connected to the transparent conductive film outside the two stacked bodies. 2. The method according to claim 1, wherein a transparent conductive film is formed on a transparent substrate.
The amorphous semiconductor layer and the metal electrode that have been subjected to the I-N junction are overlapped to form two small stacked bodies, which are connected in opposite directions through the transparent conductive film. And a power supply for applying a constant bias voltage and a bypass resistance component are provided between the transparent conductive film and the metal electrode of one of the laminates.