JPS6272183A - Manufacture of photoelectric conversion film - Google Patents

Abstract

PURPOSE:To form a photoelectric conversion film with high sensitivity and at low cost which facilitates a real time image reading method by a method wherein a heat treatment is carried out in inert gas which flows at a constant rate and contains at least oxygen whose partial pressure is 1/4-1/20. CONSTITUTION:Low melting point glass and CdCl2 are added to CdSe fine crystal powder and further organic solvent is added to make a photoconductive paste 2. The photoconductive paste 2 is applied to an insulating substrate 1 by screen printing. After the solvent in the film 2 applied to the substrate 1 is evaporated, the film 2 is rebaked in a furnace. At the time of rebaking, mixed gas of oxygen and nitrogen is let to flow at a constant rate. If the oxygen partial pressure is too high at that time, growth of particles becomes remarkable and the particle diameter grown to the extent of 5mum but, on the other hand, surface roughness becomes inferior and defects at the time of upper electrode formation or the like are created. If the oxygen partial pressure is too low, the growth of particles is suppressed and minimum necessary output can not be obtained. Therefore, in the present invention, a device is manufactured under the oxygen partial pressure of 1/20-1/4.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing a photoelectric conversion film suitable for use in a reading section of a facsimile machine, etc., and particularly to a method for improving the image signal output characteristics of a photoelectric conversion film. The present invention relates to a method for manufacturing a photoelectric conversion film that simultaneously improves photoresponse characteristics and enables the adoption of a real-time image readout method.

<Prior art> Conventionally, for example, a CCD is used in the reading section of a facsimile machine, etc.
, MO3 type sensors and other optical sensors formed using IC technology have been used.

However, since such a sensor is manufactured using IC technology, it can only be manufactured with a length of several IQ mm, and the K used in actual use requires that the original be reduced and imaged. When performing reduced imaging, the optical path length of the lens is required, generally 2
A distance of 0 crn to 30 c'rn is required from the document to the sensor. Such an optical path length poses a very big problem in reducing the size and weight of the reading unit.

In recent years, a fiber optic lens array has been used on a sensor with the same width as the original for the reduced size sensor mentioned above!
A contact type image sensor that forms an image of an IK original has been proposed.

The photoelectric conversion section of this image sensor contains Cd5xSel-
8 mixed crystal capping film, a-3i film, etc. have been used, but since both use a vacuum process, there are problems with productivity, yield, etc., and costs are high.

On the other hand, as a method for producing a photoelectric conversion film at a relatively low cost,
Cadmium sulfide, cadmium selenide, or sulfur/cadmium selenide powder is mixed with a small amount of activated impurities, a flux, and an organic binder, and the mixture is applied as a slurry onto a substrate.
This coated substrate is heated using nitrogen gas or a trace amount (0.8%).
) is known to be produced by firing in a nitrogen gas atmosphere containing oxygen gas (for example, Japanese Patent Publication No. 52
-25305 Publication).

<Problems to be solved by the invention> However, although photoelectric conversion films can be produced relatively inexpensively and with good reproducibility using the above-mentioned thick film forming method, it is difficult to use a real-time image readout method. It was not possible to produce a photoelectric conversion film with excellent image signal output characteristics and photoresponse characteristics, and it was difficult to apply it to a high-density, high-pixel reading unit such as Fufunmiri.

The present invention was devised in view of the above-mentioned problems, and aims to provide a complete method for producing a photoelectric conversion film with high sensitivity and low cost, which makes it possible to adopt a real-time image readout method. be.

Means for Solving the Problems> In order to achieve the above object, the present invention provides at least CdS
, CdSe, CdSxSe+-)(,Cd5)(T
el −X , Cd5e)<Te1−X of the photoconductor material! In the method for producing a photoelectric conversion film which has a photoconductor material as a main component and is heat-treated by adding a low-melting glass to the photoconductor material, the above heat treatment is performed at an oxygen partial pressure of 1/4 to 1/20 with respect to an inert gas. The process is performed in an inert gas containing at least oxygen flowing at a constant flow rate.

Effects and Uses> With the above structure, a photoelectric conversion film in which particle growth and surface roughness are suitably controlled is formed, and a photoelectric conversion film with stable high output can be obtained.

<Example> Next, an example using CdSe will be described in detail as an example of the present invention.

FIG. 1 is a diagram showing an example of the structure of a photoelectric conversion element equipped with a photoelectric conversion film produced according to the present invention, in which 1 is an insulating substrate, 2 is a photoconductive film produced according to the present invention, and 3
is an electrode.

CdSe as a photoconductive material of the photoconductive film 2 is prepared using a chemical precipitation method, and a fine powder is used which has been activated in advance by baking treatment. A low-melting glass and a halide are added to the above CdSe powder, and an organic solvent is further added to form a paste, which is coated onto a substrate using a screen printing method to form a predetermined film.

Specifically, insulating substrates such as ceramics and glass! C on top
dSe microcrystalline powder, low melting point glass and 3 mol of Cd
A photoconductive paste 2 containing C1z and made into a paste with an organic solvent is applied to a predetermined width. In this example, screen printing was used to coat the film to a thickness of 10 μm to 20 μm. Next, after the organic solvent of the film 2 coated on the substrate 1 is evaporated, re-baking is performed in a furnace. This firing temperature is 450'
The temperature is between 550°C and 550°C. Further, during firing, a gas containing a mixture of oxygen and nitrogen is flowed at a constant flow rate. That is, after evaporating the organic solvent at 100"C, activation treatment is performed. The activation treatment is performed at a temperature of 450°C to 550°C in a mixed atmosphere of nitrogen and oxygen, and the mixed gas is blown at a rate of 1 to IOA per minute. It flowed.

At this time, if the oxygen partial pressure is lowered, particle growth is suppressed and the photocurrent is reduced. Furthermore, when the oxygen partial pressure is increased, grain growth progresses, but the surface roughness deteriorates and the yield in electrode formation etc. decreases.

FIG. 2 shows the dependence of grain growth and surface roughness on the firing atmosphere due to activation treatment.

As is clear from FIG. 2, when the oxygen partial pressure is increased, the grain growth becomes remarkable and grows to about 5 .mu.m, but on the other hand, the surface roughness deteriorates and causes defects etc. when forming the upper electrode part. Furthermore, if the oxygen partial pressure is lowered, the growth of particles is suppressed, making it impossible to obtain the required minimum output (1.0 μA). Therefore, in the present invention, the device was manufactured with the oxygen partial pressure set to 1/20 to 1/4.

The planar electrodes 3 of 8 electrodes/mm were formed on the photoconductive film 2 prepared as described above using a lift-off process, and the output characteristics were measured. As a result, as shown in FIG. At 20 or higher, an output of 5μ8 degrees or more, which is more than the required minimum output lOμA, was obtained. Particularly oxygen partial pressure 1/l
0 or more, output 10μA or more, optical response speed s m
A sufficient result of 5 ec or less was obtained.

Although the above embodiments have been described using nitrogen as the inert gas, the present invention is not limited to this, and can be similarly carried out using other inert gases such as argon and helium. It goes without saying that it is possible.

<Effects of the Invention> As described above, according to the present invention, a photoelectric conversion film with high output stability can be produced by controlling the oxygen partial pressure during heat treatment. Furthermore, when manufacturing an element, the yield during electrode formation can be improved and an inexpensive element can be manufactured.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the structure of a photoelectric conversion element equipped with a photoelectric conversion film produced according to the present invention, and FIG. 2 is a diagram showing grain size and surface roughness with respect to oxygen and nitrogen partial pressure during heat treatment. FIG. 3 is a diagram showing the output with respect to oxygen and nitrogen partial pressures. 1... Insulating substrate, 2... Photoconductive film, 3... Electrode. Agent Patent attorney Aihiko Fukushi (and 2 others) Figure 1 Figure 2 GvtHI power of Jinchin Sai Figure 3

Claims (1)

[Claims] 1. At least CdS, CdSe, CdTe, CdS_
xSe_1_-_x, CdS_xTe_1_-_x, C
dSe_xTe_1_-_x A method for producing a photoelectric conversion film containing one or more types of photoconductor materials as a main component and heat-treating the photoconductor material by adding a low-melting glass to the photoconductor material, wherein the heat treatment is performed at an oxygen partial pressure relative to an inert gas. , 1/4 ~
A method for producing a photoelectric conversion film, which is carried out in an inert gas containing at least oxygen and flowing at a constant flow rate of 1/20.