JPS60218475A - Manufacture of chemically deposited film - Google Patents

Abstract

PURPOSE:To manufacture a chemically deposited photoconductive film with high uniformity in a short time by heating an aqueous soln. contg. Cd, holding it at a prescribed temp., and adding an aqueous soln. contg. S or Se. CONSTITUTION:An aqueous CdCl2 soln. and an aqueous ammonia soln. are charged into a reaction vessel and held at >=80 deg.C prescribed temp. in a thermostat. A substrate of glass or the like is put in the vessel, an aqueous soln. of a compound generating S ion such as thiourea is added, and the solns. are brought into a reaction at said temp. with stirring to deposit CdS on the substrate to a desired thickness. After finishing deposition, the substrate is pulled up and washed, and a deposited CdS film is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Description of the field to which the invention pertains The present invention relates to a method for producing a photoconductive film for use in an optical sensor using a chemically deposited film, such as a photoconductive film using a chemical deposition method. (2) Description of conventional technology Conventional photoconductive films of this type, such as cadmium sulfide (C
There are vacuum deposition methods and printing methods for forming cadmium selenide (Cd8e), but compared to the above methods, chemical deposition methods form a deposited film that is uniform over a wide area and has good adhesion. In recent years, it has been widely used as a method for forming elongated optical sensors for facsimile machines due to its advantages such as:

Here, to explain the precipitation of Cd8 using an example of the chemical precipitation method, an ammonia aqueous solution is added to an aqueous solution of a cadmium salt such as CdC/, (Cd(NHs) 4 )"+
A mixed solution is made by making an aqueous solution and adding a chemical such as thiourea that decomposes to generate sulfur ions. Substrates such as glass and ceramics are immersed in this solution.
Heat and stir the entire solution. As the solution temperature rises, sulfur-containing compounds decompose and generated sulfur ions react with cadmium ions and precipitate on the substrate as Cd8. A fi Cd8 precipitated film is obtained by continuing the deposition at a predetermined temperature for a time necessary to obtain a precipitated film of sufficient thickness as a photoconductive film.

However, with the method described above, the amount of 0 required for the photoconductive film is
．． 1 to 1 to form a CdS precipitated film of 3 to 0.5 μm.
Deposition has to be carried out for as long as 2 hours, and long-term deposition also causes a large amount of unnecessary Cd8 particles to adhere to the substrate, resulting in non-uniformity in the thickness and quality of the deposited film. (3) Purpose of the Invention In order to solve these drawbacks, the present invention is characterized in that an aqueous solution containing cadmium is heated to 80°C or higher in advance, and an aqueous solution containing sulfur (or selenium) is added to this solution. The purpose of this method is to reduce the time required to form a precipitated film to about half that of the conventional method, and to improve the uniformity of the precipitated film.

(4) Description of structure and operation of the invention To explain an embodiment of the present invention by taking the precipitation of Cd8 as an example, an aqueous solution of CdC/, and an aqueous ammonia solution are added to a gold reaction tank, and the reaction tank is heated to a temperature of 80°C or higher in advance. Place it in a thermostatic bathtub that is kept at a constant temperature. Next, a glass or ceramic substrate is immersed in a reaction tank, and the solution is stirred using a magnetic stirrer or a stirrer connected to a motor. When the temperature of the solution in the reaction tank reaches the predetermined temperature of 80°C or higher that was set earlier, add an aqueous solution containing sulfur to the reaction tank and keep the temperature of the solution at that temperature, or While increasing the temperature further, Cd8
The deposition is continued for 30 minutes to 1 hour until the deposited film has the required thickness.

When the deposition is finished, pull the substrate out of the solution and remove unnecessary Cd.
8 particles are removed by washing with water and dried.

The Cd8 precipitated film formed in this manner has better uniformity than the CdS precipitated film formed by the conventional method because less unnecessary CdS particles adhere to the substrate.

(5) Description of Effects As is clear from the above explanation, according to the present invention, the deposition time required to obtain a deposited film of the required thickness as a photoconductive film is longer than when deposited using a conventional method. It can be shortened to about 1/2. Furthermore, since the deposition time is shorter than in the conventional method, the deposited film does not become non-uniform due to attachment of unnecessary deposited particles to the substrate surface, and has the great advantage that a uniform deposited film can be obtained.

Claims (1)

[Claims] In a chemical precipitation method in which an aqueous solution containing sulfur or selenium is added to an aqueous solution containing cadmium to form a precipitated film of cadmium sulfide or cadmium selenide, the aqueous solution containing cadmium is heated to a predetermined temperature of 80°C or higher. A method for producing a chemically deposited film, characterized in that an aqueous solution containing sulfur or selenium is added at a constant temperature.