JPS6012285B2 - Method for producing cadmium sulfide deposited film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for obtaining a cadmium sulfide precipitated film by a homogeneous precipitation reaction using thiourea and cadmium ions as main reactants.

Conventionally, in the manufacturing method of this type of cadmium sulfide precipitated film, many studies have been conducted on the composition of the reaction solution, reaction temperature, substrate, etc. in order to increase the thickness of the film obtained in one reaction. .

However, in any case, since the reaction is a homogeneous precipitation reaction in a solution, it is difficult to increase the amount of cadmium sulfide precipitated per unit area of the substrate, and it is difficult to increase the amount of cadmium sulfide precipitated per unit area of the substrate.
The limit was to obtain a film thickness of about 5 to 0.6 mm. Moreover, the recovery rate as a membrane was also limited to about 20%. The present invention increases the amount of cadmium sulfide produced as a cadmium sulfide film compared to the amount of cadmium sulfide produced in the solution while the entire reaction of the reaction solution is completed, and thickens the concentration produced in one reaction. The present invention provides a method.

First, Table 1 shows the results of the study regarding the liquid composition, reaction temperature, reaction rate, growth rate of pus, and thickness obtained.

The reaction solution had a cadmium ion concentration of 0.0667 mol/Z, a thiourea concentration of 0.333 mol/Z, and an ammonia concentration of 1.
．． The standard was adjusted to 0.05 mol/Z and the feed was adjusted to 10.17, and the standard reaction temperature was set to 8.0.

The reaction rate was expressed as the time required for the cadmium ion concentration to decrease to 1/4 of that at the start of the reaction, and the film thickness was expressed as the film thickness obtained up to the aforementioned time. Table 1 The results of these experiments show that when the reaction rate in solution is (7, 10, 13), the film growth for a given amount of cadmium ion reaction decreases.

Also, if there is a large amount of cadmium sulfide produced in the liquid (Snake 1)
Also film growth is reduced. However, in other cases no significant differences were observed. In addition to the examples listed in Table 1, studies on the temperature dependence of liquid phase reactions were conducted using several types of mixed liquids, but these results were almost unrelated to changes in liquid composition. (-26.1×IQ/T)
...lk: reaction rate constant ko: constant (varies depending on the reaction solution) T: absolute temperature.

On the other hand, the temperature dependence of the film growth rate at the initial stage of the reaction was also expressed by a similar equation, as shown in Equation 2.

V = Voexp (11.5 x 1 pi/T) ...2V
: (Pus growth rate Vo: Constant (varies depending on the reaction solution) T: Absolute temperature From these results, it can be seen that the reaction rate and film growth rate increase exponentially as the temperature rises.

It was also confirmed that when the film was left in a fresh reaction solution, the initial growth rate was maintained, and the film thickness increased linearly with time as shown in FIG.

It was also observed that when a large amount of cadmium sulfide was produced in the reaction solution, the growth of the film stopped and a precipitate adhered to it, making it impossible to obtain a good film.

As a result of these experiments, two methods can be considered to create a thick film.

One method is to constantly flow a new reaction solution to grow the screen.

However, in this method, the recovery rate as a membrane based on the total reaction is very low, and it is not preferable for industrial purposes. The present invention provides a high recovery rate and a thick cadmium sulfide precipitated film by keeping the temperature of most of the reaction solution low and increasing the temperature of the solution on the substrate where cadmium sulfide is deposited. It is something to do.

The present invention can be implemented in the following ways.

1 Circulate the reaction solution and raise the temperature of the solution at a certain part of the substrate.
How to cool other parts.

2. A batch method in which the reaction solution is cooled and heated at the substrate plate.

3 Using a method that combines steps 1 and 2, circulate the liquid and cool it.
A method that heats only the board part.

Examples of the present invention will be described below.

Fig. 2 shows an outline of an apparatus for carrying out method 1 above, in which a reaction liquid circulation path 4 equipped with a pump 3 is connected to a high-temperature reaction tube 2 in which a substrate 1 is installed. Circulate the reaction solution.

5 is a heater for heating the reaction tube 2, 6 is a cooling pipe, 7 is an inlet of cooling water, and 8 is an outlet thereof.

According to this device, the liquid in the reaction tube 2 is heated and then cooled in the cooling tube 6, so that the reaction in the circulation path 4 is suppressed. FIG. 3 shows an apparatus for carrying out method 2 above, in which a substrate 1 is attached to the side of a reaction tank 9 containing a reaction solution, and the substrate 1 is heated from the outside by a heater 0 or the like. According to this method, the part of the reaction solution that comes into contact with the substrate is heated. The reaction rate of that part increases. FIG. 4 shows an apparatus for carrying out method 3 above.

11 is a reaction tube, the substrate 1 is attached to this and the heater 12 is
Heat.

Reference numeral 13 denotes a circulation path for a reaction solution connected to the reaction tube 11, and includes a pump 12.

14 is a cooling pipe, 15 is an inlet of cooling water, and 16 is an outlet thereof.

In this device, only the portion of the reaction liquid that comes into contact with the substrate is heated, and the other portions are cooled. Next, a specific example of method 2 above will be described.

The above-mentioned standard solution was used as the reaction solution, which was placed in a glass container and cooled from the outside.
At 0:00 am, heated oil was poured into the tank to heat it up.

According to this method, a precipitated film grew on the substrate at a rate equivalent to the film growth rate at a temperature of about 80 qo, but the reaction rate of the reaction solution was slow corresponding to the reaction at about 40 qo. . In addition, in the secondary method in which the temperature of the entire reaction solution was set to 80 qo, the cadmium ion concentration decreased due to the reaction in the liquid phase, so the growth of the film stopped at a certain thickness.
The relationship between the reaction time and the thickness of the deposited film for the above-mentioned method a of the present invention and conventional method b is as shown in FIG. 5. According to the present invention, a good quality deposited film with a thickness of 3 mm or more was obtained. As described above, according to the present invention, since the substrate portion is heated preferentially, the thickness of the deposited film can be increased, and the reaction in other liquid phase portions is suppressed, so that the film The recovery rate can be improved.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the reaction time and the thickness of the deposited film when the reaction temperature is kept constant and the substrate is always in contact with fresh reaction solution. FIG. 5, which is a diagram showing an example of the configuration of the apparatus, shows the relationship between the reaction time and the thickness of the deposited film in the method of the present invention and the conventional method. Figure 1 Figure 3 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] 1. A method in which a substrate is immersed in a solution containing thiourea and cadmium ions as main reactants, and a cadmium sulfide film is deposited on the substrate by a precipitation reaction caused by both of the reactants, the portion of the solution coming into contact with the substrate. A method for producing a cadmium sulfide precipitated film, characterized by increasing the temperature of the cadmium sulfide deposited film higher than that of other parts.