JPS5943866A - Vapor depositing method - Google Patents

Abstract

PURPOSE:To form stably a photosensitive film for electrophotography or the like having uniform concn. by vapor deposition, by specifying the specific volatility among the component elements of alloys which are materials to be evaporated. CONSTITUTION:Vapor deposition is accomplished under the condition wherein the specific volatility among component elements of alloys such as Se-Te, Se-S, Fe-Ni or the like to be used as a material to be evaporated in the stage of forming a photosensitive film, etc. is specified at 0.9-1.1. The vapor having substantially the same compsn. ratio as the compsn. ratio of the alloys can be generated under such condition and the component ratio of the vapor deposition film to be deposited on a substrate is made roughly constant. The vapor pressure ratio at the vapor deposition temp. between the respective component elements of the alloy in this method is maintained preferably at about 10:1 or above and the content of the element indicating the lower vapor pressure at about <=7wt%. A photosensitive film wherein the fluctuation of the content of Te in the part covering at least 10mum length in, for example, the film thickness direction is within about 0.5%, is obtd. by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vapor deposition method, for example, a vapor deposition method suitable for producing a photoreceptor film for an electrophotographic or photoelectric conversion element.

Conventionally, as a photoreceptor for electrophotography, a photoreceptor made of a selenium-tellurium alloy (Se-Te) containing selenium and tellurium content Lrc is known. This 5e-Te photoreceptor has excellent sensitivity particularly in the long wavelength range due to the inclusion of tellurium. Such a photoreceptor may be required to have a region where the tellurium concentration is relatively low and approximately constant (for example, charge transport layer 2 or less, abbreviated as CTL). That is, this is because such a tellurium concentration profile results in a structure with a small residual potential and carrier trap level.

Various methods have already been proposed to keep the tellurium concentration constant, but none of them can be said to be satisfactory.

For example, there is a method of charging a large amount of evaporation charge and partially evaporating it from the surface of the thin molten layer on the front side, but this method has a low evaporation rate and requires a large amount of vapor to obtain a deposited film of a constant thickness. Raw materials have to be used, the size of the evaporation source is large, and costs are high. However, the method of generating different vapors from multiple evaporation sources from dissimilar materials arranged separately and mixing them in the vapor phase did not allow for sufficient mixing of the vapors, and furthermore, it was difficult to obtain the results due to the non-uniformity of the mixing. Concentration irregularities tend to occur in the deposited film. Furthermore, there is a flash evaporation method in which alloy wire is melted and evaporated through an evaporation block, but
When depositing the above films, the evaporation is unstable, and each weighing member must be placed in the chamber, which complicates the structure.

The present invention solves the deficiencies of the conventional method as described above, simplifies and
This was developed to propose a method for stably obtaining a deposited film with a uniform concentration at a low cost. The present invention relates to a vapor deposition method characterized in that vapor deposition is carried out under conditions such that the specific volatility of is 0.9 to 1.1.

According to the present invention, since the relative volatility between the constituent elements of the alloy as the evaporation material is set to be 0.9 to 1.1,
It is possible to generate vapor having a composition ratio substantially the same as that of the alloy, and therefore the composition ratio of the vapor deposited film deposited on the substrate can be made approximately constant. As a result, for example, a vapor deposited film having a low and almost constant tellurium concentration can be formed, and a 5e-Te photoreceptor having excellent characteristics as described above can be produced. Moreover, since it is only necessary to control the specific volatility, the structure inside the deposition tank (chamber) is simplified compared to the conventional method described above, less raw materials are used, and the vapor composition is always stable. , the concentration distribution of the deposited film becomes uniform.

In the method according to the present invention, the vapor pressure ratio at the vapor deposition temperature between each component element of the alloy is 1021 (preferably 5
00:1) or more (however, the ratio of vapor pressures when each element is in a pure state) is preferable. Also, among the constituent elements of the alloy, 1. h#) The content of elements showing low vapor pressure is 7% by weight.
It is desirable that the content be below (preferably 5.5% by weight or below).

Usable alloys include those consisting essentially of selenium and tellurium, as well as selenium-sulfur, iron-nickel,
Other alloys such as silver bromide-iodine and the like may also be used.

Furthermore, the photoreceptor film produced by the method of the present invention is such that the tellurium content varies within 0.5% in terms of content over a length of at least 10 μm in the film thickness direction. It is best to evaporate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of a vapor deposition apparatus for carrying out the method according to the invention.

In this vapor deposition apparatus, an evaporation source 5 and a vapor deposition drum 6 facing the evaporation source 5 are arranged in a pelger (not shown). The evaporation source 5 is configured in a so-called Knudsen cell type, and the first evaporation source 5 has a Te concentration of 7% by weight or less, for example 5 parts by weight, in the container 7.
5e-Tc evaporation material 8 and the Te concentration is, for example, 22.5.
parts by weight of the second 5e-Te evaporation material 9; ing. Heaters 1, 0, and 11 are placed above these evaporated materials, and the evaporated materials are caused to fly toward the drum 6 from the opening 12 at the top of the container 7 under the control of the heat of the heaters.

What should be noted here is that the evaporative material 80 alloy contains tellurium at a low concentration of less than 7% by weight.

Originally, pure selenium and tellurium have a vapor pressure ratio of 500.
: 1, and selenium evaporates much more easily. However, it has been found that when the alloy composition is made as described above, vapor having a composition substantially the same as that of the alloy (melt), ie, Se:Te=95:5, for example, is generated. In other words, when the tellurium concentration is as low as mentioned above, the specific volatility of selenium and tellurium is 0.9 to 1.1, particularly substantially 1.0, so the tellurium in the obtained vapor deposited film is The content remains almost constant, and the desired concentration profile can be obtained.

FIG. 2 shows a photoreceptor obtained by the above method, in which a Te content of 3 to 7% by weight, for example 5% by weight, is formed on a conductive support substrate 6 made of aluminum or the like. A charge transport layer CTL2 made of 8e-Te with a thickness of 10 to 20% by weight and a thickness of 2 to 5 μm and a charge (photocarrier) generation layer CGL3 is provided. CTL2 is the deposition of the evaporation material 8 described above, and CGL3 is
is a film formed by vapor deposition of the above-mentioned evaporation material 9.

To give a specific example of the vapor deposition operation, the M substrate 6 is held at 70°C, and 5e-Te with a Te concentration of 5 is used as the first evaporation material 8.
300 g of alloy, Te concentration is 22 as second evaporation material 9
．． 200 g of 5% 5e-Te alloy was used. First, the first
The evaporated material was heated to 2900G for 40 minutes to form CTL2, and then cooled to 100°C.

Thereafter, the temperature of the second evaporation source 9 was raised to 300° C., and evaporation was performed for 10 minutes to form CGL on the surface of CTL. The Te concentration profile of the obtained photoreceptor is shown in FIG.

According to this, CTL2 formed according to the present invention is 5
Since the tellurium concentration is approximately constant at about 1.5%, a photoreceptor with low residual potential and few trap levels can be obtained. Since CGL3 has a high tellurium concentration, it has good photosensitivity.

As mentioned above, in order to make the specific volatility substantially 1.0, the alloy composition of the evaporation material should have a low tellurium concentration (
In particular, VC (7% by weight or less) should be selected. This specific volatility can be measured by measuring the vapor concentration using an atomic absorption monitor (manufactured by Japan Vacuum Technology Co., Ltd.). In addition, if the heating temperature of the evaporation material is set higher, the alloy composition range in which the specific volatility can be made to be 1.0 tends to be wider.
It is desirable to keep the temperature above ℃. Generally, the degree of vacuum in the Pelger is preferably set to a high vacuum of 10-3 Torr or more.

In addition, as shown by the broken line in Figure 3, the tellurium concentration is 596
The area may be further extended. In this case, only the first evaporation material 8 described above is evaporated.

Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, the alloy used is not limited to S e −T c, but also ε
(E-8, Fe-Ni%AgBr-I, etc. are suitable, and various alloy compositions that can be set to the specific volatility in the present invention can be selected.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a schematic diagram of the main parts of a vacuum ablation apparatus, Fig. 2 is a sectional view of the obtained photoreceptor, and Fig. 3 is its 71.1et6i degree. It is a figure showing a profile. In addition, as shown in the drawing, in the symbol 2...C'l'L (charge transport layer) 3...
......CGL (charge generation layer) 5...
...Evaporation source 6...Base 8.9...Evaporation materials 10, 11...Heater. 382 9 -

Claims (1)

[Claims] When evaporating an evaporation material consisting of a 10 alloy and depositing it on a substrate to be evaporated, under conditions such that the relative volatility among the constituent elements of the alloy is 0.9 to 1.1. A vapor deposition method characterized by vapor deposition. 2. The method according to claim 1, wherein the vapor pressure ratio at the vapor deposition temperature between each component element of the alloy is 10:1 or more. 30. The method according to claim 2, wherein the vapor pressure ratio is 500:1 or more. 4. Among the constituent elements of the alloy, the content of the element exhibiting a lower vapor pressure is 7% by weight or less, the first claim of claim 1.
The method described in any one of Items 1 to 3. 5. The method according to claim 4, wherein the content of the low vapor pressure element is 5.5% by weight or less. 6. The method according to any one of claims 1 to 5, characterized in that the alloy consists essentially of selenium and tellurium. 7. A patent claim characterized by a photoreceptor film in which the tellurium content varies within 0.5% in terms of content over a length of at least 10 μm in the thickness direction of the vapor-deposited film formed by vapor deposition. The method described in Section 6 of the scope of