JPS6161386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an electrophotographic photoreceptor.

Conventionally, Se, CdS, ZnO were used as electrophotographic photoreceptors.
Inorganic photoconductive materials such as polyvinyl carbazole (PVK), and organic photoconductive materials such as trinitrofluorenone (TNF) are commonly used.

However, it has problems such as insufficient sensitivity in the long wavelength region and being a polluting material.

The present invention provides a novel electrophotographic photoreceptor for solving the above problems.

An essential condition for an electrophotographic photoreceptor is that the charged charge must be retained until the completion of post-processing such as transfer, and the higher the dark resistance value of the photoreceptor, the better the charge retention ability. Currently, this dark resistance value is required to be 10 ¹² Ω·cm or more, although it depends on the device conditions.

By the way, amorphous Si produced by the glow discharge decomposition method of silane gas
The film is known to be a photoconductor with good sensitivity to long wavelengths. However, this dark resistivity is as low as 10 ⁸ to ^{10 10} Ω·cm, making it unsuitable for use as an electrophotographic photoreceptor.

The present invention aims to improve the amorphous silicon, which is said to have insufficient dark resistance, and to provide a highly sensitive electrophotographic photoreceptor with a multilayer structure.

In other words, the photoconductivity of an amorphous Si film strongly depends on the temperature of the substrate during film formation, and as the substrate temperature increases, the photosensitivity increases.
The bright resistivity at ℃ is 10 ⁵ Ω・cm for 1000 lx light. On the other hand, at this substrate temperature, the dark resistivity is 10 ⁸ ~ 10 ⁹
As low as Ω・cm. Conversely, when the substrate temperature is low, around 100°C, the dark resistivity is high at 10 ¹⁰ to 10 ¹¹ Ω·cm, and the bright resistivity is low at 10 ⁷ to ^{10 8} Ω·cm with 1000 lx light.

Therefore, in the present invention, firstly, the substrate temperature is 80-130℃.
By mixing oxygen into silane gas when forming amorphous Si film,
An H--Si--O compound is formed in the film to increase the resistance. In this case, when the oxygen (O ₂ ) gas content in the monosilane (SiH ₄ ) gas is 0.5% by volume or less, the dark resistivity of the formed amorphous silicon film is 10 ¹² Ω・cm or less, while when the content of oxygen (O 2 ) gas in the monosilane (SiH 4 ) gas is 6% by volume. If it exceeds this value, the bright resistivity of the photoconductive material increases too much (approaching the dark resistivity) and is not suitable for use as an electrophotographic photoreceptor.

Second, by heat-treating the first layer amorphous Si film formed as described above at 200-250°C, defects in the film are reduced and carrier transport efficiency is increased.

Furthermore, thirdly, a second layer of amorphous Si film is grown on the heat-treated first layer at a substrate temperature of 200-250° C. using silane gas having an oxygen content of 0.1% by volume or less. Although the second layer Si film has a low dark resistivity, it is a highly sensitive photoconductor and has a very high photocarrier generation efficiency.

The structure of the electrophotographic photoreceptor formed as described above is shown in FIG. In the figure, A is a conductive substrate that becomes an electrode, B is a first layer of Si film with high resistance and high charge transport efficiency, and C is a second layer of Si film with high sensitivity and high photocarrier generation efficiency. It is a membrane. When this electrophotographic photoreceptor is uniformly charged with a corona discharger D and irradiated with light E locally through a desired mask F, etc., light carriers are generated on the second layer Si film C. , the optical carriers are injected into the first layer of Si film B, and are transported very quickly to the electrode A due to the high electric field present in the first layer B, thereby dissipating the charged charges. It is understood that the electrophotographic photoreceptor of the present invention has extremely high sensitivity due to the above mechanism.

Example (first step) In a capacitive high frequency glow discharge device, a conductive substrate was attached to a substrate holder. Next, after exhausting the air in the vacuum chamber of this device, the temperature of the substrate was raised to 120°C using a heater. Then, silane gas containing 4% by volume of oxygen was introduced, and the degree of vacuum was 5.
A high frequency (13.56MHz) with a power of 10W was applied to the discharge electrode while maintaining the voltage at ×10 ^-2 Torr. thus,
A first layer of Si film with a thickness of 2.8 μm was formed on the substrate.

(Second Step) While maintaining the same degree of vacuum as in the first step, the substrate temperature was raised to 220° C. and held for 1 hour.

(Third step) The first layer obtained in the first step by replacing the electric atmosphere in the vacuum with oxygen-free silane gas at a vacuum level of 5 × 10 ^-2 Torr and applying 10 W of high frequency to the discharge electrode. The first layer of Si with a thickness of 0.6 μm is deposited on the Si film of
A film was formed.

The characteristics of the amorphous Si film produced by the above three steps as an electrophotographic photoreceptor were investigated. The results are shown in FIG. 2. In this measurement, charging was performed by -5.5 kV corona discharge, and exposure was performed with light of 4 μW/cm ² at a wavelength of 0.6 μm. The half-life time due to optical attenuation was 0.5 seconds. In the figure, the horizontal axis represents time, and the vertical axis represents the surface potential of the photoreceptor.

As described above, according to the present invention, it is possible to provide an electrophotographic photoreceptor that has the characteristic of reducing the electrical charge with long wavelength light and extremely weak light, and is suitable for use in high-speed laser printers and the like.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view illustrating the structure of an electrophotographic photoreceptor manufactured according to the present invention. A is an electrode, B is a first Si layer responsible for charge transport, C is a second Si layer responsible for charge generation, and D is a corona discharger. FIG. 2 is a diagram showing changes in surface potential of an amorphous silicon film electrophotographic photoreceptor manufactured according to the present invention.

Claims (1)

[Scope of Claims] 1. In a method for producing an electrophotographic photoreceptor in which a photoreceptor layer is formed on the surface of a conductive substrate by performing glow discharge in a gas containing silane gas, the method comprises silane gas containing 0.5 to 6 mol% oxygen and the balance being under pressure. ^10-1 to ^10-3 Torr
A step of placing the conductive substrate at a temperature of 80°C to 130°C in the gas and forming a first layer on the conductive substrate by performing glow discharge; The conductive substrate is kept at 200℃ to 250℃ for a predetermined period of time, and then the temperature is lowered into a gas consisting of 0 to 0.1 mol% oxygen and the balance silane gas at a pressure of 10 ^-1 to ^{10 -3} Torr.
A method for manufacturing an electrophotographic photoreceptor, comprising the steps of: disposing a conductive substrate maintained at 200° C. to 250° C. and forming a second layer on the first layer by performing glow discharge.