JPH04191747A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance the charging property and improve the image quality by specifying the grain size of crystal Si in a photosensitive layer mainly consisting of amorphous silicon. CONSTITUTION:This photosensitive body has a photosensitive layer mainly consisting of amorphous silicon. The photosensitive layer is formed on a support body, for example, by glow-discharging a mixture of silane gas with hydrogen. The crystal grain size determined from the half value width of the diffraction peak revealed in correspondence to the surface (iii) of the crystal Si in the photosensitive layer in X-ray diffraction using CuKalpha ray is less than 50Angstrom . When this size is larger than the above value, the charging property of the photosensitive body is aggregated, and the density of a copy image is reduced, resulting in an image of rough image quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic photoreceptor, and particularly to an electrophotographic photoreceptor using amorphous silicon in the photosensitive layer.

[Conventional technology]

Electrophotography is a method in which an electrostatic latent image is formed by charging a photoreceptor and image exposure, and this latent image is developed with a developer, and then the toner image is transferred to transfer paper and fixed to obtain a copy. Are known. The photoreceptor used in this electrophotographic method basically has a photosensitive layer laminated on a conductive substrate. Conventionally, the materials constituting the photosensitive layer include inorganic photosensitive materials such as selenium or selenium alloys, cadmium sulfide, and zinc oxide;
Alternatively, organic photosensitive materials such as polyvinylcarbazole, trinitrofluorenone, bisazo pigments, phthalocyanine, pyrazoline, and hydrazone are known, and the photosensitive layer is used as a single layer or in a stacked structure.

However, these conventionally used photosensitive layers have problems that still need to be solved in terms of durability, heat resistance, photosensitivity, etc.

In recent years, amorphous silicon (a-5i) has been used as this photosensitive layer.
Photoreceptors using the same are known, and various improvements have been attempted. A photoreceptor using this amorphous silicon is made of silane (SiH
2) An amorphous film of silicon is formed on a conductive substrate by treating a gas using a glow discharge decomposition method, etc., and hydrogen atoms are incorporated into the amorphous silicon film to provide photoconductivity. It is intended to be presented. This amorphous silicon photoreceptor has a photosensitive layer that has a high surface hardness, is hard to be scratched, is resistant to abrasion, has high heat resistance, and is excellent in mechanical strength. Furthermore, amorphous silicon has excellent photosensitivity, such as a wide spectral sensitivity range and high photosensitivity.

[Problem to be solved by the invention]

However, on the other hand, electrophotographic photoreceptors using amorphous silicon have the disadvantage that dark decay is large and a sufficient charging potential cannot be obtained even when charged.

That is, when an amorphous silicon photoreceptor is charged, imagewise exposed to form an electrostatic latent image, and then developed, the surface charge on the photoreceptor increases until the imagewise exposure process or the development process. Even the charge on the portions not irradiated with light is attenuated, making it impossible to obtain the charging potential necessary for development. If a copy is made using such a photoreceptor with a large dark decay of the charged potential, the resulting copy will have low image density and poor reproducibility of intermediate tones.

Therefore, it is an object of the present invention to provide an amorphous silicon electrophotographic photoreceptor that has a low residual potential, high chargeability, and is capable of obtaining images of good quality.

Another object of the present invention is to provide an electrophotographic photoreceptor that has excellent heat resistance and chemical stability, high mechanical strength, and excellent abrasion resistance.

[Means and effects for solving the problem] The present inventors,
The inventors have discovered that the diffraction peak in X-ray diffraction of a photosensitive layer mainly composed of amorphous silicon is related to the electrophotographic characteristics of an electrophotographic photoreceptor, and have completed the present invention.

The present invention relates to an electrophotographic photoreceptor comprising a photosensitive layer mainly made of amorphous silicon on a support, which exhibits diffraction that appears corresponding to the (111) plane of crystalline Si in X-ray diffraction of the photosensitive layer. It is characterized in that the crystal grain size determined from the half value of the peak is 50 Å or less.

The present invention will be explained in detail below.

In the electrophotographic photoreceptor of the present invention, the support may be either electrically conductive or insulating.

As the conductive support, metals or alloys such as stainless steel and aluminum are used. Examples of the insulating support include synthetic resin films or sheets such as polyester, polyethylene, polycarbonate, polystyrene, and polyamide, glass, ceramic, paper, etc., or in the case of an insulating support, at least one layer that is in contact with another layer. It is necessary that the surface to be used is conductive treated.

These conductive treatments can be performed by vapor deposition, sputtering, lamination, or other treatments for the metal used in the conductive support. The support may have any shape, such as a cylinder, a belt, or a plate. Further, the support may have a multilayer structure. The thickness of the support is appropriately selected depending on the desired electrophotographic photoreceptor, but a thickness of 10 m+ or more is usually suitable.

The photosensitive layer is mainly composed of silicon, but in the present invention, the crystal grain size determined from the half-width of the diffraction peak that appears corresponding to the (111) plane of crystalline Si in X-ray diffraction, or 50 Å or less. It is necessary that

This crystal grain size is determined by the formula of 5cherrer%, where t: crystal grain size of Si (person) λ: wavelength of incident X-ray used (person) B: half-width of diffraction peak (rad) θB of crystal Si It is determined from the Bragg angle (') at which the diffraction peak corresponding to the (111) plane appears. When the crystal grain size in the photosensitive layer is larger than 50, the charging property of the electrophotographic photoreceptor deteriorates, and therefore, the obtained copy image has a low image density and a rough image quality.

The photosensitive layer in the present invention can be formed by a known method. For example, it can be formed by a glow discharge method, a sputtering method, an ion blating method, a vacuum evaporation method, or the like. These film forming methods are appropriately selected depending on the purpose, but it is preferable to use a plasma CVD method to decompose silane (SiH4) or a silane-based gas by glow discharge. A film containing hydrogen with a relatively high dark resistance and high photosensitivity is formed, and suitable characteristics can be obtained.

The case of forming by plasma CVD method will be explained below. This is carried out by placing the support at a predetermined position in a plasma CVD apparatus and introducing a raw material gas. is used. Silane or silane derivatives include S iH4, S 12H6,5
iC14,5IHC1,,5in2C12,S 13
Examples include H8, S 14 HIO, etc.

In this case, hydrogen gas may be introduced simultaneously with the silane gas, but it is preferable to use the hydrogen gas at a flow rate in the range of 0 to IO times the silane gas. When the flow rate ratio of hydrogen gas exceeds 10 times, the crystal grain size may become larger than 50 times.

Taking AC discharge as an example, the film forming conditions are a frequency of 50
Hz ~5 GHz, reactor internal pressure 10-' ~5To
rr, and the discharge power is appropriately set in the range of IO to 2000W. Preferably, the support temperature is set at about 300°C or less.

A more preferable range is 250°C or lower. If the substrate temperature is higher than about 300°C, the grain size may increase to greater than 50°C.

In the present invention, the thickness of the photosensitive layer can be arbitrarily set, but is in the range of ■- to 1.00 μs, particularly 5- to 5 μs.
It is preferable to set it within the range of 0 addition.

In the electrophotographic photoreceptor of the present invention, a charge injection blocking layer may be provided between the support and the photosensitive layer. Examples of the charge injection blocking layer include a p-type semiconductor layer, an n-type semiconductor layer, an insulating layer, etc. made of amorphous silicon doped with an element from group Ⅰ or group V of the periodic table of elements, and the like. Film thickness is 0. It is appropriately set in the range of O1 to O10.

Further, in the electrophotographic photoreceptor of the present invention, a surface layer may be formed for the purpose of surface protection.

Preferably, the surface layer is mainly composed of amorphous silicon to which nitrogen atoms, carbon atoms, or the like are added.

〔Example〕

Hereinafter, the present invention will be explained by examples.

Example 1 A capacitive plasma CVD apparatus capable of forming an amorphous silicon film on a cylindrical support was used. A photosensitive layer having a thickness of about 18 mm was formed on a cylindrical aluminum support by glow discharge decomposition of a mixture of silane (SiH4) gas and hydrogen gas (H2). The film forming conditions at this time were as follows.

100% silane gas flow rate: 50cJ/ff1in10
0% hydrogen gas flow rate: 50cI+? /ll1n 1oOpp of hydrogen dilution, m B 2H6 gas flow rate: 50cnf
/1ain Reactor internal pressure: 0.4 Torr Discharge type crab 50V Discharge frequency: 13.58MHz Substrate temperature = 250°C Regarding the obtained photosensitive layer, λ-1,5 as incident X-ray
Using CuKα of four people, we measured the mid-half value of the diffraction peak (theoretical value: 28.4', actual #1 value: 27.8') that appears corresponding to the (111) plane of the Si crystal.
B was 75° (0,13 rad). Therefore, the crystal grain size determined from these was 11.0. When the obtained electrophotographic photoreceptor was subjected to characteristic evaluation and copying, it was found that the charging property was good and high, and the copied image had excellent image quality without defects.

Comparative Example 1 The substrate temperature in Example 1 was 300°C, and the 100% hydrogen gas flow rate was 550°C (except that it was changed to J/win).
A photosensitive layer was formed in the same manner as in Example 1. The crystal grain size of this photosensitive layer was determined in the same manner as in Example 1, and the half width was approximately 0.4° (0,007 ra).
d), and therefore, the crystal grain size determined from these was 204. When the obtained electrophotographic photoreceptor was subjected to characteristic evaluation and copying, it was found that the electrostatic chargeability was low, and the copied image had a low image density and rough image quality.

Example 2 A capacitive plasma CVD apparatus capable of forming an amorphous silicon film on a cylindrical support was used. A photosensitive layer having a thickness of about 25 mm was formed on a cylindrical aluminum support by glow discharge decomposition of a mixture of silane (SiH4) gas and hydrogen gas (H2). The film forming conditions at this time were as follows.

100% silane gas flow rate: 150 c+J/5ini
oox hydrogen gas flow rate: 100 cl/s+in hydrogen dilution 1001) l) IB2 H6 gas flow rate = 10 c/s
Sin reactor internal pressure: 0.7 Torr Discharge type crab 80V Discharge frequency: 13,56 Mtlz Substrate temperature = 250°C Regarding the obtained photosensitive layer, λ-1,5 as incident X-ray
(111) of Si crystal using 4 CLIK(Z)
Diffraction peak that appears corresponding to the surface (theoretical value = 28.4°,
When n1 was determined for the half value of the measured value (27.8''), B was 1.8' (0.03 rad).

Therefore, the grain size determined from these is 4
There were 5 people. When the obtained electrophotographic photoreceptor was subjected to characteristic evaluation and copying, it was found that the charging property was good and high, and the copied image had excellent image quality without defects.

Comparative Example 2 A photosensitive layer was formed in the same manner as in Example 1, except that the substrate temperature in Example 2 was changed to 310° C. and the 100% hydrogen gas flow rate was changed to 9000 J/min. The crystal grain size of this photosensitive layer was determined in the same manner as in Example 2, and the half width was approximately 1.4° (0.02 rad).
), and therefore, the crystal grain size determined from these was 60. Characteristic evaluation and copying of the obtained electrophotographic photoreceptor revealed that it had low chargeability.
The copied image had low image density and roughness in some parts.

〔Effect of the invention〕

In the present invention, crystalline Si in X-ray diffraction of the photosensitive layer
Since the crystal grain size determined from the half width of the diffraction peak that appears corresponding to the (111) plane of is 50 Å or less,
The electrophotographic photoreceptor of the present invention exhibits excellent charging properties, and the resulting copy images are likely to have excellent image quality with high image density and no defects.

Applicant: Fuji Xerox Co., Ltd.

Claims (1)

[Claims] (1) In an electrophotographic photoreceptor in which a photosensitive layer mainly composed of amorphous silicon is provided on a support, a diffraction peak that appears corresponding to the (111) plane of crystalline Si in the X-ray diffraction of the photosensitive layer The grain size determined from the half-width is 50 Å.
An electrophotographic photoreceptor characterized by the following: