JPS63143559A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the excellent reliability of the titled body which can be used for long period, without generating the deterioration of electric characteristics by providing a specific a-Si type intermediate layer on a a-Si photosensitive layer formed on a substrate body, followed by providing a diamond like carbon film on the intermediate layer. CONSTITUTION:The titled body is formed by providing the intermediate layer 4 of the amorphous (a-SiCH or a-SiNH) composed of Si atom and carbon atom and/or nitrogen atom on the a-Si photosensitive layer 3 formed on the conductive substrate 1, followed by providing the diamond like carbon film 5 on said intermediate layer 4. And, the intermediate layer 4 has optical band gap of 2.0-3.0 eV, and preferably the film thickness of 0.03-0.5mum. The interfacial defective level between the layers 3 and 5 is lessened by interposing the intermediate layer 4 between the a-Si sensitive layer 3 and the carbon film 5. Therefore, the deterioration of the electric characteristics of the titled body such as sensitivity, receptive voltage, dark attenuation and and residual voltage, etc. does not occur in case of using it for long period, thereby improving the reliability of the titled body, without trapping the carrier caused by charging and exposing steps at the interfacial defective level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor used in electronic copying machines, laser printers, LED printers, and the like.

[Conventional technology]

Electrophotographic technology involves exposing characters and image information to the surface of a charged photoreceptor to generate an electrostatic image, which is then developed and visualized before being transferred to paper. It is applied to various printers including.

Various photoconductive materials such as selenium have traditionally been used as photoreceptors for this purpose, but recently amorphous silicon, which has improved electrical properties and mechanical strength, has been widely used.

Such photoreceptors are required to produce stable images over a long period of time, but although amorphous silicon has high hardness and strength, it can be damaged or worn out, and it also suffers from corona discharge during the charging process. Deterioration due to repeated exposure to 1. As a result, electrical properties such as photosensitivity, acceptance potential, dark decay, and residual potential of the amorphous silicon photosensitive layer deteriorate, resulting in lower printing quality and short service life.

As a means to solve this drawback, for example, Japanese Patent Laid-Open No. 57-1
Japanese Patent No. 14146 discloses that the surface of an amorphous silicon photosensitive layer is covered with a diamond-shaped protective film made of carbon.

However, although the diamond-like protective film reduces damage and abrasion of the amorphous silicon photosensitive layer and improves corona discharge resistance, it still tends to cause electrical customization to deteriorate (in addition, the diamond-like protective film easily peels off, etc.). There are some drawbacks, and it has not achieved sufficient reliability as a photoreceptor.The reason for this is not necessarily clear, but the strain caused by the difference in composition between the amorphous silicon photosensitive layer and the diamond-like carbon protective film has caused problems in the adhesion between the two. It is thought that this is because this strain has an adverse effect on the strain, and this strain creates many defect levels at the interface between the two.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION In view of the conventional circumstances, it is an object of the present invention to provide an electrophotographic photoreceptor that is provided with an amorphous silicon photosensitive layer and that can be stably used for a long period of time and has excellent reliability.

[Means for solving problems]

The electrophotographic photoreceptor of the present invention comprises: an amorphous silicon photosensitive layer formed on a conductive substrate; an amorphous intermediate layer formed on the photosensitive layer formed of silicon atoms and carbon atoms and/or nitrogen atoms; It is characterized by having a diamond-like carbon film formed on the intermediate layer.

The conductive substrate is At+Cr, Ni, Mo, Nb
The material may be a conventionally used metal or alloy such as Ta, stainless steel, etc., and its shape and thickness are appropriately selected depending on the purpose of use. In addition, the conductive substrate may be an electrically insulating polymer material such as polyester, polyethylene, polycarbonate, or polyvinyl chloride, or an insulating support such as glass, ceramics, or paper with a conductive layer formed on the surface. You can also do it. In this case, the conductive layer is made of the same metal or alloy as the conductive substrate, or In2O5 or 5n02.
It is a thin film such as, and is formed by a conventional method such as vacuum evaporation, sputtering, ion blasting, or lamination.

The photosensitive layer of amorphous silicon (a-8i) may be essentially made of amorphous silicon, and even if it contains hydrogen and/or fluorine due to the manufacturing method, germanium may be added to change the electrical or optical properties. Alternatively, boron or the like may be added. Furthermore, it is preferable to provide an amorphous silicon layer containing nitrogen or carbon as a carrier injection prevention layer between the amorphous silicon photosensitive layer and the conductive substrate. Such amorphous silicon is represented by a-8iNH or a-8iCH, and the added amount of nitrogen or carbon atoms k"10.7≦(C or &tN)/St
A range of ≦1.5 is preferable.

The intermediate layer is an amorphous layer composed of silicon atoms and carbon atoms and/or nitrogen atoms, and has a composition and properties intermediate between an amorphous silicon photosensitive layer and a diamond-like carbon film. Optical breadth gap of the interlayer that bends
(Eg) is preferably 2.0 to 3.0 eV, and the film thickness is preferably 0.03 to 0.5 μm.

These amorphous silicon photosensitive layer, carrier injection prevention layer and intermediate layer are formed using plasma CVD method.

Optical CVD method, Sui? It can be formed according to conventional methods such as the tuttering method and the ion plate ink method.

Furthermore, the diamond-like carbon film is also called i-carbon film, and its electrical, mechanical, optical, and chemical properties are different from ordinary carbon films and are close to diamond.

That is, the resistivity is 1080 degrees or more, the optical band gap is 2 eV or more, and the Vickers hardness is 1500 or more. Such a diamond-like carbon film can be formed by plasma CV
It can be formed by the D method, the Suno-ni-Tuta-link method, the ion beam deposition method, or the laser evaporation method.

[Function] In the photoreceptor of the present invention, an intermediate layer having a composition and properties intermediate between these two layers is interposed between the amorphous silicon photosensitive layer and the diamond-like carbon film.
The strain between the conventionally adjacent amorphous silicon photosensitive layer and diamond-like carbon film is absorbed, and the interface defect levels between these layers are reduced. As a result, carriers generated during the charging and exposure processes are no longer trapped in interfacial defect levels, and electrical properties such as photosensitivity, acceptance potential, dark decay, and residual potential do not deteriorate even after long-term use. do not have. This action is due to the acceptance potential per unit film thickness of the photoreceptor (
This is particularly noticeable when the acceptance potential/thickness from the surface of the conductive substrate to the photosensitive layer is positively charged at 40 V/μm or more.

The optical breadth f (
Eg) is 2.0-3. Oe V is preferred, 2.0eV
If the value is less than
This is because if it exceeds 3.0 eV, it becomes difficult to absorb strain sufficiently. Moreover, the film thickness of the intermediate layer is 0.03 to 0.0.
The thickness is preferably 5 μm; if the film thickness is less than 0.03 μm, strain absorption will not be sufficient, and if it exceeds 0.5 μm, the residual potential will become large, which is disadvantageous.

In addition, since the outermost diamond-like carbon film is a protective layer, a film thickness of 0.05 to 1.0 μm is sufficient; if it is less than 0.05 μm, the mechanical strength may not be sufficient (,
If it exceeds 1.0 μm, the absorption of incident light increases, resulting in a decrease in sensitivity ().

〔Example〕

A specific example of the electrophotographic photoreceptor of the present invention will be described below.

A photoreceptor having the structure shown in the drawings was manufactured by sequentially forming each layer on an aluminum conductive substrate 1 by plasma CVD. That is, SiH4 is used as the carrier injection prevention layer 2.
A-
8iNH was formed, and SiH4 (150sec
) was subjected to glow discharge decomposition at a pressure Q of 15 Torr and an RF power of 200 W to form an a-8i photosensitive film 3 having a film thickness of 15 μm. Furthermore, SiH4 (100 scem) and C2H4 (100 scem) were
secm) at a pressure of 0.2 Torr and an RF power of 100
The film thickness is 0 by the plasma CVD method using glow discharge decomposition with W.
．． a-8 with an optical bandgap of 2.5 eV at 2 μm
An i-C intermediate layer 4 was formed. Finally, the diamond-like carbon film 5 was coated with CH4 (20 sec) at a pressure of 0. I Tor
The film was formed to a thickness of 0.2 μm using a plasma CVD method in which glow discharge decomposition was performed using r and RF' power of 500 W. In the formation of each layer, the substrate temperature was 220° C. and the RF frequency was 13.56 MHz.

A copying durability test was conducted using the obtained photoconductor of the present invention and a conventional photoconductor that does not have the intermediate layer 4. As a result, the contrast of the conventional photoconductor deteriorated and the image became clear after 500,000 copies. Although the photoreceptor of the present invention still produced clear images even after 1 million copies, copying was still possible.

〔Effect of the invention〕

According to the present invention, an intermediate layer having a composition and properties intermediate between these two layers is interposed between the amorphous silicon photosensitive layer and the diamond-like carbon film, thereby absorbing strain between the two layers and reducing interface defects. (can be,
Carriers generated during the charging and exposure processes are not trapped in interfacial defect levels (therefore, the electrical characteristics do not deteriorate and an excellently reliable electrophotographic photoreceptor that can be used stably for a long period of time is provided. be able to.

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view of a specific example of the electrophotographic photoreceptor of the present invention. 1... Conductive substrate 2... Carrier injection prevention layer 3.
...Photosensitive layer 4...Intermediate layer 5...Diamond-like carbon film

Claims (3)

[Claims] (1) A photosensitive layer of amorphous silicon formed on a conductive substrate, an amorphous intermediate layer formed on the photosensitive layer consisting of silicon atoms and carbon atoms and/or nitrogen atoms, and an amorphous intermediate layer formed on the intermediate layer. An electrophotographic photoreceptor comprising a diamond-like carbon film. (2) The optical bandgap (Eg) of the intermediate layer is 2
．． The electrophotographic photoreceptor according to claim (1), which has a voltage of 0 to 3.0 eV. (3) Claim (1) or (2) characterized in that the thickness of the intermediate layer is 0.03 to 0.5 μm.
The electrophotographic photoreceptor described in .