JPH0555861B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technology to which the invention pertains] The present invention relates to an electrophotographic photoreceptor having excellent durability and high photosensitivity.

[Prior art and its problems]

Currently, electrophotographic photoreceptors include Se, CdS,
OPC etc. are in practical use, but these have disadvantages in mechanical strength and sensitivity, and Se, CdS, etc. are also toxic, so a- Intensive research is being conducted to use Si in electrophotographic photoreceptors. However, since a-Si has a resistivity of about 10''Ω-cm, it is not possible to obtain sufficient dielectric relaxation time by simply depositing it on an Al substrate like Se, so usually the bond between the Al substrate and a-Si is between p
Alternatively, an n-type a-Si layer is formed to prevent carrier injection from the Al substrate and lengthen the dielectric relaxation time. In this way, an electrophotographic photoreceptor can be made using a-Si, but for example, when forming a normally used photoreceptor for positive charging, the μγ product of holes in a-Si is at most 10 ^-7
cm ² /V, the film thickness can only be about 30μ at most. On the other hand, since the surface potential is normally required to be 500 V or more, the electric field in the photoreceptor becomes very large, about 2×10 ⁵ V/cm. For this reason, in the photoreceptor described above, the layer that prevents the injection of cerrier from the substrate is likely to break down, causing scratches on the image. In addition, the p layer used for the blocking layer is made of Si, for example, B.
Doping about 10 ^-3 to B, but doping B to 10 ^-4 or more
Doped a-Si is relatively brittle and easily cracks, and does not have sufficient mechanical strength. As a result, thin cracks form in the blocking layer, causing damage to the image and, in severe cases, causing the photoreceptor to separate from the substrate.

[Purpose of the invention]

This invention improves the drawbacks of the above-mentioned prior art and has a sufficiently long dielectric relaxation time and sufficient breakdown voltage.
It is an object of the present invention to provide an a-Si electrophotographic photoreceptor that can stably obtain good images without causing the photoreceptor to peel off from the substrate.

[Summary of the invention]

In the present invention, blocking is provided between the substrate and the photoreceptor layer to prevent carrier injection from the substrate.
For example, if the layer is positively charged, Si and C are charged from the substrate side.
A p-type a-Si layer in which Si is doped with an element of group a subgroup such as B having a matrix of about 10 ^-3 , followed by an i layer, and a P etc. having a matrix of Si or Si and C. By stacking n-type a-Si or a-SiC layers in which Si is doped with an element of Group A subgroup of about 10 ^-4 in order, the withstand voltage of the blocking layer can be improved and the blocking layer can be improved. Alleviate the strain
This prevents the occurrence of micro cracks and allows stable images to be obtained.

〔Effect of the invention〕

In the present invention, the blocking layer is, for example, a p-type semiconductor layer doped with B to a-SiCx from the substrate in the case of positive charging, an i-layer, and then a-Si or a-SiCx.
For example, an n-type semiconductor layer doped with P is stacked on top of the layer to form a p-n junction and blocking
In addition to improving the withstand voltage of the layer, the p-type semiconductor layer in contact with the substrate is made of a-SiCx to alleviate the internal strain of this layer and prevent film peeling, so you can always obtain stable and good images. . Note that a is added to the n-type semiconductor layer.
-Using SiCx is more effective in alleviating strain in the blocking layer.

[Embodiments of the invention]

Let us take as an example the case of a positively charging photoreceptor. (See FIG. 1) As the substrate, an Al drum is used, and after degreasing the drum, a-Si is deposited by decomposing raw materials such as SiH ₄ gas by well-known glow discharge decomposition. That is, after raising the temperature of the Al drum ¹⁰¹⁾ to 200℃, a mixed gas of SiH ₄ , B ₂ H ₆ and CH ₄ was heated at 0.5 torr.
P-type a-SiCx doped with B at a ratio of 10 ^{-3 to} Si by glow discharge decomposition at 25 W: 0.1μ of H layer ¹⁰²⁾ was deposited, followed by i-type a-Si doped with B at a ratio of ^-6 to Si: H layer ¹⁰³⁾ 1μ,
Furthermore, mixed gas of SiH ₄ , PH ₃ and CH ₄ 0.5torr, 25W
P was doped with a ratio of 10 ^-4 to Si by glow discharge decomposition.
A 0.1 μm type a-SiCx:H layer ¹⁰⁴⁾ was formed to serve as a blocking layer. Then, 20μ of an i-type a-Si:H layer ¹⁰⁵⁾ doped with B at a ratio of 10 ^-6 to Si is deposited on top of this by glow discharge at 0.5 torr and 100W to form a photosensitive layer, and on top of this, SiH ₄ and
a-SiCx by glow discharge of mixed gas of _CH4 :
A protective layer was formed by forming 0.1 μm of H ¹⁰⁶⁾ . The photoreceptor drum ¹⁰⁷⁾ obtained in this way does not block even if an image is copied with a surface potential of +600V and a developing bias of 100V.
The layer does not break down, and the internal strain of the blocking layer is sufficiently relaxed, so micro
No cracks occur and there are no scratches on the image caused by this.
Since the photoreceptor does not peel off from the Al drum, stable and good images can be obtained at all times.

In the above example, the blocking layer has a p-i-n structure, but it may also be a p-n junction. However, in this case, it is necessary to make the p layer sufficiently thick and slowly form the film to suppress the state within the gap to a sufficiently low level.

Examples are shown below. (See Figure 2) SiH ₄ was placed on an Al drum heated to 200℃ as in the previous example.
a-Si was deposited by glow discharge decomposition of raw material gases such as That is, first, SiH ₄ and CH ₄ are placed on the Al drum ^201).
P-type a-SiCx:H doped with B at a ratio of 10 ^-3 to Si by glow discharge decomposition with a mixed gas of B ₂ H ₆ at 0.5 torr 5 W.
0.8μ ²⁰²⁾ , followed by a mixed gas of SiH ₄ , CH ₄ and PH _3.
P to Si ratio of 10 ^-4 dope with 0.5torr, 5W glow discharge
²⁰³⁾ Deposit 0.2μ of n-type a-SiCx:H.
Use as a blocking layer. On top of this, add B to Si ratio 10 ^-6 dope
A 20 μm i-type a-Si:H layer ²⁰⁴⁾ was deposited to form a photosensitive layer. Finally, 0.1 μm of a-SiCx:H ²⁰⁵⁾ was formed as a protective layer by glow discharge of a mixed gas of SiH ₄ and CH ₄ . The thus obtained photoreceptor drum was able to stably obtain good images as in the above-mentioned examples even when images were produced at a surface potential of +550 V and a developing bias of 80 V.

In the above example, only the positive charging drum was illustrated, but blocking can also be applied to the negative charging drum.
Layer and n-type a-SiCx: H/i type a-
Si:H/p-type a-SiCx:H or n-
Similar effects can be obtained by setting type a-SiCx:H/p-type a-SiCx:H.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views for explaining an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. An electrophotographic photoreceptor formed on a predetermined conductive substrate and having a charge injection blocking layer between the substrate and a photosensitive layer, wherein the photosensitive layer is made of amorphous Si, and the photosensitive layer is formed on a predetermined conductive substrate. A first p-type semiconductor whose matrix is Si and C, in which the injection blocking layer carries a large number of holes from the substrate side.
layer, the second i-layer of a semiconductor based on intrinsic Si
layer, a third layer of an n-type semiconductor with majority carriers of electrons, or a first layer of an n-type semiconductor with Si and C as a matrix, with majority carriers of electrons from the substrate side, a second layer of an i-layer An electrophotographic photoreceptor comprising a third layer of a p-type semiconductor having a large number of holes as carriers. 2. The electrophotographic photoreceptor according to claim 1, wherein the third layer of the charge injection blocking layer is an n-type or p-type semiconductor containing Si and C as base materials. 3. The electrophotographic photoreceptor according to claim 1, wherein the charge injection blocking layer has a structure in which the second i-layer is covered. 4. The electrophotographic photoreceptor according to claim 1 or 2, wherein the photosensitive layer is made of amorphous Si containing a trace amount of B. 5. The electrophotographic photoreceptor according to claim 1 or 2, wherein the photosensitive layer is amorphous Si containing hydrogen and a trace amount of B. 6. The p-type or n-type semiconductor layer constituting the charge injection blocking layer is a semiconductor containing Si or Si and C as a matrix to which an element of Group A or Group A of the Periodic Law is added. Said claim 1
The electrophotographic photoreceptor according to item 2, item 2, or item 3.