JPH01295268A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance photosensitivity on both sides of a longer wavelength region and a shorter wavelength region by laminating a photoconductive a-Si layer, and a photoconductive a-SiC layer with each of Si/C atomic ratio and thickness and the content of an element of group Va controlled in a specified range. CONSTITUTION:The photoconductive a-Si layer 6, and the photoconductive a-SiC 7 composed of the first layer region 7a containing the element of group Va of the periodic table and the second layer region 7b not containing it are successively laminated on a conductive substrate 5 and the layer 7 has an Si/C atomic ratio of x as follows; 0.01<=x<=0.5, and it is necessary to set the thickness of the layer region 7a to 0.05-5mum. The first layer region 7a contains the element of group Va in a uniform concentration distribution within the range of 0.5-100ppm in the layer thickness direction, and the thickness of the second layer region 7b is set to 0.02-2mum, thus permitting photosensitivity on both sides of shorter and longer wavelength regions to be enhanced.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention increases the photosensitivity on both the short wavelength side and the long wavelength side,
Moreover, the present invention relates to an electrophotographic photoreceptor that has increased charging ability and is therefore suitable for ordinary paper copying machines.

(Prior art and its problems) In recent years, the development of ultra-high-speed copying machines and laser beam printers has been actively progressing, and along with this, the electrophotographic photoreceptor drums installed in these devices have been required to have stable operating characteristics. In addition, durability is required. In response to this demand, amorphous silicon is attracting attention because it has excellent abrasion resistance, heat resistance, non-pollution properties, and photosensitivity characteristics.

As an electrophotographic photoreceptor made of amorphous silicon (hereinafter abbreviated as a-3i), a laminated type photoreceptor as shown in FIG. 3 has been proposed.

That is, according to FIG. 3, a carrier injection blocking layer (2), an a-3i carrier generation layer (3), and a surface protection layer (4) are sequentially laminated on a conductive substrate (1) such as aluminum. The carrier injection blocking layer (2) is formed to block the injection of carriers from the substrate (1) and reduce the residual potential, and the surface protective layer (4) is made of a highly hard material. is used to increase the durability of the photoreceptor.

However, in such an a-Si photoreceptor,
The light sensitivity on the long wavelength side is high, so when this photoreceptor is installed in a plain paper copying machine (hereinafter abbreviated as RPC) that uses white light such as a halogen lamp as a light source, it will not be sensitive to waves near red. Reproducibility is poor compared to bands. In order to solve this problem, a filter is used to cut down the red wavelength light, but this reduces the intensity of the light that enters the photosensitive layer, and as a result, the photosensitivity of the photoreceptor itself decreases. appears to be lower.

In addition to the above-mentioned photosensitivity, the required characteristics required for the a-3i photosensitivity include high charging ability. If this required property is achieved, high image density is obtained and
The degree of freedom in designing the developing system of a copying machine is increased, and an electrophotographic photoreceptor that is easy to use can be obtained.

(Object of the Invention) Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor that can increase the photosensitivity on the short wavelength side and on the long wavelength side.

Another object of the present invention is to provide an electrophotographic photoreceptor with high charging ability.

Still another object of the present invention is to provide an electrophotographic photoreceptor suitable for RPC.

(Means for Solving the Problems) According to the present invention, at least a photoconductive a-3i layer and a photoconductive amorphous silicon carbide layer (hereinafter referred to as amorphous silicon carbide) are formed on a conductive substrate.
This is an electrophotographic photoreceptor in which silicon (Sl) element of the total SiC layer and carbon (abbreviated as 3iC) are sequentially formed.
C) The atomic ratio of the element is Si (1-x + X value of Cx is 0
．． 01≦x≦0.5 and the thickness is 0.01≦x≦0.5.
A first layer region in which the a-3iC layer contains 0.5 to 100 ppm of a Group Va element of the periodic table and a second layer region that does not contain a Group Va element of the periodic table. An electrophotographic photoreceptor is provided, characterized in that the layer regions are sequentially laminated, and the thickness of the second layer region is set within a range of 0.02 to 2 μm.

The present invention will be explained in detail below.

The basic layer structure of the electrophotographic photoreceptor of the present invention is as shown in FIG. 1, in which a photoconductive a-3i layer (6) and a photoconductive a-3iC layer (7 ) are sequentially stacked, and the a-5iC layer (7) is a first layer region (7a
) and a second layer region (7b) that does not contain it are sequentially laminated.

The present inventors have discovered that when the a-5iC layer (7) contains a predetermined amount of Va group element, the photosensitivity on the short wavelength side is significantly increased, and based on this knowledge, the present invention has been developed. It has now been completed.

According to the layer structure shown in Figure 1, when the thickness of layer (7) is set within a predetermined range, the short wavelength side of the incident light is a
-3iC layer (7) absorbs, and the a-5iC
The light transmitted through the layer (7), that is, the light on the long wavelength side
It is absorbed by layer (6), thereby increasing the photosensitivity on both the short wavelength side and the long wavelength side.

Furthermore, it was found that when the a-5iC layer (7) contained Va group elements in this way, the photosensitivity on the short wavelength side was increased, but on the other hand, the charging ability tended to decrease. Therefore,
In the present invention, in order to solve this problem, a-5iC
The layer (7) was made up of at least a first layer region (7a) and a second layer region (7b), thereby making it possible to significantly increase the charging ability.

First, according to the above a-3iCN (7), the amorphous Si element and C element are essential constituent elements,
Hydrogen (11) to terminate the dangling truth
Photoconductivity is produced by containing elements or halogen elements within a predetermined range. The present inventors conducted experiments to confirm photoconductivity by changing the carbon content ratio in many ways, and found that the atomic ratio of Si element and C element, that is, Si
(When the X value of 1-ゎCX is set within the range of 0.01≦x≦0.5, preferably within the range of 0.05≦×≦0.3, the dark conductivity becomes small and the short wavelength side can increase the photosensitivity of

In addition, the content of elements for dangling bond termination such as 11 elements and halogen elements is C3iu-ゎCx], -A
(A) y-direction expressed by y is 0.05≦y≦0.5,
Preferably 0.05≦y≦0.4, optimally 01≦y≦-
It is preferable to set it within the range of 6=0.3. As such an element, I (element) is usually used because it is easily incorporated into the terminal portion of the dangling bond and the local unit density in the band gap is reduced.

The thickness of this a-3iC layer (7) is preferably set within the range of 0.05 to 5 μm, preferably 0.1 to 3 μm, and if this thickness is less than 0.05 μm, absorption of short wavelength light is reduced. If the thickness exceeds 5 μm, the residual potential becomes large.

Further, the a-3iC layer (7) may have either a case where the atomic ratio of the Si element and the C element, that is, the x value is uniform over the layer thickness direction, or a case where the x value changes. .

When the X value changes in the layer thickness direction, the thickness of the SiC layer (7) is determined so that the x value is within the range o, oi ≦x≦0.5, and the ta1'9E
It is also necessary to set the diameter within the range of 0.05 to 5 μm, preferably 0.1 to 3 pm.

Examples of carbon doping distributions in which the X value changes in the layer thickness direction are shown in FIGS. 4 to 9, for example.

In each figure, the horizontal axis indicates the layer thickness direction of the total SiC layer (7), a is the interface with the a-3i layer (6), and b
is the interface on the opposite side, and the vertical axis represents the carbon content.

Further, the first layer region (7a) preferably contains a Va group element uniformly in the range of 0.5 to 1100 ppm, preferably 1 to 50 ppm over the layer thickness direction. When the content is less than 0.5 ppm, sufficiently high photosensitivity cannot be obtained, and on the other hand, when the content exceeds 1100 ppm, the charging ability decreases.

The above-mentioned Va group elements include It, P, Hes, Sb, and Bi. Among them, P has excellent covalent bonding properties and can sensitively change semiconductor properties. This is desirable in that sensitivity can be obtained.

When the Va group element is contained in the first layer region (7a) in this way, the l·-ping distribution may be made non-uniform over the layer thickness direction, for example, as shown in FIGS. 10 to 15. As shown.

In each figure, the horizontal axis indicates the layer thickness direction of the a-3iC layer (7), a is the interface with the a-3iC layer (6), b is the interface on the opposite side, and 7a is the first layer. layer area,
7b represents the second layer region, and the vertical axis represents the Va group element content.

In addition, when the Va group element content is changed over the layer thickness direction, the content corresponds to the average value for the entire first layer region (7a).

In this way, the first layer region (7a) is added to the a-5iC layer (7).
By forming the second layer region (7b), it was possible to increase the photosensitivity on the short wavelength side, and by further forming the second layer region (7b), it was possible to significantly increase the charging ability. That is, charges are accumulated on the surface of the photoreceptor due to corona charging, and on the other hand,
Carriers are induced inside the photoreceptor, and when both are neutralized, the surface potential decreases, but on the other hand, the second layer region (7b) has the function of preventing the above neutralization, As a result, charging ability can be increased.

The thickness of the second layer region (7b) is 0.02 to 2 μm,
Preferably, it may be set within the range of 0.05 to 1 μm.
If it is less than 0.02 μm, the charging ability cannot be increased, while if it exceeds 2 μm, this layer region (
7b), short wavelength light is absorbed by the first layer region (7b).
There is less short wavelength light reaching a), and this layer region (7a)
This makes it difficult to increase photosensitivity.

Further, the total Si layer (6) contains amorphous Si element and 11 for terminating the dangling bond.
It consists of elements and halogen elements, and mainly absorbs light on the longer wavelength side of the incident light.

The IW h of the A-5+ layer (6) is 5-100 ttm
, preferably within the range of 10 to 50 μm, which is advantageous in that high charging ability can be obtained and long wavelength light can be effectively absorbed.

Further, the a-5+ layer (6) may be a layer containing substantially no carbon element, or may contain a very small amount of carbon. In this case, the carbon is 11,000 pp or less,
Preferably, within the range of 500 ppm or less, the photosensitivity to long wavelength light does not decrease significantly.

Furthermore, the a-3i layer (6) contains 0.01 to 1 of Va group elements.
It may be contained in a range of 0 ppm, preferably 0.1 to 5 ppm; within this range, it is advantageous in that high charging ability can be obtained and residual potential can be reduced. Note that the doping distribution of this Va group element may be either uniform or non-uniform over the layer thickness direction, and in the case of non-uniform doping, the content corresponds to the average value of the entire N(6). .

The Va group elements contained in this a-5i layer (6) include N, P, As, Sb, and Bi.

Thus, when the electrophotographic photoreceptor of the present invention is mounted on a PPC using white light such as a halogen lamp as a light source, light on the short wavelength side is mainly absorbed by the a-5iC layer, and moreover, light on the long wavelength side is absorbed mainly in the a-5iC layer. light is mainly absorbed by the a-3i layer, which eliminates the need for a filter to cut off infrared wavelength light, significantly increases the photosensitivity of the photoreceptor itself, and provides high charging ability. .

Although the electrophotographic photoreceptor of the present invention essentially has the above-mentioned two-layer structure, a carrier injection blocking layer or a surface protection layer may be formed in addition to the two-layer structure.

For example, Figure 2 shows a typical layer structure, with a substrate (5
) and the a-5i layer (6).
), and a surface protective layer (9) on the SiC layer (7).
) is formed.

Regarding the carrier injection blocking layer (8), the substrate (5)
The surface protection layer (9) protects the total SiC layer (7) and improves moisture resistance, etc.
and layer (9) can both reduce the dark conductivity of the photoreceptor and increase the charging ability.

Various materials can be used for this surface protective layer (9) as long as they themselves have high insulating properties, high corrosion resistance, and high hardness. For example, organic materials such as polyimide resin, and inorganic materials such as SiC, SiOXAl□03, and SiN can be used.

Further, the carrier injection blocking layer (8) can also be made of the same material as the surface protection wear material described in (h).

Next, a method for manufacturing an electrophotographic photoreceptor according to the present invention will be described.

-11= To form the a-3i layer or the a-3iC layer, there are thin film forming methods such as glow discharge decomposition method, ion blating method, reactive sputtering method, vacuum evaporation method, and CVD method.

When using the glow discharge decomposition method, a Si element-containing gas or a combination of the Si element-containing gas and a C element-containing gas are used to perform glow discharge decomposition. This Si element-containing gas contains Si 114.
5izH6, 5i3Ha, SiF4.5ICI4.5
illCh, etc., and C element-containing gases include CI
There are L, C2+14, C2H2, C3118, etc.
Among these, C2H2 is desirable in that it can provide high-speed film formation.

A capacitively coupled glow discharge decomposition device used in an embodiment of the present invention will be explained with reference to FIG.

In the figure, the first, second, third, fourth, fifth, and sixth tanks (1
0) (11) (12) (13) (14) (1
5), Si](4, CJz, ■+3(UZ
0.2x (contains 0.2x when diluted with gas), PH3 (contains 40 ppm when diluted with +12 gas), H2, and NO gases, and 112 is also used as a carrier gas. These gases correspond to the first, second, third, fourth, and fifth gases, respectively.
, 6th regulating valve (16) (17) (18) (19)
It is released by opening (20) and (21), and its flow rate is controlled by mass flow controllers (22) and (23).
(24) (25) (26) (27), the first, second, third, fourth, and fifth tanks (10) (
11) (12) (13) The gas from (14) is sent to the first main pipe (28), and the NO gas from the sixth tank (15) is sent to the second main pipe (29). Furthermore, (30) (31
) is a stop valve. The first main pipe (28) and the second main pipe (2
The gas flowing through 9) is sent to the reaction tube (32), and a capacitively coupled discharge electrode (33) is installed inside this reaction tube (32), and the high frequency power applied to it is 50 power ~3KW, and frequency is 1~50
M It z is appropriate. Inside the reaction tube (32), a cylindrical film-forming substrate (34) made of aluminum is placed on a sample holder (35).
) is rotationally driven by a motor (36), and the substrate (34) is uniformly heated to a temperature of about 200 to 400°C, preferably about 200 to 350°C, by a suitable heating means. be done. Furthermore, the inside of the reaction tube (32) requires a high vacuum state (gas pressure during discharge of 0.1 to 2.0 Torr) when forming the a-3iC film, so a rotary pump (37) and a diffusion pump (38) are used. is connected to.

In the glow discharge decomposition device configured as above,
For example, when forming an a-5iC film on the substrate (34), the first, second, and fifth regulating valves (16) (17) (20
) to release 5iHa, C2112, and H2 gas from each, and the amount of release is controlled by the mass flow controller (2
2) Controlled by (23) and (26), S i II
The mixed gas of a, C211□, and H2 is in the first main pipe (28)
into the reaction tube (32). The inside of the reaction tube (32) is in a vacuum state of about 0.1 to 2.0 Torr, the substrate temperature is 200 to 400°C, and the high frequency power applied to the capacitively coupled discharge electrode (33) is 50W to 3XH.
Coupled with this setting, a glow discharge occurs,
The gas decomposes and an a-3iC film is formed on the substrate at high speed.

(Example) Next, the present invention will be explained in detail.

(Example 1) Using the glow discharge decomposition apparatus shown in Fig. 16, photoconductive a
The -3i layer (6), the first layer region (7a), and the second layer region (7b) were sequentially laminated to produce a photoreceptor drum as shown in FIG.

(Left below) The thus obtained photoreceptor drum was irradiated with monochromatic light of 0.3 μm/cm2 separated by a visible light spectrometer, and the spectral sensitivity was measured by determining the half-life time of the surface potential.
The results shown in Figure 7 were obtained.

In the figure, the horizontal axis is the wavelength, the vertical axis is the photosensitivity, and the circles are the plots of the measurement results, which are the characteristic curves of a and b.

Further, FIG. 17 shows a photoconductor drum as a comparative example in which the second layer region is removed from the photoconductor drum described above, and when its spectral sensitivity was measured, the plot of the measurement results indicated by the mark . b is its characteristic curve.

As is clear from the results, it can be seen that the photosensitive drum of the present invention has significantly increased photosensitivity on the short wavelength side.

In addition, when the amount of carbon in the SiC layer of the photoconductivity meter was determined by ESCA analysis, it was found that X (l!f
It is 0.12, and its P content is a secondary ionic substance.

It was found to be 2 oppm as determined by a quantitative analyzer.

(Example 2) In this example, a carrier injection blocking layer (8), a photoconductive a-5i layer (6), a photoconductive a-3iC Layer (7) and surface protection layer (9) were laminated in sequence to produce a photosensitive drum as shown in FIG. 2.

(Left below) The photosensitive drum thus obtained was mounted on a PPC, and a halogen lamp was used as a light source without using a red cut filter, and a voltage of -5.6 KV was applied with a corona charger to negatively charge it. When the surface potential, photosensitivity, and residual potential were measured using this method, the results shown below were obtained.

Surface potential: -498v Light sensitivity (recording exposure amount): 0.54 lux -
5ec residual potential (value 5 seconds after the start of n light): 22V Also, when this photoreceptor drum was mounted on a high-speed PPC and an image output test was performed at a speed of 70 sheets/min, black and red areas were It was possible to obtain faithful reproducibility of images, and also to obtain clear images with high density and no fog.

(Example 3) Next, in this example, the photoreceptor drum obtained in (Example 2) except for the second layer region, and the other layers were formed as shown in (Example 2). When the electrophotographic characteristics of the drum were measured, the results were as follows.

Surface potential: -370v Light sensitivity (recording exposure amount): 0.50 lux -
5ec residual potential (value 5 seconds after the start of exposure): As is clear from the results for each 18V, the residual potential decreased slightly and the photosensitivity increased slightly, but on the other hand, the surface potential decreased significantly. ing.

(Example 4) In this example, the stacking order of the first layer area and the second layer area from the photoreceptor drum obtained in (Example 2) is reversed, that is, the second layer is placed on the a-5i layer. When the electrophotographic properties of the photoreceptor tram were measured in which the layer region and the first layer region were sequentially laminated, and the other layers were formed as shown in (Example 2), the following results were obtained. Ta.

Surface potential...-368v Photosensitivity (recording exposure ft)...0.521ux ・
As is clear from the results at 20 V for sec residual potential (reference value 5 seconds after the start of exposure), the surface potential of this photosensitive tram also significantly decreased.

(Example 5) In this example, the thickness of each of the photoconductive a-3iC layer and the second layer region was changed from the photoconductor drum obtained in (Example 2) in a number of ways. Drum A
When the electrophotographic characteristics of each photoreceptor drum were measured, the results shown in Table 3 were obtained.

(The following is a margin) The photoreceptor drums marked with * in Table 3 are those outside the scope of the present invention.
As is clear from the table, it can be seen that the photosensitive drum C-G of the present invention had a high surface potential, a small residual potential, and excellent photosensitivity.

However, the photoreceptor ram A is inferior in photosensitivity and surface potential, the photoreceptor tram B is inferior in surface potential, and the photoreceptor drums +1 and I have large residual potentials.

(Example 6) In this example, the amount of carbon in the photoconductive a-5iC layer and the P content in the first layer region were varied in several ways from the photoreceptor drum obtained in (Example 2). Photosensitive drums J to 0 were manufactured in this way, and the electrophotographic characteristics of each photosensitive drum were measured, and the results shown in Table 4 were obtained.

(Hereinafter, blank space) Table 4 As is clear from Table 4, photosensitive drums 1 of the present invention, ~
It can be seen that 0 has a high surface potential, a low residual potential, and an excellent photoreceptor.

However, photosensitive drum J has poor photosensitivity, and photosensitive drums P and Q have low surface potential, high residual potential, and poor photosensitivity.

In addition, the present inventors have also discovered the above-mentioned photoreceptor drums B to G and 1. ~
0 was installed on a high-speed PPC and an image output test was conducted at a speed of 70 images per minute. As a result, faithful reproduction of black and red areas was obtained, and clear images with high density and no fog were obtained. It was confirmed that images could be obtained.

(Effects of the Invention) As described above, according to the electrophotographic photoreceptor of the present invention, the photoconductive a-3i layer and the photoconductive a-3iC layer are laminated, and the a-
-3 When the carbon atomic ratio and thickness of the iC layer and the Va group element content are each set within predetermined ranges, the photosensitivity on both the long wavelength side and the short wavelength side can be increased,
Furthermore, an electrophotographic photoreceptor for PPC is provided which has enhanced charging ability and, as a result, can obtain excellent photosensitivity without using an infrared wavelength light filter.

Further, according to the electrophotographic photoreceptor of the present invention, a high charging ability can be obtained, thereby a high image density can be obtained, and the degree of freedom in designing the developing system of a copying machine has been increased, making it easier to use.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the basic layer structure of the electrophotographic photoreceptor of the present invention, FIG. 2 is a cross-sectional view showing the typical layer structure of the electrophotographic photoreceptor of the present invention, and FIG. 3 is a conventional electrophotographic photoreceptor. 4, 5, 6, 7, 8 and 9 are diagrams showing the carbon doping distribution.
Figure 11, Figure 12, Figure 13, Figure 14 and Figure 15 are diagrams showing the doping distribution of group Va elements in the periodic table. Figure 16 is a schematic diagram of the glow discharge decomposition device. 17 is a diagram showing spectral sensitivity. 1.5 ・ ・ Conductive 1 radical + anti 2.8 ・ ・ Carrier injection blocking layers 4, 9 ... Surface protection layer 6 ... Photoconductive amorphous silicon layer 7 ...
Photoconductive amorphous silicon carbide layer 7a...First layer region 7b...Second layer region Patent applicant (663) Kyocera Co., Ltd. Brewer
Presenters: Kinjudo Anjo, Takao Kawamura

Claims (1)

[Claims] An electrophotographic photoreceptor in which at least a photoconductive amorphous silicon layer and a photoconductive amorphous silicon carbide layer are sequentially formed on a conductive substrate, the atomic ratio of silicon element and carbon element in the amorphous silicon carbide layer being The x value of Si_(_1_−_x_)C_x is within the range of 0.01≦x≦0.5, and the thickness is set within the range of 0.05 to 5 μm, and the amorphous silicon carbide layer has a periodic rule. A first layer region containing 0.5 to 100 ppm of a group Va element in the table and a second layer region not containing a group Va element in the periodic table are sequentially laminated, and the thickness of the second layer region is 0. .02~2μ
An electrophotographic photoreceptor characterized in that the temperature is set within a range of m.