JPH01173050A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance the photosensitive on long wavelength and short wavelength sides by laminating a photoconductive amorphous a-Si layer and photoconductive SiC layer, specifying the atomic ratio, thickness and group IIIa element content of the a-SiC layer to a prescribed range, and decreasing the content of said element from a substrate to the surface of a photosensitive body in the layer thickness direction. CONSTITUTION:The photoconductive a-Si layer 6 and the photoconductive a-SiC layer 7 are successively laminated on the conductive substrate 5. The a-SiC layer 7 is so formed that the atomic ratio of the Si element and C element is within a 0.01<=x<=0.5 range in x value of Si(1-x)Cx. The thickness of the layer 7 is set in a 0.05-5mum range to absorb the short wavelength side of the incident light in the layer 7. The light on the long wavelength side past the layer 7 is absorbed by the layer 6 so that the photosensitivity on both the short wavelength side and long wavelength side is enhanced. Further, the layer region contg. 0.5-100ppm group IIIa element of the periodic table is formed on the layer 7 and the content thereof is gradually decreased from the substrate toward the photosensitive body, by which the electrostatic chargeability is greatly 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,
Furthermore, the present invention relates to an electrophotographic photoreceptor that has increased charging ability and is therefore suitable for use in plain 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 of its excellent wear resistance, heat resistance, non-pollution properties, and photosensitivity characteristics.

As an electrophotographic photoreceptor made of amorphous silicon (hereinafter abbreviated as a-5i), a laminated type photoreceptor as shown in FIG. 3 has been proposed.

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 to lower the residual potential, and the surface protective layer (4) is made of a highly hard material. The durability of the photoreceptor is increased by using materials.

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 is sensitive to light in the wavelength band near red. reproducibility is poor compared to In order to solve this problem, a filter is used to cut out red wavelength light, but this reduces the intensity of light incident on the photosensitive layer, and as a result, the apparent photosensitivity of the photoreceptor itself decreases. Up and down.

In addition to the above-mentioned photosensitivity, the a-Si photoconductor is required to have a high charging ability. If these required characteristics are achieved, high image density can be obtained;
Further, 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) Therefore, an object of the present invention is to provide an electrophotographic photoreceptor that can increase the photosensitivity on the short wavelength side and 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-5iF! and a photoconductive amorphous silicon carbide layer (hereinafter amorphous silicon carbide is referred to as a).
An electrophotographic photoreceptor in which the atomic ratio of silicon (Si) element and carbon (C) element in the a-5iC layer is 0. The a-
Periodic table IIIa with 3iC layer from 0.5 to 1100 pp
Provided is an electrophotographic photoreceptor, comprising a layer region containing a Group IIIa element, and the content of the Group IIIa element gradually decreases in the layer thickness direction from the substrate toward the surface of the photoreceptor. be done.

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. The a-SiC layers are sequentially laminated and have the layer regions as described above.

In such a layer structure, the present inventors have found that when the a-3iC layer contains a predetermined amount of Group IIIa elements, the photosensitivity on the short wavelength side is significantly increased, and based on this knowledge, Based on this, the present invention has been completed.

That is, according to the layer structure shown in Fig. 1, when the thickness of the layer is set within a predetermined range, the short wavelength side of the incident light is absorbed by the a-3iC layer, and moreover, the short wavelength side of the incident light is absorbed by the a-3iC layer. The light that has passed through the a-5i 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-SiC layer contained Group IIIa 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-SiC
Another feature is that a layer region containing Group IIIa elements is formed in the layer, and the content is gradually decreased in the layer thickness direction from the substrate to the photoreceptor, thereby significantly increasing the charging ability. It is.

First, according to the a-3iC layer, amorphous S
Photoconductivity is produced by forming i element and C element as essential constituent elements and containing hydrogen (H) element or halogen element within a required range to terminate the dangling bond. The inventors conducted experiments to confirm photosensitive atrophy by varying the carbon content ratio, and found that
Atomic ratio of Si element and C element, i.e. 5in-+o C
xOX value is 0.01; x≦Oo5, preferably 0.05≦
When it is set within the range of X≦0.3, the dark conductivity becomes small and the photosensitivity on the short wavelength side can be increased.

In addition, the content of elements for dangling bond termination such as H element and halogen element is (St (1-X) CX) 1
□ [^], the y value expressed as 0.05≦y≦0.5, preferably 0.05≦y≦0.4, optimally 0.1≦y≦0
．． It is recommended to set the element A to be within the range of 3. Generally, this element A has the advantage that it is easily incorporated into the terminal part of the dangling bond and the localized level density in the band gap is reduced. ! One element is used.

The thickness of such a-5iC layer is 0.05~5 uv
b. It is preferably set within the range of 0.1 to 3 μl; if this thickness is less than 0.05 μl, absorption of short wavelength light becomes insufficient and photosensitivity cannot be increased; 5μ
If it exceeds m, the residual potential becomes large.

This may be the case, or the X value may change.

When the X value changes over the layer thickness direction, the X value is 0. The thickness of the layer is determined within the range of O1≦×≦0.5, and the thickness determined in this way also ranges from 0°05 to 5 μm.
It is necessary to set it preferably within the range of 0.1 to 3 μm.

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 is a-SiCF! indicates the layer thickness direction, a is the interface with the a-St layer (6), and b
is the interface on the opposite side, and the vertical axis represents the carbon content.

The a-SiC layer is formed with a Group IIIa element gradually decreasing in the layer thickness direction, and
Its content is 0°5 to 110 per whole a-3iC layer.
The content is preferably 0ppm, preferably within the range of 1 to 50ppm.If the content is less than 0.5pph, sufficiently high photosensitivity cannot be obtained, while if it exceeds 1100pph, the charging ability is reduced. descend.

When such a doping distribution is set, the maximum content of Group IIIa elements is 200 pp- or less, preferably 1100 pp- or less.
It is desirable to set it to less than pp, and if it is set within this range, it is good in that a high charging ability can be obtained.

The above Iua group elements include B, A1. There are Ga, In, etc., and B is particularly desirable because it has excellent covalent bonding properties and can sensitively change semiconductor characteristics, and also because it can provide excellent charging ability and photosensitivity.

In this way, when including IIIa group elements in the a-3iC layer, the doping distribution is as shown in Figs.
There is a street shown in Fig. 17.

In each figure, the horizontal axis indicates the layer thickness direction of the a-SiCWJ, a is the interface with the a-5i layer (6), b is the interface on the opposite side, and the vertical axis is the layer thickness direction of the IIIa Represents the group element content.

Further, the a-Si layer (6) is made of amorphous St.
element and H to terminate its dangling bond
It is made of elements and halogen elements, and absorbs light on the longer wavelength side of the incident light.

The thickness of this a-Si layer (6) is desirably set within the range of 5 to 100 μm, preferably 10 to 50 μm. Within this range, high charging ability can be obtained, and long wavelength light is advantageous in that it is effectively absorbed.

Furthermore, although the a-Si layer (6) is a layer that does not substantially contain carbon elements, it may contain a very small amount of carbon. Within this range, the photosensitivity to long wavelength light does not decrease significantly.

Furthermore, the a-Si layer (6) contains 0. O
It may be contained in a range of 1 to 10 ppm, preferably 0.1 to 5 ppm, and 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 the IIIa group element may be uniform or non-uniform over the layer thickness direction, and in the case of non-uniform doping, the content is the average value of the entire N(6).

Then, II contained in the a-3i layer (6) in this way
Group Ia elements include R9^1. There are Ga, In, etc.

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-3iC layer, and moreover, light on the long wavelength side is absorbed mainly in the a-3iC layer. light is now mainly absorbed by a-SiiJ, which eliminates the need for a filter to cut off infrared wavelength light, significantly increases the photosensitivity of the color light body itself, and also increases charging ability. is obtained.

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

For example, Figure 2 depicts a typical layer structure, with a substrate (5
) and the a-Si layer (6), there is a carrier injection blocking layer (8) between the
and a surface protective layer (9) on top of a-5iCWA.
is formed.

Regarding the carrier injection blocking layer (8), the substrate (5)
The surface protective layer (9) protects the a-5iCIm and improves moisture resistance, etc.
and fi (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 SiCs, SiOs, and SiN can be used.

Moreover, the same material as the above-mentioned material for the surface protection layer can be used for the carrier injection blocking layer (8).

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

To form the a-Si layer or a-3iCN, there are thin film forming methods such as a glow discharge decomposition method, an ion blating method, a reactive sputtering method, a vacuum evaporation method, and a CVO 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 SiH4,5iJ
6.5iJs, SiF4.5IC14% 5tl(C
1:+ etc., and gas containing C element has C)+4
, CzHa, CzHz, C, 11, etc. Among them, C and H2 are preferable because they 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) includes SiN4, C2H2, Bz)1. (
Hz gas dilution contains 0.2χ), Bdlh (1 (2 gas dilution contains 38 ppm), H2, and NO gases are sealed, and H2 is also used as a carrier gas. , second, third, fourth,
Fifth and sixth regulating valves (16) (17) (18) (1
9) (20) (21) are released, and the flow rate is controlled by the mass flow controller (22) (23
) (24) (25) (26) (27), and the first, second, third, fourth, and fifth tanks (10)
(11) (12) (13) Gas from (14) goes to the first main pipe (28), NO from the sixth tank (15)
Gas is sent to the second main pipe (29). Furthermore, (30) (
31) is a stop valve. Gas flowing through the first main pipe (28) and the second main pipe (29) is sent into the reaction tube (32), and a capacitively coupled discharge electrode (33) is installed inside this reaction tube (32). The high frequency power applied to it is 50 to 3, and the frequency is 1 to 5.
0MHz is appropriate. Inside the reaction tube (32), a cylindrical film-forming substrate (34) made of aluminum is placed on a sample holder (35). This holding stand (35)
is adapted to be 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. . Furthermore, the inside of the reaction tube (32) is a-
A high degree of vacuum condition (discharge voltage 0.1 to 2.
Rotary pump (37
) and a diffusion pump (38).

In the glow discharge decomposition device configured as above,
For example, when forming a-SiC on the substrate (34), open the first, second, and fifth regulating valves (16), (17), and (20) to release 11□ gas at 5ill CzHz, respectively. The amount of release is determined by the mass flow controller (22)
(23) Controlled by (26), S i If
The mixed gas of 4, C, t+2, and UZ is flowed into the reaction tube (32) via the first main pipe (28).

The inside of the reaction tube (32) is 0.1 to 2. Torr
The vacuum state is approximately 200°C, the substrate temperature is 200 to 400°C, and the high frequency power applied to the capacitively coupled discharge electrode (33) is 50°C.
Coupled with the setting of W to 3 KW, glow discharge occurs, 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. 18, photoconductive a
-SilJ (6) and a photoconductive a-5iC layer were sequentially laminated to produce a photoreceptor drum as shown in FIG.

(Hereinafter, blank space) The thus obtained photoreceptor drum was irradiated with monochromatic light of 0.3μ-/cIl12, which was separated by a visible light spectrometer,
When the spectral sensitivity was measured by determining the half-life time of the surface potential, the results shown in FIG. 19 were obtained.

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

Further, FIG. 19 shows a photoconductive a-S from the photoreceptor drum.
A photosensitive drum from which the iC layer has been removed is shown as a comparative example, and when its spectral sensitivity was measured, a plot of the measurement results indicated by * was obtained, and 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, the amount of carbon in the photoconductive a-3iC layer was determined by ESCA.
As determined by analysis, the X value of St+□C is 0°1
2, and its maximum B content was determined to be 6 ppm using a secondary ion mass spectrometer.

(Example 2) In this example, a carrier injection blocking layer (8), a photoconductive a-3L layer (6), a photoconductive B-5iC A photoreceptor drum as shown in FIG. 2 was manufactured by sequentially laminating layers and a surface protective layer (9).

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

Surface potential...+495v Light sensitivity (recording exposure It)...0.56 lux
-5ec residual potential (value 5 seconds after the start of n light): 22V In addition, this photoreceptor drum was mounted on a high-speed PPC, and 70 sheets 7
When an image output test was carried out at a speed of 1 minute, faithful reproducibility of black and red areas was obtained, and clear images with high density and no fog were obtained.

(Example 3) Next, in this example, the amount of B contained in the photoconductive a-5iC layer of the photosensitive drum obtained in (Example 2) was
Electrophotographic properties were measured on a photoreceptor drum in which the other layers were formed as shown in (Example 2), with the content being uniformly contained in the layer thickness direction and the content being set at 6 ppm. The result was as follows.

Surface potential...+390V Photosensitivity (recording exposure amount)...0.541ux-3ec Residual potential 1! Value 5 seconds after the start of light): 20V As is clear from the results, the residual potential decreased slightly and the photosensitivity also increased slightly, but on the other hand, the surface potential decreased significantly.

(Example 4) In this example, photoconductive a-
Photoreceptor drums A to F were manufactured by changing the thickness of the SiC layer in a number of ways, and the electrophotographic characteristics of each photoreceptor drum were measured, and the results shown in Table 3 were obtained.

(Hereinafter, blank space) The photoconductor drum in the main part of Table 3 is outside the scope of the present invention (Example 5) Next, in this example, the photoconductor drum obtained in (Example 2) has a higher photoconductivity. When the carbon content and B content of a-3iC15 were changed in several ways to produce photoreceptor drums G-N, and the electrophotographic characteristics of each photoreceptor drum were measured, the results were as shown in Table 4. The results were obtained.

Note that the above B content was gradually decreased in the same manner as in Example 2, and the amount is the average value for the entire a-3iC layer.

(Hereinafter, blank space) The photoreceptor drum marked with the 4th table rate is the 4th photoreceptor drum that is outside the scope of the present invention.
As is clear from the table, it can be seen that the photosensitive drum IL of the present invention has a high surface potential, a small residual potential, and excellent photosensitivity.

However, the photosensitive drums G and H have poor photosensitivity, and the photosensitive drums M and N have a small surface potential, a large residual potential, and are also poor in photosensitivity.

In addition, the inventors mounted photoreceptors 1 and rams B-E and -L on a high-speed PPC and performed an image output test at a speed of 70 sheets/min. It was confirmed that a clear image with high density and no fogging could be obtained.

(Effects of the Invention) As described above, according to the electrophotographic photoreceptor of the present invention, a photoconductive a-Si layer and a photoconductive a-SiC layer are laminated, and the a-
- By setting the atomic ratio and thickness of the SiC layer and the Group IIIa element content within predetermined ranges, it is possible to increase the photosensitivity on both the long wavelength side and the short wavelength side, and in addition, the charging ability Provided is an electrophotographic photoreceptor for PPC, which can increase the photoresistance and, as a result, can obtain excellent photosensitivity without using an infrared wavelength light cut 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 0, Figure 11, Figure 12, Figure 13, Figure 14, Figure 1
5, 16 and 17 are diagrams showing the doping distribution of group IIIa elements of the periodic table, FIG. 18 is a schematic diagram of a glow discharge decomposition device, and FIG. 19 is a diagram showing spectral sensitivity. 1.5...Conductive substrate 2.8...Carrier injection blocking layer 4.9...Surface protection layer 6...Amorphous silicon layer 7...
Hikari'J Electrical Amorphous Silicon Carbide Layer Patent Applicant (663) Kyocera Corporation Representative Kin Judo 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 Si_(_1_−_x_)C_x
The x value of the amorphous silicon carbide layer is set 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 is 0.5 to 100 ppm.
m, and the content of the Group IIIa element gradually decreases in the layer thickness direction from the substrate toward the surface of the photoreceptor. Electrophotographic photoreceptor.