JPH01173049A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance the photosensitivity 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, laminating a 1st layer which contains said element and 2nd layer which does not contain said element and setting the thickness of the 2nd layer at a specific value. CONSTITUTION:The photoconductive a-Si layer 6 and the photoconductive a-SiC layer 7 which has the atomic ratio of the Si element and C element within a 0.01<=x<=0.5 range in x value of Si(1-x)Cx and has the thickness within a 0.05-5mum range are successively laminated on a conductive substrate 5. The a-SiC layer 7 is formed by successively laminating the 1st layer region 7 which contains 0.5-100ppm group IIIa element and the 2nd layer region 7b which does not contain said element and has the thickness within a 0.02-2mum range. The photosensitivity on the short wavelength side increases greatly when the prescribed ratio of the group IIIa element is incorporated into the a a-SiC layer 7. The light on the short wavelength side is absorbed in the layer 7 and the layer 6 so that the photosensitivity on both the short wavelength side and long wavelength side is improved when the thickness of the layer 7 is set within the prescribed range.

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-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-5i carrier generation layer (3), and a surface protection layer (4) are sequentially laminated on a conductive substrate (1) made of aluminum or the like. 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 a-5t adverse photosensitivity,
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-5i layer and a photoconductive amorphous silicon carbide layer (hereinafter referred to as amorphous silicon carbide) are formed on a conductive substrate.
5iC) is sequentially formed, the atomic ratio of silicon (Si) element and carbon (C) element in the a-SiC layer being Si (+-+o C11 x value of 0.01). ≦×≦0.5, and the thickness is set within the range of 0.05 to 5μ steel, and the a-3i
The C layer is formed by sequentially laminating a first layer region containing a group IIIa element of the periodic table of 0.5 to 1100 pp and a second layer region not containing an element of group 111a of the periodic table, and There is provided an electrophotographic photoreceptor characterized in that the thickness of the 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-St layer (6) and a photoconductive a-3iC layer (7 ) are sequentially stacked, and a-5iCJi (7) is from IIIa of the periodic table.
A first layer region (7a) containing a group element (hereinafter abbreviated as a group IIIa element) and a second layer region (7b) not containing it.
are successively laminated.

In such a layer configuration, the present inventor has developed an a-SiC layer (
It has been discovered that when a predetermined amount of I[[a group element is contained in 7), the photosensitivity on the short wavelength side is significantly increased, and the present invention has been completed based on this knowledge.

That is, according to the layer structure shown in FIG. 1, if the thickness of the layer (7) is set within a predetermined range, the short wavelength side of the incident light will be absorbed by the a-SiC layer (7), and the a-
The light transmitted through the SiC layer (7), that is, the light on the long wavelength side is a
It is characterized in that it is absorbed by the -3i layer (6), thereby increasing the photosensitivity on both the short wavelength side and the long wavelength side.

In addition, when the a-5iC layer (7) contains a Group IIIa element in this way, the photosensitivity on the short wavelength side was increased;
On the other hand, it was found that the charging ability tended to decrease. Therefore, in the present invention, in order to solve the problem, a-5
Another feature is that the iC layer (7) is made up of at least a first layer region (7a) and a second layer region (7b), thereby significantly increasing the charging ability.

First, according to the a-3iC layer (7), the amorphous SL element and C element are essential constituent elements, and hydrogen (11) element and halogen element are added to the required range in order to terminate the dangling bond. Photoconductivity is produced by inclusion within. The present inventors conducted experiments to confirm photoconductivity by changing the carbon content ratio in many ways, and found that the atomic ratio of St element and C element was 5t(1-
X) CXOX value is 0.01≦x≦0.5, preferably 0
．． When it is set within the range of 05≦X≦0.3, the dark conductivity becomes small and the photosensitivity on the short wavelength side can be increased.

In addition, the content of element A for dangling pond termination such as ■ element and halogen element is (Si (1-X) Cx) +
-, (A) X value expressed by y is 0.05≦y≦0.5, preferably 0.05≦y≦0.4, optimally 0.1≦y≦
It is preferable to set it within the range of 0°3. Eleven elements are usually used because they are easily incorporated into the terminal portion of the dangling bond and the localized level density in the band gap is reduced.

The thickness of such a-SiC layer (7) is 0.05 to 51
1m.

It is preferable to set the thickness within the range of 0.1 to 3 μl; if the thickness is less than 0.05 μm, absorption of short wavelength light will be insufficient and photosensitivity cannot be increased, and if the thickness exceeds 5 μm. In some cases, 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 4
E is 0. The thickness of N(7) is determined within the range of Ol ≦X≦0.5, and the thickness determined in this way is also 0.05.
It is necessary to set it within the range of ~5 μm, preferably 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 indicates the layer thickness direction of the a-SiC layer (7), a is the interface with the a-Si layer (6),
b is the interface on the opposite side, and the vertical axis represents the carbon content.

Further, in the first layer region (7a), 0.5 to 100 pp+m of the l1la group element is applied uniformly over the layer thickness direction.
It is preferably contained within the range of 1 to 50 ppm,
If this content is less than 0.5 ppm, sufficiently high photosensitivity cannot be obtained, while if it exceeds 100 ppm, the charging ability will decrease.

The above group 111a elements include n, ^1. Although there are Ga+In and the like, 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.

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

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

In addition, when the Group IIIa element content is changed over the layer thickness direction, the content is an average value for the entire first layer region (7a).

In this way, the first layer region (7a) is formed on the a-SiC 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 2μ,
Preferably, it should be set within the range of 0.05 to 1 μm (,
If it is less than 0.02μ, the charging ability cannot be increased, while if it exceeds 2μ, this layer region (
7b), short wavelength light is absorbed by the first layer region (7b).
There is less short wavelength light reaching a) (this layer region (7a)
This makes it difficult to increase photosensitivity.

Further, the a-Si layer (6) is made of amorphous Si.
element and I for terminating its dangling bond
It is composed of + elements and halogen elements, and mainly absorbs light on the longer wavelength side of the incident light.

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

Further, although the a-Si layer (6) is a layer that does not substantially contain carbon element, it may contain a very small amount of carbon. In that case, this carbon is 1000 ppm or less,
Preferably, within the range of 500 ppm or less, the photosensitivity to long wavelength light does not decrease significantly.

Furthermore, 0.01 of Group IIIa elements are added to the a-Si layer (6).
The content may be in the range of 10 ppm to 10 ppm, preferably 0.1 to 5 pp+w, 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 Group IIIa element may be uniform or non-uniform over the layer thickness direction,
In the case of non-uniform F'-ping, the content is that layer (6)
This is the overall average value.

Then, II contained in the a-Si layer (6) in this way
Group Ia elements include B, ^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-SiC layer, and moreover, light on the long wavelength side is absorbed mainly in the a-SiC layer. The light of 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 preservation iiM 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 the a-SiC layer (7).
) is formed.

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

Various materials can be used for this surface retention glJiW (9) as long as they themselves have high insulation properties, high corrosion resistance, and high hardness. For example, organic materials such as polyimide resin, and inorganic materials such as SiC, SiO, Ah03, 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-5i layer or the a-SiC layer, a thin film forming method such as a glow discharge decomposition method, an ion blating method, a reactive sputtering method, a vacuum evaporation method, a CVO method, etc., or a gas containing the C element and the like are used. The gases are combined and decomposed by glow discharge. This Si element-containing gas contains St+14.51zHh.
%5iJa, 5IF4.5iC1a, Si! Ic
I:+, etc., and C element-containing gases include CH4,
There are C11la, Ct II, CJa, etc., and C and U are particularly desirable in that 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 11th, second, third, fourth, fifth, and sixth tanks (1
0) (11) (12) (13) (14) (1
5) include StI+, , CzHt, BzHi, respectively.
(Contains 0.2% lh gas dilution), B, II.

(Contains 38 ppm when diluted with 11□ gas), H2, and NO gas are sealed, and H2 is also used as a carrier gas. These gases are controlled by the corresponding first, second, third, fourth, fifth, and sixth til valves (16) (17)
(1B) (19) (20) It is released by opening (21), and its flow rate is controlled by the mass flow controller (
22) (23) (24) (25) (26) (
27), the first, second, third, fourth, fifth
Tank (10) (11) (12) (13) (1
4) to the first main pipe (28) and the sixth tank (1
NO gas from 5) is sent to the second main pipe (29). Note that (30) and (31) are stop valves. 1st supervisor (28
) and the second main pipe (29), the gas flows through the reaction pipe (
32), but a capacitively coupled discharge electrode (33) is installed inside this reaction tube (32).
Appropriately, the high frequency power applied thereto is 50 W to 3 KW, and the frequency is 1 to 50 MH2. Reaction tube (32
) contains a cylindrical film-forming substrate (3) made of aluminum.
4) is placed on a sample holder (35), this holder (35) is rotated by a motor (36), and the substrate (34) is heated appropriately. Approximately 200 to 400°C depending on the means, preferably approximately 200 to 400°C
It is heated uniformly to a temperature of 350°C. Furthermore, a reaction tube (32
) is connected to a rotary pump (37) and a diffusion pump (38) by requiring a high degree of vacuum B (discharge voltage 0.1 to 2.0 Torr) for the a-SiC film formation film.

In the glow discharge decomposition device configured as above,
For example, when forming an a-SiC film on the substrate (34), open the first, second, and fifth regulating valves (16, 17, and 20) to supply SiH C, H, II, and gas respectively. The amount of release is determined by the mass flow controller (22)
(23) Controlled by (26), 5in4, CJz
, H2 is passed through the first main pipe (28) to the reaction tube (
32).

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. 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.

(Hereinafter, blank space) The thus obtained photoreceptor drum was irradiated with monochromatic light of 0.3μ-/cI+12 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. 17 were obtained.

In the figure, the horizontal axis is the wavelength, the vertical axis is the photosensitivity, the O mark is a plot of the measurement results, and a is the characteristic curve.

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, the amount of carbon in the photoconductive a-SiC layer was determined by ESCA.
As determined by analysis, “11-X C” is 0.
12, and its B content is expressed as secondary ion Wff
The content was determined to be 6 ppm using an i-analyzer.

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

(Hereinafter, blank space) The photoreceptor drum obtained in this way 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. When the surface potential, photosensitivity, and residual potential were measured using positive charging, the results shown below were obtained.

Surface potential...+513V Light sensitivity (recording exposure 1i)...0.57 lux
-5ec residual potential (value 5 seconds after the start of exposure): 25V In addition, when this photoreceptor drum was mounted on a high-speed PPC and an image output test was performed at a speed equivalent to 70 sheets, 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...+390v Light sensitivity (recording exposure...0.54 lux -5
EC residual potential (value 5 seconds after the start of exposure): 20V As is clear from these results, the residual potential has decreased slightly and the photosensitivity has also increased slightly (but on the other hand, the surface potential has become noticeably smaller). ing.

(Example 4) In this example, the stacking order of the first layer area and the second layer area is reversed from the photoreceptor drum obtained in (Example 2), that is, the second layer is placed on the a-S4 layer. When the electrophotographic properties of a photoreceptor drum in which the layer region and the first layer region were laminated in sequence, and the other layers were formed as shown in (Example 2), the following results were obtained. Ta.

Surface potential...+373v Light sensitivity (recording exposure amount)...0.55 lux -
5ec residual potential (value 5 seconds after the start of exposure): 22V As is clear from these results, the surface potential of this photosensitive drum also decreased significantly.

(Example 5) Next, in this example, the thickness of each of the photoconductive a-SiC layer and the second 181 area was changed in several ways from the photoreceptor drum obtained in (Example 2). When photoreceptor drum A-1 was manufactured and the electrophotographic characteristics of each photoreceptor drum were measured, the results shown in Table 3 were obtained.

(Hereinafter, blank space) The photosensitive drum of mm in Table 3 is the third drum which is outside the scope of the present invention.
As is clear from the table, it can be seen that the photosensitive drums B-G of the present invention had a high surface potential, a small residual potential, and excellent photosensitivity.

However, photoreceptor drum A is inferior in photosensitivity and surface potential, photoreceptor drum B is inferior in surface potential, and photoreceptor drum H1I has a large residual potential.

(Example 6) In this example, the amount of carbon in the photoconductive a-3iC layer and the B content in the first layer region were varied in several ways from the photoreceptor drum obtained in (Example 2). Photoreceptor drums J-Q were manufactured in this manner, and the electrophotographic characteristics of each photoreceptor drum were measured, and the results shown in Table 4 were obtained.

(Hereinafter, blank space) The photosensitive drums marked with the main mark in Table 4 are those outside the scope of the present invention.
As is clear from the table, it can be seen that the photosensitive drums L to 0 of the present invention have a high surface potential, a small residual potential, and excellent photosensitivity.

However, the photosensitive drum J has poor photosensitivity, and the photosensitive drums P and Q have a small surface potential, a large residual potential, and are also poor in photosensitivity.

In addition, the present inventors have discovered that the photoreceptor drums B-G and L-0 are
We installed each on a high-speed PPC and performed an image output test at a speed of 70 images per minute, and it was found that faithful reproducibility of black and red areas was obtained, as well as clear images with high density and no fog. V& has confirmed that this can be obtained.

(Effects of the Invention) As described above, according to the electrophotographic photoreceptor of the present invention, a photoconductive a-St layer and a photoconductive a-SiC layer are laminated, and the a-
The atomic ratio and thickness of the -5iC layer and the nIa group element content are each set within predetermined ranges, thereby increasing the photosensitivity on both the long wavelength side and the short wavelength side,
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 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 and Figure 15 are diagrams showing the doping distribution of group IIIa elements of the periodic table, Figure 16 is a schematic diagram of the glow discharge decomposition device, 1
7 is a diagram showing spectral sensitivity. 1.5...Conductive substrate 2.8...Carrier injection blocking layer 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 Corporation Representative Kin Judo Anjo Representative Takao Kawamura (8898) 1) Hara Katsuhiko No. 4 - Immediate ON Fig. 6 Fig. 7 Fig. 8 Fig. 9 Fig. 10 Fig. 11 Fig. 13 Fig. 14 Fig. 15

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 thereof is set within the range of 0.05 to 5 μm, and the amorphous silicon carbide layer is set to be 0.01 to 5 μm. 5-100ppm
A first layer region containing a group IIIa element of the periodic table and a second layer region not containing a group IIIa element of the periodic table are sequentially laminated, and the thickness of the second layer region is 0.02 to 0.02. 2
An electrophotographic photoreceptor characterized in that the photoreceptor is set within the range of μm.