JPS63133159A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To decrease residual potential and to obviate generation of fogging in an image by forming a carrier injection blocking layer and carrier transfer layer of a-SiC and carrier generating layer of a-SiGe and setting the atomic compsn. ratios thereof within respective prescribed ranges. CONSTITUTION:At least the carrier injection blocking layer 5, the carrier transfer layer 6 and the carrier generating layer 7 are formed on a substrate 1. The carrier injection blocking layer consists of amorphous silicon carbide (a-SiC and the atomic compsn. ratio of carbon and silicon is set in a 1:9-9:1 range. The carrier transfer layer 6 consists of a-SiC and the atomic compsn. ratio of carbon and silicon is set in a 1:100-1:9 range. The carrier generating layer consists of amorphous silicon germanium (a-SiGe) and the atomic compsn. ratio of silicon and germanium is set in a 2:1-100:1 range. the residual potential is thereby decreased and the generation of the fogging in the image is obviated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor that has a low residual potential to prevent image fogging and is capable of high-speed copying suitable for semiconductor laser beam printers. It is.

[Prior art and its problems]

In recent years, progress in electrophotographic photoreceptors has been remarkable, and the development of ultra-high-speed copying machines and laser beam printers is actively underway.The photoreceptors used in these devices are used at high speeds for long periods of time, so their operation is slow. Stability and durability are required. In response to this demand, hydrogenated amorphous silicon is attracting attention because it has excellent heat resistance, wear resistance, non-pollution properties, and photosensitivity characteristics.

In addition, with the development of laser beam printers capable of high-speed printing, compact and highly reliable semiconductor lasers have come to be used as laser light sources, but amorphous silicon (hereinafter abbreviated as a-5i) has been used in these printers. ) When a photoreceptor is mounted, there is a problem in that the oscillation wavelength of this laser light is in the vicinity of near infrared rays, so that the photosensitivity characteristics of the a-3i light on the light receiving side are inferior. In order to solve this problem, it has been proposed to dope the a-3i photoconductive layer of the photoreceptor with an appropriate amount of germanium element (Ge) to shift the photosensitivity region of this layer to the longer wavelength side. The problem has been that the surface potential becomes smaller as a result.

In order to solve this problem, a functionally separated type photoreceptor as shown in FIG. 2 has been proposed in Japanese Patent Laid-Open No. 192044/1983.

That is, according to FIG. 2, a carrier U transport layer (2) made of amorphous silicon carbide is placed on a conductive substrate (1).
), amorphous silicon germanium (hereinafter a-
A laminate has been proposed in which a carrier generation layer (3) and a surface protection layer (4) made of 5iGe (abbreviated as 5iGe) are sequentially formed, and this carrier transport layer (2) has a dark resistivity and a carrier mobility. It is made of amorphous silicon carbide (hereinafter abbreviated as a-5iC), which can be a large material, and is intended to have excellent surface potential and photosensitivity, and a small residual potential.

However, in forming the carrier transport layer made of amorphous silicon carbide (hereinafter abbreviated as a-3iC) disclosed in this publication, silicon element (Si)
and carbon element (C) at an atomic composition ratio of 1:9 to 9:1.
If the setting is within the range of As a result, fogging tends to occur in the image.

[Purpose of the invention]

Therefore, the present invention was completed in view of the above circumstances, and its purpose is to further improve the carrier mobility of the a-3iC carrier transport layer, thereby reducing the residual potential and preventing fogging on images. An object of the present invention is to provide an electrophotographic photoreceptor that has the following properties.

Another object of the present invention is to provide an electrophotographic photoreceptor for semiconductor laser beam printers capable of high-speed copying and high-speed printing.

[Means for solving problems]

According to the present invention, in the electrophotographic photoreceptor in which at least a carrier injection blocking layer, a carrier transporting layer, and a carrier generating layer are formed on a substrate, the carrier injection blocking layer is a-5.
The carrier transport layer is made of iC, and the atomic composition ratio of C and St is set within the range of 1=9 to 9:1, and the carrier transport layer is a-5.
Consists of iC and has an atomic composition ratio of C and Si of 1:100.
The carrier generation layer is set within the range of 1 to 9, and the carrier generation layer is a
-3iGe with an atomic composition ratio of Si and Ge of 2
Provided is an electrophotographic photoreceptor characterized in that the ratio is set within the range of :1 to 100:1.

The present invention will be explained in detail below.

FIG. 1 shows a typical layer structure of the electrophotographic photoreceptor of the present invention. According to this figure, a carrier injection blocking layer (5), a carrier transporting layer (6) are formed on a conductive substrate (1). , shows a laminated photoreceptor in which a carrier generation layer (7) and a surface protection layer (8) are formed in sequence, and a carrier transport layer (6) and a carrier generation layer (7) are formed on this photoreceptor. A laminated photoreceptor with a different lamination order may also be used.

According to the present invention, when forming the carrier transport layer (6) using -4=a-3iC, the atomic composition ratio of C element and Si element is set within the range of 1:100 to 1:9, preferably 1:1. :50 to 1:9, thereby improving the carrier mobility of this carrier transport layer (6), and further forming the carrier generation layer (7) with a-SiGe.
At the same time, the atomic composition ratio is set within a predetermined range, thereby increasing the photosensitivity to long wavelength light.
Furthermore, the carrier injection blocking layer (5) is formed of a-3iC, thereby further increasing charging ability, reducing dark decay, and reducing residual potential.

First, the reason why the carrier transport layer (6) was determined to have the above atomic composition ratio is that the atomic composition ratio of C element and Si element is 1:
]00, the effect of increasing the surface potential by increasing the dark resistivity of the carrier transport layer becomes less noticeable, and when this atomic composition ratio deviates from 1=9, the dark resistivity of the carrier transport layer increases. This is because, although the surface potential becomes higher as a result, the carrier mobility tends to decrease, which increases the residual potential and tends to cause fogging on the image.

The thickness of the carrier transport layer (6) is preferably set within a range of 1 to 50 μm, preferably 5 to 30 μm, and 1 to 50 μm.
If it is less than μm, the charge retention ability will be poor and the ghost phenomenon will become noticeable, and if it exceeds 50 μm, the image resolution will deteriorate and the residual potential will increase.

This carrier transport layer (6) contains Group Va elements of the periodic table (
(hereinafter abbreviated as Group Va elements) or Group Ma elements of the periodic table (
(hereinafter abbreviated as lTa group element) may be contained within a required range.

That is, when containing Va group elements, the content is 0 to 10,000 ppm, preferably 0.1 to 1100 ppm%.
When the content is within the range of 0 pp, the photoreceptor becomes advantageous for negative charging, and examples of the Va group element include P, N, As, and Sb, and P is particularly desirable.

In addition, when containing I[Ia group element, the content is 0.1 to 10. OOOppm, preferably in the range of 0.5 to 11,000 ppm, provides a photoreceptor that is advantageous for positive charging.
, Ga.

Among them, B is preferable.

When doping impurity elements as described above to charge the material as required, it is advantageous to add a Ma group element for the purpose of further increasing the dark resistivity and increasing the surface potential. .

Since the carrier generation layer (7) is formed of an a-3iGe layer, the spectral sensitivity peak shifts to the longer wavelength side compared to the a-Si layer. The atomic composition ratio of St and Ge in this layer (7) is 2=1 to 100:l, preferably 3:1 to 3.
It is important to set the ratio within the range of 0:1, and as a result, the photosensitivity characteristics to semiconductor laser light having an oscillation wavelength of about 780 nm are significantly improved compared to a photoreceptor equipped with an a-S+ carrier generation layer. . According to experiments conducted by the present inventors, for a functionally separated photoreceptor formed with an a-SiC carrier transport layer, the atomic composition ratio of Si and Ge is set at 3:1 to l0 = 1. It is desirable to set it within this range, and within this range, the residual potential becomes small and a photoreceptor with even higher charging ability can be obtained.

The carrier injection blocking layer (5) is a carrier transporting layer (6).
It is formed of a-3iC in order to prevent carrier injection into the a-3iC, and the atomic composition ratio of the C element and the Si element is within the range of 1:9 to 9:1, preferably 2:8 to 8:2. It is recommended to set it to .

This lowers the surface potential and increases dark decay, 9
: If it deviates from 1, the inhibiting effect on the injection of excited carriers into the substrate side becomes significant and the residual potential increases.

In forming this carrier injection blocking layer (5),
When the photoreceptor is charged to a positive polarity, its conductivity type is preferably controlled to P type, and when charged to negative polarity, it is preferably controlled to N type, thereby further improving the carrier injection blocking effect. For example, this P-type semiconductor material includes I such as B.
[50 to 10% of the Ia group element and the Va group element such as P for the type semiconductor material. The content is within the range of OOOppm.

Further, the thickness of the carrier injection blocking layer (5) is 0.2 to 5.
．． It is preferable to set the thickness to 0 μm, preferably within the range of 0.5 to 3.0 μm; if the thickness is within this range, the ability to stop carriers from the substrate will be sufficient and the residual potential will be small. desirable.

Further, when both the a-3iC injection blocking layer (6) and the a-3iC carrier transporting layer (7) contain a Va group element or a Ma group element, the carrier injection blocking layer (6) is a carrier transporting layer ( It is preferable to contain a larger amount than in 7), which has an advantageous effect of inhibiting carrier injection.

The carrier injection blocking layer (5) and the carrier transport layer (
6) and carrier generation layer (7) are a-5iC or a-5
Although it is essentially composed of iGe, hydrogen element (l) is added to terminate the dangling bonds in its amorphous state.
It is necessary to contain ( ) and halogen elements, and the content of these elements is 5 to 50 atomic %, preferably 5 to 40 atomic %.
atomic%, optimally 10 to 30 atomic%, usually H
elements are used. When this H element is used, it is easily taken into the terminal portion, thereby reducing the localized level density in the hand gear, thereby providing excellent semiconductor characteristics.

In addition, a part of these 11 elements may be replaced with a halogen element, thereby lowering the localized unit density of this layer and increasing the photoconductivity and heat resistance (temperature characteristics), and the substitution ratio is 0.01 of all elements for dangling bond termination.
It is preferably from 1 to 50 atom %, preferably from 1 to 30 atom %. This halogen element includes F, CI, 13r, I, At, etc., but especially when F is used, the bond between atoms increases due to its large electronegativity, which results in excellent thermal stability. desirable.

Various materials can be used for the surface protection layer (8) as long as they themselves have high insulation properties, high corrosion resistance, and high hardness properties. For example, organic materials such as polyimide resin, SiO□, SiO+Ah (h, SiC, Si3N,
, a-5i, a-3iC, and the like, thereby increasing the durability and environmental resistance of the photoreceptor.

Next, a method for manufacturing the electrophotographic photoreceptor of the present invention will be described.

a-SiC carrier injection blocking layer (5), a-3iC carrier transport layer (6) and a-5iGe carrier generation layer (
7) can be formed by a thin film forming method such as a glow discharge decomposition method, an ion blating method, a reactive sputtering method, a vacuum evaporation method, or a thermal CVD method. Moreover, the raw material used for this may be solid, liquid, or gas.

For example, gaseous raw materials used in the glow discharge decomposition method include Si-based gases such as 5i114, 5izH6, 5i311e, and 5iFa, CI4. , C2H4, C2H2, C21
C-based gas such as 16, C, HIl, GeH4, Ge2l
Ge-based gas such as -16 may be used, and +12,
He, Ne, Ar, etc. are used as carrier gas.

In addition, when forming the surface protective layer (8), if the layer is formed of a-3i or a-3iC,
This is desirable in that similar thin film forming means can be used, and furthermore, when the same film forming apparatus is used, there is an advantage that the same thin film forming means can be used to successively laminate layers.

Next, when the electrophotographic photoreceptor described in the embodiments of the present invention is formed from a total of 5iGe or a-5iC using a glow discharge decomposition method, the manufacturing method will be explained using a capacitively coupled glow discharge decomposition apparatus shown in FIG. do.

In the figure, tanks (9) (10) (11) (12)
(13) (14) respectively 5i) Ia, +CzH
□+Get+4+BJb (20pp with tlz gas dilution
m-containing), 112. NO gas is sealed and H2 is also used as a carrier gas. These gases are controlled by the corresponding regulating valves (15) (16) (17) (18)
(19) Released by opening (20),
The flow rate is the mass flow controller (21) (22)
(23) (24) (25) (26) City I
Tank (9) (10) (11) (12
) The gas from (13) goes to the main pipe (27) and then to the tank (1
NO gas from 4) is sent to the main pipe (28). still,(
29) (30) is a stop valve.

The gas flowing through the main pipes (27) and (28) flows through the reaction pipes (
31), but a capacitively coupled discharge electrode (32) is installed inside this reaction tube (31).
Appropriately, the high frequency power applied thereto is 50-3 KW, and the frequency is IMllz-50 J'l Hz. Inside the reaction tube (31), a cylindrical film-forming substrate (33) made of aluminum is placed on a sample holder (34), and this holder (34) is connected to a motor (35).
), and the substrate (33) is heated uniformly to a temperature of about 200 to 400 degrees Celsius, preferably about 200 to 350 degrees Celsius, by suitable heating means.

Furthermore, the inside of the reaction tube (31) is kept in a high vacuum state (gas pressure during discharge of 0.1 to 2.0 Torr) during the formation of the a-8iC film.
r ) is connected to a rotary pump (36) and a diffusion pump (37).

In the glow discharge decomposition device configured as above,
For example, when forming an a-3iGe film on the substrate (34), open the regulating valves (15), (17), and (19) to set S+Hn, Get+4. Release H2 gas. The amount of release is determined by the mass flow controller (21) (23) (2
5), and these mixed gases are distributed to the main pipe (
27) into the reaction tube (31). Then, the inside of the reaction tube (31) is 0.1 to 2.0 Torr.
Coupled with the fact that the vacuum state is about r, the substrate temperature is 200 to 400 degrees Celsius, the high frequency power of the capacitively coupled discharge electrode (32) is set to 50 to 3 cm, and the frequency is set to 1 to 50 MHz. A glow discharge occurs, the gas decomposes, and a-3
An iGe film is rapidly formed on the substrate.

〔Example〕

Next, examples of the present invention will be described.

(Example 1) Using the glow discharge decomposition apparatus shown in FIG. 3 and manufacturing conditions shown in Table 1, a carrier injection blocking layer (5), a carrier transport layer (6), and a carrier generation layer are formed on the substrate (30). (
7) and the surface protective layer (8) were sequentially formed to produce an electrophotographic photosensitive drum. Note that the carrier injection blocking layer (5) is doped with oxygen and nitrogen using NO gas to improve its adhesion to the substrate.

[Margin below]

When the photoreceptor thus obtained was corona charged to +5.6KV, the surface potential became approximately 750V, and the photoreceptor was charged with monochromatic light with a wavelength of 780nm (exposure amount: 0.3μ-8). m2), the photosensitivity was 0.
20cm2erg-', and the residual potential was significantly reduced to about 20V2. When this photosensitive drum was attached to a semiconductor laser beam printer (copying speed: 40 sheets/min) and an image was produced, a high-density, highly clear image without fogging was obtained.

Note that a part of the film forming substrate (33) is cut out, a 3x3 cm rectangular aluminum flat plate is attached to the cutout, and the carrier transport layer is placed on this flat plate under the conditions shown in Table 1. The content ratio of C and Si in the film was analyzed by Auger electron spectroscopy and found to be 1:30.

(Example 2) In this example, (Example 1) in forming the intermediate carrier transport layer (6) and the carrier injection blocking layer (5), S i I+
4 gas and C2)+2 gas, and when forming the carrier generation layer (7), S
By changing the release flow rates of 1H4 gas and GeH4 gas, carrier transport layers and carrier generation layers having various atomic composition ratios as shown in Table 2 are formed, and a surface protective layer (8) is formed. The photoreceptors were formed under the same conditions as in Example 1), and thus 10 types of photoreceptors were manufactured.

These photoreceptors are installed in a semiconductor laser beam printer (copying speed 40 sheets/min) equipped with the harsh conditions where fogging is most likely to occur, and images are produced, and the density of these images or if fogging occurs. When the fog density was measured using an image densitometer, the results shown in Table 2 were obtained.

In addition, the image quality evaluation in the table is divided into the standard ◎ mark, O mark, and △ mark. ◎ mark indicates that the image density is high and no fogging occurs, ○ mark indicates that the image density is high (, The mark Δ represents a case where almost no fogging is observed and there is virtually no problem, and the mark Δ represents a case where the image density is slightly low or some fogging is observed.

[Margins below] -18~ As is clear from Table 2, excellent image quality was obtained for photoreceptors E, F, and G, which are within the scope of the present invention, and in particular, photoreceptor F did not cause any fogging. There wasn't. However, photoreceptor A,
, B, C, , H1■, and J have a carrier injection blocking layer, a carrier transport layer, or a carrier generating layer having an atomic composition ratio outside the range of the present invention, so the image density is slightly low and some fogging is observed. Ta.

〔Effect of the invention〕

As described above, according to the electrophotographic photoreceptor of the present invention, a-5
When manufacturing a functionally separated photoreceptor comprising an iC carrier transport layer, by setting the atomic composition ratio of C and Si within a predetermined range, the residual potential is reduced and no fogging occurs in the image. According to this photoreceptor, the effect is remarkable when it is installed in a high-speed copying machine where fogging is most likely to occur.Therefore, the electrophotographic photoreceptor of the present invention can be provided as a photoreceptor suitable for high-speed copying machines. can.

Further, according to the electrophotographic photoreceptor of the present invention, by forming a B-3iC carrier injection blocking layer having a predetermined atomic composition ratio =20=, the surface potential can be further increased, thereby increasing image density and reducing fogging. It is also effective in preventing this, and as a result, it can be provided as a photoreceptor suitable for the above-mentioned high-speed copying machine.

Further, according to the electrophotographic photoreceptor of the present invention, the photosensitivity near infrared light can be increased, thereby providing an electrophotographic photoreceptor suitable for semiconductor laser beam printers capable of high-speed copying and high-speed printing. Ru.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the layer structure of an electrophotographic photoreceptor shown in an embodiment of the present invention, FIG. 2 is a sectional view showing the layer structure of a conventional functionally separated photoreceptor, and FIG. FIG. 1 is a schematic diagram of a capacitively coupled glow discharge decomposition device. 1... Conductive substrate 5... Carrier injection blocking layer 2.6... Carrier transport layer 3.7... Carrier generation layer -21 to 4.8... Surface protective layer Patent applicant (663 ) Kyocera Corporation Representative Kinjudo Anjo Takao Shizai

Claims (1)

[Claims] In an electrophotographic photoreceptor in which at least a carrier injection blocking layer, a carrier transporting layer, and a carrier generation layer are formed on a substrate, the carrier injection blocking layer is made of amorphous silicon carbide, and the atomic composition ratio of carbon and silicon is 1:9 to 9. :1, the carrier transport layer is made of amorphous silicon carbide, and the atomic composition ratio of carbon and silicon is 1:100 to 1.
:9, the carrier generation layer is made of amorphous silicon germanium, and the atomic composition ratio of silicon and germanium is set within the range of 2:1 to 100:1. .