JPS63127248A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance mobility of carriers, to reduce residual potential, and to prevent image fog by setting the molar proportion of C and Si contained in a carrier transfer layer made of amorphous silicon carbide within a specified range. CONSTITUTION:The electrophotographic sensitive body to be used is a laminate type photosensitive body provided with a carrier injection layer 6, the carrier transfer layer 7, a carrier generating layer 8, and a surface protective layer 9 on a conductive substrate 1. The layer 7 is made of amorphous silicon carbide hydride containing C and Si in a C to Si molar ratio set within the specified range of 1:100-1:9, preferably, 1:50-1:9, thus permitting the carrier mobility in the carrier transfer layer 7 to be remarkably enhanced, accordingly, residual potential to be reduced, and image fog to be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrophotographic photoreceptor whose residual potential is reduced to prevent fogging on images.

[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.

Such amorphous silicon (hereinafter abbreviated as a-3i)
As an electrophotographic photoreceptor, a laminated type photoreceptor as shown in FIG. 2 has been proposed.

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

However, according to this a-Si photoreceptor, the dark resistivity of the a-Si carrier generation N(3) itself is 1011Ω·
CIl+, which increases the dark decay rate of this photoreceptor and makes it difficult to increase its own charging ability.As a result, when this photoreceptor is used for high-speed copying, it suffers from the optical memory effect. There is a problem in that the previous image remains without being completely removed, and the previous image reappears with the formation of the next image (ghost phenomenon).

In order to solve this problem, a functionally separated photoreceptor as shown in FIG. 3 has been proposed.

That is, according to FIG. 3, the carrier injection blocking layer (
A carrier transport layer (5) is formed between the carrier generation N (2a) and the carrier generation N (3a), and this carrier transport layer (5) is made of a material having high dark resistivity and carrier mobility. As a result, a high-performance photoreceptor with excellent surface potential and photosensitivity and low residual potential can be obtained, and as a result, no ghost phenomenon occurs.

For this carrier transport layer (5), it is recommended to use hydrogenated amorphous silicon carbide, which has high resistance, wide bandgap, and semiconductor properties.
It has been proposed in Publication No. 192046 and the like.

However, when forming a carrier transport layer made of hydrogenated amorphous silicon carbide (hereinafter referred to as a-S+C) shown in this publication, silicon element (
When the atomic composition ratio of Si) and carbon element (C) is set within the range of 1=9 to 9:1, carrier mobility tends to decrease, and as a result, carriers are trapped in the a-5iC carrier transport layer. This makes it difficult to achieve high photosensitivity characteristics and further reduce residual potential, and as a result, images tend to become foggy.

[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-5iC 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.

[Means for solving problems]

According to the present invention, in an electrophotographic photoreceptor in which at least a carrier transport layer and a carrier generation layer are formed on a substrate, the carrier transport layer is made of a-SiC, and C and Si.
Provided is an electrophotographic photoreceptor characterized in that the atomic composition ratio of is set within the range of 1:100 to 1:9.

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 (6), a carrier transporting layer (7) are formed on a conductive substrate (1). , shows a laminated photoreceptor in which a carrier generation layer (8) and a surface protection layer (9) are sequentially formed, and a carrier transport layer (7) and a carrier generation layer (8) are formed on this photoreceptor. A laminated photoreceptor with a different lamination order may also be used.

According to the present invention, the carrier transport layer (7) is a-3i
When forming with C, the atomic composition ratio of C element and Si element is set within the range of 1:100 to 1:9, preferably within the range of 1:50 to 1:9, thereby improving this carrier transport. It is characterized by being able to improve the carrier mobility of N(7).

When the atomic composition ratio of C element and Si element deviates from 1:100, the effect of increasing the dark resistivity of the carrier transport layer and making the surface potential uniform becomes less noticeable, and this atomic composition ratio becomes 1:9. If it deviates from this, the dark resistivity of the carrier transport layer increases and the surface potential increases, but on the other hand, the carrier mobility tends to decrease, which increases the residual potential and tends to cause image fogging. .

This gear transport layer (7) is substantially composed of a-5iC, but it is necessary to contain hydrogen elements (H) and halogen elements in order to terminate the dangling bonds in the amorphous state. The content is 5 to 5
The content is preferably 0 atomic %, preferably 5 to 40 atomic %, optimally 10 to 30 atomic %, and H element is usually used. When this H element is used, it is easily incorporated into the terminal portion, thereby reducing the localized level density in the band gap, thereby providing excellent semiconductor properties.

In addition, a part of this H element may be replaced with a halogen element, which lowers the localized level density of this layer and increases photoconductivity and heat resistance (temperature characteristics). The ratio is preferably 0.01 to 50 atomic %, preferably 1 to 30 atomic %, of all the elements for dangling bond termination. This halogen element includes F, CI, Br+I, At, etc., but F is particularly desirable because its large electronegativity increases the bonding between atoms, resulting in excellent thermal stability. .

The thickness of the carrier transport layer (7) 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 (7) contains elements of Group Va of the periodic table (
(hereinafter abbreviated as group Va elements) or group II elements of the periodic table (hereinafter abbreviated as group ma elements) may be contained within a required range.

In the case of containing a Va group element, the content should be 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 a Ma group element, the content should be reduced to 0.
．． 1 to 10. OOOppm, preferably 0.5 to 1
When the content is within the range of 1000 pp, the photoreceptor becomes advantageous for positive charging, and the MA group elements include B, AI, and 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. .

According to the present invention, for the carrier generation layer (8), a photoelectric conversion material that is well known per se can be used, such as PV
Organic semiconductors such as K, Se, 5e-Te, 5e-As.

CdS, ZnO, a-3i, a-3iC, a-3iGe
, a-3iGeC and other inorganic semiconductors.

The carrier injection blocking layer (6) is a carrier transporting layer (7).
is formed to prevent carrier injection into the
For example, organic materials such as polyimide resin, 5iOz, Si
O, AlzO++SiC+5iJ4. a-St, a
It is formed using an inorganic material such as -5iC.

In forming this carrier injection blocking layer (6) from a semiconductor material, the conductivity type is controlled to be P type when the photoreceptor is charged to a positive polarity, and to N type when charged to a negative polarity. It is preferable to control this, and thereby the carrier injection blocking effect is further improved. For example, the P-type semiconductor material contains 11lla group elements such as B, and the N-type semiconductor material contains 50 to 5000 Va group elements such as P.
There is a-Si or a-SiC contained within a ppm range.

Various materials can be used for the surface protective layer (9) as long as they themselves have high insulation properties, high corrosion resistance, and high hardness properties. For example, the carrier injection layer (6)
The same inorganic or organic materials used in the photoreceptor can be used, 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-3iC carrier transport layer (7) is formed by glow discharge decomposition method,
It can be formed by a thin film forming method such as an ion blasting method, a reactive sputtering method, a vacuum evaporation method, or a thermal CVO 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 5ilt, 5IJs, St:+IIe, C) 14. .

C-based gas such as Czllt, C211□, CJi, and CJe may be used, and furthermore, Hz+He+Ne+Ar or the like may be used as a carrier gas.

Further, when forming layers other than the carrier transport layer (7), it is preferable that the layers are formed of a-3i or a-5iC, since similar thin film forming means can be used, and furthermore, the same When this film forming apparatus is used, there is an advantage that layers can be continuously stacked using a common thin film forming means.

Next, when the electrophotographic photoreceptor used in the embodiments of the present invention is formed from a-3i or a-5iC using the glow discharge decomposition method, the manufacturing method is performed using the capacitively coupled glow discharge decomposition apparatus shown in FIG. explain.

In the figure, tanks (10) (11) (12) (13)
(14) respectively 5i114. CzHz+BJ6
(12 gas dilution containing 0.2χ), 11□, 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), and the flow rate is controlled by the mass flow controller (2).
0) (21) (22) (23) (24), tank (10) (11) (12) (1
3) is sent to the main pipe (25), and NO gas from the tank (14) is sent to the main pipe (26). Furthermore, (27)
(28) is a stop valve. The gas flowing through the main pipes (25) and (26) is sent to the reaction pipe (29),
Inside this reaction tube (29) is a capacitively coupled discharge electrode (
30) is installed, and the high frequency power applied to it is 50-3KW, and the frequency is IMHz to 10KW.
M1lz is suitable. Inside the reaction tube (29), a cylindrical film-forming substrate (31) made of aluminum is placed on a sample holder (32).
is rotatably driven by a motor (33), and the substrate (31) is heated by suitable heating means.
about 200 to 400 degrees, preferably about 200 to 350 degrees
Evenly heated to a temperature of ℃. Furthermore, inside the reaction tube (29), a rotary pump (34) and a diffusion pump (35) are required because a high vacuum condition (gas pressure during discharge of 0.1 to 2.0 Torr) is required during a-5iC film formation. ) is connected to.

In the glow discharge decomposition device configured as above,
For example, when forming an a-SiC film on the substrate (32), the regulating valves (15), (16), and (18) are opened to release 5iH4 and I C2H2+ llz gases, respectively.

The amount of release is determined by the mass flow controller (20) (21)
(23), and these mixed gases are controlled by the main pipe (23).
5) into the reaction tube (29). The interior of the reaction tube (29) 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 of the capacitively coupled discharge electrode (30) is 50 to 3K.
W, the frequency is set from 1 to 50 MHz, glow discharge occurs, the gas decomposes, and a-5
An iC film is formed on a substrate at high speed.

〔Example〕

Next, examples of the present invention will be described.

(Example 1) Using the glow discharge decomposition apparatus shown in FIG. 4 and the manufacturing conditions shown in Table 1, carrier injection is inhibited 1' onto the substrate (31)! ! (6), carrier transport Ji (7), carrier generation layer (8), and surface protection layer (9) were sequentially formed to produce an electrophotographic photosensitive drum. Note that the carrier injection blocking layer (
6) doping with oxygen and nitrogen using NO gas to form
Improves adhesion to the substrate.

Margin below c] When the photoconductor thus obtained was corona charged at +5.6KV, the surface potential became approximately 800V. As a result of irradiation with 0.3μW/cm2), the photosensitivity was 0.3μW/cm2).
The voltage was 50cm2erg, and the residual potential was significantly reduced to about 20V. When this photosensitive drum was attached to an ultrahigh-speed copying machine (copying speed: 70 sheets/min) and an image was produced, a high-density, highly clear image without fogging was obtained.

Incidentally, a part of the film forming substrate (3) was cut out, a 3 x 30 ffl rectangular aluminum flat plate was attached to the cut out part, and the carrier generation layer was placed on this flat plate as shown in Table 1. A film was formed under these conditions, and the content ratio of C and Si in the film was analyzed by Auger electron spectroscopy, and it was found to be 1:30.

(Example 2) In this example, (Example 1) When forming the medium carrier transport layer (7), the CzHz gas flow rate was changed to 30 seconds, and the film forming time was further changed to 190 minutes to form a carrier transport layer with a thickness of 25 μm. The other layers were a carrier injection blocking layer (6) and a carrier generation layer (8) under the same conditions as in (Example 1).
And a surface protective layer (9) was formed.

When the surface potential, photosensitivity, and residual potential of the thus obtained photoreceptor were measured under the same conditions as in Example 1, they were approximately 900 V, 0.40 cm2 erg-', and approximately 50 V, respectively, and the C(!) of the carrier transport layer was measured. :Si content ratio was measured and found to be 1:3.

As described above, the above photoreceptor had a higher surface potential than the photoreceptor of Example 1, but on the other hand, the photosensitivity was reduced and the residual potential was also increased. When this photoreceptor drum was mounted on an ultrahigh-speed copying machine (copying speed 70 sheets/min) equipped with severe conditions where fogging is most likely to occur and an image was produced, a slight amount of fogging was observed.

〔Effect of the invention〕

As mentioned above, according to the electrophotographic photoreceptor of the present invention, a-3
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.

[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 conventionally well-known amorphous silicon photoreceptor, and FIG. 3 is a sectional view showing the conventional function. A cross-sectional view of a layer structure illustrating a separate type photoreceptor, and
FIG. 4 is a schematic diagram of a capacitively coupled glow discharge decomposition device. 1... Conductive substrate 2.2a, 6... Carrier injection blocking layer 5.7...
-Carrier transport layer 3.3a, 8...Carrier generation layer 4.9...Surface image 1IFi! Patent Applicant (663) Kyocera Corporation Representative Kinju Anjo Stain Material Takao Yo Rinto (8898) Patent Attorney Katsuhiko Tahara Figure 1 Figure 2

Claims (1)

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