JPS61128252A - Photoconductive member - Google Patents

Abstract

PURPOSE:To obtain a photoconductive member holding surface potential for a long period in the dark, vanishing rapidly the potential when light is irradiated, and applicable to an electrophotographic process by forming an amorphous carbon layer as at least one of blocking layers. CONSTITUTION:An amorphous carbon layer is formed as at least one of blocking layers. A photoconductive member is obtd. by successively forming a blocking layer 2, the photoconductive layer 3 of amorphous silicon hydride (a-Si;H) and an electrostatically chargeable surface layer 4 of amorphous silicon carbide (a-Si;C) on the electrically conductive substrate 1 of Al or the like. The blocking layer 2 is composed of an amorphous carbon (a-C) layer 2-1 and an a-Si;C layer 2-2. The layer 2-1d is formed by decomposing gas contg. carbon by glow discharge. The layer 2-2 is produced on the interface between the a-C layer 2-1 and the a-Si;H layer 3 when the layer 3 is formed on the layer 2-1. Both the layers 2-1, 2-2 shown superior characteristics as the blocking layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a photoconductive member using an amorphous semiconductor as a photoconductive material.

[Technical background of the invention and its problems]

Conventional photoconductive materials such as photoconductive materials for electrophotographic photoreceptors include Se-based, CdS-based, and ZnO-based materials.

Organic photoconductors have been used, but 8e series, CdS
These systems have safety problems, and ZnO-based and organic photoconductors have problems of poor moisture resistance and short lifespans.

Therefore, in recent years, amorphous silicon (hereinafter referred to as a-3i
) has been attracting attention as a photoconductive material for electrophotographic photoreceptors. Compared to the conventional photoreceptor mentioned above, the a-3i photoreceptor has a half-reduced exposure sensitivity of 1-eux compared to white light irradiation (2
In addition to extremely high sensitivity of -sec or less, the spectral sensitivity is also 800.
Light with a wavelength of nm (up to 2, furthermore (= has a lifetime of 10)
It has the advantage of being able to print 100,000 copies and being essentially non-polluting.

However, the specific resistance of the a-8i photosensitive material in the dark is 10
It has the disadvantage of being small, Ωα. For example, hydrogenated amorphous silicon (hereinafter referred to as !-8
! The sump with the film (denoted as H) has a problem in that a sufficient narrow surface potential cannot be obtained even if DC corona charging is performed. Therefore, various impurity gases were added to 84H, 8i.
A proposal has been made to improve the above-mentioned problem by mixing it with a gas containing 81 such as l(, etc.) and performing glow discharge.

There are two types of proposals currently being made. One is to reduce photosensitivity by mixing raw material gas (O8) gas containing 8iH4 and diborane (ntH@) gas. There is a method of increasing the dark resistance ratio without causing the a-8i; There are various methods of forming blocking films.Many proposals have been made for blocking films in the past.In other words, high resistance or insulating film formed on a conductive substrate such as A. -8iHC film or a-Si
; 0@ film, a-f9iiN film, or the second base a 8i ; B film sufficiently doped with poron.

However, with these blocking films, there was a problem that the surface potential was not maintained for a long time in the dark (2) when direct current corona discharge was performed.
Therefore, when positive charges are applied to the surface of the photoconductor (2), the induced negative charges flow into the photoconductor (2), and this recombines with the positive charges that have flowed into the photoconductor from the surface of the photoconductor (2). It is.

Due to such a phenomenon, the positive surface potential is attenuated, making it impossible to maintain a sufficient surface potential for a long time, making it difficult to obtain a high-quality electrophotographic photoreceptor.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and has the main feature of maintaining the surface potential for a long time in the dark, and furthermore, (= when irradiated with light, the surface potential is quickly attenuated and erased, The purpose of the present invention is to provide a photoconductive member that can be used in two electrophotographic processes.

[Summary of the invention]

The present invention provides a conductive substrate to achieve the above object.

Layer configuration of blocking layer and photoconductive layer (2)
At least one of the blocking layers is amorphous carbon (
Hereinafter, it is characterized by being 1-C).

[Embodiments of the invention]

The present invention will be described below based on an embodiment shown in FIG. sexual substrate (1
) (=blocking layer (2), hydrogenated amorphous silicon (a-8i; H) photoconductive layer (3) and amorphous silicon carbide (a-8i; C) surface charged layer (4) formed. Here, (2-1) is the amorphous carbon (hereinafter referred to as 1-C) layered on the conductive substrate (1).
This a-C layer (2-1) is obtained by decomposing a carbon-containing gas (for example, CH, . a-8
r; C4 (2-2) is a-st;) i layer (described later)
3) is laminated on the above a-04 (2-1), one layer of interface (2) is formed, and the above a-C layer (2-1) and a-
Both layers of the 3iHC layer (2-2) exhibit excellent properties as the blocking layer (2). Here, above a-8
The iHH layer (3) is made of a gas containing Si (for example, 81H,
, 8iH, etc.) by the glow discharge decomposition method, and this photoconductive layer (3) is formed on the blocking layer (2) (although it is formed by laminating Reaction pressure and applied pressure during membrane formation.

Conditions such as substrate temperature may be within the same range as for the blocking layer (2-1). The film thickness of the above a-8i;

Further, the a-8iHC layer (4) is a surface charged layer. This a-8i;04 surface charged layer (4) has a high resistance (10" or more) formed on the above a-8i;H photoconductive layer (3).
When the surface of the photoreceptor is charged with C nicorona with the film ≦;
This is a layer to maintain surface position. This a-8i;C
The formation of the N-plane charged layer (4) is carried out using the aforementioned gas containing Si (for example, 8iH, H@, etc.) and the gas containing C (
For example, CH4e CIH, C, H, etc.) may be mixed in a reactor and then decomposed by a glow discharge decomposition method, and the reaction pressure, applied pressure, substrate temperature, etc. during film formation are as described above. The same range as in the case of the blocking layer (2) and the a-8i;H photoconductive layer (3) may be used.

That is, the appropriate reaction pressure is 0.1 to 3 torr, and preferably the range of 20,4 to 1 tar.The applied pressure for glow discharge decomposition is 50W~10v is suitable, and C100~500W
It is desirable that the range be within the range of . Further, the substrate temperature during the reaction is suitably in the range of 150° to 400°C, and more preferably in the range of 2200° to goot:'.

In addition, when a photoreceptor is formed with the above configuration, the film thickness of the a-C layer (2-1) has a large influence on the time C:
The appropriate film thickness is 1000λ to 1μm, and 3
000-5000λ is desirable. If the film thickness is outside this range, a good blocking layer (2) cannot be formed. That is, when the film thickness becomes less than 100 i, the photoconductor fi[I (when duality is imparted (the reason is that charges are injected into the photoconductor from the two substrate side and cannot be blocked) is based on 1000^ If the film is as thin as below, it becomes difficult to maintain a uniform film thickness, and the desired charge blocking cannot be achieved, making it impossible to obtain good electrophotographic properties.

On the other hand, the a-siHc layer (2-2) is as described above (;1
- above the C layer (2-1) (2 a-st; H photoconductive layer (3)
) is formed at the interface C2 between these two layers, and the characteristics of this film are the above a-8i;H photoconductive layer (3) and the '-8tiC layer (2 -2) is controlled by the film forming conditions. Therefore, to give an effective example, it is preferable to provide a PM blocking layer (2) as an interface layer. In other words, the interface layer with the booking function, A:
b Chea-at; By doping C/I (2-2) with poron (by making it P-type), the booking function of the photoreceptor of the present invention can be improved and the characteristics can be stabilized. .

Example 1 Coating = 1 shows an example of film forming conditions for an electrophotographic photoreceptor having the configuration shown in FIG.

This electrophotographic photoreceptor is manufactured by placing an aluminum drum as a conductive substrate (1) in a reduced pressure reaction chamber, and applying high frequency power between the drum and the electrode facing the drum. The film is formed by introducing a gas (high frequency glow discharge CVD method C2 to form an amorphous film).

First, the blocking layer (2) is formed in the following manner. The pressure inside the reaction chamber was set to 1.5 t o r r,
1, and then introduce CH and gas into the reaction chamber. This C
The flow rate of H gas is 11008 CC. At the same time, the drum is heated to 280 C and a high frequency power of 400 W is applied between the counter electrode and the drum. By maintaining this state, a blocking layer with a thickness of 0.5 μm is formed.

Next, the application of high frequency power is interrupted, and after exhausting the gas remaining in the reaction chamber, a photoconductive layer (3) is formed. In this case, 8iH4 gas was introduced into the reaction chamber as a raw material gas at a flow rate of 25008 CCM, the applied high frequency power was 800 W, the pressure inside the reaction chamber was 1 Otorr*
Then, film formation is performed in the same manner as described above. Photoconductive layer (3)
is formed to a thickness of 25 μm. Similarly, using a mixed gas of 8 iH gas and CI gas as the raw material gas, the applied high frequency power was 200 W, and the pressure inside the reaction chamber was 1
．． The surface charged layer (4) is formed at a temperature of 01 orr. The surface charged layer (4) is formed to a thickness of 0.5 μm. In this case, the flow rate of the raw material gas is 11008 CC% of 8iH4 gas.
CH4 gas is 500SCCM, mixing ratio C)(/8i
H, is 500*.

Note that the temperature of the drum was maintained at 280C throughout the three-layer film formation. For this reason, a heater is disposed inside the hollow part of the drum, and is arranged so as to heat the second side of the drum.

The film forming conditions explained above are summarized in Table 1.

This table: IC: Sample 1 is an electrophotographic photoreceptor whose film was formed according to the film forming conditions shown.

1. Next, FIG. 2 shows the layer structure of an electrophotographic photoreceptor showing another embodiment of the present invention. This photoreceptor consists of a blocking layer (5) on a conductive substrate (1) made of the same A material as mentioned above, and a hydrogenated amorphous silicon doped with holon (a-szH).
@)) Photoconductive layer (6) and a-8LHC surface charging layer (
4). Here, (5-1) is a boron-doped amorphous carbon (a-CHB) layer (two layers) on the conductive substrate (1), and this a-CH8 layer (
5-1) is a gas containing C (for example, CH, c, H4
, C, H, etc.) and B-containing gases (e.g., BtHl
a-81CH) is mixed in a reaction vessel, and then decomposed using the glow discharge decomposition method (secondary decomposition).
The B layer (5-2) is formed when the a-8iHH layer (6) described later is seeded on the a-CHB layer (5-1), and the interface f between both layers is formed. CHB layer (5-1') Amorphous silicon carbide doped with tophoron (a-3
Both shoulders of the i C=B layer (5-2) exhibit better properties as a blocking layer (5). Here, the above a-sI; It is laminated on the blocking layer (5).

In addition, the a-3iHC layer (4) is a surface charged layer, and this 1-3iHC layer (4) is a surface charged layer.
Bl; Cek surface layer conductive layer) is formed by mixing SI with muscle gas and C-containing gas in a reaction vessel and then decomposing it by glow discharge decomposition method in the same manner as described above. C of
Flow rate g of gas containing (C) and flow rate g of gas containing B
The ratio g (B)/g (C) with (B) varies depending on the gas (=) used and is preferably in the range of 0.1S to 10%.

Further, the thickness of the a-CHB layer (5-1) is suitably 1000 A to 1 μm as described above, and C2aoo.

It is desirable to have ~5,000 people.

On the other hand, the B-8iCgB layer (5-2) is 1
- When the photoconductive layer (6) is formed on the CAB layer (5-1) (C2, the interface 1 between these two layers); 1-C on the substrate (1);・
By diffusing B in layer B (5-1> to this interface layer, this layer becomes a P-type blocking layer (5). In other words, in this example, a is used as the first blocking layer.
It has two layers: a -can layer (5-1) and a P-type a-8iCHB layer (5-2) as a second blocking layer, and good blocking properties can be obtained.

This blocking layer (5) is the same as the blocking layer (2) shown in one embodiment, i.e. a as the first blocking layer.
It has the advantage of superior charging performance (-) compared to a photoconductor having two layers: -CIfi (2-1) and a-8L;0 layer (2-2) as the second blocking layer.

Next (2) The above a-8iHH (B) layer (6) is a photoconductive layer, and this photoconductive layer (6) is obtained by decomposing a gas containing Si by a glow discharge decomposition method as described above. but,
At this time, immediately after the film was formed, it was an a-8i; H layer, but as time passed, B contained in the second blocking layer C diffused, so B was doped. -81;H(B)74 (
6). This a-8i;H(B) light-guiding magnetic layer (6) is doped with B (it has the advantage that peeling or cracking of the film does not occur due to the double layer).

Furthermore, a-8i; CIfi (4) is the surface charged layer of the same line as described above, and the gas used, film thickness, characteristics, etc. are the same as in the first embodiment. Further, regarding the diffusion of B, it does not reach the above 1-8i; C surface charged layer (4) (2).

Legend 2 Table 2 shows an example of film forming conditions for the electrophotographic photoreceptor having the structure shown in FIG. Same as the film formation example shown in Table 1 (2. High frequency glow radiation CVD method (2-up film formation). The film formation procedure is the same as the example in Table 1, so it will not be described in detail. Sample 2 is an electrophotographic photoreceptor in which a two-layer film is formed under the film forming condition C of =2.

(Leaving space below) Table: 2 Example 3 Table 8 shows, as a comparative example, an example of film forming conditions for an X-ray photoreceptor using an amorphous silicon carbide film as a conventional blocking layer.

This electrophotographic photoreceptor has an amorphous silicon carbide film blocking 4, a hydrogenated amorphous silicon film photoconductive layer, and an amorphous silicon carbide film surface charging layer formed on the surface of an aluminum sheet. . This film was also formed by the high frequency glow emission '4cvo method, similar to Sample 1 shown in FIG.

Therefore, as shown below (two deposited samples 1.2 and 3)
When the electrophotographic characteristics of C were evaluated, narrowness: 4
The results shown in Table 5 were obtained.

Or: 4 Table: 5 As is clear from the above Table: 4, C2, sample l according to the present invention
Compared with the conventional sample 3, sample 2 has an initial subsurface potential (2 excellent) and a good potential retention rate after 15 seconds. Samples 1 and 2 according to the present invention are also excellent and can be used for practical use.

In addition, as is clear from Section 5, Samples 1 and 2 based on the present invention showed very little decrease in surface potential even after repeated use in the electrophotographic process (2), and they were further tested in similar repeated tests. Sensitivity (Good results were obtained even when two were used.

Also, although not shown on the machine, low temperature 10 C to high temperature (capital)
Almost no change was observed in the electrophotographic properties described above in the range of C and low humidity RH 20% to high temperature RH 90%. Furthermore, as a result of loading Samples 1 and 2 according to the present invention into an electrophotographic copying machine and a laser printer and forming images, very good images were obtained, and the results showed that samples 1 and 2 according to the present invention were loaded into an electrophotographic copying machine and a laser printer, and very good images were obtained. However, no change in image clarity was observed.

〔Effect of the invention〕

As explained above, the present invention (according to the conductive substrate).

Layer configuration of blocking layer and photoconductive layer ≦:
Since at least one of the blocking layers is made of amorphous carbon, it has an excellent effect of being able to form good images when used as an electrophotographic photoreceptor.

[Brief explanation of drawings]

FIG. 1 is a schematic structural diagram of a photoconductive member showing one embodiment of the present invention, and FIG. 2 is a schematic structural diagram of a photoconductive member showing another embodiment. 1... Conductive substrate 2.5... Blocking layer 8
...Photoconductive layer 4...Surface charged layer 6...Photoconductive layer agent Patent attorney Mr. Inoue Figure 1 Figure 2

Claims (5)

[Claims] (1) In a photoconductive member in which at least one blocking layer is provided between a conductive substrate and a photoconductive layer made of amorphous silicon, at least one of the blocking layers is amorphous carbon. A photoconductive member characterized by: (2) Claim 1, characterized in that the blocking layer made of amorphous carbon is doped with a group IIa element at a ratio of 10 atomic ppm to 10 atomic %.
The photoconductive member described in . (3) The photoconductive member according to claim 2, wherein the Group IIa element is boron. (4) The thickness of the blocking layer made of amorphous carbon is 1,
The photoconductive member according to claim 1 or 2, wherein the photoconductive member has a thickness of 000 Å to 1 μm. (5) By laminating a photoconductive layer made of amorphous silicon on a blocking layer made of amorphous carbon or amorphous carbon containing boron, an amorphous silicon carbide layer or The light according to any one of claims 2, 3, or 4, wherein an amorphous silicon carbide layer containing boron or an amorphous silicon carbide layer containing boron is produced. conductive member.