JP2756569B2 - Electrophotographic photoreceptor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrophotographic photoreceptor in which a main photoconductive layer is an amorphous silicon carbide layer.

[Prior art and its problems]

In recent years, amorphous silicon carbide (hereinafter, a-
An electrophotographic photoreceptor comprising a photoconductive layer (abbreviated as SiC) has been proposed. This photoreceptor is capable of obtaining a wide spectral sensitivity characteristic (peak 600 to 700 nm) by appropriately changing the carbon content thereof, or easily. Attention is paid to the fact that a high dark resistivity can be obtained.

According to the above electrophotographic photoreceptor, when forming the a-SiC photoconductive layer on the aluminum substrate, oxygen or nitrogen is contained in the layer region on the substrate side inside the layer, whereby the adhesion of the film to the substrate is reduced. It has been proposed to have a function to increase the injection and to prevent the injection of carriers from the substrate.

However, as described above, when a large amount of oxygen or nitrogen (hereinafter, abbreviated as NO element) is contained, the adhesion of the film is increased, but carriers are trapped in the layer region and the residual potential is increased. .

Therefore, if the content of the NO element is decreased to lower the residual potential, a problem arises in that the adhesion of the film decreases.

Accordingly, the present invention has been completed in view of the above,
It is an object of the present invention to provide an electrophotographic photoreceptor in which the adhesion of an a-SiC layer to a substrate is increased and the residual potential is reduced.

[Means for solving the problem]

In the electrophotographic photoreceptor of the present invention, a first a-SiC layer containing 500 to 5000 ppm of a Va continuation element of the periodic table and a second a-SiC layer having photoconductivity are sequentially laminated on a conductive substrate. The NO element is contained in the first a-SiC layer in a total amount of 0.01%.
It is characterized in that a first layer region containing a large amount of NO element and a second layer region containing a small amount of NO element are sequentially formed in the range of up to 30 atomic%.

 Hereinafter, the present invention will be described in detail.

FIG. 1 shows the basic layer structure of the electrophotographic photoreceptor of the present invention, and FIG. 2 shows the typical layer structure.

In FIG. 1, a first a-SiC layer (2) and a second a-SiC layer (2) are formed on a conductive substrate (1) made of aluminum or the like.
-SiC layer (3) is sequentially laminated, and a first a-SiC layer (2)
Are the first layer region (2a) and the second layer region (2a) from the substrate side.
b) are sequentially formed. According to FIG. 2, a surface protective layer (4) is formed on the second a-SiC layer (3).

The second a-SiC layer (3) is a substantial photocarrier generation layer having photoconductivity, and the first a-SiC layer (2) prevents carrier injection from the substrate and forms a film on the substrate. To increase the adhesion. The first a-SiC layer (2) contains a group Va element of the periodic table (hereinafter abbreviated as a group Va element) within a predetermined range to enhance the carrier injection blocking function, The body has a negative charge type.

In the present invention, the first a-SiC layer (2) is formed as two types of layer regions depending on the difference in the content of the NO element.
It is characterized in that the function of preventing carrier injection is enhanced and the film adhesion to the substrate is enhanced.

First, the first a-SiC layer (2) contains N for the above purpose.
O element in a total amount of 0.01 to 30 atomic%, preferably 0.1 to 30 atomic%.
It is good to make it contain within the range of ~ 20 atomic%, and the content is
If it is less than 0.01 atomic%, there is no effect of increasing the adhesion,
Or it has no effect of increasing the surface potential, while 30 atom%
, The residual potential increases.

However, the first a-SiC layer (2) is a layer containing a predetermined amount of a Va group element and having a determined thickness.
The element is expressed as an average content within the layer thickness range.

The first a-SiC layer (2) includes a first layer region (2a) having a high NO element content and a second layer region (2b) having a low NO element content.
Are formed successively, and the first layer region (2a) mainly has an action of increasing the adhesion to the substrate, and the second layer region (2a)
b) mainly enhances the function of preventing carrier injection.

In such two-layer regions (2a) and (2b), for example, FIG.
There is an NO element content distribution as shown in FIG.

In these figures, the horizontal axis is the layer thickness direction, and the vertical axis is
S is the interface between the substrate (1) and the first layer region (2a), and t is the boundary between the first layer region (2a) and the second layer region (2b). And u is the second layer region (2
This is the interface between b) and the second a-SiC layer (3).

The thickness of the two-layer regions (2a) and (2b) may be set as follows.

The thickness of the first layer region (2a) is 0.01 to 1 μm, preferably
The thickness may be set in the range of 0.05 to 0.5 μm, and within this range, the adhesion to the substrate is increased and the residual potential is reduced.

The thickness of the second layer region (2b) may be set in the range of 0.5 to 5 μm, preferably 1 to 4 μm. In this range, the surface potential is increased and the withstand (electric) pressure of the photoconductor is reduced. It is good in that it raises.

The first a-SiC layer (2) contains a group Va element in an average value of 500 to 5,000 ppm, preferably 1,000 to 2,000 ppm in the thickness direction.
To be included. If the content is less than 500 ppm, the ability to stop the injection of positive charges from the substrate side becomes insufficient,
When the content exceeds 00 ppm, the number of defects in the film increases, thereby increasing the dark conductivity and decreasing the above-described carrier injection stopping ability.

The Va group elements include N, P, As, Sb, and Bi. However, P is excellent in covalent bonding and can change semiconductor characteristics sensitively. In addition, excellent charging ability and photosensitivity can be obtained. This is desirable.

The second a-SiC layer (3) has a composition formula (Si _1-x C _x )
_When expressed as _1-y A _y (A represents an element of hydrogen or halogen), it is set in the range of 0.05 <x <0.5, preferably 0.1 <x <0.4 0.2 <y <0.5, preferably 0.25 <y <0.45. It is preferable that the content is within this range, whereby the high surface potential, the spectral sensitivity close to the visible light sensitivity, and the reduction of the internal stress of the film can be most advantageously achieved.

The composition ratio of the first a-SiC layer (2) is 0.05 <x <0.7, preferably 0.1 <x <0.5, 0.2 <x <
0.5, preferably 0.25 <y <0.45 is set, and within this range, the residual potential is reduced and the surface potential is further increased.

The surface protective layer (4) is required to have high hardness properties,
This results in an electrophotographic photoreceptor having excellent durability. Further, the optical band gap of the layer (4) is preferably 2.0 eV or more, whereby high light sensitivity can be maintained.

The surface material satisfying such conditions includes the second a-Si
There is a-SiC containing more carbon than the C layer (3),
In addition, there are amorphous silicon oxide, amorphous silicon nitride, amorphous carbon, and the like.

Thus, the electrophotographic photoreceptor of the present invention has the a-SiC two-layer regions having different NO element contents, so that the adhesion to the substrate is enhanced and the residual potential is reduced.

Further, the electrophotographic photosensitive member of the present invention is provided as a negative charging type.

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

For forming the a-SiC layer, there are a thin film forming method such as a glow discharge decomposition method, an ion plating method, a reactive sputtering method, a vacuum evaporation method, and a CVD method.

When glow discharge decomposition is used, the gas containing Si element and C
Element-containing gases are combined, and this mixed gas is plasma-decomposed to form a film. The Si element-containing gas includes SiH ₄ , Si ₂ H ₆ ,
There are Si ₃ H ₈ , SiF ₄ , SiCl ₄ , SiHCl _3, etc., and the C element containing gas includes CH ₄ , C ₂ H ₄ , C ₂ H ₂ , C ₃ H _8, etc.
C ₂ H ₂ is desirable in that high-speed film forming properties can be obtained.

The glow discharge decomposition apparatus used in this embodiment will be described with reference to FIG.

In the figure, the first tank (5), the second tank (6), the third tank (7), the fourth tank (8), and the fifth tank (9) are respectively SiH ₄ , C ₂ H ₂ , PH ₃ (PH ₃ is diluted with hydrogen at a concentration of 0.2%), H ₂ and NO are sealed, and these gases are respectively corresponding to the first control valve (10), the second control valve (11), and the third control valve (11).
Regulating valve (12), fourth regulating valve (13) and fifth regulating valve (14)
Released by opening The flow rates of the released gas are the mass flow controllers (15) (16) (17) (18) (1
9), each gas is mixed and the main pipe (2
0) Sent to (21). Incidentally, (22) and (23) are stop valves.

The gas flowing through the main pipe (20) (21) is the reaction pipe (24)
A discharge electrode (25) is provided inside the reaction tube (24), and a cylindrical film-forming substrate (26) is placed on a substrate support (27). The substrate support (27) is mounted and rotated by a motor (28), and the substrate (26) rotates accordingly. Then, power 50 is applied to the electrode (25).
High frequency power of W to 3 kW and frequency of 1 to 50 MHz is applied, and the substrate (26) is heated to about 200 to 400
C., preferably at a temperature of about 200-350.degree. Further, the reaction tube (24) is connected to a rotary pump (29) and a diffusion pump (30), so that a reduced pressure required for forming a film by glow discharge (gas pressure at discharge: 0.01 to 2.0 Torr).
Can be set.

When the a-SiC layer is formed on the substrate (26) using the glow discharge decomposition apparatus having such a configuration, the first regulating valve (1
0), the second control valve (11), the third control valve (12), the fourth control valve (13), and the fifth control valve (14) are opened to open SiH ₄ , C ₂ H ₂ , P
Each gas of H ₃ , H ₂ , and NO is released, and the amount of the released gas is controlled by mass flow controllers (15), (16), (17), (18), (19). ) Flows into the reaction tube (24) via (21). When the depressurized state inside the reaction tube, the substrate temperature, and the high-frequency power for electrode application are set to predetermined conditions, glow discharge occurs, and the P-, N-, and O-element-containing a-SiC film is generated with the decomposition of the gas. Are formed on the substrate at high speed.

〔Example〕

 Next, examples of the present invention will be described.

Example 1 An electrophotographic photoreceptor having the layer configuration shown in FIG. 1 was manufactured using the glow discharge decomposition apparatus shown in FIG. 9 under the film forming conditions shown in Table 1.

Carbon, P, NO in each layer of the electrophotographic photosensitive member
When the contents of the elements were measured, the results as shown in Table 2 were obtained. Further, the average content of the NO element in the first a-SiC layer was 7.3 atomic%.

When the electrophotographic characteristics of the electrophotographic photoreceptor thus obtained were measured, an excellent charging ability (about 750 V) and photosensitivity (recording exposure amount of 0.6 lux · sec) were obtained, and a low residual potential (20 V or less). was gotten.

Further, when a film of the photoreceptor was scratched and subjected to an adhesion test in which the film was immersed in water, no peeling from the vicinity of the scratch occurred even after 24 hours.

(Example 2) In this example, the first layer region of (Example 1) was not formed, and the other layers had exactly the same layer configuration as (Example 1). As a result of measurement, the charging ability was reduced by about 15% as compared with the photoconductor of (Example 1).
In addition, when a film adhesion test was performed, 24 hours later,
Peeling spread from the vicinity of the scratch, and the adhesion was significantly reduced.

(Example 3) Next, in the electrophotographic photoreceptor of (Example 1), the content of the NO element in both layer regions (2a) and (2b) was changed in various ways, and other film forming conditions were the same as in (Example 1). Were prepared, and the surface potential, breakdown voltage and residual potential, and the adhesion of the film were measured. The results shown in Table 3 were obtained.

 Each measurement result was evaluated as follows.

Regarding the surface potential, three categories of evaluation criteria were determined, and ◎, ○ and Δ were sequentially compared in order of superiority, and relative comparison was performed.

Also, with respect to the withstand voltage, relative evaluation criteria were similarly defined by the mark ◎, the mark △, and the mark △.

Regarding the residual potential, the mark 最 も indicates the case where it was most reduced, the mark ○ is slightly higher, but there was no problem in practical use, and the mark △ was in the case where it was significantly increased and there was no problem in practical use. is there.

Regarding the adhesion, the adhesion test was performed as described above, and the case where no peeling was observed after 24 hours was marked as ◎, and the peeling was slightly observed, but the case where no further progress was observed was marked with ○, Then, peeling was recognized, and further progressing of the peeling was marked with a triangle.

As is evident from Table 3, the photoconductors B to G of the present invention are excellent in all of the various characteristics.

Although the photosensitive member A has an excellent residual potential,
Poor surface potential, withstand voltage and adhesion. Further, the photosensitive member H is inferior in residual potential.

Example 4 Next, the present inventors manufactured an electrophotographic photosensitive member having a layer configuration shown in FIG. 2 under the film forming conditions shown in Table 4.

When the contents of the carbon, P, and NO elements in the respective layers of the electrophotographic photosensitive member were measured, the results shown in Table 5 were obtained.

When the electrophotographic characteristics of the electrophotographic photoreceptor thus obtained were measured, excellent charging ability (780 V) and photosensitivity (recording exposure amount 0.65 lux · sec) were obtained, and a low residual potential (20 V or less) was obtained. Obtained.

When the adhesion test was performed, no peeling occurred.

The present inventors have confirmed that similar results can be obtained by using oxygen (O ₂ ) gas or nitrogen (N ₂ ) gas instead of the NO gas in addition to the above examples.

〔The invention's effect〕

As described above, according to the present invention, it was possible to provide an electrophotographic photoreceptor which was excellent in film adhesion and in which various electrophotographic characteristics such as a reduction in residual potential were improved.

[Brief description of the drawings]

FIGS. 1 and 2 are cross-sectional views showing the layer structure of the electrophotographic photoreceptor of the present invention. FIGS. 3, 4, 5, 6, 7, and 8 show the NO element. FIG. 9 is a diagram showing a content distribution, and FIG. 9 is an explanatory diagram of a glow discharge decomposition device. DESCRIPTION OF SYMBOLS 1 ... Conductive substrate 2 ... 1st amorphous silicon carbide layer 2a ... 1st layer area 2b ... 2nd layer area 3 ... 2nd amorphous silicon carbide layer

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Ito 1166, Haseno, Hachimizo-cho, Yokaichi, Shiga Prefecture Inside the Shiga Yokaichi Plant, Kyocera Corporation (72) Inventor, Nishi Takemura 1166, Hanaeno, Hachimizo-cho, Yokaichi, Shiga Prefecture (6) References JP-A-64-62659 (JP, A) JP-A-63-2068 (JP, A) JP-A-60-73628 (JP, A) JP JP-A-59-212840 (JP, A) JP-A-61-250653 (JP, A) JP-A-62-198866 (JP, A) JP-A-63-83725 (JP, A) A)

Claims (3)

(57) [Claims] 1. A method according to claim 1, wherein a group Va element of the periodic table is provided on a conductive substrate.
A first amorphous silicon carbide layer containing about 5000 ppm and a second amorphous silicon carbide layer having photoconductivity are sequentially laminated, and at least one additional element selected from oxygen and nitrogen is added to the first amorphous silicon carbide layer. A first layer region containing a large amount of the additional element and a second layer region containing a small amount of the additional element are sequentially formed in the total amount in the range of 0.01 to 30 atomic%. Electrophotographic photoreceptor. 2. The electrophotographic photosensitive member according to claim 1, wherein the thickness of the first layer region is in the range of 0.01 to 1 μm. 3. The electrophotographic photosensitive member according to claim 1, wherein the thickness of the second layer region is in the range of 0.5 to 5 μm.