JP2632887B2 - Photoconductive member - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various photoconductive members utilizing photoconductivity, such as an electrophotographic photoreceptor or an optical sensor made of, for example, photoconductive amorphous silicon carbide. The present invention relates to a photoconductive member capable of increasing the ability to prevent carrier injection.

(Prior art and its problems) In recent years, light-receiving elements using photoconductive amorphous silicon carbide (hereinafter, amorphous silicon carbide is abbreviated as a-SiC) have been used, and for example, in the field of electrophotographic photoreceptors. Has been proposed to be a substantially photoconductive layer thereof.

When the a-SiC layer is used as a photoconductive member in this manner, carriers generated in response to light reception are moved to the substrate, whereas carriers of the other polarity injected from the substrate side are blocked. There must be.

In the field of electrophotographic photoreceptors, usually a carrier injection blocking layer is formed between the substrate and the photoconductive layer,
Carriers generated in the photoconductive layer flow smoothly to the substrate, while carriers on the substrate side are blocked by the injection blocking layer. As a result, the charging ability of the photoconductor itself is increased, and the residual potential is reduced.

It has been proposed to use the same a-SiC layer as the photoconductive layer for such a carrier injection blocking layer.

However, as described above, the a-SiC carrier injection blocking layer does not yet have a sufficient ability to prevent carrier injection from the substrate side, and as a result, a desired high chargeability and low residual potential are obtained. Absent.

(Object of the Invention) Accordingly, the present invention has been completed in view of the above circumstances, and an object of the present invention is to provide a photoconductive member comprising an a-SiC layer having excellent ability to prevent carrier injection from a substrate. .

Another object of the present invention is to provide a high chargeability and low residual potential a
-To provide a photoconductive member from which a SiC electrophotographic photoreceptor can be obtained.

(Means for Solving the Problems) According to the present invention, at least a-Si
Forming a C layer, said layer comprising at least a first layer region and a second layer region;
Wherein the first layer region is a photoconductive member disposed closer to the substrate than the second layer region, and the first layer region is a 50 to 5000 ppm group Va element of the periodic table. And 0.1
Containing at least 10 atomic% of oxygen and / or nitrogen, and wherein the amount of carbon in the second layer region is set in the range of 0.01 ≦ X ≦ 0.5 as the X value of Si _1-x C _x. Is provided.

 Hereinafter, the present invention will be described in detail.

FIG. 1 shows the basic layer structure of the photoconductive member of the present invention, in which an a-SiC layer (2) is formed on a substrate (1).
The layer (2) has a structure in which a first layer region (2a) and a second layer region (2b) are sequentially formed.

The a-SiC layer (2) has photoconductivity, and therefore, the second layer region (2b) or the layer of both the first layer region (2a) and the second layer region (2b). The region is provided with photoconductivity.

Such photoconductivity is caused by making amorphous or containing a hydrogen element (H) or a halogen element within a required range in order to terminate a dangling bond between the silicon element and the carbon element.

The present inventors performed a photoconductivity experiment by changing the carbon content ratio in various ways, and when expressed by the X value of Si _1-x C _x , 0.01 ≦ X ≦ 0.5, preferably 0.05 ≦ It is good to set within the range of X ≦ 0.3, and when the X value is less than 0.01, the band gap cannot be widened, so that it becomes impossible to increase the light sensitivity to short wavelength light, and the X value is increased. 0.
If it exceeds 5, the photoconductivity decreases, and the residual potential increases in the photoreceptor field.

When the second layer region (2b) is a substantial photoconductive layer, the amount of carbon in the first layer region (2a) may exceed 0.5 in X value.

In such a-SiC layer (2), the first layer region (2a) includes a group Va element of the periodic table (hereinafter abbreviated as a group Va element).
In addition, oxygen and / or nitrogen are contained within predetermined ranges, respectively.

In containing the Va group element, the doping distribution may be uniform or non-uniform in the layer thickness direction. When it is contained uniformly, the content is 50-5000pp
m, preferably within the range of 200 to 2000 ppm, 5
If it is less than 0 ppm, the ability to stop injection of positive charges from the substrate side is insufficient, while if it exceeds 5000 ppm, defects in the film increase, thereby increasing dark conductivity, and As a result, the carrier injection stopping power as described above decreases.

On the other hand, when the Va group element is non-uniformly doped, for example, there is a doping distribution as shown in FIG. 3 to FIG.

In these figures, the horizontal axis represents the layer thickness of the first layer region (2a), A is the interface of the first layer region (2a) on the substrate side, and B is
Is the opposite interface.

The content of the Va group element when non-uniformly doped is determined by the average value of the entire first layer region (2a), and the average content is also 50 to 5,000 ppm, preferably 200 to 5,000 ppm.
It is good to set within the range of -2000 ppm.

The Va group elements include P, As, Sb, and Bi. Among them, P is preferable because it has excellent covalent bonding and can sensitively change semiconductor characteristics.

Next, as for oxygen or nitrogen contained in the first layer region (2a), at least one of them is in the range of 0.1 to 10 atomic%, that is, (Si _1-x C _x ) _1-y (O, N) The _y value represented by y should be set within the range of 0.001 ≦ y ≦ 0.1, preferably 0.002 ≦ y ≦ 0.5. When the y value is less than 0.001, the effect of inhibiting carrier injection becomes insufficient, and when the y value exceeds 0.1, the first layer region (2a) itself has insulating properties,
Therefore, the rectifying property is lost, and for example, in the field of photoconductors, the residual potential becomes large.

When oxygen and / or nitrogen is contained, the doping distribution may be uniform or non-uniform in the layer thickness direction. In the case of doping non-uniformly, the content is determined by the average value of the entire first layer region (2a), and the range of the average content is as described above.

When the first layer region (2a) is non-uniformly doped with oxygen and / or nitrogen, the doping distribution is, for example, as shown in FIG. 9 to FIG.

Thus, according to the present invention, it is possible to provide a high-performance photoconductive member in which the injection of positive charges from the substrate side is effectively prevented, and the ratio between the light conductivity and the dark conductivity is significantly increased.

Next, a case where the photoconductive member of the present invention is used for an electrophotographic photosensitive member will be described as an example.

FIG. 2 shows a typical layer structure of the electrophotographic photoreceptor of the present invention, in which an a-SiC carrier injection blocking layer (4), an a-SiC photoconductive layer (5) and The surface protection layer (6) is sequentially laminated.

The carrier injection blocking layer (4) is provided in the first layer region (2a).
In addition, the photoconductive layer (5) corresponds to the second layer region (2b).

The thickness of the carrier injection blocking layer (4) is determined so that the injection blocking effect of the photoreceptor is sufficiently exerted. According to experiments repeatedly conducted by the present inventors, the thickness is 0.5 to 5 μm.
m, preferably in the range of 1 to 4 μm.

The thickness of the photoconductive layer (5) is appropriately determined in that a high surface potential can be obtained, and the range is 5 to 100.
μm, preferably in the range of 10 to 50 μm.

The surface protective layer (6) protects the photoconductive layer (5) to improve moisture resistance and the like, and can further increase the dark resistivity of the photoreceptor to increase the charging ability.

Materials having high insulating properties, high corrosion resistance and high strength properties as materials suitable for such purposes are good, for example, organic materials such as polyimide resin, SiC, SiO, Al ₂ O ₃ , SiN,
There is an inorganic material such as amorphous silicon.

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

When the a-SiC layer is formed using the glow discharge decomposition method, a gas containing silicon (Si) and a gas containing carbon (C) are combined, and the mixed gas is subjected to glow discharge decomposition.

This Si-containing gas includes SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiF ₄ , SiCl
₄ , SiHCl _{3 and} so on, of which SiH ₄ and Si ₂ H ₆ are Si
Since the element and the H element are combined, the H element is easily taken into the film, which is desirable in that the tangling bond in the film is reduced and the photoconductivity is improved.

The C-containing gas includes CH ₄ , C ₂ H ₄ , C ₂ H ₂ , C ₃ H _8, etc. Among them, C ₂ H ₂ is particularly preferable in that a high-speed film-forming property can be obtained.

In addition, PH ₃ or the like is used as a gas containing a Va group element.

Furthermore, in order to contain oxygen or nitrogen in the a-SiC layer, O ₂ , N ₂ , NO, N ₂ O, NO ₂ , NH ₃ , N ₃
Gases such as F ₃ , CO, and CO ₂ may be mixed.

(Example) Next, an example of the present invention was first modified by a glow discharge decomposition method.
The case where the a-SiC layer shown in the figure is formed will be described in detail as an example.

(Example 1) An aluminum flat plate (25 mm x 50 mm) whose surface was polished was placed inside the reaction chamber of a glow discharge decomposition apparatus, and the first layer was sequentially formed on the flat plate (7) under the film forming conditions shown in Table 1. forming a region (8) and the second layer region (9), moreover, to introduce PH ₃ gas at various flow rates in forming the first layer region (8). Next, disk-shaped (3m
mφ) aluminum electrode (10) was formed, and a photoconductive member as shown in FIG. 15 was produced.

The first layer region (8) and the second
For each layer region (9), the respective amounts of carbon and oxygen and nitrogen were determined by ESCA analysis, and the results shown in Table 1 were obtained.

In forming the first layer region (8), PH ₃
When the gas is not introduced, or the amount of the PH ₃ gas introduced is changed in various ways, so that the P content is 0, 80 ppm, 350 ppm.
A photoconductive member of each of ppm, 1000 ppm, and 6000 ppm was manufactured.

As shown in FIG. 15, a voltage is applied to the five types of photoconductive members thus obtained and the flat plate (7) is electrically connected to the ground side, thereby measuring the voltage-current characteristics. As a result, the result as shown in FIG. 16 was obtained.

In the figure, the correspondence between the plots and the characteristic curves with the respective photoconductive members is as shown in Table 2.

As is clear from the results shown in FIG. 16, the photoconductive member D
(P content: 1000 ppm) shows that the reverse current is small.

(Example 2) In this example, when forming the photoconductive member D, the introduction amount of the NO gas used for forming the first layer region was changed in various ways, and other film forming conditions were changed (Example 1). Thus, when the content of oxygen and nitrogen was represented by the y value, the photoconductive members of 0, 0.023, 0.065, and 0.12 were produced.

When the voltage-current characteristics of the four types of photoconductive members thus obtained were measured, the results shown in FIG. 17 were obtained.

In the figure, the correspondence between the plots and characteristic curves and the respective photoconductive members is as shown in Table 3.

As is clear from the results shown in FIG. 18, according to the photoconductive member G, a large current value is obtained when a positive voltage is applied, while the reverse current is small.

(Effects of the Invention) As described above, according to the photoconductive member of the present invention, the effect of inhibiting the injection of carriers from the base is enhanced. For example, in the field of an electrophotographic photoreceptor, a high charging ability is obtained and the residual potential is reduced. Become smaller.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the layer structure of the photoconductive member of the present invention, and FIG.
The figure is a cross-sectional view showing the layer structure of the electrophotographic photoreceptor, and FIGS. 3, 4, 5, 6, 7, and 8 are Va.
Diagrams showing the doping distribution of group elements, FIG. 9, FIG.
11, 12, 13 and 14 are diagrams showing the doping distributions of oxygen and nitrogen, and FIG.
FIGS. 16 and 17 are diagrams illustrating voltage-current characteristic curves for measuring current characteristics. DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Amorphous silicon carbide layer 2a ... First layer area 2b ... Second layer area

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hitoshi Takemura 1166, Haseno, Jabizo-cho, Yokaichi-shi, Shiga Prefecture 6 Inside the Shiga Yokaichi Plant, Kyocera Corporation (72) Inventor Hiroshi Ito, 1166, Haseno, Hanazo-cho, Yokaichi, Shiga Prefecture 6 Kyocera Corporation Shiga Yokaichi Plant (72) Inventor Kokichi Ishibitsu 6166 Kyoka Corporation Shiga Yokaichi Plant at 1166 Haseno, Jabizo-cho, Yokaichi City, Shiga Prefecture

Claims (1)

(57) [Claims] At least an amorphous silicon carbide layer is formed on a conductive substrate, the layer comprising at least a first silicon carbide layer.
And a second layer region, wherein the first layer region is a photoconductive member disposed closer to the substrate than the second layer region, and the first layer region has a period of 50 to 5000 ppm. It contains a Group Va element of the table and contains 0.1 to 10 atomic% of oxygen and / or nitrogen, and the amount of carbon in the second layer region is 0.01 ≦ X ≦ 0.5 as the X value of Si _1-x C _x. The photoconductive member is set within the range of: