JPH0233144B2 - DENSHISHASHIN KANKOTAI - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor. Conventionally, as electrophotographic photoreceptors, Se or Se
Photoreceptor doped with As, Te, Sb, etc., ZnO and CdS
Photoreceptors, etc., in which the compound is dispersed in a resin binder are known. However, these photoreceptors have problems in terms of environmental pollution, thermal stability, and mechanical strength. On the other hand, electrophotographic photoreceptors using amorphous silicon (hereinafter referred to as a-Si) as a matrix have been proposed in recent years. a-Si is Si-Si
It has so-called dangling bonds, in which the bonding hands of the atoms are broken, and many localized levels exist within the energy gap due to this defect. For this reason, hopping conduction of thermally excited carriers occurs, resulting in a small dark resistance, and photoexcited carriers are trapped in localized levels, resulting in poor photoconductivity. Therefore, the dangling bonds are filled by compensating for the defects with hydrogen atoms (H) and bonding H to Si. The resistivity of such amorphous hydrogenated silicon (hereinafter referred to as a-Si:H) in the dark is
It is 10 ⁸ to 10 ⁹ Ω-cm, which is about 1/10,000 times lower than that of amorphous Se. Therefore, a-Si:H
A photoreceptor consisting of a single layer has problems in that the dark decay rate of the surface potential is high and the initial charging potential is low. However, on the other hand, when irradiated with light in the visible and infrared regions, the resistivity is greatly reduced, so it has extremely excellent properties as a photosensitive layer of a photoreceptor. In addition, photoreceptors with a-Si:H surfaces are susceptible to the effects of long-term exposure to the atmosphere and moisture.
Up to now, sufficient studies have not been made regarding the chemical stability of the surface, such as the influence of chemical species generated by corona discharge. For example, it has been found that when left for more than one month, the acceptance potential decreases significantly due to the influence of moisture. On the other hand, regarding amorphous silicon carbide (hereinafter referred to as a-SiC:H),
Its manufacturing method and existence are described in "Phil.Mag.Vol.35" (1978), etc., and its characteristics include high heat resistance and surface hardness, and high dark resistance compared to a-Si:H. (10 ¹² to 10 ¹³ Ω-cm), and the optical energy gap is 1.6 to 1.6 depending on the carbon content.
It is known that it varies over a range of 2.8 eV. An electrophotographic photoreceptor combining such a-SiC:H and a-Si:H has been proposed in, for example, Japanese Patent Laid-Open No. 17952/1983. According to this, a-Si:
The H layer is a photosensitive (photoconductive) layer, a first a-SiC:H layer is formed on the light-receiving surface, and a second a-SiC:H layer is formed on the back surface (support electrode side). The photoreceptor has a three-layer structure. The present inventor took advantage of the features of such a three-layer structure, and while conducting studies that had not been previously done on the thickness and components of each layer, the present inventors developed an a-SiC:H layer for charge retention and transport, and a photosensitive layer. By forming a photoconductive layer with a unique composition, the specific resistance of the photoconductive layer can be sufficiently increased, and the present invention has been achieved by successfully imparting a dark resistance that is satisfactory as a recording medium. That is, the present invention provides at least a second amorphous hydrogenated and/or fluorinated silicon carbide layer with a thickness of 5000 Å to 80 μm and a fluorinated silicon carbide layer with a thickness of 2500 Å on the substrate.
Consisting of a laminate in which a charge generation layer made of amorphous hydrogenated and/or fluorinated silicon with a thickness of Å to 10 μm and a first amorphous hydrogenated and/or fluorinated silicon carbide layer are sequentially laminated, (a) The second amorphous hydrogenated and/or fluorinated silicon carbide layer has a carbon atom content of
10 atomic% to 90 atomic%, hydrogen atom content is 1 atomic% to 40 atomic%, contains Group A elements of the periodic table, and has a dark resistivity of 10 ¹³ Ω-
(b) The charge generation layer made of amorphous hydrogenated and/or fluorinated silicon has a hydrogen atom content of 1 atomic% to 40 atomic%, contains an element of group A of the periodic table, and has a dark resistance. (c) the first amorphous hydrogenated and/or fluorinated carbon silicon layer has a carbon atom content of 10 ¹⁰ Ω-cm or more;
40 atomic% to 90 atomic%, hydrogen atom content is 1 atomic% to 40 atomic%, contains Group A elements of the periodic table, and dark resistivity is 10 ¹³ Ω-
This invention relates to an electrophotographic photoreceptor characterized by having a diameter of cm or more. Hereinafter, the present invention will be illustrated in detail based on the drawings. For example, as shown in FIG. 1, the photoreceptor according to the present invention has the above-mentioned second a-SiC:
The H layer 2, the a-Si:H (photoconductive) layer 3, and the first a-SiC:H layer 4 are laminated in this order. The second a-SiC:H layer 2 mainly has the functions of charge blocking, potential holding, charge transport, and improving adhesion to the substrate 1,
5000Å to 80μm (more preferably 5μm to 30μm)
It is preferable that the thickness be . The photoconductive layer 3 generates charge carriers in response to light irradiation, and has a thickness of 2500 Å to 10 μm (especially
5000 Å to 5 μm). Furthermore, the first a-SiC:H layer 4 improves the surface potential characteristics of this photoreceptor, maintains long-term potential characteristics, and maintains environmental resistance (humidity, atmosphere, and chemical species generated by corona discharge). It has functions such as improving printing durability due to its high surface hardness, improving heat resistance when using a photoconductor, and improving thermal transferability (especially adhesive transferability), and acts as a surface modification layer. It is something. The thickness of this first a-SiC:H layer 4 is 50 Å to 2000
It is important to make it as thin as 400 Å to 1600 Å, preferably 400 Å to 1600 Å. What is noteworthy about this photoreceptor is that it not only has the features of the a-SiC/a-Si:H/a-SiC stacked structure as described above, but also has the advantage of being doped with Group A elements of the periodic table. first and second a
-SiC:H layer has a resistivity ρ _D1 of 10 ¹³ Ω-cm or more, and a-Si:H layer 3 as a photoconductive layer
is increased to a resistivity ρ _D2 of 10 ¹⁰ Ω-cm or more,
This prevents potential attenuation due to charge leakage phenomenon in the in-plane direction of the photoconductive layer, and increases the resistivity of both the photoconductive layer and the first and second a-SiC:H layers. A photoreceptor with high resistance and high sensitivity required for formation can be obtained. As a result of various experiments conducted by the present inventors, setting ρ _D gradually higher than that of conventional methods through impurity doping has resulted in a sufficient charging potential, a low dark decay rate, and a high photosensitivity. This is extremely important in obtaining practically excellent photoreceptor characteristics and clear images, and was proposed for the first time in the present invention. In addition, the photoreceptor shown in Figure 1 has the above-mentioned laminated structure, so compared to the conventional Se photoreceptor, it maintains a high potential with a thinner film and is resistant to light in the visible and infrared regions. a- has excellent sensitivity, good heat resistance, printing durability, and stable environmental resistance.
A Si-based photoreceptor (for example, for electrophotography) can be provided. Next, an apparatus (glow discharge apparatus) that can be used to manufacture a photoreceptor according to the present invention will be described with reference to FIG. In the vacuum chamber 12 of this apparatus 11, the substrate 1 is fixed on a substrate holder 14, and the substrate 1 can be heated to a predetermined temperature by a heater 15. A high frequency electrode 17 is arranged opposite to the substrate 1, and a glow discharge is generated between the high frequency electrode 17 and the substrate 1. In addition, 20, 21, 22, 23, 24, 27, 28,
29, 30, 35, 36, 38 are each valve, 31
is a source of SiH ₄ or a gaseous silicon compound, 3
2 is a source of CH ₄ or gaseous carbon compounds, 33 is a source of CH 4 or gaseous carbon compounds;
A carrier gas source such as Ar or H ₂ , 34 is a source of diborane gas. In this glow discharge device, first, the surface of a support, for example, an Al substrate 1, is cleaned and then placed in a vacuum chamber 12, and the valve 36 is adjusted so that the gas pressure in the vacuum chamber 12 is 10 ^-6 Torr. Then, the substrate 1 is heated and maintained at a predetermined temperature, for example, 200°C. Then SiH ₄ or gaseous silicon compound, diborane gas and CH ₄ with high purity inert gas as carrier gas
Alternatively, a mixed gas prepared by diluting an appropriate amount of a gaseous carbon compound is introduced into the vacuum chamber 12, and high frequency power is applied by the high frequency power source 16 under a reaction pressure of 0.01 to 10 Torr. As a result, each of the above reaction gases is decomposed by glow discharge, and hydrogen-containing boron-doped a-SiC:H
is deposited on the substrate 1 as the layer 24 described above. At this time, by appropriately adjusting the flow rate ratio of the silicon compound and the carbon compound and the substrate temperature, a-
Si ₁ −xCx: H (for example, x up to about 0.9) can be precipitated, and a-SiC that precipitates:
It is possible to deposit a-SiC:H at a rate of 1000 Å/min or more without significantly affecting the electrical properties of the H. Furthermore, to deposit the boron-doped a-Si:H (photosensitive layer 3 above), a gaseous compound of an element of group A of the _periodic table, _e.g. Since both gases are decomposed by glow discharge, the photoconductivity of a-Si:H can be improved and its resistance can also be increased. Both the first and second a-SiC:H layers described above,
Although it is necessary to contain hydrogen, if hydrogen is not contained, the charge retention characteristics of the photoreceptor will not be practical. Therefore, the hydrogen content is 1 to 40 atomic% (even 10 to 30 atomic%)
It is desirable to do so. The hydrogen content in the photoconductive layer 3 is essential to compensate for dangling bonds and improve photoconductivity and charge retention properties, and is usually 1 to 40 atomic%, and 10 to 40 atomic%.
More preferably, it is 30 atomic%. In this way, when forming each layer by glow discharge decomposition, especially the a-SiC:H layers 2 and 4, the photoconductive layer 3,
Regarding this, it is necessary to appropriately select the flow rate ratio of diborane gas and silicon compound gas (for example, monosilane). Figure 3 shows the change in dark resistivity (ρ _D ) depending on the flow rate ratio of diborane and monosilane (scale is logarithmic scale) when a-SiC:H layers 2 and 4 are doped. ing. In general, non-doped a-SiC:H exhibits somewhat N-type conductivity, but when doped with boron, the impurities are compensated and the state becomes essentially intrinsic, and the amount of boron doped is If you increase , it will be converted to P type. According to the results shown in FIG. 3, if the flow rate ratio (B ₂ H ₆ /SiH ₄ ) is appropriately selected to achieve the purpose of the present invention, ρ _D can be reduced to 10 ¹³ Ω−.
cm or more, and by making a-SiC:H substantially intrinsic, ρ _D can be made to be 10 ¹⁴ Ω-cm or more. In this way, by containing boron in the a-SiC:H layers 2 and 4 at a predetermined concentration, the a-SiC:
Since the dark resistivity ρ _D of SiC:H layers 2 and 4 can be increased to 10 ¹³ Ω-cm or more, incorporating such layers into the photosensitive layer increases the initial charging potential and improves electrophotographic properties such as dark decay. can be done. especially,
If ρ _D of the a-SiC:H layers 2 and 4 is set to 10 ¹⁴ Ω-cm or more, further improvement in performance can be expected. On the other hand, when ρ _D is less than 10 ¹³ Ω-cm (less than 5 × 10 ¹² Ω-cm when not doped with boron: B ₂ H ₆ /
If the flow rate ratio of SiH ₄ is 0 to 1 ppm), the above-mentioned improvement in characteristics cannot be obtained, and such a-
As a photoreceptor having SiC:H layers 2 and 4, it is not sufficient in terms of charging characteristics, dark decay characteristics, etc. a-SiC: The boron content of H layers 2 and 4 must be appropriately selected in order to obtain the above dark resistance value, and when expressed in terms of the flow rate of diborane, as shown in Figure 3.
It is desirable that B ₂ H ₆ /SiH ₄ =10 to 200 ppm,
About 100 ppm is more desirable. This flow rate ratio can be 10 to 500 ppm depending on the type of gas used. Figure 4 shows the flow rate ratio of B ₂ H ₆ /SiH ₄ when the a-Si:H layer 3 is doped.
The change in ρ _D of Si:H layer 3 is shown, and according to this, if the above flow rate ratio is set to 20 to 300 ppm, ρ _D changes.
10 ¹⁰ Ω-cm or more, and it can be seen that the object of the present invention can be achieved. If the above flow rate ratio is further selected, a
−Si:H layer 3 is substantially made intrinsic to reduce _ρD to 10 ¹¹ Ω−
In terms of cm, it is possible to further increase the resistance to 10 ¹² Ω-cm or more. Note that, depending on the type of reaction gas used, the above flow rate ratio may be set to 10 to 500 ppm. As described above, the photoreceptor according to this example can sufficiently increase the dark resistance by doping with impurities.
-SiC:H layers 2 and 4 and a-Si:H layer 3 are included, so the combination of these two layers synergistically improves the dark resistance and charging characteristics of the photoreceptor. ing. FIG. 5 shows a vapor deposition apparatus used for producing a photoreceptor according to the present invention by a vapor deposition method. The bell jar 41 is connected to a vacuum pump (not shown) via an exhaust pipe 43 having a butterfly valve 42.
The inside of the bell gear 41 is thereby brought into a high vacuum state of, for example, 10 ^-3 to 10 ^-7 Torr, and the substrate 1 is placed inside the bell gear 41 and heated to a temperature of 150 to 500° C., preferably, by a heater 45. is 250
While heating to ~450°C, a negative DC voltage of 0 to 10 KV, preferably -1 to -6 KV is applied to the substrate 1 using the DC power supply 46, and the outlet is connected to the bell gear 41 so that the outlet faces the substrate 1. While introducing active hydrogen and hydrogen ions from a hydrogen gas discharge tube 47 provided into the bell jar 41, a silicon evaporation source 48 and an aluminum evaporation source 49 provided to face the substrate 1 are heated, and the shutters S above each are heated. is opened, and silicon and aluminum are simultaneously evaporated at an evaporation rate such that the evaporation rate ratio is, for example, 1:10 ^-4 . This forms an aluminum-doped a-Si:H layer 3 (see FIG. 1). In addition, the discharge tube 50 is inserted into the bell gear 41 with the shutter S of the aluminum evaporation source 49 open.
methane gas activated by the a-SiC:H
Form layer 2 (see Figure 1). For example, when the structure of the discharge tubes 47 and 50 described above is shown for the discharge tube 47, as shown in FIG.
1 and a discharge space 63 provided with this one electrode member 62 at one end.
A discharge space member 64 made of, for example, cylindrical glass surrounding the
and another ring-shaped electrode member 66 having an outlet 65 provided at the other end of this discharge space member 64, and a direct current or alternating current is formed between the one electrode member 62 and the other electrode member 66. By applying a voltage, for example, hydrogen gas supplied via the gas inlet 61 causes a glow discharge in the discharge space 63, whereby active hydrogen consisting of hydrogen atoms or molecules activated by electron energy and ionized hydrogen are generated. The hydrogen ions are discharged from the outlet 65. The discharge space member 64 in this illustrated example has a double pipe structure and is configured to allow cooling water to flow through it.
67 and 68 indicate the cooling water inlet and outlet. 69 is a cooling fin for one electrode member 62. The distance between the electrodes in the hydrogen gas discharge tube 47 is 10 to 15 cm, the applied voltage is 600 V, and the pressure in the discharge space 63 is about 10 ^-2 Torr. Also in the photoconductor produced by the vapor deposition apparatus shown in FIGS. 5 and 6, the dark resistivity ρ _D of the a-SiC:H layers 2 and 4 and the a-Si:H layer 3 is reduced by doping with aluminum. This prevents potential attenuation due to charge leakage in the in-plane direction of the a-Si:H layer as a photoconductive layer, and improves photoconductivity. do.
Further, by doping the a-SiC:H layer, the dark resistivity is further increased, and a high-resistance photoreceptor can be obtained. For this purpose, it is necessary to add 10 to 500 ppm of aluminum vapor to silicon vapor during vapor deposition, or even 20 to 500 ppm.
A concentration of 300ppm is recommended. Next, each layer of the photoreceptor according to the present invention will be explained in more detail. First a-SiC:H layer This a-SiC:H layer 4 is indispensable in order to modify the surface of the photoreceptor and make the a-Si photoreceptor practically excellent. . That is, it enables the basic operations of an electrophotographic photoreceptor, such as charge retention on the surface and attenuation of the surface potential due to light irradiation. Therefore, the repetitive characteristics of charging and optical attenuation are very stable, and good potential characteristics can be reproduced even if left for a long period of time (for example, one month or more). On the other hand, in the case of a photoreceptor having an a-Si:H surface, it is easily affected by humidity, air, ozone atmosphere, etc., and the potential characteristics change significantly over time.
In addition, a-SiC:H has high surface hardness, so it has abrasion resistance during processes such as development, transfer, and cleaning, and it also has good heat resistance, so it can be used in processes that apply heat such as adhesive transfer. be able to. In order to achieve such excellent effects comprehensively, the film thickness of the a-SiC:H layer 4 must be set to 50 Å or more as described above.
It is important to select within the range of 2000 Å. That is, if the film thickness is 2000 Å or more, the residual potential becomes too high and the sensitivity decreases, resulting in a-
The good characteristics of a Si-based photoreceptor are lost. Furthermore, if the film thickness is less than 50 Å, charges will no longer be charged on the surface due to the tunnel effect, resulting in an increase in dark decay and a significant decrease in photosensitivity. Therefore, the film thickness of the a-SiC:H layer 4 is
The thickness is preferably less than 2000 Å and 50 Å or more. Furthermore, it has been found that it is also important to select the carbon composition of this a-SiC:H layer 4 in order to exhibit the above-mentioned effects. The composition ratio is a-
If expressed as Si ₁ −xCx:H, then x is 0.4 or more, especially 0.4
≦x≦0.9 (carbon atom content is
40 atomic% to 90 atomic%) is desirable. That is, if 0.4≦x, the optical energy gap will be approximately 2.3 eV or more, and as shown in Figure 7, the irradiated light will be reduced due to the so-called optically transparent window effect for visible and infrared light. The a-Si:H layer (charge generation layer) 3 is reached. On the contrary, x<
When it is 0.4, part of the light is absorbed by the surface layer 4,
The photosensitivity of the photoreceptor tends to decrease. Also, x
If it exceeds 0.9, most of the layer becomes carbon, and not only the semiconductor properties are lost, but also the deposition rate when forming the a-SiC:H film by the glow discharge method decreases.
It is preferable that x≦0.9. Second a-SiC:H layer This a-SiC:H layer 2 has both the functions of potential retention and charge transport, and by doping with the above impurities, the dark resistivity is improved and it has high electric field resistance. However, since the potential held per unit film thickness is high and the electrons or holes injected from the photosensitive layer 3 exhibit large mobility and long life, charge carriers are efficiently transported to the support 1 side. Further, since the size of the energy gap can be adjusted by changing the composition of carbon, charge carriers generated in the photosensitive layer 3 in response to light irradiation can be injected efficiently without creating a barrier. Further, this second a-SiC:H layer 2 also has the property of good adhesion and film formation with the support 1, for example, an Al electrode. Therefore this a
-SiC:H layer 2 maintains a high surface potential at a practical level, efficiently and quickly transports charge carriers generated in a-Si:H layer 3, and functions to create a photoreceptor with high sensitivity and no residual potential. be. In order to achieve these functions, a-SiC:H layer 2
The film thickness is preferably 5000 Å to 80 μm in order to apply a dry development method using the Carlson method, for example. If this film thickness is less than 5000 Å, it is too thin and the surface potential necessary for development cannot be obtained, and if it exceeds 80 μm, the rate of charge carriers generated in the a-Si:H layer 3 reaching the support 1 will be reduced. It will drop.
However, even if the film thickness of this a-SiC:H layer is made thinner (for example, 10-odd μm) than that of the Se photoreceptor, a surface potential at a practical level can be obtained. Moreover, this a-SiC:H layer 2 is a-Si ₁ -xCx:
When expressed as H, it is desirable that 0.1≦x≦0.9 (carbon atom content is 10 atomic % to 90 atomic %). If 0.1≦x, the a-SiC:H layer 3 can be made completely different, and if 0.9<x, most of the layer will be carbon, which will result in a loss of semiconductor properties and will cause problems during film formation. This is because the deposition rate decreases, and in order to prevent this, it is preferable to set x≦0.9. a-Si:H layer (photoconductive layer or photosensitive layer) This a-Si:H layer 3 has high photoconductivity to visible light and infrared light, as shown in FIG. , the maximum value of ρ _D /ρ _L is ~10 ⁴ for red light at a wavelength of around 650 nm. By using this a-Si:H as a photosensitive layer, it is possible to create a photoreceptor that is highly sensitive to light in the entire visible region and in the infrared region. Furthermore, doping with Group A elements of the periodic table further increases the resistivity and photoconductivity, which in turn further improves the dark resistance and photosensitivity of the photoreceptor, resulting in better charging potential and dark decay. There is. In order to absorb visible light and infrared light without waste and generate charge carriers, the thickness of the a-Si:H layer 3 should be 2500 Å or more.
It is desirable that the thickness be 10 μm. If the film thickness is less than 2500 Å, all of the irradiated light will not be absorbed and a portion will reach the underlying a-SiC:H layer 2, resulting in a significant decrease in photosensitivity. Further, the a-Si:H layer 3 does not need to be thicker than the thickness required for light absorption as a photosensitive layer, and a maximum thickness of 10 μm is sufficient. In the example explained above, in order to compensate for dangling bonds, fluorine is introduced into a-Si instead of H or in combination with H, and a-Si:F, a-Si:H:F, a-SiC:
F, a-SiC:H:F can also be used. In this case, the amount of fluorine is preferably 0.01 to 20 atomic%, and 0.5
~10 atomic% is more desirable. Note that, although the above manufacturing method is based on a glow discharge decomposition method, the photoreceptor can also be manufactured by a sputtering method, an ion plating method, or the like. The reaction gas used is
In addition to SiH ₄ , Si ₂ H ₆ , SiHF ₃ , SiF ₄ or its derivative gas, lower hydrocarbon gases other than CE ₄ such as C ₂ H ₆ and C ₃ H ₈ , and CF ₄ can be used. Further, as the impurity to be doped, in addition to the above-mentioned boron and aluminum, other Group A elements of the periodic table such as gallium and indium can be used. The photoreceptor according to the present invention may be constructed as shown in FIG. 8, for example. That is, the second a-SiC:H layer 2 has the functions of maintaining potential, preventing charge injection from the substrate 1, and improving adhesion to the substrate 1, and has a thickness of 50 Å to
It is preferably formed to a thickness of 5000 Å. Photoconductive layer 3
generates charge carriers in response to light irradiation, exhibits high sensitivity particularly in the long wavelength region of 600 to 850 nm, and preferably has a thickness of 5000 Å to 80 μm. Furthermore, a first a-SiC:H layer 4
improves the surface potential characteristics of this photoreceptor, maintains long-term potential characteristics, maintains environmental resistance (prevents the effects of humidity, atmosphere, and chemical species generated by corona discharge),
It has functions such as improved mechanical strength and printing durability due to increased surface hardness due to improved bonding energy due to carbon content, improved heat resistance when using photoreceptors, and improved thermal transferability (especially adhesive transferability). However, it functions as a surface modification layer, so to speak. Then, the thickness t of this first a-SiC:H layer 4 was set to 50 Å as described above.
It is important to select ≦t≦5000 Å. Next, an example in which the present invention is applied to an electrophotographic photoreceptor will be specifically described. Example 1 An electrophotographic photoreceptor having the structure shown in FIG. 1 was prepared on an Al support by a glow discharge decomposition method. First, a clean Al support with a smooth surface was placed in a reaction (vacuum) chamber of a glow discharge device. Inside the reaction tank
Evacuate to a high vacuum level of 10 ^-6 Torr and lower the support temperature.
After heating to 200℃, high purity Ar gas was introduced.
A high-frequency power with a frequency of 13.56 MHz and a power density of 0.04 W/cm ² was applied under a back pressure of 0.5 Torr, and a preliminary discharge was performed for 15 minutes. Next, a reaction gas consisting of SiH ₄ and CH ₄ was introduced, and the flow rate ratio was 3:1:0.5 (Ar+
By glow discharge decomposition of SiH ₄ +CH ₄ ) mixed gas and B ₂ H ₆ gas, an a-SiC:H layer having potential retention and charge transport functions was formed at a deposition rate of 2 μm/hour. The carbon content in this a-SiC:H layer was determined to be 20 atomic% by Auger electron spectroscopy.
It was hot. After the reaction tank was once evacuated, CH ₄ was not supplied and SiH ₄ and B ₂ H ₆ were discharge decomposed using Ar as a carrier gas to form a boron-doped a-Si:H photosensitive layer, and then CH ₄ was supplied again. , this time the (Ar + SiH ₄ + CH ₄ ) mixed gas with a flow rate ratio of 5:1:4 and
B ₂ H ₆ gas was decomposed by glow discharge, and a boron-doped a-SiC:H surface modification layer was further provided to complete an electrophotographic photoreceptor. The optical energy gap of this a-SiC:H surface modified layer was 2.5 eV.
Analysis also revealed that the carbon composition was 50 atomic%. The photoconductor produced in this way is coated with negative polarity.
A 6KV corona discharge was performed to charge the surface to a negative potential. After dark decay for 2 seconds, the surface potential decayed almost linearly by 1 lux light irradiation. At this time, the half-decreased exposure amount is small, and there is almost no residual potential.
The repeated charging/exposure characteristics were also very good. Example 2 An aluminum doped a-
A Si:H:Al layer 3 was formed. On this photoconductive layer,
Below, aluminum-doped a-SiC:H layers 2 and 4 were formed by the vapor deposition method described above. That is, the tank 41 is evacuated to 10 ^-4 Torr by a vacuum pump, and hydrogen gas activated by discharge (flow rate of 100 c.c./min) is introduced into the tank 41 using the discharge device 47 shown in FIG. Then, the silicon evaporation source 48 and the Al evaporation source 49 are heated with an electron gun to evaporate them, and the amount of silicon evaporation and
While detecting the amount of Al evaporation with a crystal monitor.
10 ⁴ :1 ratio (the concentration of Al evaporation amount to Si evaporation amount is 100 ppm), and the substrate voltage -
Deposited at 2KV, substrate temperature 300℃, a-Si:H:Al
Layer 3 was formed. a-SiC: When forming H layers 2 and 4, methane gas was introduced at a flow rate of 30 c.c./min,
The a-SiC:H layer was formed in the same manner as above to obtain a photoreceptor of the present invention. The photoconductor according to the present invention and the comparative photoconductor were measured using an electrometer manufactured by Kawaguchi Electric Co., Ltd. and U-BixV-
The results of a performance test using the two modified machines are shown in the table below.

【table】

[Table] In the above table, in the electrostatic characteristics, V is the initial charging potential, △V/V is the dark decay rate of the charge 6 seconds after the end of charging, and E1/2 is the half-life exposure amount (unit: lux・sec) , V _R
indicates the residual potential. This result shows that the photoreceptor according to the present invention has a sufficient charging potential, a small dark decay rate, and high sensitivity. Furthermore, clear, high-density images can be obtained even after 60,000 or more repeated copies. On the other hand, it can be seen that the comparative example has poor potential, dark decay, and photosensitivity, and is also significantly inferior in repeatability.

[Brief explanation of drawings]

The drawings illustrate the present invention, in which FIG. 1 is a cross-sectional view of a portion of an electrophotographic photoreceptor, FIG. 2 is a schematic diagram of a glow discharge apparatus for manufacturing the photoreceptor, and FIG. 3 is a doped a- When forming SiC:H film
A graph showing the change in dark resistivity depending on the B ₂ H ₆ /SiH ₄ flow rate ratio. Figure 4 is a graph similar to Figure 3 when forming a film of doped a-Si:H. Figure 5 is a graph showing the change in dark resistivity depending on the flow rate ratio of B 2 H 6 /SiH 4. A schematic cross-sectional view, FIG. 6 is a cross-sectional view of the discharge part, FIG. 7 is a graph showing the photoconductivity of a-Si:H and a-SiC:H of each composition, and FIG. 8 is a photoreceptor according to another example. FIG. In addition, in the symbols shown in the drawings, 1...
...Support (substrate), 2... Second a-SiC:H layer doped with impurities, 3... Impurity doped a
-Si:H photosensitive layer (photoconductive layer), 4... First a-SiC:H layer doped with impurities, 11... Glow discharge device, 17... High frequency electrode, 31... Gaseous silicon compound supply source, 32... gaseous carbon compound source, 33... carrier gas source, 34...
...B ₂ H ₆ supply source, 41... Vapor deposition tank, 47, 50...
. . . discharge section, 48 . . . silicon evaporation source, 49 . . . aluminum evaporation source.

Claims (1)

[Claims] 1. On the substrate, at least a thickness of 5000 Å to 80 μ
a second amorphous hydrogenated and/or fluorinated silicon carbide layer of m, a charge generation layer made of amorphous hydrogenated and/or fluorinated silicon having a thickness of 2500 Å to 10 μm, and a first amorphous hydrogenated and/or fluorinated silicon carbide layer. (a) the second amorphous hydrogenated and/or fluorinated silicon carbide layer has a carbon atom content;
10 atomic% to 90 atomic%, hydrogen atom content is 1 atomic% to 40 atomic%, contains Group A elements of the periodic table, and has a dark resistivity of 10 ¹³ Ω-
(b) The charge generation layer made of amorphous hydrogenated and/or fluorinated silicon has a hydrogen atom content of 1 atomic% to 40 atomic%, contains an element of group A of the periodic table, and has a dark resistance. (c) the first amorphous hydrogenated and/or fluorinated silicon carbide layer has a carbon atom content of 10 ¹⁰ Ω-cm or more;
40 atomic% to 90 atomic%, hydrogen atom content is 1 atomic% to 40 atomic%, contains Group A elements of the periodic table, and dark resistivity is 10 ¹³ Ω-
An electrophotographic photoreceptor characterized by having a diameter of cm or more.