JPH0342468B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical field to which the present invention pertains] The present invention provides a novel electrophotographic photosensitive method that has extremely excellent photosensitivity to visible light sources, is extremely durable, and is free from pollution and hygiene problems. More specifically, it is a method for manufacturing a two-layer electrophotographic photoreceptor made of an amorphous silicon material deposited by a high-frequency sputtering method. This invention relates to a manufacturing method with high reproducibility.

[Peripheral technology/conventional technology]

Along with the streamlining, rationalization, and automation of office processes, that is, the wave of office automation, copying technology, especially electrophotography technology, is also showing rapid progress. Since amorphous selenium (a-Se) photosensitive plates first appeared on the market, zinc oxide (ZnO) and cadmium sulfide (CdS), that is, chalcogen elements or compound semiconductors containing chalcogen elements, have dominated as electrophotographic photosensitive materials. has been built. After this,
Organic semiconductors (OPCs), typified by charge transfer complexes of polyvinylcarbazole (PVCz) and trinitrofluorenone (TNF), are also attracting attention due to the flexibility, versatility, insulation resistance, and productivity of these organic polymers. The current situation is that it has been provided to the market.

However, each of the above materials has its own advantages and
It has some disadvantages and cannot necessarily be called an ideal photoreceptor material. For example, a-
Regarding Se-based materials, photo fatigue, deterioration of properties due to surface crystallization due to repeated corona discharge,
Disadvantages include toxicity to the human body.
Regarding ZnO and CdS materials, common problems have been pointed out as lack of moisture resistance, developer cleanability, and light response speed because they are usually designed as a dispersion system with a binder. The major disadvantage of CdS is that it causes pollution to the human body and the environment. Furthermore, OPC materials lack abrasion resistance due to insufficient hardness of the surface of the photosensitive layer, and furthermore, problems remain in terms of moisture resistance and developer cleanability. Further disadvantages include a narrow spectral sensitivity range and toxicity to the human body.

In general, these photoreceptors, which are the heart of electrophotographic technology, should be treated as fine semiconductor devices, but they are destined to undergo repeated and harsh trials during the process like no other. Therefore, its durability, that is, its lifespan, becomes a major issue. The lifespan of the photoreceptor is an important issue that cannot be avoided when designing highly reliable copying technology, which is expected to further develop in the future. Furthermore, as electrophotographic technology becomes more intelligent, faster processing, higher sensitivity, and
Nowadays, there is a growing demand for higher resolution and smaller equipment, and photoreceptor materials have superior photosensitivity and
It is essential that the light source is matched with the wavelength range of a semiconductor laser, in particular, and that it has a wider range of spectral sensitivity characteristics.

Recently, amorphous silicon-based (hereinafter abbreviated as a-Si) materials have attracted much attention in the field of new electrophotographic photoreceptor materials, and vigorous research is being conducted in various places. This is because it has been found that a-Si based materials perfectly satisfy the characteristics required for electrophotographic photoreceptor materials depending on the manufacturing conditions. If a-Si type materials are evaluated from the viewpoint of electrophotographic photoreceptor materials, it can be pointed out that they are extremely excellent in each of the following properties.

(a) Electrical properties (1) Valence control Doping with group b elements (boron group elements) of the periodic table controls the valence of P-type, and doping with group B elements (tirus group elements) controls the valence of n-type. It is possible. With this control, the conductivity is
It can be changed by more than 10 orders of magnitude, from 10 ^-2 to ^{10 -14} Ω ^-1 cm ^-1 .

(2) Homojunction glow discharge decomposition method (hereinafter abbreviated as GD method), reactive sputtering method (hereinafter abbreviated as GD method)
In either method, a Pn junction or a pin junction can be easily formed by switching the doping gas.

(3) Excellent photoconductivity Generally, excellent photoconductivity can be imparted by controlling the concentration and bonding state of hydrogen and/or fluorine as dangling bond terminators in the film.

(b) Optical properties (1) Absorption spectrum The optical absorption edge is approximately 600 nm, and it is suitable for ordinary xenon lamps, halogen lamps, fluorescent lamps,
Shows good matching with visible light sources such as rare gas lasers, semiconductor lasers, liquid crystal displays, and light emitting diodes. Furthermore, by controlling the concentration of the dangling bond terminator in the film, the absorption edge can be changed by 100 nm or more.

Furthermore, by making it mixed amorphous with carbon (C) and germanium (Ge), which are also tetrahedrals, a wider spectral sensitivity range can be imparted.

(2) Large absorption coefficient Compared to single crystal or polycrystalline silicon, the absorption coefficient is approximately one order of magnitude larger. Therefore, a film thickness of several μm is sufficient for a photoelectric conversion element.

(C) Mechanical properties (1) Large surface hardness 1500-2000 in Bitkers hardness evaluation
Kg/ ^mm2 , which is as hard as ground glass. Since it is 20 to 30 times harder than the a-Se/As type, it is expected to have a long life under harsh conditions such as photoreceptors.
Furthermore, if mixed amorphization with carbon is attempted, the surface hardness will be further improved.

(d) Thermal and chemical properties (1) Great heat resistance The crystallization temperature of a-Se is extremely low at around 80℃, and at higher temperatures, its properties deteriorate significantly, whereas a-Si In,
No deterioration of characteristics is observed up to at least 350°C.

(2) Environmental resistance Chemically stable with solvent resistance, water resistance, moisture resistance, etc. Furthermore, since a-Si materials are harmless and non-toxic, there is no need to worry about environmental pollution.

A proposal to use this a-Si-based material as an electrophotographic photoreceptor was already published in West German Patent No. 2746967 in 1977.
In Japan, it was also seen in 1979 Japanese Patent Application Laid-Open No. 54-86341. Since then, various electrophotographic photoreceptors using this a-Si-based material have been proposed, but they have not necessarily been perfected as ideal photoreceptors, and there are still some unresolved problems as described below. It's on. That is, the first point is that compared to other photoreceptor materials, there are problems in terms of charge acceptance, such as a small charging potential per unit layer thickness and a large dark decay rate. The second point is that although the GD method is generally the preferred technique for depositing this a-Si material onto a substrate, when the layer thickness necessary to have photoreceptor properties is deposited, the layer surface Cracks may appear on the surface of the substrate, and peeling may occur from the substrate, which has been a major problem. The third point is that the problems of deposition speed and large area, that is, productivity and mass production, and therefore manufacturing costs, have become really major obstacles to industrialization.

Many proposals have been made so far as designs to overcome the problems mentioned above. For example, as described in JP-A-54-116930, etc., a-Si material deposited on a conductive substrate is used as a carrier generation layer;
A carrier transport layer (CGL) consisting of OPC is placed on top of this layer.
Designs that stack layers (CTL) generally greatly improve charge acceptance, but
Another major problem is that it is difficult to effectively inject carriers from the CGL to the CTL, resulting in a significant decrease in photosensitivity and a large residual potential. In addition, in the above function-separated photoreceptor design, the CGL layer made of a-Si material is
There was a major manufacturing difficulty in that the CTL layer made of OPC had to be coated while maintaining a uniform layer thickness and its physical properties. Also, for example, JP-A No. 54-145539, 55-4040, 56-24354, 56-
62254, 56-156834, etc., chemical modifiers (Chemical
(modifier) as oxygen O, nitrogen N, or carbon
In designing photoreceptors with a single layer structure containing (C), the charge acceptance tends to be improved, but generally the photoconductivity of the material is significantly impaired, and therefore the photosensitivity in electrophotographic properties is reduced. In many cases, there was also a considerable decrease in On the other hand, an intermediate layer that prevents free carriers from flowing into the surface of the photoconductive layer from the conductive substrate side and allows carriers generated by light irradiation to pass to the conductive substrate side;
That is, many proposals have been made to improve charge acceptance by providing a carrier blocking layer. For example, in a diode-type design in which an intermediate layer of a-Si doped with boron (or phosphorus) is deposited on a conductive substrate to the extent of 2000 μm, and then a relatively high-resistance a-Si photoconductive layer is superimposed. It has been demonstrated that, as a result of the intermediate layer serving as a blocking layer, charge acceptance during positive (or negative) charging is significantly improved. (I.Shimizu, T.Komatu, and E.
Inoue, Photogropbic Science and
Engineering, vol24, No.5, 251 (1980))
For example, as proposed in JP-A-57-56846 and a series of publications, a non-photoconductive blocking layer containing O, N, or C is formed on a conductive substrate. There is also a way to set it up. These photoreceptor designs in which a blocking layer is provided generally improve charge acceptance, but the properties of the photoreceptor are sensitively affected by the physical properties and layer thickness of the intermediate layer. Therefore, a fairly sophisticated technique with high reproducibility is required. especially,
Space charges trapped near the interface between the photoconductive layer and the blocking layer often create a residual potential. A non-negligible residual potential may cause fogging on copied images or shorten the life of the photoreceptor.

On the other hand, for example, JP-A No. 55-7761, 57-8548,
57-67935 etc. a-
In a photoreceptor design in which fine powder of Si-based material is dispersed and coated together with an electrically insulating binder, it is certainly possible to coat a large area when compared to a thin film type photoreceptor, but the amount of deposited a -The growth rate of fine Si powder is extremely slow, and photoreceptors with this design have inferior photosensitivity when compared to thin-film photoreceptors, and furthermore, the binder deteriorates during the electrophotographic process. The accompanying reduction in the life of the photoreceptor has been a problem.

In the GD method, a method for significantly increasing the deposition rate is achieved by introducing a higher order silane derivative gas, as proposed in JP-A-57-67938.

According to this method, the deposition rate can be reliably increased significantly, and the a-Si layer, which has both the dark conductivity and excellent photoconductivity required for an electrophotographic photoreceptor, can be formed with a thickness of 10 μm/min. The deposition rate is reported to be more than hr. (K.Ogava, I.Shimizu,
and E. Inoue, Japanese Jovrnal of Applied
Physics, Vol. 20, No. 9, L639 (1981)) On the other hand, when using monosilane gas diluted with hydrogen gas, while controlling the bonding state of hydrogen in the deposited thin film,
By optimizing the flow rate of gas introduction and the applied toner power, a deposition rate of 5 μm/hr has been obtained. (Y.Nakayama, T.Natsuhara,
N.Nagasawa and T.Kawamura, Japanese
Journal of Applied Physies, Vol.21, No.10,
L604 (1982)) [Structure of the Invention] In order to solve the above-mentioned problems and facts, the present inventors adopted a high-frequency sputtering method as a deposition technique for a-Si material to solve the above-mentioned problems. As a result of extensive research and study, we have developed an electrophotographic photoreceptor that has strong adhesion to conductive substrates, has sufficient charge acceptance, extremely high photosensitivity, extremely high durability, and is free from pollution and hygiene problems. We have succeeded in developing a manufacturing method that is simple, fast, and reproducible.

The electrophotographic photoreceptor according to the present invention is designed to have a two-layer structure of a P-type amorphous silicon layer doped with a high concentration of oxygen and a P-type amorphous silicon layer doped with a low concentration of oxygen on a conductive substrate. be done. To control the valence of each layer to P- type, diborane gas is used as a doping gas, and oxygen gas is introduced at the same time. Each layer is successively laminated one after another by an in-situ method. At this time, diborane gas and oxygen gas are at least one of rare gases such as He, Ne, Ar, Kr, and Xe, or hydrogen gas or fluorine gas as a dangling bond terminator.
It may also be diluted with seeds.

A further feature of the present invention is that each layer is further coated with SinH _2o+2 as an atmospheric gas during its deposition.
(however, n=1, 2, 3, or 4) or/and SinF _2o+2 (however, n=1, 2, 3, or 4)
Furthermore, by controlling the toner power, the toner can be deposited at a much higher speed than in the prior art.

[Description of the structure of the invention]

The present invention will be explained in detail below.

FIG. 1 shows the structure of an electrophotographic photoreceptor according to the present invention. In FIG. 1, 104 is a conductive substrate, 1
03 is a P-type amorphous silicon layer doped with a high concentration of oxygen, 102 is a P-type amorphous silicon layer doped with a low concentration of oxygen,
It has a free surface 101. The functions of each layer will be explained below in order.

First, the P-type amorphous silicon layer 103 doped with oxygen at a high concentration functions as a blocking layer during positive charging. That is, by blocking the inflow of electrons from the conductive substrate 104, the positive charges accumulated on the free surface 101 in the dark are neutralized, and the charge acceptance is therefore reduced. It has the function of preventing By providing this layer, the charged potential per unit layer thickness and its dark decay rate can be improved. The mechanism by which the P-type amorphous silicon layer doped with oxygen at a high concentration provides the above-mentioned blocking function is interpreted as follows. Generally, a non-hydrogenated amorphous silicon film has a spin density of about 10 ¹⁹ spins/cm ³ due to dangling bonds of silicon in the film. This means that a high-density localized electronic state exists near the Fermi level in the energy band, and in this state, effective valence control by photoconductivity or doping cannot be expected. Therefore, as a dangling bond terminator, for example, an amorphous silicon hydride alloy that always contains hydrogen can be used as a dangling bond terminator.
It cannot be used as a functional material unless it is a hydrogenated silicon alloy. (Usually, a-Si:
(abbreviated as H), and in the GD method also r-
In the Sp method, even if the proportion of hydrogen gas in the atmospheric gas during deposition is increased, the localized electronic state density does not necessarily decrease. It is generally believed that excess gas as a dangling bond terminator is incorporated into the film in a non-bonded state. That is, they exist in the membrane in a molecular/atomic state, which generally deteriorates the electrical properties of the membrane. G using monosilane gas.
D. In the method, the proposal to improve the electrophotographic photoreceptor characteristics by adding oxygen gas is already known in Japanese Patent Application Laid-Open No. 156834/1983 as mentioned above, but the present inventors As a result of a detailed study of the effect of adding oxygen gas in the r-Sp method, we found that the newly added oxygen gas, due to its larger electronegativity, can eliminate dangling bonds that could not be compensated by hydrogen. It was confirmed that compensation would be provided effectively. Therefore, in this case, the effect of valence control by doping is further improved compared to the case where no oxygen gas is added. In fact, when diborane (B ₂ H ₆ ) gas is used as a doping gas, boron (B) is incorporated into the network in a four-coordinate manner, resulting in extremely excellent P
It was found that it was deposited as a −-type semiconductor. In the above cases, the ratio of oxygen gas to the total gas introduced has a very large effect on the electrical and optical properties of the deposited a-Si:H film, and generally, as the ratio of oxygen gas increases, , the intrinsic dark conductivity decreases and the optical gap becomes larger. Moreover, at this time, the photoconductivity tends to decrease. The essential electronic property that a blocking layer consisting of a P-type a-Si:H layer doped with oxygen is not high generation efficiency of photogenerated carriers, but hole movement. The point is that the degree-lifetime product is larger than that of electrons. When the free surface 101 of the photoreceptor is positively charged, negative charges are induced on the conductive substrate 104 side, and as a result, an electric field is formed in the bulk direction of the photoreceptor. Under this electric field, if the negative charges on the conductive substrate side pass through the photoreceptor bulk and neutralize the positive charges on the free surface 101, this will result in a large dark decay rate of the surface potential and the charge This leads to a decrease in acceptance. As mentioned above, in the P-type a-Si:H layer doped with a high concentration of oxygen, the majority carriers are holes, and the lifetime product of electron mobility is about three orders of magnitude lower than that of holes. Therefore, by providing this layer, injection of negative polarity charges into the bulk and passage therethrough are reliably suppressed, and charge acceptance is improved.
Next, upon exposure to visible light, electrons of the photogenerated carriers generated in the photoconductive layer 102 consisting of a P-type a-Si:H layer doped with oxygen at a low concentration, which will be described later, are transferred to the positive electrode on the free surface 101. Neutralizes sexual charges. On the other hand, since the holes pass through the blocking layer 103, which is controlled so that they become majority carriers, the design is advantageous for photoinduced discharge of positive charges. As described above, the P-type doped with a high concentration of oxygen, a
-The thickness of the Si:H layer has a sharp effect on the electrophotographic properties, and is usually 100〓~2μm, preferably 200〓~1μm.
m is desirable. Although hydrogen is exemplified as the dangling bond terminator in the blocking layer, the present invention is not limited to this, and can also be applied to cases where fluorine and hydrogen are used together.

Second, P-type a- doped with a low concentration of oxygen
The Si:H layer 102 will be explained in detail below. Since the layer must have the function of forming an electrostatic latent image upon imagewise exposure, it must have the dark conductivity necessary to provide excellent photoelectric gain upon exposure to visible light and sufficient charge acceptance. It is essential to be present.

Generally, amorphous hydrogenated silicon (a-Si:H) produced by the r-SP method, amorphous amorphous silicon fluoride (hereinafter abbreviated as a-Si:F),
And amorphous hydrogenated/fluorinated silicon (hereinafter abbreviated as a-Si:H:F) has a higher localized electronic state density near the Fermi level in the energy band than that produced by the GD method. Therefore, it was thought that the photoelectric properties would also be inferior. However, the present inventors systematically controlled various parameters during fabrication, and the deposited a-Si
As a result of detailed studies on the basic optical, electrical, and physical properties of thin films of based materials, we found that GD
We have now acquired a technology for producing a-Si material thin films using the r-SP method, which have better photoelectric properties than those produced by the r-SP method. Generally, parameters in the r-SP method include the following. Ultimate vacuum pressure, total gas pressure to be introduced, total gas pressure during sputtering, partial pressure of each gas in the total gas pressure, flow rate of each gas, gas introduction path and mixing method, high frequency oscillator tube anode voltage ( or radio frequency power density), the frequency of the radio frequency, the base temperature, the base-to-target distance, the geometry of the sputter chamber, and the main sputter time. The present inventors systematically controlled the above-mentioned manufacturing parameters, examined in detail the effects of each parameter on the properties of the deposited a-Si:H film, and determined that the above-mentioned electrophotographic photoreceptor As a result of optimizing it to function as a conductive layer, the generation efficiency of photogenerated carriers is certainly excellent, and the photoelectric gain is also large, but it is not possible to perform electrophotography while maintaining these excellent photoconductive properties. It was concluded that it is not possible to provide the dark conductivity δd (usually δd<10 ^-12 Ω ^-1 cm ^-1 ) that a photoreceptor should have. By the way, in the GD method, it is well known that when diborane gas is used to control the valence to P-type, δd is reduced by about three orders of magnitude compared to the case of undoped material. (WESpear
and PGLecomber, Philosophical Magazine,
Vol. 33, 935 (1976)) The present inventors also maintained excellent photoconductive properties by controlling the valence to P-type using diborane gas in the r-SP. method. P-type amorphous hydrogenated silicon (hereinafter referred to as a-Si: H(B)) with δd of 10 ^-12 Ω ^-1 cm ^-1
We have now established a technology for producing membranes (abbreviated as ).
Therefore, the present inventors prepared the above-mentioned P-type a-
A blocking layer consisting of a Si:H layer was deposited, and the a-Si:H(B) layer described above was further superimposed on the blocking layer to fabricate a prototype electrophotographic photoreceptor, and its detailed evaluation was performed. As a result, it was confirmed that a photoreceptor with surface potential formation during positive charging, excellent photosensitivity, and negligible residual potential could be produced. However, it has become clear that the above photoreceptor has the following major problems.

(1) Rough and uneven surface morphology When a layer thickness of about 20 μm, which is necessary to have sufficient photoconductor characteristics, is deposited, the surface condition has a rough morphology with minute irregularities that can be discerned with the naked eye. have.

This is mainly due to the blistering of excess bonded and non-bonded hydrogen trapped in the membrane.
head). This surface morphology is
During the electrophotographic process, developer enters the surface of the layer, resulting in extremely poor cleaning performance. Further, the copied image was also of low quality with poor resolution.

(2) Insufficient charge acceptance When evaluating the initial characteristics of the photoreceptor, it was found that the small charging potential per unit layer thickness and the large dark decay rate, that is, the charge acceptance, were by no means satisfactory.

(3) Deterioration of charge acceptance due to repetition As a result of repeating the basic electrophotographic process of corona charging, image exposure, and static elimination, and evaluating the photoreceptor characteristics, it was found that charge acceptance gradually decreased. However, after about 2000 repetitions, it became impossible to obtain any practical charge acceptance.

The present inventors have conducted extensive research and study to solve the above-mentioned problems, and have found that the surface morphology of the P-type a-Si:H film deposited with the addition of oxygen gas is It was found that the surface was significantly improved and the surface became mirror-like. It has also been revealed that the photoreceptor with improved surface morphology has improved charge acceptance and no deterioration in charge acceptance due to repeated use.

However, as mentioned earlier, the addition of oxygen gas can reduce the δd of the generally deposited P-type a-Si:H film
At the same time, the photoconductivity Δp also decreases. In electrophotographic photoreceptors, it is thought that the ratio of photoconductivity to dark conductivity δp/δd during image exposure is more important than the absolute value of δp.As a result of a detailed study on this point, the above-mentioned , a blocking layer consisting of a P-type a-Si:H layer doped with a high concentration of oxygen, and a P-type a-Si:H layer doped with a low concentration of oxygen.
By using a photoconductive layer consisting of a -type a-Si:H layer, they succeeded in solving all of the above problems while maintaining excellent photosensitivity.

Although hydrogen is exemplified as the dangling bond terminator in the photoconductive layer, the present invention is not limited to this, and can also be applied to cases where fluorine and hydrogen are used together.

On the other hand, a blocking layer consisting of a P-type a-Si:H layer doped with a high concentration of oxygen and a P-type a-Si:H layer doped with a low concentration of oxygen were deposited as described above. As a result of detailed analysis of the infrared absorption spectra of photoconductive thin films consisting of

(1) The hydrogen concentration in each P-type a-Si:H layer is 5 to 50 at.%. Here, the hydrogen concentration in the film was calculated according to the method of Freeman and Paul. (EC
Freeman and W. Paul, Physical Review (B),
Vol. 18, No. 8, 4288 (1978) (2) In absorption of silicon-hydrogen stretching vibration mode in each P-type a ^- Si:H layer, dihydride mode absorption coefficient α (ω )
The integrated intensity ∫ ²²⁰⁰ ₂₀₀₀ α(ω)dω is more than twice as large as the integrated intensity ∫ ²⁰⁵⁰ ₁₉₅₀ α′(ω)dω of the monohydride mode absorption coefficient α′(ω) near 200 cm ⁻¹ .
That is, ∫ ²²⁰⁰ ₂₀₀₀ α(ω)dω／∫ ²⁰⁵⁰ ₁₉₅₀ α′(ω)d
Satisfies ω>2.

( ³ ) Absorption coefficient β ( ω) integrated intensity ∫ ¹⁰⁵⁰ ₉₅₀ β(ω)dω is P-type a-Si:H doped with a low concentration of oxygen
The integrated intensity of the absorption coefficient β′(ω) of the layer∫ ¹⁰⁵⁰ ₉₅₀ β′(ω
)
It is more than twice as large as dω. i.e. ∫ ¹⁰⁵⁰ ₉₅₀ β
(ω)dω/∫ ¹⁰⁵⁰ ₉₅₀ β′(ω)dω>2 is satisfied.

As described in detail above, P-type a-Si:H doped with oxygen at a high concentration on a conductive substrate
By designing an electrophotographic photoreceptor consisting of two layers: a blocking layer consisting of a photoreceptor layer, and a photoconductive layer consisting of a P-type a-Si:H layer doped with a low concentration of oxygen, an extremely superior photoreceptor can be achieved. Sufficient charge acceptance and significantly greater durability can be imparted while maintaining sensitivity.

Next, the operation of the high frequency sputtering apparatus and the method of manufacturing the electrophotographic photoreceptor of the present invention will be explained in order. FIG. 2 shows a high-frequency sputtering apparatus used for producing an electrophotographic photoreceptor according to the present invention. In Fig. 2, 1 is a sputtering material, 2 is a crystalline silicon target for sputtering, 3 is a water-cooled tube for cooling the target, 4 is a shutter, 5 is a substrate, 6 is a substrate holder, 7 is a heater for heating the substrate, and 8 is a substrate cooling tube. 9 is a thermocouple for detecting substrate temperature, 10 is a Vwing port, 11 is a Schultz type vacuum gauge, 12 is a Baratron type vacuum gauge, 13 is a B-A type vacuum gauge, 14 is a Geisler vacuum gauge, 15 is a Air leak valve, 16 is a variable leak valve, 17 is high purity nitrogen gas for sputter chamber leak, 18, 19, 20, 2
1, 22, 23, and 24 are respectively hydrogen-rare gas mixed gas, hydrogen gas, fluorine-rare gas mixed gas, SinH _2o+2 (however, n=1, 2, 3, or 4), SinF _{2o +2} (however, n=1, 2, 3 or 4),
These are oxygen gas and diborane gas. here,
Sin _H22o+2 , Sin _F2o+2 , oxygen gas, and diborane gas may optionally be diluted with at least one of hydrogen gas, fluorine gas, or rare gas. Further, 25 is a roughing valve, 26 is an auxiliary valve, 27 is a main valve, 28 is a liquid nitrogen trap, 29 is a buffer, 30 is an oil diffusion pump, 31 is a rotary pump, 32 is a rotary valve, 33 is a high frequency power source, 34 is a high frequency matching box. The silicon target for sputtering may be either single crystal or polycrystalline, but in either case it is desirable that it be of extremely high purity.
Usually, a purity of 5-nine or higher is used. The target may be an intrinsic one made of pure silicon, but
In order to control the electrical properties of the deposited a-Si:H thin film, boron group elements (B, Al, Ga,
It is also possible to use one doped with In, Tl).

Furthermore, although the high-frequency sputtering device shown in FIG. 2 is of a sputter-up type in which the target is provided at the lower part and the base is provided at the upper part, the manufacturing method according to the present invention is not limited to this. Instead, a sputter-down method in which the top and bottom are reversed is also possible.
Furthermore, since electrophotographic photoreceptors are usually used in a drum-like configuration, for example,
It is more desirable to perform sputtering on a rotating drum substrate as proposed in 78504.
The substrate used may be one whose surface has been treated to be conductive at least. For example, stainless steel, Al, Cr, Ni, Cu, Zn, Mo, Ag, Au, In,
It may be a metal plate such as Sn, PB, PD, or Pt, or an alloy plate thereof. Or In ₂ O ₃ , SnO ₂ , ITO, Al, Ag, Au on glass or ceramic surfaces.
It is also possible to use a transparent or opaque conductive substrate coated with a material such as by vacuum evaporation, electron beam evaporation, vapor phase growth, sputtering, ion plating, or the like. In some cases, the surface of a synthetic resin film such as a heat-resistant polyimide film may be subjected to the above conductive treatment, and this may be used as the substrate. After these substrates are cleaned by ultrasonic cleaning or the like, they are installed into a sputtering chamber of a high-frequency sputtering device.

A method for manufacturing an electrophotographic photoreceptor of the present invention using the above-mentioned apparatus will be described in detail below. Attach the cathode to the silicon target 2, and place the substrate 5 on the substrate holder 6.
After installing the sputter chamber into the rotary pump 30
and make a loud noise. After confirming that the Geisler vacuum tube 14 no longer shows almost any fluorescence, close the rough valve 25 and fully open the auxiliary valve 26. next,
The main valve 27 is fully opened to trap the liquid nitrogen in the oil diffusion pump section. After this, B-A
Evacuation is performed until the vacuum gauge 13 indicates the ultimate vacuum pressure of 5×10 ^-5 pa or less. On the other hand, the substrate temperature is set at a constant temperature between room temperature and 500°C, preferably between 50°C and 350°C. To set the substrate temperature,
This is carried out using a heater 7 for heating the substrate or a water-cooled pipe 8 for cooling. The atmospheric gas and doping gas are introduced while adjusting the variable leak valve 16. At this time, by applying the manufacturing method proposed in Japanese Patent Application No. 57-062363, the photoelectric properties of the deposited thin film can be improved.

P-type a-Si:H doped with high oxygen concentration
A blocking layer consisting of layers can be deposited by introducing diborane gas and oxygen gas as doping gases in addition to the atmospheric gas. Among the doping gases, diborane gas in particular is introduced for the purpose of controlling the valence to P-type, and therefore strict control of introduction on the order of ppm is required. Therefore, when used as a ready-mixed gas that has been diluted in advance with at least one of hydrogen gas, fluorine gas, or rare gas, the controllability is better. Oxygen gas can also be used as a similar premixed gas. In the production method according to the present invention, the introduction of various gases is
It is defined by the partial pressure of each gas measured by the B-A type vacuum gauge 13. That is, by applying Dalton's law of partial pressures, the molar fraction of each gas in the total introduced gas is defined. The present inventors have so far discovered a large number of P-
According to the knowledge gained from depositing and evaluating type a-Si:H films, the proportion of diborane gas in the total gas has an extremely sensitive effect on the electrical properties of the deposited thin film. be. That ratio is
If it is less than 2 ppm, there are too few boron atoms to be incorporated in the 4-coordinate substitution type, so the shift of the Fermi level to the valence band side and the compensation of uncompensated silicon dangling bonds are not effective. is not carried out. Conversely, at 2000 ppm or more, uncompensated dangling bonds are completely compensated, the Fermi level approaches the valence band, and dark conductivity is dominated by hopping conduction of holes from the acceptor level. It becomes like this. Therefore, the dark conductivity δd is
It becomes a large value of 10 ^-10 Ω ^-1 cm ^-1 or more. Furthermore, in this case, the probability of recombination of photogenerated electrons increases, resulting in a decrease in photoconductivity Δp, which is not desirable. For the above reasons, in the production method according to the present invention, the proportion of diborane gas in the total gas during deposition of the P-type a-Si:H layer is 2 ppm to 2 ppm.
It needs to be 2000ppm. On the other hand, regarding oxygen gas during the blocking layer deposition,
If the ratio is less than 4%, the blocking effect when designing the photoreceptor will not be sufficient, and if it is more than 40%, a decrease in photosensitivity and a non-negligible residual potential will be observed. , not desirable. For the above reasons, the proportion of oxygen gas in the total gas when depositing the blocking layer, which is composed of a P-type a-Si:H layer doped with a high concentration of oxygen, is 4% to 40%. It is necessary.

Furthermore, the manufacturing method according to the present invention is characterized in that at least one of hydrogen, fluorine, or a rare gas is used as an atmospheric gas during deposition of the P-type a-Si:H layer.
The seed contains SinH _2o+2 (n=1, 2, 3 or 4) or/and SinF _2o+2 (n=1, 2, 3 or 4). The purpose of further adding the above-mentioned gas as an atmospheric gas is to perform deposition at a higher speed while maintaining various properties that a photoreceptor should have.

Through the above steps, a predetermined amount of atmospheric gas and doping gas are introduced. At this time, the B-A type vacuum gauge 1
The total pressure of the introduced gas indicated by 3 is 6.7×10 ^-3 pa or
Set to the desired constant pressure of 6.7×10 ^-2 pa.
Thereafter, the main valve 27 is closed and gas continues to flow into the sputtering chamber 1. Next, after confirming that the shutter 4 is closed, the high frequency power supply 31
and apply a high-frequency electric field with an oscillation frequency of 13.56MHz. After confirming that plasma discharge has been generated in the sputtering chamber by the viewing port 10, the increase in the high frequency electric field is temporarily stopped,
By gradually opening the main valve 27, the gas pressure indicated by the Schultz type vacuum gauge 11 or the Baratron type vacuum gauge 12 is increased to 6.7×10 ^-2 pa or 6.7
Set to the desired constant pressure within ×10′pa. After waiting for the pressure value displayed on the vacuum gauge to stabilize, the oscillation tube anode voltage of the high frequency power source 31 is set to a desired constant voltage between 0.50 kv and 4.00 kv.
Next, the high frequency matching device 32 performs high frequency matching so that the oscillator tube anode current shows the maximum value.

After performing the pre-sputtering for a predetermined time as described above, the shutter 4 is opened and the main sputtering is started.

The present inventors have so far discovered a number of P-type a-
According to the knowledge gained from depositing and evaluating Si:H films, it has been found that the parameters during sputtering, especially high frequency power density and substrate temperature, are really important factors that control the physical properties of the deposited film. can give. First, the high frequency power density is 0.3W/
Below ^cm2 , the intrinsic dark conductivity generally decreases;
Although the surface morphology of the thin film tends to be improved, the deposition rate is extremely reduced and the adhesion to the substrate is also greatly degraded. Furthermore, as for the integrated intensity of the silicon-hydrogen infrared absorption coefficient mentioned above, the contribution of the monohydride mode tends to increase, while the contribution of the dihydride mode tends to decrease. P-type a-Si:H deposited under this condition
The film's photosensitivity deteriorates. On the other hand, in the case of 3.0 w/cm ² or more, the deposition rate increases significantly and the adhesion to the substrate is greatly improved, but deterioration of surface morphology due to blistering and increase in dark conductivity are observed. Therefore, P-type a-Si:H films deposited under this condition lead to a decrease in charge acceptance.

For the above reasons, in the manufacturing method according to the present invention, it is necessary that the high frequency power density during deposition of the P-type a-Si:H film is 0.3 w/cm ² or more and 3.0 w/cm ² or less.

Next, when the substrate temperature is 50°C or less, the hydrogen concentration in the film tends to increase and the dark conductivity tends to decrease, but according to the electron spin resonance method, 5× A spin density of 10 ¹⁷ spins/cm ³ was observed, indicating that the localized electron density was too high. Under this condition, P− due to boron
Valence control on type is not effective and photoconductivity also deteriorates. Conversely, at temperatures above 350°C, the hydrogen concentration in the film decreased significantly and the dark conductivity tended to increase. Furthermore, the optical conductivity also begins to deteriorate. For the above reasons, in the manufacturing method according to the present invention, it is necessary that the substrate temperature during deposition of the P-type a-Si:H film is 50°C or more and 350°C or less.

After main sputtering is performed for a predetermined time under the above parameter control, the shutter 4 is closed and the oscillation tube anode voltage of the high frequency power source 31 is lowered. Through the above steps, a P-type amorphous silicon layer doped with a high concentration of oxygen is deposited.
After this, close all variable leak valves,
Wait for the B-A type vacuum gauge 13 to indicate the initial ultimate vacuum pressure.

The present inventors have designed a number of multilayer electrophotographic photoreceptors made of amorphous silicon-based materials. As a result, in general, after depositing a certain layer, it is possible to deposit a certain layer in-situ (in-situ) without breaking the vacuum. ) it turned out to be really important to laminate the other layers successively. After depositing a certain layer, if the vacuum is broken and another layer is deposited after evacuation again, the adsorbed gas existing at the interface and other contamination may cause
A phenomenon in which the laminated second layer peeled off from the layer interface was observed. Furthermore, in this case, structural defects formed mainly at layer interfaces often had a significant adverse effect on photoelectric properties. For the above reasons, in the manufacturing method according to the present invention,
On a blocking layer made of P-type a-Si:H doped with a high concentration of oxygen, a P-type a-type doped with a low concentration of oxygen is continuously deposited by an in-situ method.
It is characterized by stacking photoconductive layers made of Si:H.

P-type a-Si:H doped with low concentration of oxygen
The deposition of the photoconductive layer consisting of layers is basically the same as that for the blocking layer described above, except that the amount of oxygen gas introduced is different. If the proportion of oxygen gas in the total gas during deposition of the photoconductive layer is 0.1% or less, it is too small to compensate for uncompensated dangling bonds, resulting in a decrease in dark conductivity and the effect of valence control. cannot be improved. Furthermore, little improvement in surface morphology was observed. Therefore, it is impossible to improve charge acceptance in a photoreceptor made of a photoconductive layer deposited under these conditions. Conversely, when the proportion of oxygen gas in the total gas is 4% or more, the dark conductivity decreases and the surface morphology is definitely improved, but the optical gap begins to increase slightly.
Photoconductivity begins to deteriorate significantly. That is, under this condition, the generation efficiency of photogenerated carriers due to imagewise exposure and the mobility/lifetime product of holes decrease. Therefore, the photosensitivity begins to deteriorate. For the above reasons, when depositing the photoconductive layer consisting of a P-type a-Si:H layer doped with oxygen at a low concentration, the proportion of oxygen gas in the total gas is 0.1% or more and less than 4%. It is necessary that

After performing main sputtering for a predetermined time under the above parameter control, the shutter 4 is closed, the oscillation tube anode voltage of the high frequency power source is lowered, all variable leak valves are closed, and the substrate temperature is Wait for it to return to room temperature, then open the sputtering room 1.
The electrophotographic photoreceptor that has been deposited is taken out.

〔Effect of the invention〕

As described in detail above, the present invention is a novel product that has strong adhesion to the substrate, has sufficient charge acceptance, extremely excellent photosensitivity, extremely high durability, and has no pollution or sanitary problems. A method for manufacturing an electrophotographic photoreceptor, which is simple, fast, and
Moreover, it provides a reproducible manufacturing method.

The electrophotographic photoreceptor according to the present invention is fully applicable not only as a photoreceptor for ordinary single-color, two-color, and color copying, but also as a photoreceptor for intelligent copiers such as liquid crystal displays, laser printers, and light-emitting diode printers. It is.

Examples of the present invention will be described below.

Example 1 Temperature (25°C) and humidity (50%) were adjusted,
Using the high-frequency sputtering device shown in Figure 2 installed in a thoroughly cleaned room, according to the procedure described above, under the conditions shown below,
A two-layer electrophotographic photoreceptor consisting of a P-type a-Si:H layer doped with oxygen was fabricated. At this time,
Common conditions for fabricating a P-type a-Si:H layer (blocking layer) doped with a high concentration of oxygen and a P-type a-Si:H layer (photoconductive layer) doped with a low concentration of oxygen. It is summarized below.

Common condition target: polycrystalline silicon
5-nine purity 120φ 6mmt Substrate: Cleaned Al plate 100×100×1mmt Distance between substrate and target: 35mm Total gas pressure introduced: 1.3×10 ^-2 pa Total gas pressure during sputtering: 8.6×10 ^-1 pa The conditions for depositing the blocking layer and the photoconductive layer are summarized below.

Conditions for blocking layer deposition 1 Substrate temperature: 150 to 180°C 2 Molar fraction of atmospheric gas and doping gas in the total introduced gas H ₂ : 40% He: 8% Ar: 40% SiH ₄ : 6.5% O ₂ : 5.5% B ₂ H ₆ : 360ppm 3 High frequency power density: 1.1w/cm ² 4 Sputtering time: 20 minutes 5 Layer thickness: 9000 Conditions for photoconductive layer deposition 1 Basic temperature: 120 to 150℃ 2 Atmosphere gas and molar fraction of doping gas in the total introduced gas H ₂ : 66% He: 8% Ar: 18% SiH ₄ : 6.5% O ₂ : 1.5% B ₂ H ₆ : 160ppm 3 High frequency power density: 1.2w/ cm ² 4 Main sputtering time: 7 hours 5 Layer thickness: 18.9 μm The electrophotographic photoreceptor fabricated above has a mirror-like surface morphology over the entire surface of the substrate, and the uniformity of the layer thickness is It was in extremely good condition. The electrophotographic photoreceptor characteristics of this photoreceptor were evaluated using a conventional electrostatic copying paper tester under the following conditions. That is, positive charging is performed under the conditions of a corona discharge voltage plus 6 kV and a scanning speed of 250 mm/sec, and the surface potential immediately after charging (initial charging potential V ₀ volts) is measured. Then, the sample is allowed to decay in the dark for 5 seconds (potential V after 5 seconds is ₅ volts), and the potential retention rate V ₅ /V ₀ is measured.
After this, tungsten light with a color temperature of 2854 and an illuminance of 5 lux is used to reduce the surface potential to V ₅ /2.
The amount of exposure required for attenuation to volts (half-reduced exposure amount E1/2 lux·sec) is recorded as the photosensitivity.
Also, the potential remaining when an exposure amount of 25 lux seconds is applied is recorded as the residual potential V _R volts.
Additionally, this test device is equipped with a differentiation circuit to output the time differential of the surface potential.
Photoinduced discharge rate dVL/dt (volt/
seconds) are recorded at the same time.

As a result of the above evaluation, initial charging potential V ₀ = 570 volts Potential retention rate after 5 seconds (V ₅ /V ₀ ) x 100 = 79% Residual potential V _R = 0 volts Half-reduced exposure amount E1/2 = 1.5 Lux・The photoinduced discharge rate was dVL/dt=1100 volts/second, and it exhibited extremely excellent characteristics as an electrophotographic photoreceptor.

Next, the light source of the test apparatus was replaced with a xenon lamp light source, and the spectral sensitivity characteristics of the photoreceptor were measured by irradiating monochromatic light with a monochromator. The irradiated monochromatic light was adjusted to an energy unit of approximately 0.2 μw/cm ² . The results are shown in FIG. It can be seen that compared to conventional photoreceptor materials, it has extremely high sensitivity and a wide spectral sensitivity range.

Next, when this photoreceptor was used to form an image by a normal cascade development method, it was possible to obtain a high-quality image with high resolution and extremely clarity. Furthermore, even after repeating this image processing 100,000 times, we were able to obtain images of the same high quality as the initial image. Further, when the electrophotographic characteristics in this case were compared with the initial values, there was no difference at all, and therefore, no deterioration of the photoreceptor could be observed.

On the other hand, as a result of measuring and analyzing the infrared absorption spectra of samples deposited on crystalline silicon substrates under the same conditions as the blocking layer and photoconductive layer of the photoreceptor, it was found that the hydrogen concentration in both films was between 5 and 50. between atomic % and ∫ ²²⁰⁰ ₂₀₀₀ α(ω)dω／∫ ²⁰⁵⁰ ₁₉₅₀ α′(ω)dω＞2 and ∫ ¹⁰⁵⁰ ₉₅₀ β(ω)dω／∫ ¹⁰⁵⁰ ₉₅₀ β′(ω)dω＞2 I was satisfied.

Example 2 A two-layer electrophotographic photoreceptor produced under the same conditions as Example 1, except that the molar fraction of oxygen gas in the total introduced gas was changed during the deposition of the blocking layer and photoconductive layer. I will describe the case of Here, a pre-mixed gas diluted to 25% in Ar gas is used as the oxygen gas, and hydrogen gas is used to adjust the excess or deficiency of the total pressure of the introduced gas as the molar fraction of oxygen gas changes. Therefore, a change in the mole fraction of oxygen gas causes a corresponding change in the mole fractions of hydrogen gas and Ar gas.

The table summarizes the changed molar fraction of oxygen gas and the electrophotographic photoreceptor characteristics for each sample. It can be seen that excellent characteristics are exhibited in both cases.

On the other hand, in Figure 4, the molar fraction of oxygen gas is 0.5.
% (A in the figure), 1.5% (B in the figure), 2.5% (C in the figure),
and 4.0% (D in the figure) of silicon-hydrogen stretching vibration mode infrared absorption spectrum (transmittance display). As a result of the analysis, the hydrogen concentration in the film was between 5 and 50 atomic % in all cases, satisfying ∫ ²²⁰⁰ ₂₀₀₀ α(ω)dω/∫ ²⁰⁵⁰ ₁₉₅₀ α′(ω)dω>2. Furthermore, as a result of analyzing the infrared absorption spectra of the blocking layer and photoconductive layer for each sample summarized in the table, it was found that ∫ ¹⁰⁵⁰ ₉₅₀ β(ω)dω／∫ ¹⁰⁵⁰ ₉₅₀ β′(ω)dω＞2 .

■■■ Turtle Shell [0030] ■■■ Example 3 A two-layer electrophotographic photoreceptor fabricated under the same conditions as Example 1 except that the high-frequency power density was changed during photoconductive layer deposition. Describe the case. Here, since the sputtering deposition rate increases approximately in proportion to the high frequency power density, the layer thickness was adjusted to a constant value of about 19 μm by adjusting the sputtering time. Furthermore, since the substrate temperature is greatly affected by the radiant heat in the plasma, and the radiant heat increases with the radio frequency power density, it was controlled between 130°C and 180°C by adjusting the heater current for heating the substrate.

The table summarizes the changed high frequency power density and the electrophotographic photoreceptor characteristics for each sample. It can be seen that excellent characteristics are exhibited in both cases.

On the other hand, as a result of analyzing the infrared absorption spectrum of a sample prepared under the same conditions as those used for depositing the photoconductive layer in this example, it was found that, in general, increasing the high-frequency power density tends to reduce the hydrogen concentration in the film. , containing at least 10 atomic percent hydrogen. Further, the integrated intensity ratio of the absorption coefficient was similar to that of Example 2.

■■■ Tortoise Shell [0031] ■■■ Example 4 In the case of a two-layer electrophotographic photoreceptor produced under the same conditions as in Example 1, except that the substrate temperature was changed during the deposition of the photoconductive layer. I will write about.

The table below summarizes the changed substrate temperatures and the electrophotographic photoreceptor characteristics for each sample. It can be seen that excellent characteristics are exhibited in both cases.

On the other hand, as a result of analyzing the infrared absorption spectrum of a sample prepared under the same conditions as those used for depositing the photoconductive layer in this example, the hydrogen concentration in the film generally tends to decrease as the substrate temperature increases; It also contained more than 10 atomic percent hydrogen. Further, the integrated intensity ratio of the absorption coefficient was similar to that of Example 2.

■■■ Turtle Shell [0032] ■■■ Next, in order to clarify the effects of the method for manufacturing an electrophotographic photoreceptor of the present invention in comparison with the conventional technology and cases other than the claims. A comparative example will be explained.

Comparative Example 1 The following describes a case in which the basic manufacturing conditions are the same as in Example 1, but one of the parameters during sputtering is set outside the claimed range. In each case, the main sputtering time was adjusted so that the total thickness of the two photoreceptor layers was about 20 μm.

In sample number 5-1, the molar fraction of oxygen gas in the total gas introduced during photoconductive layer deposition was 4.5%.
I did it. The surface morphology of this sample is deposited as an ideal mirror surface, but the analysis of the infrared absorption spectrum shows that ∫ ¹⁰⁵⁰ ₉₅₀ β(ω)dω／∫ ¹⁰⁵⁰ ₉₅₀ β′(ω)dω=1.3
>2.

For sample number 5-2, when depositing the blocking layer, the main sputtering time was set to 60 minutes, and the layer thickness was increased.
It was set to 2.7 μm.

For sample No. 5-3, the photoconductive layer was deposited at a high frequency power density of 3.1 W/cm ² .

Sample No. 5-4 was carried out with the substrate temperature between 20 and 40° C. during photoconductive layer deposition.

Sample number 5-5 shows the proportion of diborancus in the total introduced gas during photoconductive layer deposition.
I did it at 2050ppm.

The electrophotographic photoreceptor characteristics of the above five types of photoreceptor samples are summarized in the table below. It can be seen that in all cases, at least one of charge acceptance, residual potential, and photosensitivity is not satisfied.

■■■ Turtle shell [0033] ■■■ Comparative example 2 P-type a-Si:H doped with high concentration of oxygen
It was produced under the same conditions as in Example 1 except that the blocking layer consisting of layers was not provided. Results of evaluating the characteristics of a single-layer electrophotographic photoreceptor with only a photoconductive layer Initial charging potential V ₀ = 465 volts Potential retention rate after 5 seconds (V ₅ /V ₀ ) x 100 = 71% Residual potential V _R = 0 Volts Half-life exposure E1/2 = 1.4 lux·sec Photoinduced discharge rate dVL/dt = 1025 volts/sec. The photoreceptor according to this comparative example shows the above-mentioned excellent characteristics in a test after being left in a dark place for a long time, but in general, the rise of the charged level tends to be poor when repeated repeatedly. Ta. That is, the charge acceptance decreases with image exposure and static elimination light exposure. This is not due to inherent deterioration of the photoreceptor material a-Si:H(B,O), but due to carriers photo-generated during exposure processing that are not recombined and trapped, and conductivity during charging. This is caused by charge trapped in the bulk of the photoreceptor, ie, space charge, among the carriers injected from the substrate surface. Therefore, if the space charge is released by leaving it in the dark for an appropriate amount of time, it will recover to its initial value.
As a practical photoreceptor, images and
This leads to changes in concentration, which is undesirable.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of an electrophotographic photoreceptor according to the present invention, FIG. 2 is a schematic diagram of a high-speed sputtering device used in the method for manufacturing an electrophotographic photoreceptor according to the present invention, and FIG. 3 is a diagram showing the structure of an electrophotographic photoreceptor according to the present invention. FIG. 4 is a diagram showing the spectral sensitivity characteristics of the electrophotographic photoreceptor, and FIG. 4 is a diagram showing changes in the silicon-hydrogen stretching vibration mode when the molar fraction of oxygen gas during deposition is changed. 101: Free surface, 102: Photoconductive layer, 10
3: Blocking layer, 104: Conductive substrate, 1:
Sputtering chamber, 2: Crystalline silicon target for sputtering, 5: Substrate, 11: Schulz type vacuum gauge,
13: B-A type vacuum gauge, 16: Variable leak valve, 18: Hydrogen-rare gas mixed gas, 21:
SihH _2o+2 gas (n=1, 2, 3 or 4),
23: Oxygen gas, 24: Diborane gas, 31: Rotary pump, 33: High frequency power supply.

Claims (1)

[Claims] 1. By introducing diborane gas in addition to oxygen gas as a doping gas onto the conductive substrate,
A method in which two layers, a P-type amorphous silicon layer doped with a high concentration of oxygen and a P-type amorphous silicon layer doped with a low concentration of oxygen, are sequentially deposited by a high-frequency sputtering method. ,
and (a) each amorphous silicon layer has a high frequency power density of 0.3 W/cm ² to 3.0 W/cm ² when deposited; (c) The P-type amorphous silicon layer doped with a high concentration of oxygen has a substrate temperature of 50° C. to 350° C. The ratio of oxygen gas to the total gas during deposition is 4% to 40° C. (d) In the P-type amorphous silicon layer doped with a low concentration of oxygen, the proportion of oxygen gas in the total gas at the time of deposition is 0.1% to 4%. (e) Each amorphous silicon layer has a proportion of diborane gas in the total gas during its deposition.
A method for producing an electrophotographic photoreceptor, characterized in that the concentration is 2ppm to 2000ppm.