JPS63243954A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve the traveling property of generated carriers by alternately laminating thin films of two kinds of amorphous Si contg. a prescribed element in at least one of the two kinds to form an electric charge retaining layer and by continuously varying the concn. of the element. CONSTITUTION:A photoconductive layer 3 consisting of an electric charge retaining layer 5 and an electric charge generating layer 6 is formed on an electrically conductive support 1 preferably with a barrier layer 2 in-between. The layer 5 is formed by alternately laminating thin films of two kinds of amorphous Si contg. one or more element among C, O and N in at least one of the two kinds and the concns. of the elements are continuously varied in the vicinity of the interface between the thin films. The layer 6 is formed by alternately laminating thin amorphous Si films and thin microcrystalline Si films. An element selected from group III or V of the periodic table is preferably incorporated into the layer 3 and one or more among C, O and N are preferably incorporated into the layer 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to an electrophotographic photoreceptor having excellent band 7 & characteristics, dark decay characteristics, photosensitivity characteristics, environmental resistance, etc.

(Prior art) Amorphous silicon (hereinafter referred to as a) containing hydrogen (H)
-8l:H) has recently attracted attention as a photoelectric conversion material, and has been applied to photoreceptors in electrophotographic processes as well as solar cells, thin film transistors, and image sensors.

Conventionally, inorganic materials such as CdS e ZnO, Se s or 5s-Tv, or poly-H-vinylcarbazole (PVC) have been used as materials constituting the photoconductive layer of electrophotographic photoreceptors.
z) or organic materials such as trinitrofluorenone (TNF). However, a-8t:H
Compared to these inorganic or organic materials, it is a non-polluting substance and does not require recovery treatment, has high spectral sensitivity in the visible light region, and has a high surface hardness and is resistant to abrasion and impact. It has advantages such as excellent solubility. For this reason, a-Sl:H is attracting attention as a photoreceptor for electrophotographic processes.

This a-Sl:H is being studied as a photoreceptor material based on the Carlson method, but in this case, the photoreceptor is required to have high resistance and photosensitivity.

However, it is difficult to satisfy both of these characteristics with a single photoreceptor, so a barrier layer was provided between the photoconductive layer and the conductive support, and a surface charge retention layer was provided on the photoconductor vLR5. These requirements are satisfied by using a layered structure.

(Problems to be Solved by the Invention) By the way, s a-81: H is usually formed by a glow discharge decomposition method using a silane gas, but at this time, hydrogen is not present in the a-st:a film. is taken in, and the stain's atmospheric and optical properties vary greatly depending on the difference in the amount of hydrogen. That is,
a-8l * As the amount of hydrogen entering the H layer increases,
Optical band gear, f increases, a − S i :
Although the resistance of H increases, the photosensitivity to long-wavelength light decreases accordingly, making it difficult to use, for example, in a Rede beam printer equipped with a semiconductor Rade.

In addition, when the content of 7 in the a-St:H layer increases, depending on the film formation conditions, (siH2)n and SiH2
In some cases, a bond structure such as occupies most of the area in the film. In this case, voids increase and silicon dangling bonds increase, resulting in deterioration of photoconductive properties and rendering the material unusable as an electrophotographic photoreceptor. On the contrary, a-
As the amount of hydrogen incorporated into 8i:H decreases, the optical band gap decreases and its resistance decreases, but the photosensitivity to long wavelength light increases. However, when the hydrogen content is low, there is less residual hydrogen that binds to and reduces silicon dangling bonds. For this reason, the mobility of the generated carriers is reduced, the life span is shortened, and the photoconductive properties are deteriorated, making it difficult to use as an electrophotographic photoreceptor.

In this way, the photoconductive layer of the electrophotographic photoreceptor can be formed into a single a-8
If the structure is made up of only the 1:H layer, there is a problem that the characteristics change greatly depending on the manufacturing conditions of the a-Si:H layer, and desired characteristics cannot be obtained.

The present invention has been made in view of such circumstances, and
To provide an electrophotographic photoreceptor that has excellent charging ability, low residual potential, high photosensitivity over a wide wavelength range up to the near infrared region, good adhesion to a substrate, and excellent environmental resistance. With the goal.

[Structure of the Invention] (Means for Solving the Problems) As a result of extensive research, the present inventors have devised a structure in which the photoconductive layer of an electrophotographic photoreceptor has a charge retention layer and a charge generation layer. death,
The charge retention layer is composed of a superlattice structure, which is a stack of multiple semiconductor films containing carbon, etc., and having different concentrations, and the 0 degree of carbon, etc. near the interface of these semiconductor films is continuously changed. The inventors have discovered that the above object can be achieved, and have come to form the present invention.

That is, the electrophotographic photoreceptor of the present invention has a conductive support and light 4
i1! an electrophotographic photoreceptor comprising a layer, wherein the photoconductive layer has a charge generation layer and a charge retention layer, and the charge generation layer includes alternating amorphous silicon thin films and microcrystalline silicon thin films. The charge retention layer is constructed by alternately laminating two amorphous silicon thin films, at least one of which contains at least one of the elements selected from carbon, oxygen, and nitrogen, and the charge retention layer is composed of two amorphous silicon thin films, at least one of which contains at least one of the elements selected from carbon, oxygen, and nitrogen, It is characterized in that the concentration of the thin film changes continuously near the interface of the thin film.

The concentration of carbon, oxygen, and mysterious elements contained in the amorphous silicon thin film is preferably 0.1 to 40 atoms, more preferably 0.5 to 30 atoms.

The microcrystalline silicon (μc-81) used in the present invention is thought to be formed from a mixed phase of microcrystalline silicon and amorphous silicon with a grain size of approximately several tens of angstroms, and has the following physical properties. It has characteristics. First, X-ray diffraction measurements show a crystal diffraction pattern with 2θ in the vicinity of 28 to 28.5°, which is clearly distinguishable from amorphous a-St in which only a halo appears. @Second, μc-8
It can be adjusted to a dark resistance of 1,010Ω·α or more, and is clearly distinguished from polycrystalline silicon, which has a dark resistance of -1,050Ω·α.

The μc-8t optical band gear used in the present invention, Eg', is desirably set to, for example, 1.55·V.

However, it can be set arbitrarily within a certain range. Preferably, a predetermined amount of hydrogen is added to each to obtain the desired gg 6 and used as μe-8t:H. This compensates for the dangling bonds of silicon, balances dark resistance and bright resistance, and improves photoconductive properties.

(Function) In the electrophotographic photoreceptor of the present invention, since the superlattice structure is provided in the charge retention layer, carriers generated in this region have a long lifetime and a high mobility. Although the theory has not yet been fully established, there is no doubt that this is a quantum effect due to the periodic well potential characteristic of the superlattice structure, and this is particularly referred to as the superlattice effect.

In this way, the mobility of carriers in the charge retention layer increases, and the lifetime of the carriers increases, resulting in a marked improvement in the sensitivity of the electrophotographic photoreceptor.

In addition, in the present invention, a-8 constituting the charge retention layer
Since the thin film contains at least one of carbon, oxygen, and spiritual elements, it not only adjusts the gap and gap as described above, but also increases the resistance of the photoconductive layer and retains charge on the surface. You can improve your abilities.

(Example) FIG. 1 is a diagram showing a cross-sectional structure of an electrophotographic photoreceptor according to an example of the present invention. In the figure, conductive support 1
A barrier #2 is formed on top of the barrier #2, and a light guide magnet WI3 consisting of a charge retention layer 5 and a charge generation layer 6 is formed thereon. Further, a surface layer 4 is formed on the charge generation layer 6. Note that the charge retention layer 5 and the charge generation layer 6 have a superlattice structure.

Hereinafter, the structure of the electrophotographic photoreceptor shown in Figure @1 will be explained in more detail.

The conductive support 1 usually consists of a drum made of aluminum.

The barrier $2 may be formed using μc-81 or a-8t:H, or h-BN: ] ((amorphous boron to which nitrogen and hydrogen are added). For example, μc-81:H and a-
By incorporating one or more elements selected from carbon C1 nitrogen N and oxygen O into 81:H, a high-resistance insulating barrier layer can be formed. The thickness of barrier layer 2 is 10
0x-10 μm is preferred.

The barrier layer 2 is formed to enhance the charge retention function of the photoconductor surface by suppressing the flow of charges between the conductive support 1 and the charge generation H5, and to increase the charging ability of the photoconductor. It is something that Therefore, when a Carlson type photoreceptor is constructed using a semiconductor layer as a barrier layer, the barrier 2 is made to be P type or N type in order not to reduce the ability to retain charges charged on the surface. That is, when the surface of the photoreceptor is to be positively charged, the barrier layer 2 is made of PP to prevent electrons that neutralize the surface charge from being injected into the charge generation layer.

Conversely, when the surface is negatively charged, the barrier layer 2 is made of N type,
Holes that neutralize surface charges are prevented from being injected into the charge generation layer. Since the carriers injected from the barrier layer 2 act as a nozzle for the carriers generated in the charge generation layer 6 upon original injection, preventing carrier injection as described above improves the sensitivity. In addition, pc-8t:
H or a-81: In order to make H type P, elements belonging to Group Ⅰ of the periodic table, such as boron B1 aluminum A
t1 Gallium Ga, Indium In, and Thallium Tt
It is preferable to dope. Also, μa-8i
:H or a-Si a To make H into N-type, elements belonging to Group Ⅰ of the periodic table, such as nitrogen, phosphorus P, arsenic A8
, antimony Sb, bismuth B1, etc. are preferably doped.

The charge generation layer 6 generates carriers due to original incidence, and these carriers, of one polarity, form a band ti on the surface of the photoreceptor.
The other one travels within the one-load holding M5 and reaches the conductive support 1.

The charge retention layer 5 and the charge generation layer 6 are constructed by alternately laminating two types of thin layers. These thin layers have different optical bandgaps and each have a thickness in the range of 30-500X.

Ideally, the superlattice structure constituting the charge generating reJS should have, for example, thin films with different optical band gaps forming a discontinuous periodic potential, as shown in FIG.

However, in order to deposit such a superlattice structure, it is necessary to purge the gas in the reaction chamber after each thin film is deposited to prevent impurities from entering the thin film during the next deposition. However, there are disadvantages in that the film forming time is extremely long and mass productivity is poor. In addition, when forming a film by plasma CVD, ions constantly collide with the film forming surface (ion membrane).
occurs, which causes impurities to diffuse into the thin film, making it impossible to form the discontinuous periodic potential shown in FIG.

On the other hand, in the superlattice structure of the charge retention layer according to the present invention, as shown in FIG. 3, the element concentration, that is, the optical band gap, in the vicinity of the interface of each thin film is continuously changed. Such a superlattice structure can be created by slightly lowering the high frequency power to weaken the ion membrane, introducing a large amount of H2 gas, and changing the flow rate of gas containing impurities while keeping the high frequency power constant. Alternatively, it can be obtained by changing the high frequency power while keeping the gas flow rate constant. By forming a film using such a method, the ion membrane is weakened, and a periodic potential as shown in FIG. 3, in which the characteristics near the interface change continuously, can be obtained.

In this way, near the interface of the thin film, the concentration of carbon etc.
Therefore, by adopting a superlattice structure in which the optical bandgap is continuously changed, films can be formed one after another without stabilizing the film forming conditions. This results in a significant reduction in time and excellent mass productivity. Furthermore, since the film formation is continuous, the adhesion between each Ni film is improved.

As explained above, by stacking thin J- layers with mutually different optical band gaps, 1. A superlattice structure having a periodic potential barrier is formed in which a layer with a large optical bandgap acts as a barrier based on a layer with a small optical bandgap. In this superlattice structure,
Since the barrier thin film is extremely thin, carriers pass through the barrier and travel in the superlattice structure due to carrier tunneling in the thin film. Furthermore, in such a superlattice structure, a large number of carriers are generated due to original incidence.

Therefore, it has high photosensitivity. Note that by changing the band ear and film thickness of the thin film having the superlattice structure, the apparent bandgap of the layer having the Peter junction superlattice structure can be freely adjusted.

a-81 constituting the charge retention layer 5 and charge generation RJ6
The hydrogen content in :H and μe-8i:H is 0
．． 01 to 30 atom % is preferable, and 1 to 25 atom % is more preferable. Such a hydrogen content compensates for the dangling of silicon, brings the dark resistance and bright resistance into balance, and improves the photoconductive properties.

In order to synthesize a-8t:H,l1li by the glow discharge decomposition method, SiH4 and 5L2H6v silane gases are introduced into the anti-stone chamber as raw materials, and a thin layer is formed by high-frequency jiglow discharge. Ht- can be added in it.

If necessary, hydrogen or helium gas can be used as a carrier gas for silanes. On the other hand, SiF
Silicon halides such as 4 gas and SIC24 gas can be used as source gases. (9) Ht-containing a-St:H can be similarly formed by reacting with a mixed gas of silane gas and silicon halide gas. Note that these thin films can be formed not only by the glow discharge decomposition method but also by a physical method such as sputtering.

Similarly to the a-8i:l, the μc-81 layer can also be formed using a high-frequency glow discharge decomposition method using silane gas as a raw material. In this case, the temperature of the support is a-81:
It is set higher than when forming H, and the high frequency power is also a
-St: If you set it higher than in the case of H, μ(1-
8l:H becomes easier to form. Furthermore, by increasing the support temperature and high frequency power, the flow rate of source gas such as silane gas can be increased, and as a result, the film formation rate can be increased. In addition, the raw material gas SiH4
By using a gas obtained by diluting a high-order silane gas such as S1□H6 with hydrogen, μc-8t:H can be formed with higher efficiency.

μc ” Ska H and a-81: In order to make the Htp type, doping with elements belonging to the SGM group of the periodic table, such as boron B, aluminum At1 gallium Ga, indium In, and thallium Tt, etc. is preferable, and in order to make μe-8t:H and a-8t:H n-type, an element belonging to group Ⅰ of the periodic table, for example,
Nitrogen N1 phosphorus P, arsenic As, antimony Sb.

It is preferable to dope with hibismuth Bi or the like.

This doping with p-type impurities or n-type impurities prevents charges from moving from the support side to the photoconductive layer. On the other hand, in μc-3i:H and Hatake-3i:H, carbon C1
By containing at least one element selected from nitride N and oxygen O, high resistance can be achieved and the surface charge retention ability can be increased.

A surface FI 4 is provided on the charge generation layer 6 .

Since the a-8t:H and the like of the charge generation layer 6 has a relatively large refractive index of 3 to 3.4, light reflection easily occurs on the surface. When such light reflection occurs, the ratio of the amount of light absorbed by the charge generation layer decreases, and light loss increases. For this reason, it is preferable to provide the surface M4 to prevent reflection. Further, by providing the surface N4, the charge generation layer 6 is protected from damage. Furthermore, by forming the surface layer, the charging ability is improved, and the charge can be easily deposited on the surface. As the material forming the surface layer, a-8IN:
H.

These include inorganic compounds such as a-81O:H, and a-SIC:H, and organic materials such as polyvinyl chloride and polyamide.

When the surface of the electrophotographic photoreceptor constructed as described above is charged with a positive voltage of about 5 oov by corona discharge, a /tension pariah is formed. When light (hv) is incident on this photoreceptor, carriers of electrons and holes are generated in the charge generation layer 6. Electrons in this conduction band are moved by the electric field in the photoreceptor,
The holes are accelerated toward the surface layer 4 side, and the holes are accelerated toward the conductive support 1 side. In this case, in the charge retention layer, in the potential well layer, the lifetime of carriers is 55% compared to the case of a single layer without a superlattice structure due to the quantum effect.
Furthermore, in a superlattice structure, a periodic barrier layer is formed due to the discontinuity of the band gap, but carriers easily pass through the bias layer due to the tunnel effect, so the carrier The effective mobility is similar to that in bulk, and carrier mobility is excellent. As described above, the superlattice structure in which thin layers with different optical band gaps are laminated can provide high photoconductivity and provide clearer images than conventional photoreceptors.

Below, with reference to Figure @4, an apparatus and a manufacturing method for manufacturing the electrophotographic photoreceptor of the above embodiment by a glow discharge method will be described. In the figure, gas cylinders 21, 22, 23.
24, for example, 5IH4# B21 (6a H
2, raw material gas such as CH4 is accommodated. These are the gases in Sugonpe! Pulp 26 and piping 2 for adjustment
7 to a mixer 28.

A pressure gauge 25 is installed in each cylinder, and the pressure gauge 25 is installed in each cylinder.
By subjecting the pulp 26 to vIIIi while monitoring 5, the flow rate and mixing ratio of each raw material gas supplied to the mixer 28 can be adjusted. The gas mixed in the mixer 28 is transferred to the reaction container 2
9. A rotating shaft 30 is attached to the bottom 31 of the reaction vessel 29 so as to be rotatable in a vertical direction.

A disk-shaped support 32 is fixed to the upper end of the rotating shaft 30 with its surface perpendicular to the rotating shaft 30. Reaction container 29
Inside, a cylindrical electrode 33 is installed on the bottom 31 with its axial center aligned with the axial center of the rotating shaft 30. A drum base 34 of a photoreceptor is placed on a support base 32 with its axial center aligned with the axial center of the rotating shaft 30, and a heater 35 for heating the drum base is arranged inside the drum base 34. It is set up. A high frequency power source 36 is connected between the electrode 33 and the drum base 34, and υ, 1! A high frequency current is supplied between the pole 33 and the drum base 34. The rotating shaft 30 is driven by a motor 38 for multiple rotations.

The reaction vessel 29 is connected to suitable exhaust means.

When manufacturing a photoreceptor using the above manufacturing apparatus, after installing the drum base 34 in the reaction container 29, the dirt pulp 39 is opened and the inside of the reaction container 29 is heated to about Q, l Torr.
Evacuate to below pressure. Next? Npe21.22,2
From 3.24 onwards, required reaction gases are mixed at a predetermined mixing ratio and introduced into the reaction vessel 29.

In this case, the flow rate of gas introduced into one reaction vessel 29 is set so that the pressure within the reaction vessel 29 is 0.1 to 1.0 TorrK. Next, the motor 38 is operated to rotate the drum base 34, and the heater 35 rotates the drum base 34.
4 is heated to a constant temperature, and a high frequency current is supplied between the stain electrode 33 and the P ram base 34 by the high frequency power source 36 to form a glow discharge between them. As a result, a-81:H is deposited on the drum base 34. Note that N20. NH3, NO2, N2. CH4, C2H
These elements can be contained in a-8l:H by using 4,0□ gas or the like.

As described above, since the electrophotographic photoreceptor according to the present invention can be manufactured using a closed system manufacturing apparatus,
Safe for humans.

Next, the results of testing the electrophotographic properties of an electrophotographic photoreceptor according to the present invention formed into a film will be described.

Sample sample 1 If necessary, in order to prevent interference, an aluminum drum base with a diameter of 80 m and a width of 350 m, which has been subjected to acid treatment, alkali treatment, and sand blast treatment, is installed in the reaction vessel. was evacuated to a vacuum of approximately 10-5 torr.

While heating the drum base to 250°C and rotating it at 10 rpm, 5IH4 gas was introduced into the reaction vessel at a flow rate of 500 SCCM and B2H6 gas was introduced into the reaction vessel at a flow rate of 10 at a flow rate ratio of 10 to 5iH4 gas, and the pressure inside the reaction vessel was set to 1 Torr. It was adjusted to Then, a high frequency power of 13.56 MHz is applied to generate plasma, and p-type a-b is formed on the drum base.
i: H barrier layer was formed.

Next, the flow rates of 5 liter (4 gas and H gas were 400 SCCM and 800 SCCM, respectively, the pressure inside the reaction vessel was I Torr, and high frequency power of 200 W was applied for 2 minutes to form an a-81:H thin film. .

Then, with the high frequency power applied, the current i 60 SC
CM CH4 gas was introduced for 2 minutes, *-SiC: H
A thin film (carbon concentration: 5 atoms ts) was formed. Such operations were repeated to form a charge retention layer of 20 μm in which the carbon concentration near the interface changed continuously.

Thereafter, 400 SCCM of SiH4 gas and 200 SCCM of H2 gas were introduced, and a high frequency power of 300 W was applied to form a 50X a-S i :H thin film.

Next, 5IH4 gas was used at 50 SCCM, N2 gas was used at 5008 CCM, and soowO high frequency power was applied to form a 100X μe-81:H thin film. This operation was repeated to form a charge generation layer with a thickness of approximately 5 μm.

Finally, a surface layer made of a-8t:H with a thickness of 0.5 μm was formed.

When the surface of the photoreceptor thus formed is positively charged at about 500 V and exposed to white light, this light is absorbed at a rate of charge generation/m, and carriers of electron-hole pairs are generated. In this test example, a large number of carriers were generated, the carriers had a long life, and high running performance was obtained. This resulted in clear, high-quality images. In addition, when the photoreceptor manufactured in this test example was repeatedly charged, the reproducibility and stability of the transferred image were extremely good. It has been proven that it has excellent durability.

Test Example 2 An electrophotographic photoreceptor was manufactured in the same manner as Test Example 1, except that two types of a-SiC:H thin films having different carbon concentrations were alternately laminated to constitute a charge retention layer. Note that the charge retention layer was obtained as follows.

First, 5IR4 gas was introduced at 400 SCCM, N2 gas was introduced at SOO8 CCM, CH4 gas was introduced at 308 CCM, the pressure in the reaction chamber was set to I Torr, and 200 W of high frequency power was applied for 2 minutes. f) a-SiC:
H thin film (carbon concentration: 2 atoms S>0 then C
A -SiC:H thin film (
A carbon concentration of 28 atoms was formed. These operations were repeated to obtain a charge retention layer of 20 μm.

When an image was formed using this photoreceptor in the same manner as in Test Example 1, a clear and high quality image was obtained.

Test Example 3 Electrophotographic exposure was performed in the same manner as Test Example 1, except that an a-StN:H711 film (nitrogen concentration: 5 at%) was formed in place of the a-Sac:H thin film constituting the charge retention layer. manufactured a body. In addition, the h-8LN:H thin film is
It was obtained by introducing t 90 SCCM of N2 gas for 2 minutes while applying radio frequency power.

When an image was formed using this photoreceptor in the same manner as in Test Example 1, a clear and high quality image was obtained.

Test Example 4 An electrophotographic photoreceptor was manufactured in the same manner as Test Example 1, except that two types of a-SIN:H thin films having different nitrogen concentrations were alternately laminated to form a charge retention layer. In addition,
The charge retention layer was obtained as follows.

First, add 400% SiH4 gas to 80% N2 gas.
0 SCCM and 508 CCM of N2 gas were introduced, the pressure in the reaction chamber was set to f, I Torr, and a high frequency power of 200 W was applied for 2 minutes to form an a-SIN:H thin film (nitrogen concentration: 2 W, %). Then N2f
! The high frequency power is set to 120SCCM and the high frequency power is 2
By applying it for a minute, an a-SIN:H thin film (nitrogen concentration = 8 atomic %) was formed. These operations were repeated to obtain a charge retention layer of 20 μm.

When an image was formed using this photoreceptor in the same manner as in Test Example 1, a clear and high quality image was obtained.

The above describes a test example in which the light guide 1E layer is composed of two types of thin films, but the invention is not limited to this, and three or more types of thin films may be laminated.In short, a boundary between thin films with different optical band gaps is formed. That's good.

[Effects of the Invention] According to the present invention, since the photoconductive layer uses a superlattice structure formed by laminating thin films with mutually different optical band gaps, carrier mobility is high and the resistance is high. And obi 1! An electrophotographic photoreceptor with excellent characteristics can be obtained. In particular, it adopts a structure that continuously changes the concentration of carbon, etc. near the interface that makes up the charge retention layer.
It has excellent mass productivity, and because the film formation is continuous, the adhesion between each thin film is good. Furthermore, the electrophotographic photoreceptor of the present invention has the advantage that by appropriately combining materials forming the thin film, a photoreceptor having optimal photoconductive properties for light in any wavelength band can be obtained. There is.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an electrophotographic photoreceptor according to an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing energy bands of a superlattice structure, and FIG. 1 is a diagram showing an apparatus for manufacturing a photographic photoreceptor. 1: Conductive support, 2: Barrier layer, 3: Photoconductive layer, 4: Surface layer, 5: Charge retention layer, 6: Charge generation layer. Applicant's agent Patent attorney Takeshi Suzue Music Figure 1 Figure 2 Figure 3

Claims (9)

[Claims] (1) In an electrophotographic photoreceptor comprising a conductive support and a photoconductive layer, the photoconductive layer has a charge generation layer and a charge retention layer, and the charge generation layer is an amorphous silicon thin film. The charge retention layer is formed by alternately laminating two amorphous silicon thin films, at least one of which contains at least one of the elements selected from carbon, oxygen, and nitrogen. 1. An electrophotographic photoreceptor, characterized in that the concentration of the element changes continuously near an interface of the thin film. (2) The electrophotographic photoreceptor according to claim 1, wherein the thin film has a thickness of 30 to 500 Å. (3) The electrophotographic photosensitive material according to claim 1 or 2, wherein the photoconductive layer contains at least one element selected from elements belonging to Group III or V of the periodic table. body. (4) The electrophotography according to any one of claims 1 to 3, wherein the charge generation layer contains at least one element selected from carbon, oxygen, and nitrogen. Photoreceptor. (5) In the charge generation layer, the crystallinity of each thin film changes continuously in the vicinity of the interface of each thin film. Photographic photoreceptor. (6) A barrier layer made of an amorphous material or at least a partially microcrystalline semiconductor material is provided between the conductive support and the photoconductive layer. electrophotographic photoreceptor. (7) The electrophotographic photoreceptor according to claim 6, wherein the barrier layer contains at least one element selected from elements belonging to Group III or V of the periodic table. (8) The electrophotographic photoreceptor according to claim 6, wherein the barrier layer contains at least one element selected from the group consisting of carbon, oxygen, and nitrogen. (9) The electrophotographic photoreceptor according to claim 1, further comprising a surface layer on the photoconductive layer.