JPS63201661A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain optimum photoconductive characteristics to the rays of light in an optical wavelength region by using superlattice structure obtained by alternately laminating thin layers different in optical band gap from each other for a photoconductive layer and properly combining materials for forming the thin layers. CONSTITUTION:An electrophotographic sensitive body is obtained by successively laminating on a conductive substrate 1 a blocking layer 2, the photoconductive layer 3 composed of an electric charge holding layer 5, and a charge generating layer 6, and on this layer 6 a surface layer 4. Each of the layers 5, 6 has superlattice structure, and the layer 6 is constituted by alternately laminating thin films of microcrystalline silicon different in crystallization degree, the layer 5 is constituted by alternately laminating thin films of amorphous silicon and thin films of amorphous silicon containing at least one of C, O, and N, and the concentration of said element is changed in the film thickness direction in each thin film, thus permitting the obtained electrophotographic sensitive body to be superior in electrification characteristics, dark attenuation resistance and photosensitivity characteristics, and superior in resistance to environmental conditions or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor having excellent charging characteristics, dark decay characteristics, photosensitivity characteristics, environmental resistance, and the like.

[Prior Art] Hydrogen (H) Th-containing amorphous silicon (hereinafter abbreviated as a-8t:H) has recently attracted attention as a photoelectric conversion material, and is used in solar cells, thin film transistors, image sensors, etc. It is applied to photoreceptors in electrophotographic processes.

Conventionally, materials constituting the photoconductive layer ft of electrophotographic photoreceptors have been inorganic materials such as CdS, ZnO, Se, or 5e-To, or u ho+) -N-vinylcarbazole (PV
Organic materials such as Cz) or trinitrofluorenone (TNF') have been used. However, a-81
Compared to these inorganic or organic materials, H is a non-polluting substance, does not require recovery treatment, has high spectral sensitivity in the visible light region, and has high surface hardness and wear resistance. It has advantages such as excellent impact resistance. For this reason, a-81:H is attracting attention as a photoreceptor material for electrophotographic processes.

This a-81:H is being studied as a photoreceptor material based on the Carlson method, but in this case, high resistance and photosensitivity are required as photoreceptor characteristics. However, it is difficult to satisfy both of these characteristics with a single photoreceptor, so a barrier layer is provided between the photoconductive layer and the conductive support, and a surface charge retention layer is provided on the photoconductive layer. These requirements are met by creating a multilayer structure.

[Problems to be Solved by the Invention] By the way, a-81:H is usually formed by a glow discharge decomposition method using a silane gas, but at this time, in the a-81:H layer, Hydrogen is taken in, and the electrical and optical characteristics vary greatly due to the difference in the amount of hydrogen. That is, a
As the amount of hydrogen that enters the -8i:H film increases, the optical band gear becomes larger and the resistance of a-8t:H increases, but as a result, the photosensitivity to long wavelength light decreases. Therefore, it is difficult to use it, for example, in a radar beam printer equipped with a semiconductor radar. Furthermore, when the hydrogen content in the a-St;H layer increases, depending on the film forming conditions, those having bonding structures such as (SiB6)n and 5IH2 may occupy most of the area in the film.

Then, the gate increases, rounding increases silicon dangling bonds, photoconductive properties deteriorate, and 'ilL
It becomes unusable as a secondary photographic photoreceptor. On the contrary, a-8t:
Decreasing the amount of hydrogen incorporated into H reduces the optical arm gap and its resistance, but increases photosensitivity to long wavelength light. However, when the hydrogen content is low, there is less hydrogen to combine with and reduce the dangling bonds of silicon. 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
1: If the structure is made up of only the H layer, there is a problem that the characteristics change greatly depending on the manufacturing conditions of the a-8L: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 various studies, the present inventors have constructed a photoconductive layer of an electrophotographic photoreceptor consisting of a charge retention layer and a charge generation layer. ,
The inventors have discovered that the above object can be achieved by stacking a plurality of predetermined semiconductor films, that is, forming a region with a superlattice structure, and have thus completed the present invention.

That is, the electrophotographic photoreceptor of the present invention is an electrophotographic photoreceptor comprising an electrically conductive support and a photoconductive layer, the photoconductive layer comprising a charge generation layer and a charge retention layer, The generation layer is composed of alternating layers of microcrystalline silicon thin films having different degrees of crystallization, and the charge retention layer is composed of an amorphous silicon thin film and an amorphous silicon film containing at least one element selected from carbon, oxygen, and nitrogen. The structure is made by alternately laminating thin films of high quality silicon.

The microcrystalline silicon (μc-81) used in the present invention is thought to be formed by a mixed layer of microcrystalline silicon and amorphous silicon with a grain size of about several tens of Angstroms, It has the following physical characteristics.

First, X-ray diffraction measurement shows a crystal diffraction with 9 turns with 2θ around 28 to 28.5°, which is clearly distinguishable from amorphous a-8t in which only a halo appears. Second, μc
-8t dark resistance k'.

It can be adjusted to 1010Ω・α or more, and the dark resistance d?
”.

It is also clearly distinguished from the 105Ω sub-polycrystalline silicon.

The above μc-81 optical band gear used in the present invention!
(Eg') is preferably set to 1.55 cV, for example. However, it can be set arbitrarily within a certain range.

It is preferable to add the required amount of hydrogen to each to obtain the desired Eg"k and use it as μc-81:H. This compensates for the dangling bonds of silicon and balances the dark resistance and bright resistance. is removed, and the photoconductive properties are improved.

Note that an actual μc-8t film often takes on a weak P type or N type depending on specific factors such as manufacturing conditions (it is particularly susceptible to becoming an N type). Therefore, in order to obtain the fiI type necessary for forming a superlattice structure, it is desirable to lightly dope impurities having opposite conductivity types to cancel out the pfi or Nu.

In addition, the concentration of the latter element in each amorphous silicon thin film is
Preferably 0.1 to 30 atoms, more preferably 5 to 1
It is preferable to change it within a range of 5 atoms.

(Function) In the electrophotographic photoreceptor of the present invention, since the photoconductive layer is provided with the superlattice structure, carriers generated in this region have a long life 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, carrier mobility in the photoconductive layer increases,
Furthermore, the sensitivity of the electrophotographic photoreceptor is significantly improved due to the longer life of the carrier.

(Example) FIG. 1 is a diagram showing a cross-sectional structure of an electrophotographic photoreceptor according to an example of the present invention. 5 in the same figure, conductive support 1
A barrier layer 2 is formed thereon, and a photoconductive layer 3 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 both the charge retention layer 5 and the charge generation layer 6 have a superlattice structure.

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

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

The barrier layer 2 may be formed using μc-81 or a-81:H, or may be formed using a-BN:H (amorphous boron a>t- to which nitrogen and hydrogen are added. For example, by incorporating one or more elements selected from carbon, nitrogen, nitrogen, and oxygen into μc-8i:H and a-8i:H, a high-resistance insulation film may be used. A sexual barrier layer can be formed.

The thickness of the barrier W52 is preferably 1001 to 10 μm.

The barrier layer 2 is formed to enhance the charge retention function of the surface of the photoreceptor by suppressing the flow of charges between the conductive support 1 and the charge generation layer 5, thereby increasing the charging ability of the photoreceptor. It is something that will be done. Therefore, when forming a Carlson type photoreceptor using a semiconductor layer as a barrier layer, the barrier layer 2t
- Pi or N type. That is, when the surface of the photoreceptor is positively charged, the barrier layer 2 is made of P type to prevent electrons that neutralize the surface charge from being injected into the charge generation layer.

Conversely, when the surface is negatively charged, a barrier layer of XfN type is used.
This prevents holes that neutralize surface charges from being injected into the charge generation layer. Since the carriers injected from the barrier layer 2 become noise to the carriers generated in the charge generation layer 6 by the incidence of light, preventing carrier injection as described above also improves the sensitivity. vinegar. In addition, μc-8t:
H+a-8i: Replace H with P 凰 Next is an element belonging to Group Ⅰ of the periodic table, such as boron B, aluminum At, and flium Ga.

It is preferable to dope with indium In, thallium Tt, or the like. Also, μc-8l: H+a-8
l: To make HfN type, elements belonging to Group Ⅰ of the periodic table, such as nitrogen, phosphorus P, arsenic A6, antimony s
It is preferable to dope with B, bismuth Bi, or the like.

The charge generation layer 6 generates carriers upon incidence of light, and these carriers, of one polarity, form a band i! on the surface of the photoreceptor.
The heavy charges are neutralized, and the other one travels within the charge retention layer 5 and reaches the conductive support 1 .

Both the charge retention layer 5 and the charge generation layer 6 are constructed by alternately laminating 25i type thin films.

These thin films have different optical bandgaps, and each has a thickness in the range of 30 to 200X. In this way, by stacking thin layers with mutually different optical band gaps, the optical band gap can be adjusted based on the layer with the smaller optical band gap, regardless of the size of the optical band gap itself. A superlattice structure having periodic potential maria is formed in which the layer with a large gap is 9 ria. In this superlattice structure, the thin barrier layer is extremely thin, so due to the tunneling effect of carriers in the thin layer, carriers pass through the thin layer and travel through the superlattice structure. Furthermore, in such a superlattice structure, a large number of carriers are generated by incident light. Therefore, it has high photosensitivity. By changing the thickness of the thin layer of the superlattice structure, the apparent breadth f2 of the layer having the heterojunction superlattice structure can be freely adjusted.

a-8i constituting the charge retention layer 5 and charge generation layer 6:
The hydrogen content in H and μc-81:H is 0.
01 to 30 atoms are preferred, and 1 to 25 atoms are even more preferred. Such a hydrogen content compensates for the dangling effect of silicon, brings the dark resistance and bright resistance into balance, and improves the photoconductive properties.

To form the a-8tSH layer by the glow discharge decomposition method, silane gases such as SiH4 and 512H5 are introduced into the reaction chamber as raw materials, and H is added into the thin film by glow discharge using high frequency. Can be done.

If necessary, hydrogen or helium gas can be used as a carrier gas for the silanes.

On the other hand, silicon halide such as 5IF4ff gas and 5icz4 gas can be used as the source gas. Further, a-8l:H containing H can be similarly formed by reacting with a mixed gas of silica/silicon gas and 710 silicon gas. Note that these thin layers can be formed not by the glow discharge decomposition method but also by a physical method such as sputtering.

Similarly to a-8i:H, the μe-81 layer can also be formed using a high-frequency glow discharge decomposition method using silica/gas as a raw material. In this case, the temperature of the support is set to a-8t
: If it is set higher than in the case of Hf formation, and the high frequency power is also set as high < m than in the case of a-8i:H, μc-8l
:H becomes easier to form. Furthermore, by increasing the support acid and high frequency power, the flow rate of raw material gas such as silane gas can be increased, and as a result, the film formation rate can be increased. In addition, 5IH4 and S of the raw material gas
By using a gas obtained by diluting a high-order silane gas such as i2H6 with hydrogen, .mu.c-8i:Ht- can be formed with even higher efficiency.

In order to make μc-8l:H and a-8l:H P-type, an element belonging to Group Ⅰ of the periodic table, such as boron B,
Aluminum At, gallium Ga, indium In
.

And thallium TLh4f is preferably doped, μc-8t : H and a-8l : Hf Ninthly, an element belonging to group V of the periodic table, such as nitrogen N.

/ P t As *It is preferable to dope with antimony Sb, bismuth Bi, etc. 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-8i:H and a-8l:H, carbon C9
By containing at least 1'm of an element selected from nitrogen (N) and oxygen (O), high resistance can be achieved and the surface charge retention ability can be increased. The content of these elements is 5 to 40 atoms, preferably 10 to 30 atoms.

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

Since a-81:H and the like of the charge generation layer 6 have a relatively large refractive index of 3 to 3.4, light reflection easily occurs on the surface. When such light reflection occurs, the proportion of the amount of light absorbed by the photoconductive layer or the charge generation layer decreases, resulting in increased light loss. For this reason, it is preferable to provide the surface layer 4 to prevent reflection. Moreover, by providing the surface layer 4,
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. The material forming the surface layer is a
-8IN: H, a-8IO: H, and a-8iC
There are inorganic compounds such as :H, and organic materials such as vinyl chloride and polyamide.

When the surface of the electrophotographic photoreceptor constructed in this manner is charged with a positive voltage of about 500 V by corona discharge, a potential barrier is formed. When light (hv) is incident on this photoreceptor, carriers of electrons and holes are generated in the superlattice structure of the charge generation layer 6. Electrons in the conduction band are accelerated toward the surface layer 4 side, and holes are accelerated toward the conductive support 1 side by the electric field in the photoreceptor. In this case, the number of carriers generated at the boundaries of thin layers with different optical dimensions is much larger than the number of carriers generated in the bulk. In this superlattice structure, It has high photosensitivity.Also, due to quantum effects in the potential well layer, the lifetime of carriers is 5 to 10 times longer than in the case of a single layer without a superlattice structure. is due to bandgap discontinuity,
Although a periodic barrier layer is formed, carriers easily pass through the bias layer due to the tunnel effect, so the effective mobility of carriers is equivalent to that in the bulk, and carrier mobility is excellent.

Similarly, in the case of the charge retention layer 5, due to quantum effects, the lifetime of carriers in the potential well layer is 5 to 10 times longer than in the case of a single layer without a superlattice structure.

In addition, in the superlattice structure, a periodic barrier layer is formed due to the discontinuity of the band gear, f, but carriers easily pass through the bias layer due to the tunnel effect.
The effective mobility of the carrier is equivalent to that in the bulk, 17 and the carrier has excellent mobility. As mentioned above,
A superlattice structure in which thin layers with different optical band gaps are laminated can provide high photoconductivity and provide clearer images than conventional photoreceptors.

Referring to FIG. 2, an apparatus and a manufacturing method for manufacturing needles of the electrophotographic photoreceptor of the above embodiment by a glow discharge method will be described below. In the same figure, Gas Zenpe 21, 22, 23,
24, for example, S r H4rB2H6, H2,
A raw material gas such as CH4 is contained.

The gas in these gas cylinders is fed by a pulp 26 for flow rate adjustment.
and is supplied to the mixer 28 via a pipe 27t. A pressure gauge 25 is installed in each tank, and by monitoring the pressure gauge 25 and adjusting the pulse f26t, the flow rate and mixing ratio of each raw material goss supplied to the mixer 28 can be adjusted.

The gases mixed in the mixer 28 are supplied to a reaction vessel 29. A rotating shaft 30 is attached to the bottom 31 of the reaction vessel 29 so as to be rotatable in a vertical direction. The rotating shaft 3
At the upper end of 0, a disk-shaped support 32 has its surface aligned with the rotation axis 30.
It is fixed vertically. Inside the reaction vessel 29, 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 rotation @ 3 degrees, and this drum base 34
A heater 35 for heating the drum base is disposed inside the drum. A high frequency power source 36 is connected between the electrode 33 and the drum base 34.
A high frequency current is supplied between them. The rotating shaft 3o is rotationally driven by a motor 38. Reaction container 29
The internal pressure is monitored by a pressure gauge 37, and the reaction vessel 29 is connected via a dart pulp 38 to a suitable exhaust means such as a vacuum pump.

When manufacturing a photoreceptor using the above-mentioned manufacturing apparatus, after installing the drum base 34 in the reaction vessel 29, the r-) pulp 39 is opened and the inside of the reaction vessel 29 is heated to approximately 0.1 Torr.
Evacuate to below pressure. Then Inbe 21.22,2
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 the gas introduced into the reaction container 29 is such that the pressure inside the reaction container 29 ranges from 0.1 to 1. Set it to QTorr. Next, the motor 38 is operated to rotate the drum base 34, and the heater 35 rotates the drum base 34.
While heating to a constant temperature, a high frequency current is supplied between the electrode 33 and the drum base 34 by the high frequency power supply 36, thereby forming a gas discharge between them. As a result, a-81:H is deposited on the drum base 34. Note that N20°NH, NO□, N2. CH41C2H41
When using O2 gas, etc.! : Yoshi, carbon, oxygen, nitrogen t-a-8i : Can be contained in H.

As described above, the electrophotographic photoreceptor according to the present invention can be manufactured using a closed system manufacturing apparatus, and therefore is safe for the human body.

Next, the results of testing the electrophotographic properties of the entire electrophotographic photoreceptor according to the present invention will be described.

Test Example 1 If necessary, to prevent interference, an aluminum drum base with a diameter of 80 mm and a width of 350 mm, which has been subjected to acid treatment, alkali treatment, and sandplast treatment, is installed in the reaction vessel. The vacuum was evacuated to approximately 10-5 Torr. While heating the drum base to 250°C and rotating it at 10 rpm, 5iH4f was heated at 500 SCCM, B
2H61f st-8tH4,tl'x was introduced into the reaction vessel at a flow rate of 10, and the pressure in the reaction vessel was adjusted to f:I Torr. And 13.56
Plasma was generated by applying high frequency power of MHz to form an a-8iC:H barrier layer of pfJm on the drum substrate.

Next, SiH4, f Sumi 500 SCCM, CM4
Gas was introduced into the reaction vessel at a flow rate of t-308CCM, and a high frequency power of 400W was fully applied.
C: A thin H layer was formed. Next, the CH4 gas was set to O, and the flow rate ratio of the B2H6 gas to the SiH4 gas was 10.
Introduced into the reaction vessel at a flow rate of
i: A thin H layer was formed. By repeating this operation, 500 layers of a-8IC:H thin layer and 500 layers of a-8T:
A charge retention layer having a superlattice structure of 12 μm and consisting of a thin H layer was formed.

In addition, when forming the a-8iC:H thin layer, the flow rate of CH4 gas was gradually reduced after each thin layer was formed, and the carbon concentration was changed from 6 atoms to 2 atoms to finally reach 108 CCM. I let it happen.

Then, 5IH4,ff 100 SCCM, H,
Gas f: Introduced at a flow rate of 1.2 SLM, and setting the pressure inside the reaction vessel to 1.2 Torr, 1. A full high frequency power of 0 kW was applied to form a 1001 μc-8t:H thin layer. The crystallinity of this thin layer was 85 degrees. Next, the high frequency power is 600W! : and the same K 1001 (7)
Aa-8t:H thin layer was formed. The crystallinity of this thin layer was 65%. These operations were repeated to form a charge generation layer having a superlattice structure of 5 .mu.m and consisting of a combination of 200 .mu.a-8t:H thin layers each having different crystallinity.

Finally, both top and bottom layers were formed of a-8IC:H thin layers of 0.5 μm.

When the surface of the photoreceptor thus formed is positively charged at about 500 V and exposed to white light, this light is absorbed by the charge generation layer 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 nine photoreceptors manufactured in the Jin test example were repeatedly charged, the reproducibility and stability of the transferred images were extremely good, and the photoreceptor had excellent K and corona resistance.

It has been proven that it has excellent durability such as moisture resistance and abrasion resistance.

The photoreceptor manufactured in this manner has high sensitivity even to long wavelength light of 780 to 790 nm, which is the oscillation wavelength of a semiconductor radar. This photoreceptor was mounted on a semiconductor laser printer to form an image using the Carlson process, and even when the exposure amount on the photoreceptor surface was 25 ergσ, a clear, high-resolution image could be obtained.

Test Example 2 Except that an a-8iN:H thin layer was formed in place of the a-8iCSH thin layer, which is one of the constituent layers of the charge retention layer.
An electrophotographic photoreceptor was produced in the same manner as in Test Example 1.

Note that the a-8IN:H thin layer is made of SiH4 gas'e
500 SCCM.

The following was obtained by introducing N2 gas into the reaction vessel at a flow rate of 80 SCCM and applying 500 W of high frequency power. In this case, as each thin layer was formed, the flow rate of N2 gas was gradually reduced to 30 SCCM, and the nitrogen concentration was changed from 5 atoms to 1 atoms.

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 The carbon concentration of the a-8iC:H layer, which is one of the constituent layers of the charge retention layer, was gradually reduced at the rate shown in Figure 3 (a), (b), and (c). An electrophotographic photoreceptor was produced in the same manner as in Test Example 1 except for the following.

Images were formed using these photoreceptors in the same manner as in Test Example 1, and clear, high-quality images were obtained.

Test Example 4 The nitrogen concentration of the a-8IN:H layer, which is one of the constituent layers of the charge retention layer, was gradually reduced at the rate shown in Figure 3 (a), (b), and (c). An electrophotographic photoreceptor was produced in the same manner as in Test Example 2 except for the following.

When images were formed using these photoreceptors in the same manner as in Test Example 1, clear and high quality images were obtained.

Note that the types of thin layers constituting the charge retention layer and the charge generation layer are not limited to two types as in the above test example, but three or more types of thin layers may be laminated. It is sufficient to form boundaries between different thin layers.

According to this invention, since the optical band gear uses a superlattice structure composed of laminated thin layers with different f values, the carrier has high running properties, high resistance, and excellent charging characteristics. An electrophotographic photoreceptor can be obtained.

In particular, the present invention has the advantage that by appropriately combining the materials forming the thin layer, it is possible to obtain a photoreceptor having optimal photoconductive properties for light in any wavelength band.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an electrophotographic photoreceptor according to an embodiment of the present invention, FIG. 2 is a diagram showing an apparatus for manufacturing an electrophotographic photoreceptor according to an embodiment of the present invention, and FIG. 3 is a diagram showing elements of a thin layer. FIG. 3 is a diagram showing changes in concentration. 1st evil 2nd layer 1 (a) (c) 3) #1 (b) prisoner

Claims (10)

[Claims] (1) In an electrophotographic photoreceptor having a conductive support and a photoconductive layer, the photoconductive layer is composed of a charge generation layer and a charge retention layer, and the charge generation layer is made of microcrystalline silicon having different crystallinity. The charge retention layer is configured by alternately laminating thin films, and the charge retention layer is configured by alternately laminating amorphous silicon thin films and amorphous silicon thin films containing at least one element of carbon, oxygen, and nitrogen. An electrophotographic photosensitive member characterized in that the concentration of the element in each amorphous silicon thin film changes in the layer thickness direction. (2) The electrophotographic photoreceptor according to claim 1, wherein the thin film has a thickness of 30 to 200 Å. (3) The photoconductive layer contains at least one element selected from elements belonging to Group III and Group V of the periodic table. Photographic photoreceptor. (4) The electrophotographic photoreceptor 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. . (5) The electrophotographic photoreceptor according to claim 4, wherein the concentration of the element contained in the charge generation layer changes in the layer thickness direction. (6) The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein the charge generation layer has a crystallinity that changes in the layer thickness direction. (7) A patent claim characterized in that a barrier layer made of an amorphous material or a semiconductor material in which at least a portion thereof is microcrystallized is formed between the conductive support and the photoconductive layer. The electrophotographic photoreceptor according to item 1. (8) The electrophotographic photoreceptor according to claim 7, wherein the barrier layer contains at least one element selected from elements belonging to Group III and Group V of the periodic table. . (9) The electrophotographic photoreceptor according to claim 7 or 8, wherein the barrier layer contains at least one element selected from carbon, oxygen, and nitrogen. (10) The electrophotographic photoreceptor according to claim 1, wherein a surface layer is formed on the photoconductive layer.