JPS59212842A - Photosensitive body - Google Patents

Abstract

PURPOSE:To permit a thin film to retain high potential by forming a photosensitive body composed of an inorg. surface-modified layer, an a(amorphous)-Si type photoconductive layer, an a-SiC type electrostatic charge transfer layer, and an a-SiC type charge blocking layer. CONSTITUTION:A charge blocking layer 5 made of a-SiC hydride or fluoride doped with a comparatively large amt. of element of group IIIA of the periodic table, such as boron, is formed on a substrate 1. On this layer 5 a charge transfer layer 2 made of a-SiC hydride or fluoride contg. 10-30atomic% C and doped with a comparatively small amt. of element of group IIIA of the periodic table is formed. On this layer 2, a photoconductive layer 3 made of a-Si hydride or fluoride is formed. Further on this layer 3, an inorg. surface-modified layer 4 made of e.g. a-SiC hydride or fluoride is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to a photoreceptor, and particularly to an electrophotographic photoreceptor suitable for use with positive charging.

2. Prior art Conventionally, as an electrophotographic photoreceptor, Se, or Se and As,
Photoreceptor doped with Te, Sb, etc., ZnO or CdS
Photoreceptors, etc., in which the compound is dispersed in a resin binder are known. However, these photoreceptors have problems in terms of environmental pollution, thermal stability, and mechanical strength.

On the other hand, electrophotographic photoreceptors using amorphous silicon (a-St) as the entire matrix have been proposed in recent years. a-8i has a so-called dangling bond in which the 5i-8t bond is broken, and many localized levels exist within the energy gap due to this defect.

For this reason, hopping conduction of thermally excited carriers occurs, resulting in a small dark resistance, and photoexcited carriers are trapped in localized levels, resulting in poor photoconductivity. Therefore, the dangling bonds are filled by compensating the defects with hydrogen atoms (H) and bonding H to St.

Such amorphous hydrogenated silicon (hereinafter referred to as a-8
It is called t:H. ) has a resistivity of 108 to 109 in the dark.
Ω-m, which is about 1/10,000 times lower than that of amorphous Se. Therefore, a photoreceptor made of a single layer of a-8t:H has problems in that the dark decay rate of the surface potential is high and the initial charging potential is low.

However, on the other hand, when irradiated with light in the visible and infrared regions, the resistivity is greatly reduced, so it has extremely excellent properties as a photosensitive layer of a photoreceptor.

Therefore, in order to impart potential holding ability to this solid a-8i:H, the resistivity was reduced to 10 by doping with boron, etc.
Although it is possible to increase the resistance to 12Ω-zK, it is not easy to control the amount of boron etc. accurately. Also,
By introducing a small amount of oxygen along with boron etc.
Although it is possible to increase the resistance to about Ω-m, when this is used in a photoreceptor, the photosensitivity decreases, causing problems such as worsening of edge breakage and generation of residual potential.

In addition, photoreceptors with a-8t:H surfaces are susceptible to surface chemical stability, such as the effects of long-term exposure to the atmosphere and moisture, and the effects of chemical species generated by corona discharge. , has not been sufficiently investigated so far. For example 1
It is known that if the device is left for more than a month, it will be affected by moisture and its receptive potential will drop significantly. On the other hand, amorphous hydrogenated silicon carbide (hereinafter referred to as a-8iC:H).

), its manufacturing method and existence are -Ph1l, Mag
, VoL, 35 = (1978), etc., and its characteristics include high heat resistance and surface hardness, asi:
High dark resistivity (10-10 Ω-cr
It is known that the optical energy gap changes over a range of 1.6 to 2.8 eV depending on the carbon content. However, the inclusion of carbon widens the bandgap, resulting in poor long-wavelength sensitivity.

An electrophotographic photoreceptor combining such a-8iC:H and a-8i:H has been proposed, for example, in Japanese Patent Laid-Open No. 127083/1983. According to this, a-8t: The upper layer is a photosensitive (photoconductive) layer, and the a-8i layer is below this photoconductive layer.
C: Create a functionally separated two-layer structure with the upper layer as a charge transport layer, obtain photosensitivity in a wide wavelength range from the upper layer a-8i:H, and from the a-8t: upper layer. The lower layer a-SiC:H forming the terror junction is used to improve the band N and potential. However, the dark decay of the a-8i:H layer cannot be sufficiently prevented, the charging potential is still insufficient and it is not practical, and the a-8t:H layer is present on the surface. This leads to poor chemical stability, mechanical strength, heat resistance, etc. Moreover, the carbon atom content of the charge transport layer has not been studied, and the thickness of each layer has also been taken into account, so it has not been possible to satisfy the physical characteristics required for an electrophotographic photoreceptor. Not yet.

On the other hand, JP-A-57-17952 discloses a-8i:
A first a-8iC:H layer is formed as a surface modification layer on the photoconductive layer consisting of H, and on the back surface (support electrode ml!l)
A second a-8iC:H layer is formed as a charge transport layer to provide a functionally separated three-layer photoreceptor.

Although this known photoreceptor has the effect of preventing dark decay of the a-8t:H layer, no study has been made on the carbon atom content of the a-8iC:H layer, especially the charge transport layer. a-8i: Sensitivity decreases depending on the bonding state with the H layer, residual potential also increases, and does not have the durability to withstand multiple copies.

3. Purpose of the Invention The present inventor has made extensive studies on the problems of the prior art as described above, and has devised a photoreceptor with a novel structure that has the features of a functionally separated photoreceptor such as the three-layer structure described above. In particular, it is important to find out that the carbon atom content of the charge transport layer and the impurity concentrations of the charge transport layer and charge blocking layer greatly affect the characteristics of the photoreceptor, and to set the carbon atom and impurity contents within appropriate ranges. As a result, we have succeeded in obtaining a photoreceptor that is excellent in photosensitivity, residual potential, potential holding ability, durability, etc. especially when positively charged.

4. Structure of the Invention That is, the present invention comprises a photoconductive layer made of amorphous hydrogenated and/or fluorinated silicon (e.g. a-8t:H), and an inorganic material (particularly a-8t:H) formed on the photoconductive layer. 8
amorphous hydrogenated and/or fluorinated silicon carbide (e.g. aSiC: H) and a charge transport layer formed under the charge transport layer and having a charge transport layer of Tll of the periodic table.
Amorphous hydrogenated and/or fluorinated silicon carbide doped with relatively large amounts of Group A elements (e.g. a-8iC:
H), and the charge transport layer has a carbon atom content of 10 to 30 atomic
%.

5. Examples Hereinafter, the photoreceptor according to the present invention will be illustrated in detail.
The progress that led to the present invention will be explained.

The photoreceptor shown in FIG.
It consists of a C:H layer (charge transport layer) 2, an a-8i:H layer (photoconductive layer) 3, and an a-8iC:H layer (surface modification layer) 4 laminated in this order.

The a-8iC:H layer 2 mainly has the functions of holding potential, transporting charges, and improving adhesion to the substrate 1, and its carbon atom content is 10 to 30 atomic% (St and C
It is important to set the ratio to the total number of atoms), and it is preferable to form the door with a thickness of 10 μrn to 30 μrn. The photoconductive layer 3 generates charge carriers in response to light irradiation, and has a thickness of 2,500 mm.
It is desirable that the thickness is A~5 μm. Furthermore, a-8iC:H
Layer 4 improves the surface potential characteristics of this photoreceptor, maintains the potential characteristics over a long period of time, maintains environmental resistance (prevents the effects of humidity, atmosphere, and chemical species generated by corona discharge), and has high surface hardness. It has functions such as improved printing durability, improved heat resistance when using a photoreceptor, and improved thermal transferability (especially adhesive transferability).
It functions as a surface modification layer, so to speak. And Koo
a-8iC: H layer 4 thickness t 400X ~ 5oo
oX.

In particular, it is important to make it much thinner than the conventional one, 400A≦t (2000A).

By configuring the photoreceptor in this way, the conventional Se
Compared to photoreceptors, it maintains a high potential with a film thickness that is even thicker, exhibits excellent sensitivity to light in the visible and infrared regions, has good heat resistance and printing durability, and has stable environmental resistance. have a-8
This makes it possible to provide a t-type photoreceptor (for example, for electrophotography).

Moreover, what is noteworthy is that by setting the carbon atom content of the charge transport layer within a specific range of 10 to 30 atomic%, the photoreceptor has more than enough mechanical properties. be. This revision will be explained in detail below.

First, it has been confirmed that the optical energy gap (Ep, opt) of a-8iC:H generally increases as the carbon atom content increases, as shown in FIG. This Et corresponds to the band gap, and as the carbon atom content increases, the a
It can be seen that the difference between −8t:H and Et (approximately 1.71 eV) becomes large.

On the other hand, the carbon atom content is <a-8iC as shown in Figure 3.
:H affects the specific resistance (ρD = resistivity in the dark, ρG: resistivity when irradiated with green light), and if the carbon content (i.e. Ef) is increased, the photosensitivity (ρD/ρ0) decreases above a certain range. The result will be as shown in Figure 4. When the wavelength of the irradiated light is changed, as shown in Figure 5, a-8iC:H
light sensitivity changes.

FIG. 6 shows the energy band of the photoreceptor having the layer structure described in FIG. In this energy band diagram, as described above, the carbon atom content of the charge transport layer 2 is 1
0 to 30 atomic % (15 a in the example shown)
tomic %: By = 2.1 eV), the Et of the charge transport layer 2 itself has an appropriate size, and the Et of the a-8i:H layer 3 (I
In particular, the interface with J 1.71 eV) forms a band gap that does not substantially form a barrier to electrons. That is, when the surface of this photoreceptor is operated with a negative charge, holes indicated by the 0 mark are injected from the base 1 side as shown by the dashed line, but these holes are a-8iC:
The energy barrier of the valence span EV of the H layer 2 cannot be overcome, and as a result, negative charges on the surface of the photoreceptor are sufficiently retained, dark decay is reduced, and potential retention ability is improved. Moreover, among the carriers (holes indicated by Q, electrons indicated by .) generated in the photoconductive layer 3 during light irradiation,
For electrons, the conduction band Ec is shown as a dotted line through the a-8iC:H layer 2 because there is almost no barrier between layers 2 and 3 (that is, the matching of energy levels is good). Thus, the holes can easily move toward the substrate 1 side, and the holes can also easily move toward the surface side through the thin surface layer 4 to selectively neutralize surface negative charges and efficiently form an electrostatic latent image. Therefore, this photoreceptor has good photosensitivity in addition to the above-mentioned potential holding ability.

In order to obtain these remarkable effects, especially the charge transport layer 2
It has become clear that the carbon atom content of 10 to 30 atomic% must be specified. That is, when the carbon atom content is less than 10 atomic 1, a -
8iC: The specific resistance of H layer 2 is 10Ω- which is necessary for potential holding ability.
In particular, since the charging potential is insufficient because the cnl is worn (see Fig. 3), it is inappropriate. Also, the carbon atom content is 3
If it exceeds 0 atomic %, the specific resistance will decrease considerably, and at the same time, the number of defects in the a-8iC:H layer will increase due to too many carbon atoms, resulting in poor carrier transport ability itself.

Further, in the photoreceptor shown in FIG. 1, the photoconductive layer 3 contains the first
■It is also important that no impurities such as Group A are doped. However, as in the prior art, the a-8t:H layer is doped with impurities to increase its resistance (ρ, = 10
~10 Ω-crn), impurity doping lowers the electron carrier range (μτ) e1 (mobility lifetime), which causes the optical attenuation curve to tail, resulting in lower sensitivity and lower image quality. I end up. FIG. 7 shows the optical attenuation characteristics of the above-mentioned photoreceptor in which the photoconductive layer 3 is not doped with impurities. When doping (for example, (B2H6)/CSiH4 in the glow discharge method described later) = 20 pp
m), it was found that the attenuation curve tailed during light irradiation.

The present inventor has discovered that although the functionally separated photoreceptor with the three-layer structure shown in FIG. 1 has the remarkable advantages described above, it also has the following problems. I stopped.

That is, as understood from the energy band diagram of FIG. 6 and the above explanation, the photoreceptor shown in FIG. 1 is a photoreceptor for negative charging, and has low charging ability and dark decay for positive charging. It gets bigger. As is clear from Figure 6, for example, when the carbon atom content of the charge transport layer 2 is 15 at.
omic %, Er, opt 2.06eVf6 le/, ji? When the surface of the light body is used with a positive charge, electrons are easily injected from the substrate 1 side, exceeding the Ec of the charge transport layer 2, neutralizing the positive charge on the surface and attenuating the surface potential. Easy to do. Moreover, among the carriers generated in the photoconductive layer 3 during light irradiation, the holes are the EvO between both layers 3-2.
It becomes difficult for energy to move from the photoconductive layer 3 to the charge transport layer 2 due to energy gap or barrier (△E) (
Ey of a-8t, opt is 1.71 eV, a-
Ey of 8iC, opt is 2.06 eV).

For these reasons, the above-mentioned photoreceptor has poor charging ability during positive charging, has a large amount of dark decay, and has poor photosensitivity, so only the attenuation curve shown in Figure 9 can be obtained, making it unsuitable for use in positive charging. be.

Therefore, as shown in FIG. 10, in order to prevent the injection of electrons from the substrate 1 in the photoreceptor shown in FIG.
It has been considered to provide a boron-doped P-type a-8iC:H layer 5 between the substrate 1 and the substrate 1 as a charge blocking layer. As a result, as shown in FIG. 11, it is possible to prevent the injection of electrons from the substrate 1 and maintain the positive charge on the surface of the photoreceptor (that is, to reduce dark decay), but this is similar to the above. The energy barrier (ΔE) causes poor photosensitivity, and as shown in FIG. 12, the surface potential tails when irradiated with light.

As a result of intensive study of the above-mentioned problems that occur during positive charging, the inventors of the present invention found that it is inappropriate to simply provide a charge blocking PA5 to prevent carrier injection. It has been recognized that it is necessary to take effective means to efficiently move holes generated during irradiation to the charge transport layer 2 side.

As such a means, one idea is to reduce the carbon content of a-8iC:H constituting the charge transport layer 2 based on the data shown in FIG. 2 to reduce the ΔE between both layers 3-2. However, for this purpose, the carbon atom content must be 10 atoms.
Since it is necessary to significantly reduce c to less than 96, the resistance of the a-8iC:H layer 2 becomes low and the charging potential of the photoreceptor is significantly lowered.

The present inventor has determined that the carbon atom content of the a-8iC:H layer 2 is 1 in order to achieve EV level matching between both layers 3-2.
The above-mentioned problems can be solved by doping a comparatively small amount of Group 1nA elements of the periodic table into the a-8iC:H layer 2 while keeping the charging properties and transportability at 0 to 30 atomic %. They discovered that the problem could be solved satisfactorily and arrived at the present invention.

That is, although the photoreceptor according to the present invention has the basic layer structure shown in FIG. a-8iC:H for charge blocking while doping with a small amount
The layer 5 is doped with a relatively large amount of a group HA element of the periodic table (for example, poron), and the carbon atom content of the a-8iC:H layer 2 is maintained at 10 to 30 atomic %. 0 As a result, as shown in FIG.
b. It is possible to sufficiently match the energy levels between the two layers. This allows holes generated in the photoconductive layer 3 during light irradiation to be smoothly injected into the charge transport layer 2. In addition, the presence of the charge blocking layer 5 can also effectively block electron injection from the substrate 1.

In this way, as shown in FIG. 14, it became possible for the first time to obtain a photoreceptor exhibiting sufficient attenuation characteristics for positive charging use. That is, in this photoreceptor, the photosensitivity is increased, the residual potential is reduced, and the optical attenuation curve does not tail), and the charged potential can be maintained at a high level.

Note that the carbon atom content of the above a-8iC:H layer 2 is 1
0 to 30 atomic units (e.g. 15 atomic units)
However, in addition to the above-mentioned reasons (i.e., retention of charged potential and improvement of transport ability), this is based on reasons specific to positive charging. However, if the carbon content is increased to more than 30 atomic %, the energy gap will be widened, and it will be necessary to increase the amount of poron doping in order to match the energy level related to Ev.

However, if a large amount of poron is doped in this way, the resistance will be lowered more than necessary, resulting in poor charging characteristics.Additionally, it will be difficult to control the doping amount, and the energy level matching with the photoconductive layer will become worse. And it becomes 9 difficult.

In order to obtain the photoreceptor according to the present invention illustrated in FIG. 13, the amount of boron doped in each of the a-8iC:1 layers 2 and 5 is important as described above. In particular, the charge transport layer controls the flow rate ratio of diborane and monosilane to CB2ae)/(5iH4
) = 5 to 100 ppm (for example, 10 ppm), and the charge blocking layer has a flow rate ratio of diborane to monosilane of (B2H6)/[ SiH,
) = 200-2000 ppm (e.g. 1010
It is desirable that the material be formed into a P type by glue discharge decomposition under conditions of 00 pp.

Next, each layer of the photoreceptor according to the present invention will be explained in more detail.

First a-8iC: H layer (surface modified layer) This a-8iC
:H layer 4 is indispensable for modifying the surface of the photoreceptor and making the a-8t-based photoresistance practically excellent. That is, it enables the basic operations of an electrophotographic photoreceptor, such as charge retention on the surface and attenuation of the surface potential due to light irradiation. Therefore, the repetitive characteristics of charging and optical attenuation are very stable, and good potential characteristics can be reproduced even if left for a long period of time (for example, one month or more).

On the other hand, in the case of a photoreceptor having a-8i:H as its surface, it is easily affected by humidity, air, ozone atmosphere, etc., and the potential characteristics change significantly over time. Also, a-8iC:H
Because of its high surface hardness, it has good abrasion resistance during processes such as development, transfer, and cleaning, and also has good heat resistance, so it can be applied to processes that apply heat such as adhesive transfer.

In order to achieve such excellent effects comprehensively, a-
8iC:H layer 4 has a thickness of 400A≦t (50
It is extremely important to select within the range of 00A (especially 400A≦t (2000A). In other words, the film thickness should be 50A).
If it is more than 000 A, as shown in FIG. 15, the residual potential vR will be too high and the sensitivity EV2 (described later) will be lowered, and the good characteristics as an a-8i type photosensitive will be lost. In addition, if the film thickness is less than 400A, charges will not be charged on the surface due to the tunnel effect, so it is preferable to set it to 400X or more (less than the increase in dark decay), but such a thickness range is conventionally known. This is completely unimaginable from this technology.

Furthermore, regarding the a-8iC:H layer 4, it was found that it is also important to select its carbon composition in order to exhibit the above-mentioned effects. If the composition ratio is expressed as a-8il-xcx:H, then X is 0.1 to 0.7 (carbon atom content is 10 atomic% to 70 atomic%).
%) is desirable. That is, if 0.1≦X, the optical energy gap is approximately 2. At OeV or higher, the irradiated light reaches the a-8t:H layer (charge generation layer) 3 due to the so-called optically transparent window effect for visible and infrared light (Figure 4, Diagram 5). vice versa! <
If it is 0.1, part of the light will be absorbed by the surface layer 4, and the photosensitivity of the photoreceptor will tend to decrease. Furthermore, if X exceeds 0.7, most of the layer will be carbon, and not only will the semiconductor properties be lost, but the deposition rate will decrease when forming the a-8iC:H film by the glow discharge method. , X≦0.7.

Second a-8iCSH layer (N transport layer) This a-8iC
:1 layer 2 has both the functions of potential retention and charge transport, has a dark resistivity of 10 Ω-m or more, has high electric field resistance, and has a high potential retained per unit film thickness. In addition, the impurity doping (light doping) described above can reduce the barrier to holes injected from the photosensitive layer 3, allowing holes to efficiently transfer to the support 11 with large mobility and lifetime.
Transport to 1111. In addition, the composition of carbon (10 to 30
Since the size of the energy gap can be adjusted by changing the energy gap (atomic%), holes generated in the photosensitive layer 3 in response to light irradiation can be efficiently injected without creating a barrier. Therefore, this a-8iC:1 layer 2 maintains a high surface potential at a practical level, and 'a-8i:H
It has the function of efficiently and quickly transporting the charge carriers generated in the layer 3, resulting in a photoreceptor with high sensitivity and no residual potential.

In order to fulfill these functions, the film thickness of the a-8iC:H layer 2 is preferably 10 μm to 30 μm in order to apply a dry development method using the Carlnon method, for example.

If the film thickness is less than 10 μm, it is too thin and the surface potential necessary for development cannot be obtained, and if it exceeds 30 μm, the rate at which the carrier reaches the support 1 decreases. However, even if the film thickness of this a-8iC:H layer is made thinner (for example, 10-odd μm) than that of the Se photoreceptor, a surface potential at a practical level can be obtained.

a-8i: H layer (photoconductive layer or photosensitive layer) a-8i:
The H layer 3 has high photoconductivity for visible light and infrared light, and as shown in FIG.
ρD/ρL is maximum ~10 for red light in the vicinity.

By using this a-8i:H as a photosensitive layer, it is possible to create a photoreceptor that is highly sensitive to light in the entire visible region and in the infrared region.

In order to absorb visible light and infrared light without waste and generate charge carriers, the thickness of the a-8i:H layer 3' is preferably 25,001 to 5 μm.

If the film thickness is less than 2500 A, all of the irradiated light will not be absorbed and a portion will reach the underlying a-8iC:H layer 2, resulting in a significant decrease in photosensitivity. Also, a-8t:H
Layer 3 has a large charge transport ability but a resistivity of ~109
Ω-m and does not have potential retention properties by itself, so there is no need to make the photosensitive layer thicker than necessary for light absorption, and a maximum thickness of 5 μm is sufficient. . Furthermore, if the thickness exceeds 5 μm, carriers tend to diffuse laterally in the layer, resulting in a decrease in sensitivity.

Third a-8iC: HM (Charge Blocking Layer) This blocking layer 5 is to block the injection of electrons from the substrate 1, and to form the necessary energy gap difference between the substrate 1 and the substrate 1. , is heavily doped (heavy doping) with Group 111A elements of the periodic table. Since this blocking layer is made of the a-8iC:H layer, it has the characteristics of good adhesion to the substrate 1 and good film adhesion.

This blocking layer 5 is preferably provided with a thickness of 4008 to 1 μm in order to fully exhibit its function. 400
If it is less than A, it will be too thin and the blocking function will deteriorate, and the thickness will be 1μ.
If it exceeds m, the layer itself becomes thick and has a low resistance, making it easy for carriers to diffuse in the lateral direction.

Further, the carbon atom content in the blocking layer 5 is 10 to 3
It is desirable to set it to 0 atomic fy.

Next, an apparatus (glow discharge apparatus) that can be used to manufacture a photoreceptor according to the present invention will be described with reference to FIG.

In the vacuum chamber 12 of this apparatus 11, the above-described substrate 1 is fixed on a substrate holding part 14, and the substrate 1 can be heated to a predetermined temperature with a heater 15. A high frequency electrode 17 is arranged opposite to the substrate 1, and a glow discharge is generated between the high frequency electrode 17 and the substrate 1. In addition, 20.21.22.23 in the diagram
, u125.27.2B, 29.30.35.36.3
8.39 is each pulp, 31 is a source of S i H4 or a gaseous silicon compound, 32 is a source of CH or a gaseous carbon compound, 33 is a carrier gas source such as Ar or H2, 34 is B, H6 supply source, 37 is SiF4 gas supply source (fluorine supply source). In this glow discharge device, first, the surface of a support such as an AL substrate is cleaned, and then placed in a vacuum chamber 12, and the pulp 36 is adjusted so that the gas pressure in the vacuum chamber 12 is 10 Torr. The air is evacuated, and the substrate 1 is heated and maintained at a predetermined temperature, for example, 200°C. Then, using a high purity inert gas as a carrier gas, SiH4 or a gaseous silicon compound and CH
, or a mixed gas prepared by diluting an appropriate amount of gaseous carbon compound is introduced into the vacuum chamber 12 together with B2H if necessary.
High frequency power is applied to the high frequency power supply 16 under a reaction pressure of 1 to 10 Torr. As a result, each of the above reaction gases is decomposed by glow discharge, and boron-doped a-8i containing hydrogen is decomposed.
a-8i which further contains hydrogen with C:H as the above layer 5.2
C:H is deposited on the substrate 1 as layer 4 above. At this time, by appropriately adjusting the flow rate ratio of the silicon compound and the carbon compound and the substrate temperature, a-Si I-xCx having a desired composition ratio and optical energy gap:
H (for example, up to about 0.9) can be precipitated, and the &- It is possible to deposit 8iC:H. Furthermore, in order to deposit a-8i:H (photosensitive layer 3 above), the silicon compound may be decomposed by glow discharge without supplying the carbon compound.

Both a-8iC:H layers 5.2.4 above need to contain hydrogen, but if they do not contain hydrogen, the charge retention characteristics of the photoreceptor will not be practical. . Therefore, the hydrogen content is 10-30 atomic
It is desirable that the If it is less than 10 atomic degrees, the compensation for dangling bonds is insufficient, and 30
If it exceeds atomic%, defects are more likely to occur.The hydrogen content in the photoconductive layer 3 is essential to compensate for dangling bonds and improve photoconductivity and charge retention, and is usually ~3°atomic% is desirable for the same reason as above.In addition, in order to compensate for dangling bonds, a-8
For t, fluorine is introduced into the above-mentioned H substitute 9 or in combination with H (supply source is S i F4), a-8
t:F, a-8t:H:FXa-8iC:F,a-8i
It can also be set as C:H:F. In this case, the amount of fluorine is preferably 0.5 to 10 atomic%.

The above manufacturing method is based on the glow discharge decomposition method, but other methods include sputtering method, ion blating method, and vapor deposition of a-8i under the introduction of activated or ionized hydrogen with a hydrogen discharge tube. (In particular, the method of
The above photoreceptor can also be manufactured by the method of No. 52455).

The reaction gases used are SiH4, SiF, and Si2.
H6, SiHF3 or its derivative gas, other than CH4
, H6, C', H.

Lower hydrocarbon gases such as CF4 and CF4 can be used.

Next, an example in which the present invention is applied to an electron η-high light body will be specifically described.

An electrophotographic photoreceptor having the structure shown in FIG. 10 was prepared on an At support by glow discharge decomposition. First, a clean M support with a smooth surface was placed in a reaction (vacuum) chamber of a glow discharge device. The inside of the reaction tank was evacuated to a high degree of vacuum on the order of 106 Torr, the support was heated to 20θ°C, high purity Ar gas was introduced, and the frequency was set at 13.5 Torr under a back pressure of 0.5 Torr.
56 MHz s Power density 0.04'II/cdl
F) High frequency power was applied and preliminary discharge was performed for 15 minutes.

Next, a reaction gas consisting of SiH4 and C1(4 and B2'H) was introduced, and the flow rate ratio was adjusted (Ar+SiH,+
CH4+B2H11) a-8iC:H, which plays a charge blocking function by decomposing the mixed gas by glow discharge
An a-stcrH layer having a potential holding and charge transporting function was formed to a predetermined thickness at a deposition rate of asOX/min.

To form the a-8i:H photosensitive layer, after the reaction layer is once evacuated, CH4 is not supplied and SiH4 is discharge decomposed using Ar as a carrier gas to form the a-St:H photosensitive layer of a predetermined thickness. Formed. After that, CH was supplied again, the flow rate ratio was adjusted, and the mixed gas (Ar + SiH4 + CH4) was decomposed by glow discharge, and an a-8iC:H surface modification layer of a predetermined thickness was further provided, and the electrophotographic photoreceptor was completed.

The thus prepared photoreceptor was subjected to 6" corona discharge with positive polarity, and various electrophotographic characteristics were measured. In this case, each sample (sample 41 to 15), the results shown in FIG. 17 were obtained.

In this test, the electrophotographic photoreceptor prepared as described above was attached to an electrometer SP-428 model (manufactured by Kawaguchi Denki@), and the voltage applied to the discharge electrode of the charger was set to +6 KV for 10 seconds. If 'r4i, the charged potential on the surface of the photoreceptor immediately after this charging operation is set as Voff), and after 5 seconds of dark decay, the amount of irradiation light required to falsely attenuate the charged potential is halved by the exposure amount E.
'/2 (1uc*sec). The light attenuation curve of the surface potential becomes 7 lats at a certain finite potential, and may not become completely zero, but this potential is defined as the residual potential vR (v
). Regarding the image quality, the photoreceptor was made into a drum shape, and the electrophotographic copying machine U-
ixV (manufactured by Konishi Roku Photo Industry ■), an image was printed, and the initial image quality (image quality after 1000 copies) and the image quality after multiple uses (image quality after 200,000 copies) were evaluated as follows.

Image acidity 1.0 or more ◎ (Very good image quality) 0.
6 to 1.0 0 (Good image quality) Less than I 096 Δ (Blurry occurs in the image depth) It can be seen that the sample plate 2 of the present invention, which has an impurity-doped structure, exhibits superior characteristics compared to sample plate 1 which is not doped with impurities. In addition, as is clear from samples A3-Black 6 and AI2-15, the doping amount of the blocking layer was changed to CB2H.
a)/(SiH4:] = 200~2000pp
m, and dope the charge transport layer from 5 to 1100p.
If it is set to p, it is possible to significantly improve the durability when copying a large number of sheets while maintaining the photosensitivity and residual potential at favorable values. Furthermore, it can be seen that it is important to set the composition, thickness, etc. of each layer within the above-mentioned desirable ranges.

6. Effects of the Invention As described above, the present invention provides a surface-modified layer made of an inorganic material, an a-8i-based photoconductive layer, an a-8iCi charge transport layer, and an a-8i Ci charge transport layer.
Since the photoreceptor is composed of a laminate with an 8iCi charge blocking layer, it maintains a high potential with a thin film thickness, exhibits excellent sensitivity to light in the visible and infrared regions, and has excellent heat resistance and
a-8i with good printing durability and stable environmental resistance
This makes it possible to provide a system with poor sensitivity (for example, for electrophotography).

In addition, level matching with the photoconductive layer can be achieved by doping the charge transport layer with impurities, making it possible to increase photosensitivity by smoothing the movement of photocarriers, while increasing the amount of impurity doping in the charge blocking layer. Since the energy barrier against undesired injected carriers is increased, the ability to hold the charged potential and the effect of preventing dark decay can be enhanced.

What is noteworthy is that by setting the carbon atom content of the charge transport layer within a specific range of 10 to 30 atomic %, it is possible to improve the characteristics required for photoreceptors (especially high sensitivity, low residual potential, and high potential retention). Noh, repeated 1llil Kusumi)
It will be fully equipped with the following.

[Brief explanation of the drawing]

1 to 12 illustrate the present invention. FIG. 1 is a cross-sectional view of a part of an electrophotographic photoreceptor, and FIG. 2 is an optical diagram of a-8iC:H depending on the carbon atom content. Graph showing changes in energy gap, Figure 3 shows changes in specific resistance of a-8iC:H due to optical energy gap, Figure 4 shows changes in a-8iC:H resistivity due to optical energy gap.
A graph showing the photosensitivity characteristics of 8iC:H, Fig. 5 is a graph showing a comparison of photosensitivity characteristics depending on the wavelength of irradiated light, Fig. 6 is an energy band diagram of each layer of the photoreceptor, and Fig. 7 is a graph showing the photosensitivity characteristics of the photoreceptor. Potential attenuation characteristic diagram, Figure 8 is a potential attenuation characteristic diagram of another photoreceptor, Figure 9 is a potential attenuation curve diagram of the photoreceptor in Figure 1 when positively charged, and Figure 10 is a part of another photoreceptor. 11 is an energy band diagram of each layer of the photoconductor in FIG. 10, FIG. 12 is a potential attenuation curve diagram of the photoconductor in FIG. 10 when positively charged, and FIGS. 13 to 17 are the main FIG. 13 is an energy band diagram of each layer of the photoreceptor, and FIG. 14 is a diagram illustrating the invention.
The figure is a potential attenuation curve of the photoreceptor during positive charging, Figure 15 is a graph showing characteristic changes depending on the thickness K of the surface modification layer, Figure 16 is a schematic cross-sectional view of the photoreceptor manufacturing equipment, and Figure 17 is FIG. 3 is a diagram collectively showing the characteristics of various photoreceptors. In addition, in the symbols shown in the drawings, 1-------
- One support (substrate) 2 ------- a -S i C: H layer (charge transport layer) 3 ------- a - S i : H photosensitive layer (photoconductive layer) 4 - ------- a-8iC: H layer (surface modified layer) 5 ------- First blocking layer 11 -
------- Glow discharge device 17 ------- High frequency electrode 31 ------- Gaseous silicon compound supply shaft 3: L
-------- Gaseous carbon compound supply source 33-1---
--Carrier gas supply source 34----, B, H,
Supply source 37 ---------8iF4 supply source By, opt --- Optical energy gap ρD/ρG ---Dark resistivity/Resistivity during light irradiation EH
--- One-half exposure amount VR --- One-- Residual potential. Figure 1 Figure 6 Figure 9 Time (luxury) Figure 10 Exchange figure 11 Figure 12 Time (remainder 0 Figure 13 also 141 sword thickness (, uR) (self-proposed) Procedure 7 City official book January 1982 2 days), Indication of the incident 1988 Patent Side beam No. 86893 2, Name of invention Photoconductor 3, ? Relationship with the case of a person who commits iti rectification Patent applicant address: 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name:
(127) Roku Konishi Photo Industry Co., Ltd. 4, Agent 6, Number of inventions increased by amendment 7, Detailed explanation of the invention in the specification subject to amendment 8, Contents of amendment fil, Specification page 26 bottom "About 0.9" on the 5th line
First, correct it to "about 0.3 or 0.7." (2), ``5 seconds'' on page 30, line 6, 1-2 seconds''
I will correct it. One or more -

Claims (1)

[Claims] 1. A photoconductive layer made of amorphous hydrogenated and/or fluorinated silicon, a surface modification layer formed on this photoconductive layer and made of an inorganic substance, and a surface modification layer formed below the photoconductive layer. a charge transport layer made of amorphous hydrogenated and/or fluorinated silicon carbide doped with a relatively small amount of a Group HA element of the periodic table; A photoreceptor comprising a charge blocking layer made of heavily doped amorphous hydrogenated and/or fluorinated silicon carbide, and wherein the charge transport layer has a carbon atom content of 10 to 30 atomic atoms. 2. The charge transport layer is formed by glow discharge decomposition under conditions where the flow rate ratio of diborane and monosilane is CBtHa:]/[5iH4) = 5 to 1100 pp), and the charge blocking layer is The flow rate ratio of diborane and monosilane is (B2H6) / C5iH4) = 2
The photoreceptor according to claim 1, which is formed into a P type by glow discharge decomposition under conditions of 00 to 2000 ppm. 3. The hydrogen atom content of the charge transport layer is 10 to 30 ato
The photoreceptor according to claim 1 or 2, wherein the photoreceptor has a fluorine atom content of 0, s to 10 atoznic % if it contains fluorine atoms. 4. Hydrogen atom content of the photoconductive layer is 10 to 30 atoms
ic% (if it contains fluorine atoms, the fluorine atom content is 0.5 to 10 atomic%), as set forth in any one of claims 1 to 3. 5. The photoreceptor according to any one of claims 1 to 4, wherein the surface modification layer is made of amorphous hydrogenated and/or fluorinated silicon carbide. 6. The carbon atom content of the surface modified layer is 10 to 70 ato
Microchip, hydrogen atom content is 10-30 at
The photoreceptor according to claim 5, which has a fluorine atom content of 0.5 to 10 atomic% when containing 7 fluorine atoms. 7. The carbon atom content of the charge blocking layer is 10 to 30
atomic%, and the hydrogen atom content is 10 to 30
atomic f& (if it contains fluorine atoms, the fluorine atom content is 0.5-10 atomic f&)
Any one of claims 1 to 6, which is
Photoreceptor described in section. 8. The thickness of the surface modification layer is 400A to 5000A, the thickness of the photoconductive layer is 2500A to 5 μm, the thickness of the charge transport layer is 10 μm to 30 μm, and the thickness of the charge blocking layer is 40 μm.
Items 1 to 70 of the scope of claims, which are 0A to 1 μm.
1. The photoreceptor described in any one of 1. 9. The photoreceptor according to claim 8, wherein the surface modified layer has a thickness of 400 Å to 200 OA.