JPS6381441A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide high dark resistance and negative chargeability by forming a specified photoconductive amorphous silicon carbide layer contg. 0-10,000ppm group Va element of the periodic table on a substrate. CONSTITUTION:A photoconductive amorphous silicon carbide (a-SiC) layer 5b is formed on a substrate 1. The a-SiC layer 5b is composed essentially of a first layered region 6, a second layered region and a third layered region 8 arranged in this order from the substrate 1 side toward the surface of the resulting sensitive body. The third region 8 contains a larger amount of C than the second region 7. The second region 7 contains 0-10,000ppm group Va element in the periodic table, and the first region 6 contains a larger amount of the group Va element than the second region 7. The resulting sensitive body is made especially negatively chargeable, high dark resistance and superior photosensitivity are provided, and a protective surface layer and a carrier injection blocking layer are made practically unnecessary.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrophotographic photoreceptor comprising a photoconductive amorphous silicon carbide layer, and particularly to an electrophotographic photoreceptor that can be charged to a negative polarity.

[Prior art and its problems]

In recent years, progress in electrophotographic photoreceptors has been remarkable, and with the development of copying machines, printers, etc. equipped with photoreceptors, various characteristics are required of the photoreceptors themselves.

In response to this demand, amorphous silicon layers are attracting attention because they have excellent heat resistance, wear resistance, non-pollution properties, and photosensitivity characteristics.

However, the amorphous silicon (hereinafter abbreviated as a-5i) layer cannot obtain a dark resistance value of about 10'Ωcm unless it is doped with any impurity element, and this is used in electrophotographic photoreceptors. When used, it is necessary to increase the charge retention ability by setting the dark resistance value to 1°12 Ω·cm or more. For this purpose, it is possible to increase the resistance by doping a small amount of elements such as oxygen or nitrogen, but on the other hand, there is a problem that the photoconductivity decreases.

Further, even if boron or the like is added, a high resistance can be expected, but a sufficiently satisfactory dark resistance value cannot be obtained and is only about 10 days Ω·cm.

On the other hand, along with the development of doping agents as mentioned above, a-Si
A laminated photoreceptor has been proposed in which a photoconductive layer is laminated with another non-photoconductive layer.

For example, Figure 2 shows this laminated photoreceptor, with the substrate (1)
A carrier injection blocking layer (2), an a-Si photoconductive layer (3) and a surface protection layer (4) are sequentially laminated thereon.

According to this laminated light body, the carrier injection blocking layer (2) blocks injection of carriers from the substrate (1), and the surface protection layer (4) blocks the a-Si photoconductive layer (3). It protects and improves moisture resistance etc., but both layers (2)
The purpose of both (4) and (4) is to increase the dark resistance value of the photoreceptor to increase the charging ability, and for that purpose, it is not necessary to make these layers photoconductive.

As described above, the conventionally well-known a-Si electrophotographic photoreceptor has a major feature in that the photocarrier generation layer is formed of an a-Si photoconductive layer, and as a result, it has excellent heat resistance, durability, and photosensitivity characteristics. However, since the dark resistance value is insufficient, the dark resistance value is increased by using a doping agent or by forming a laminated type photoreceptor. That is, carrier injection prevention 1'i formed on the laminated photoreceptor
(2) and the surface protective layer (4) complement the defects of the a-Si photoconductive layer itself, and can be said to be layers that can be substantially distinguished from the a-5t photoconductive layer (3).

[Purpose of the invention]

In view of the above circumstances, the present inventors have conducted intensive research and found that amorphous silicon carbide (hereinafter abbreviated as a-SiC)
It has photoconductivity and the dark resistance value easily becomes 10'3 Ωcm or more regardless of the presence or absence of a doping agent, and furthermore, it can be made into an electrophotographic photoreceptor that can be charged to a negative polarity depending on the selection of the doping agent. I found it.

Therefore, the present invention was completed based on the above findings, and its purpose is to provide a photoconductive a-S having a large dark resistance value.
An object of the present invention is to provide an electrophotographic photoreceptor made of iCN.

Another object of the present invention is to provide an electrophotographic photoreceptor that substantially eliminates the need for a surface protective layer and a carrier injection blocking layer and is made of photoconductive a-5iC throughout the entire layer.

Still another object of the present invention is to provide an electrophotographic photoreceptor that can be negatively charged.

[Means for solving problems]

According to the present invention, O to 10. OOOppm
Provided is an electrophotographic photoreceptor capable of being charged to a negative polarity, which is characterized by forming a photoconductive amorphous silicon carbide layer containing a Group Va element of the periodic table.

The present invention will be explained in detail below.

The electrophotographic photoreceptor of the present invention can obtain a large dark resistance value by forming a photoconductive a-5iC layer on a substrate using a thin film forming means, and further contains 0 to 10,0 of Group Va elements of the periodic table.
It is characterized by being negatively charged when it is contained in an amount of 0.00 ppm, and FIG. 1 shows a photoreceptor having the basic structure thereof.

That is, according to FIG. 1, a photoconductive a-5iC layer (5) is formed on a conductive substrate (1) by, for example, a glow discharge decomposition method, and carbon and periodic elements are formed over the thickness direction of this layer. Group Va elements (hereinafter abbreviated as Va group elements) are contained in the same content ratio. It was discovered that this resulted in a dark resistivity of 10" cm Ω or more, which was also 1000 times higher than the bright resistivity. As is clear from the examples described below based on this knowledge, only this single composition layer This was an unexpected result in that a fully practical a-StC photoreceptor could be created.

Furthermore, when the present inventors charged this a-3iC photoreceptor to positive or negative polarity and compared the charging performance of both, this a-5iCJ! (5) contains Va group elements from 0 to 10, O
It has also been found that doping in the range of OO ppm, preferably in the range of 0 to 11000 ppm, can advantageously increase the charging ability with negative polarity.

Although it is still a matter of speculation that doping or non-doping with Va group elements makes it easier to be negatively charged, it is clear that the a-SiC layer has a resistivity high enough to retain negative charges. This is believed to be due to the fact that it has excellent durability, is also effective in preventing injection of positive charges from the substrate, and has excellent charge mobility with respect to negative charges.

In addition, the Va group elements include N, P, ^s, Sb,
Among Bi, P is preferable because it has excellent covalent bonding properties and can sensitively change the semiconductor properties.Also, even if it is non-doped, stable properties can be obtained because the constituent elements in the film are reduced. Moreover, it is desirable because it has excellent charging ability and sensitivity.

The reason why the a-5iC layer of the present invention has photoconductivity is that amorphous silicon and carbon are essential constituent elements, and H and halogen elements are added within the required range to terminate the dang bond. It is thought that photoconductivity is produced by containing . The present inventors conducted experiments to confirm the presence or absence of photoconductivity by changing the content ratio of carbon in many ways, and found that carbon was added in a-SiCN (5) from 1 to 90 atoms χ, preferably from 5 to 90 atoms. 50 atoms χ
The carbon content may be within this range, or the carbon content may be varied within this range in the thickness direction.

In addition, the content of II and halogen elements is 5 to 50 atoms 2
, preferably 5 to 40 atoms 2, optimally 10 to 30 atoms χ, and usually 2 is used. Since this (2) is easily incorporated into the terminal portion of the dangling bond, the localized level density in the band gap is reduced, thereby providing excellent semiconductor characteristics.

Furthermore, a part of this H may be replaced with a halogen element, thereby lowering the local level density of the a-5iC layer and improving photoconductivity and heat resistance (temperature characteristics). Its substitution ratio is 0.01 among all elements for dangling bond termination.
It is preferably between 1 and 50 atoms χ, preferably between 1 and 30 atoms χ. In addition, this halogen element includes F+CI+Br+ I, At
Among these, the use of F is preferable because its large electronegativity increases the bonding between atoms, resulting in excellent thermal stability.

Further, the thickness of the photoconductive a-SiC (5) should be at least 5 μm or more, so that the surface potential is 200 μm or more.
On the other hand, the upper limit of the thickness of N(5) is appropriately selected within the range of image resolution and image blurring, and according to experiments conducted by the present inventors, the thickness of N(5) is 5 to 100 V.
It is preferably set within the range of IO to 50 μm.

When we determined the spectral sensitivity characteristics, dark decay curve, and light decay curve of this a-5iC layer, we found that the former has a spectral sensitivity peak (peak wavelength of approximately 600 nm) in the visible light region.
), and it has been found that this can be fully applied to tungsten lamps commonly used as light sources for copying machines. It was also found that the latter decay curve also had a high surface potential, excellent photosensitivity characteristics, and a small residual potential.

In this way, an electrophotographic photoreceptor is provided which can be put into practical use with just a photoconductive a-5iC layer having a single composition.

Therefore, based on the above results, the present inventors conducted further research and found that various N
It has been found that the electrophotographic properties can be further improved by creating a fil region.

That is, in the electrophotographic photoreceptor of the present invention, the content ratio of carbon or Va group element as a constituent element is changed over the layer thickness direction, thereby generating a plurality of layer regions, and the number of Fieff regions is Correspondingly, the following first to fourth aspects
An electrophotographic photoreceptor according to the embodiments described above can be obtained.

Hereinafter, embodiments of the electrophotographic photoreceptor according to the present invention will be explained with reference to FIGS. 3 to 24.

According to a first aspect of the invention, there is provided an electrophotographic photoreceptor in which a photoconductive a-5iC layer is formed on a substrate, wherein the a-3iC layer covers at least a first layer region and a second layer region. The first layer region is disposed closer to the substrate than the second layer region, and is chargeable to a negative polarity, characterized in that the first layer region contains more Va group elements than the second layer region. An electrophotographic photoreceptor is provided.

That is, according to this first aspect, by incorporating a Va group element into the photoconductive a-SiC layer having a single composition shown in FIG. 1 and changing the content ratio accordingly, at least A first NSi region and a second layer region are generated, and this aspect will be explained with reference to FIGS. 3 to 9.

In FIG. 3, a first layer region (
6) and a second layer region (7) are successively formed, both layer regions are made of integrated photoconductive a-SiCrri (5a), and a first N'pM region (6) is formed. There is a second
It is important that the Va group element is contained in a larger amount than in the layer region (7).

The second layer region (7) has a Va group element content of O to 10
．． 000 ppm, preferably 0 to 1.00 ppm
It is suitably controlled within the range of 0 pp+m, and as a result, it is charged to a negative polarity and required electrophotographic properties such as surface potential and photosensitivity properties are obtained. Then, Va
When the first layer region (6) containing a large amount of group elements is formed, photoconductive a-SiCF! The conductivity increases in the substrate side region of (5a), which prevents carrier injection from the substrate side and allows photocarriers generated in the entire region of the a-3tC layer to flow smoothly to the substrate. found that the photosensitivity characteristics improved as the surface potential increased.

This first layer region (6) is photoconductive over its entire region, which makes it possible to avoid the conventional a shown in FIG.
- Prevention of carrier injection into 3t electrophotographic photoreceptor! (2
) can be distinguished from

That is, the first layer region (6) improves the photosensitivity characteristics over the whole area due to the photoconductivity of the entire region. In particular, excellent photosensitivity characteristics can be obtained for relatively long wavelength light that easily reaches the first layer region (6), making it suitable for electrophotographic photoreceptors using semiconductor lasers as recording light sources. becomes.

Further, according to the conventional a-Si electrophotographic photoreceptor, the layer thickness of the carrier injection blocking N(2) is set to 3.
), whereas according to the electrophotographic photoreceptor of the present invention, the layer thickness of the first layer region (6) is set to be 175 times or less than that of the second layer region (7). Even if the layer thickness ratio is less than double, the residual potential can be sufficiently reduced and the photosensitivity characteristics can be improved.The preferred layer thickness ratio is 172 or less, and optimally 174
It is recommended to set it as below.

The carbon content of this photoconductive a-SiC layer (5a) is as shown in FIGS. It shows the content. Note that (6) on this horizontal axis.

Each range shown in (7) represents a first layer region and a second layer region.

That is, in FIG. 4, the carbon content ratio is constant throughout the entire layer, or in FIG. 5, the carbon content is reduced in the first layer region, whereas in FIGS. indicates that the first layer region contains more carbon than the second layer region, which further increases the surface potential and improves the photosensitivity characteristics. Further, if the carbon content is gradually changed in the layer thickness direction as shown in FIGS. 7 to 9, the surface potential and photosensitivity will be further increased and the residual potential will be reduced.

Further, the first layer region (6) may contain at least one of oxygen and nitrogen (by this, a-SiC
The adhesion of the layer (5a) to the substrate (1) is improved.

According to a second aspect of the invention, there is provided an electrophotographic photoreceptor in which a photoconductive a-5iC layer is formed on a substrate, the a-5iC layer forming at least a first layer region and a second layer region. a layer region and a third layer region, the first layer region is located closer to the substrate than the second rrI region, the second layer region is located closer to the third WJ layer region, and the third layer region The region contains more carbon than the second layer region, and the second layer region has a carbon content of 0 to 10.0.
An electrophotographic photoreceptor capable of being charged to a negative polarity is characterized in that the first layer region contains 00 ppm of Va group elements, and the first layer region contains more Va group elements than the second layer region. provided.

That is, according to this second aspect, as shown in FIG.
A third layer region (8) is further formed on the second layer region (7) shown in the first embodiment, and the carbon content of the third layer region (8) is accordingly increased. and the first layer region (6), the second layer region (7) and the third Jig Si region (8) are substantially integrated to form a photoconductive layer. It was referred to as a-SiC1i (5b).

When this third layer region (8) is formed, a-SiCN (
It has been found that the dark resistance value on the surface side of 5b) increases, and the surface potential of the photoreceptor increases markedly.

That is, the third layer region (8) is made of photoconductive a-SiCWJ.
It is formed to increase the resistance of the surface side of (5b), and is completely distinguishable from the conventionally known surface protective layer (4) described in FIG. In addition, according to a functionally separated photoreceptor that is divided into a photocarrier generation layer and a carrier transport layer, the carrier transport layer has a high resistance of 10'3 Ωcm or more, but this layer has exceptionally high photoconductivity. Not required, typically a ratio of photoconductivity to dark conductivity of 100
The photoconductivity is only set to be less than 0 times. On the other hand, the third layer region (8) has a photoconductivity that is 1000 times higher in this ratio or more, and can be sufficiently distinguished from the carrier transport layer.

The layer thickness of the third Wi layer region 8) is the same as that of the second Ri layer region 7).
It is preferably 1 times or less, preferably 1/2 times or less, and optimally 174 times or less, compared to .

According to the present invention, the carbon content distribution of the photoconductive a-SiC layer (5b) is as shown in FIGS. 11 to 16, where the horizontal axis indicates the layer thickness direction from the substrate to the surface of the photoreceptor, The vertical axis shows carbon content. Furthermore, on this horizontal axis, (6
) (7) Each range shown in (8) represents a first layer region, a second layer region, and a third layer region.

Figures 12, 14, 15, and 16 show that the carbon content is gradually changed in the layer thickness direction, which improves the surface potential, provides excellent photosensitivity, and reduces residual potential. .

According to a third aspect of the present invention, there is provided an electrophotographic photoreceptor in which a photoconductive a-SiC layer is formed on a substrate, wherein the a-5iC layer covers at least a first layer region, a second layer region, and a second layer region. A TIa region, a third layer region, and a fourth layer region are sequentially provided from the substrate side toward the photoreceptor surface, and the third layer region has the following characteristics compared to the second layer region:
The fourth layer region contains more carbon than the third layer region, and the second layer region contains 0 to 10.00% carbon.
An electrophotographic photoreceptor capable of being charged to a negative polarity is characterized in that it contains 0 ppm of Va group elements, and that the first layer region contains more Va group elements than the second layer region. provided.

That is, according to the third aspect, as shown in FIG.
A fourth layer region (9) is further formed on the third layer region (8) shown in the embodiment, and accordingly, a fourth layer region (9) is formed.
) contains more carbon than the third layer region (8), and the first layer region (6) to the fourth layer region (9)
were substantially integrated to form a photoconductive a-SiC layer (5c).

This fourth Jig '6M area (9) is the third layer area (8
), it contains more carbon and has a higher resistance, which increases the charging ability and improves the surface potential.
As a result, a photoreceptor with high withstand voltage and long life can be obtained.

According to the present invention, the carbon content distribution of the photoconductive a-3iC layer (5c) is as shown in FIGS. 18 to 21, where the horizontal axis indicates the layer thickness direction from the substrate to the photoreceptor surface, The vertical axis shows carbon content. Furthermore, on this horizontal axis, (6
) (7) (8) The respective ranges shown in (9) represent the first [I region, the second layer region, the third layer region, and the fourth region.

In FIGS. 19 and 21, the carbon content is gradually changed in the layer thickness direction, thereby improving the surface potential and photosensitivity, and reducing the residual potential.

According to the embodiment shown in FIG. 4, there is provided an electrophotographic photoreceptor in which a photoconductive a-SiC layer and an a-3tc surface protection layer are sequentially formed on a substrate, and the a-5iCii is at least the first layer. It comprises a first layer region, a second layer region and a third layer region, the first layer region being closer to the substrate than the second layer region, and the second region being closer to the substrate than the second layer region.
The third layer region contains more carbon than the second NeTI region, and the first layer region contains O to 10,000 ppm of Va group elements. There is provided an electrophotographic photoreceptor capable of being charged to a negative polarity, characterized in that the first layer region contains more Va group elements than the second layer region.

That is, according to this fourth aspect, as shown in FIG.
Further a on the third layer region (8) shown in the second embodiment
-SiC surface protection 1i (10) is formed,
This a-5iC surface protective layer (10) is a photoconductive a-Si
It is formed to overcoat and protect the surface of the C layer (5b).

The a-3iC surface protection layer (10) is the same as the photoconductive a-SiC layer (5b) in that it is made of a-SiC, but it has a higher carbon content to make it highly hard, thereby protecting the surface. bring about action.

This a-5iC surface protective layer (10) can be made photoconductive or non-photoconductive by changing the composition ratio of its constituent elements; increasing the carbon content tends to make it non-photoconductive. With this, high hardness characteristics are obtained, and high hardness is A-5.
It becomes an iC surface protective layer.

According to the fourth aspect, the carbon content distribution is shown in FIGS.
As shown in FIG. 4, the horizontal axis indicates the layer thickness direction from the substrate to the surface of the photoreceptor, and the vertical axis indicates the carbon content. Furthermore, on this horizontal axis (6) (7) (8) (10)
The respective ranges shown in are the first layer region, the second layer region,
It represents the third layer region and the a-SiC surface protection layer.

According to the present invention, the single-composition a-SiCPfj and the a-5iC layers of the first to third embodiments are both made of photoconductive a-SiCN, which provides sufficient practical electrophotographic properties. However, a conventionally known surface protective layer may be formed on the surface of these a-3iC layers.

Various materials can be used for this layer as long as they themselves have high insulating properties, high corrosion resistance, and high hardness properties, such as organic materials such as polyimide resin, a-SiC layer, etc.
5iOz, sio, Al1031 SiC layer Si
, H4,a-5t, a-Si:H,a-5i:F,a
Inorganic materials such as -3iC:H and Ha-5iC:F can be used.

Next, a method for manufacturing the electrophotographic photoreceptor of the present invention will be described.

In forming the a-SiC layer according to the present invention, thin film production techniques such as glow discharge decomposition method, ion blating method, reactive sputtering method, vacuum evaporation method, and CVD method can be used. The raw material may be solid, liquid, or gas. For example, 5i14, 5iJ6 as gaseous raw materials used in glow discharge decomposition method.
Si-based gas such as +5iJs, CH4, CzH4, Cz
A C-based gas such as Hz, CzHb, or C3Ha may be used, and furthermore, Hz + He + Ne + Ar or the like may be used as a carrier gas.

In addition, when forming an a-5iC film by glow discharge decomposition method, a high film formation rate (approximately 5 to 20 μm/hour) can be obtained by using SiH, gas, and C, I+, gas as the raw material. The film forming time can be significantly reduced. Incidentally, using SiH, gas and C114 residue, a
When a −3iC film is produced, the deposition rate is about 0.3 to 1 μm/hour.

Further, a capacitively coupled glow discharge decomposition device used in an embodiment of the present invention will be explained with reference to FIG.

In the figure, No. 18, No. 2. Third. 4th. Fifth. 6th tank (1
1) (12) (13) (14) (15) (16
) are SiH4 and Czllz, respectively.

PH3 () containing 0.2χ with lz gas dilution), PH3
(Contains 33 ppm when diluted with Hz gas), lh, and No gases are sealed, and 11□ is also used as a carrier gas. These gases correspond to the first. Second. Third. 4th. Fifth. No. 68) 1 Valve Adjustment (17) (1B) (19)
(20) (21) It is released by opening (22), and the flow rate is controlled by the mass flow controller (23).
(24) (25) (26) (27) (28), and the first. 2nd, 3rd. 4th. 5th tank (11
) (12) (13) (14) Gas from (15) goes to the first main pipe (29), N from the sixth tank (16)
o gas is sent to the second main pipe (30). Furthermore, (31)
(32) is a stop valve. Gas flowing through the first main pipe (29) and the second main pipe (30) is sent into the reaction tube (33), and a capacitively coupled discharge electrode (34) is installed inside this reaction tube (33). The high frequency power applied to it is 50 to 3, and the frequency is 1
11H2 to 10 M tl z is suitable. Inside the reaction tube (33), a cylindrical film-forming substrate (35) made of aluminum is placed on a sample holder (36), and this holder (36) is moved by a motor (37). The substrate (35) is rotated and heated uniformly to a temperature of about 200 to 400°C, preferably about 200 to 350°C, by suitable heating means. Furthermore, the interior of the reaction tube (33) requires a high degree of vacuum (discharge voltage 0.1 to 2.0 Torr) when forming the a-5iC film, so a rotary pump (38) and a diffusion pump (38) are required.
39).

In the glow discharge decomposition device configured as above,
For example, an a-5iC film (containing P) is used as a substrate (35).
1. Second. Third. Fifth regulating valve (
17) (18) (19) Open (21) and release 5IH41CzHz, PH3, Hz gas from each. The release amount is determined by the mass flow controller (23) (24
) (25) (27), SiH4,C
The mixed gas of Jz, PHz, and Hz is flowed into the reaction tube (33) via the first main pipe (29). Then, the inside of the reaction tube (33) is in a vacuum state of about 0.1 to 2.0 Torr, the substrate temperature is 200 to 400°C, and the high frequency power of the capacitive discharge electrode (34) is 50 to 3 Kw, or the frequency is set at 1 to 10 MHz, glow discharge occurs, the gas decomposes, and an a-5iC film containing P is formed on the substrate at high speed.

〔Example〕

Next, embodiments of the present invention will be described in detail.

(Example 1) In this example, a photoconductive a-5iC layer was formed on an aluminum film-forming substrate, and its conductivity with respect to the blending ratio of CJz gas was measured.

That is, using the capacitively coupled glow discharge decomposition device shown in FIG.
At a flow rate of 1005e, H2 gas is released from the fifth tank (15) at a flow rate of 300 seconds, and then from the second tank (12).
When C, H2 gas was released at a flow rate of 10 to 101005 e and the dark conductivity and photoconductivity of an a-SiC film with a thickness of about 5 μm were measured based on the glow discharge decomposition method, the results are shown in Figure 26. The results shown were obtained. In addition, as manufacturing conditions, the substrate temperature was set to 300° C., the gas pressure was set to 0.45 Torr, and the high frequency power was set to 150 −.

According to FIG. 26, the horizontal axis shows CJ2 gas flow 1 (!+CC1
), the vertical axis represents the conductivity [(Ω・c+m)−′),
- The mark is a plot of dark conductivity, the mark O is a plot of photoconductivity, and a and b are respective characteristic curves.

As is clear from Figure 26, the dark conductivity is 10-'''
(Ω・cm)-' or more, with a maximum of 1O-1s(Ω
・cm)-' or more was obtained. Furthermore, the photoconductivity was 1000 times or more as compared to the dark conductivity, which indicates that this a-SiC layer has photoconductivity that is sufficiently satisfactory for use in electrophotographic photoreceptors.

(Example 2) In this example, based on (Example 1), Pll, gas (or a,) 1. When dark conductivity and photoconductivity were measured by introducing gas), the results shown in FIG. 27 were obtained.

In the figure, the horizontal axis is P for the total flow rate of SiH and CzHt.
H.

The pure amount (this is the absolute flow rate of PH3 calculated from the dilution ratio of H2 gas). In addition, PH,
A case where the pure amount is replaced with the pure amount of BzH6 is also described as a reference example.

According to FIG. 27, the mark is a plot of dark conductivity,
The Q mark is a plot of photoconductivity, and C1d is the respective characteristic curve.

As is clear from Fig. 27, the photoconductivity is more than 1000 times that of the dark conductivity, and the a-
The SiC layer has satisfactory photoconductivity for use in electrophotographic photoreceptors.

(Example 3) In this example, (Example 1) medium CzHz gas flow rate is 101
The spectral sensitivity characteristics of the a-SiCFi obtained with the setting of 05e were measured, and the results were the spectral sensitivity curve e shown in FIG. Note that this figure shows the photoconductivity when irradiated with equal energy light at each wavelength.

As is clear from FIG. 28, photosensitivity is observed in the visible light region, and as a result, it can be satisfactorily used as a photoconductor for electrophotography.

(Example 4) In this example, the middle 0211□ gas flow rate of (Example 1) is set to 10
a-3iCP (thickness 30μ) obtained by setting 105e
The characteristics of surface potential, dark decay, and light decay were measured for m). This measurement was performed by negatively charging the surface with a -5,6 KV corona charger, and measuring the change in surface potential over time in the dark and the
This figure follows the change in surface potential over time immediately after irradiation with 50 nm monochromatic light.

The results are shown in FIG. 29, where f and g are the dark decay curve and the light decay curve, respectively.

As is clear from FIG. 29, the surface potential is as large as about -530 V, and the dark decay is about 30% after 5 seconds, indicating excellent charge retention ability. It can also be said that it has excellent photoconductivity and low residual potential.

In addition, the a-3iC layer obtained in (Example 4) was heated to +5.6KV.
When positively charged with a corona charger, the surface potential was several tens of volts.

And a-SiC manufactured based on this (Example 4)
Layered photoreceptor photoreceptor - Negatively charged with a 5.6KV corona charger, then exposed to image light to perform magnetic brush phenomenon.As a result, high image density, high contrast, and high quality images were obtained, and after 200,000 cycles. Even after repeated tests, no deterioration of the initial image was observed, and it was confirmed that the durability was good.

(Example 5) In this example, a photoreceptor of the first embodiment was manufactured.

That is, the aluminum drum for the substrate is installed in the reaction tube (33) of the capacitively coupled glow discharge decomposition device shown in FIG. From (12), czt+z gas is added to the third
PH3 gas from tank (13), 5th tank (15)
More II.

Gas and NO gas were released from the sixth tank (16), respectively, and the first layer region and the second layer region were formed under the manufacturing conditions shown in Table 1.

The electrophotographic properties of the photoreceptor thus obtained were -5 in the dark.
, charged to negative polarity in a corona charge connected to a high voltage source of 6 KV, and then split into monochromatic light (650 nm).
was irradiated onto the surface of the photoreceptor, and the following characteristics were obtained. Note that the residual potential is the value 5 seconds after the start of exposure.

Surface potential...-720V Photosensitivity...l), 53cm"erg-'residual potential...
30V (Example 6) In this example, a photoreceptor of the first embodiment was manufactured in the same manner as in (Example 4).

The manufacturing conditions were as shown in Table 2, and the electrophotographic properties were as follows.

Surface potential...-680v Photosensitivity...0.63cIl! erg-1 residual potential...
-30V +1-Y-111 (Example 7) In this example, a photoreceptor of the second embodiment was manufactured under the conditions shown in Table 3, and the following electrophotographic characteristics were obtained.

Surface potential...-720v Light sensitivity...0.65Cierg-heavy Residual potential...25V ゛、 □－・・＼□ ゝ＼ \、 \,.

\.

(Example 8) In this example, a photoreceptor of the third embodiment was manufactured under the conditions shown in Table 4, and the following electrophotographic characteristics were obtained.

Surface potential...-790V Photosensitivity...0.65c+++"erg-' residual potential...
・・30V \2, ゛・8, ′+ I+〆′ 〆−～11, ゝ・, ゛, ゛＼ Also, the characteristics of the surface potential, dark decay, and light decay of this photoreceptor (Example 4) When measured in the same manner as above, the 30th
The results shown in the figure were obtained. In the figure, h and i are a dark decay curve and a light decay curve, respectively.

As is clear from FIG. 30, the surface potential is significantly large at approximately -790V, and the dark decay is approximately 24χ after 5 seconds, indicating excellent charge retention ability.

(Example 9) In this example, a photoreceptor of the fourth embodiment was manufactured under the conditions shown in Table 5, and the following electrophotographic characteristics were obtained.

Surface potential: -830 ■ Photosensitivity: 0.63 cIl12erg-1-n (Example 10) In this example, the film formation rate was adjusted using the glow discharge decomposition apparatus shown in Fig. 25 under the following manufacturing conditions. When measured, the results shown in FIG. 31 were obtained.

RF power...150W Gas pressure...0.45TOrr Substrate temperature...300℃ SiH*Gas flow rate...100s1005e Gas flow rate・
...300sccn+ In Fig. 31, the circle mark is a plot of the measurement results, and j is its characteristic curve.

As is clear from FIG. 31, as the content ratio of CzHz gas increases, the film formation rate increases, reaching a film formation rate of about 5 to 13 μm.

(Example 11) In this example, we tracked the hydrogen content in the film while changing the content ratio of 0211□ gas under the same manufacturing conditions as in (Example 10), and the results shown in Figure 32 were obtained. Ta.

In FIG. 32, the marks O and * are plots showing the amount of H bonded to C and St, respectively, and k and 1 are their characteristic curves, respectively.

As is clear from Fig. 32, as the content ratio of CzHz gas increases, the number of C-H bonds increases and the number of S-
It can be seen that H-bonds are reduced.

〔Effect of the invention〕

As described above, according to the electrophotographic photoreceptor of the present invention, a-3iC, which has photoconductivity throughout the entire layer, has a high dark resistance value and also has excellent photosensitivity characteristics, thereby effectively protecting the surface. As a result, an electrophotographic photoreceptor consisting only of a photoconductive a-3iC layer could be provided.

Further, according to the electrophotographic photoreceptor of the present invention, by changing the content of carbon and Va group elements in the layer thickness direction, the surface potential is improved, the photosensitivity characteristics are enhanced, and the residual potential is significantly reduced. be able to. In particular, when the carbon content is varied in the layer thickness direction, the resistivity can be controlled and the required NeI range can be obtained, and as a result, an electrophotographic photoreceptor with significantly higher performance can be provided.

Further, according to the present invention, there is provided an electrophotographic photoreceptor for negative polarity that can be advantageously charged to negative polarity.

Furthermore, when a conventional a-Si photoreceptor is used for a long period of time, local discharge damage on the photoreceptor surface is likely to occur due to corona discharge, and this causes spots to appear on the image. However, according to the present invention, a-Si
The dielectric constant of a-SiC is ε=12, while the dielectric constant of a-SiC is ε・
7, it has excellent charging ability, and as a result, the above-mentioned discharge breakdown does not occur even if the surface potential is increased, and as a result, a high quality and highly reliable electrophotographic photoreceptor can be produced. is provided.

Further, since the electrophotographic photoreceptor of the present invention has excellent charging ability and environmental resistance by itself, there is no need to provide a protective layer, and, for example, there is no need to provide a protective layer, and the electrophotographic photoreceptor itself does not need to be provided with a protective layer. When the surface of a photoconductor is deteriorated due to filming, etc., the initial characteristics of the photoconductor can be maintained without being limited by the amount of polishing even if the degraded surface is re-polished with an abrasive or the like. This makes it possible to stably supply a good initial image over a long period of time.

Furthermore, when the electrophotographic photoreceptor of the present invention is compared with a conventional a-Si photoreceptor, problems with the a-Si photoreceptor include poor moisture resistance, which tends to cause image deletion, and chargeability. However, in order to solve this problem, a heater is used to heat the a-Si photoreceptor when the a-Si photoreceptor is used, thereby preventing the ghost phenomenon from occurring. On the other hand, the electrophotographic photoreceptor of the present invention has an advantage in that it does not need to be used with a heater as described above because it has excellent moisture resistance and charging ability.

Further, compared to the a-Si photoreceptor, the electrophotographic photoreceptor of the present invention can obtain a wide range of spectral sensitivity characteristics (peak 600 to 700 nm) and increase the photosensitivity itself by simply changing the carbon content. Furthermore, there is an advantage that sensitization on the long wavelength side is also possible by doping with an impurity element as necessary.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the layer structure of the electrophotographic photoreceptor of the present invention, FIG. 2 is an explanatory diagram showing the layer structure of a conventional electrophotographic photoreceptor, and FIG. Explanatory diagrams showing the WI layer area of the photoreceptor, FIGS. 4, 5, 6, 7, and 8
9 and 9 are explanatory diagrams showing the carbon content of the photoconductor of the first embodiment according to the present invention, respectively, and FIG. 10 is an explanatory diagram showing the layer area of the photoconductor of the second embodiment according to the present invention, Figure 11,
12, 13, 14, 15, and 16 are explanatory diagrams showing the carbon content of the photoreceptor according to the second embodiment of the present invention, and FIG. 17 is an explanatory diagram showing the carbon content of the photoreceptor according to the second embodiment of the present invention. 18, 19, 20, and 21 are explanatory diagrams showing the carbon content of the photoconductor of the third embodiment according to the present invention, respectively. , FIG. 22 is an explanatory diagram showing the NjI region of the fourth B-type photoreceptor according to the present invention, and FIGS. 23 and 24 show the carbon content of the fourth embodiment photoreceptor according to the present invention. An explanatory diagram, FIG. 25 is an explanatory diagram of a capacitively coupled glow discharge decomposition device used in an embodiment of the present invention,
Figure 26 is a diagram showing the electrical conductivity versus the flow rate ratio of CJt gas, Figure 27 is a diagram showing the electrical conductivity versus each flow rate ratio of PH3 gas and BJi gas, and Figure 28 is a diagram showing the spectral sensitivity of the amorphous silicon carbide layer. 29 is a diagram showing the dark attenuation and optical attenuation of the amorphous silicon carbide layer; FIG. 30 is a diagram showing the dark attenuation and optical attenuation of the amorphous silicon carbide layer of the third embodiment; FIG. FIG. 31 is a diagram showing the film formation rate with respect to the flow rate ratio of CtHz gas, and FIG. 32 is a diagram showing the bonding ratio of hydrogen atoms with respect to the flow rate ratio of C, H□ gas. 1...Substrate 5.5a, 5b, 5c...Photoconductive amorphous silicon carbide layer 6...First layer region 7...Second layer region 8...Third layer region 9...Fourth layer region 10...Amorphous silicon carbide surface protective layer Patent applicant (663) Kyocera Corporation Takao Kawamura

Claims (2)

[Claims] (1) An electrophotographic photoreceptor in which a photoconductive amorphous silicon carbide layer is formed on a substrate, the amorphous silicon carbide layer forming at least a first layer region;
It has a second layer region and a third layer region, the first layer region is located closer to the substrate than the second layer region, the second layer region is located closer to the substrate than the third layer region, and the third layer region is located closer to the substrate than the third layer region. The layer region contains more carbon than the second layer region, and the second layer region contains 0 to 10,000 ppm of Group Va elements of the periodic law, and furthermore, the first layer region contains more carbon than the second layer region. An electrophotographic photoreceptor capable of being charged to a negative polarity, characterized in that the second layer region contains a larger amount of Group Va elements of the periodic table than the second layer region. (2) An electrophotographic photoreceptor in which a photoconductive amorphous silicon carbide layer and an amorphous silicon carbide surface protection layer are sequentially formed on a substrate, wherein the photoconductive amorphous silicon carbide layer is formed in at least a first layer region, a second layer region, and a second layer region. and a third layer region, the first layer region being closer to the substrate than the second layer region, and the second region being closer to the third layer region.
are arranged closer to the substrate than the layer regions, and the third layer region contains more carbon than the second layer region, and the first layer region contains carbon in the range of 0 to 10,000 ppm in the periodic table. An electrophotographic photosensitive material capable of being charged to a negative polarity, characterized in that the first layer region contains a group Va element of the periodic table in a larger amount than the second layer region. body.