JPS61219962A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To prevent deterioration and to improve an image by laminating a photoconductive layer of amorphous silicon (a-Si) type and an a-Si type buffer layer and a surface layer made of a specified a-C hydride on a conductive substrate. CONSTITUTION:A blocking layer 121 is formed on the conductive substrate 110 to block injection of electrostatic charge from the substrate 110, the photoconductive layer 122 made of a-Si is formed on the layer 121 to exhibit charge acceptance and photosensitivity, further, the buffer layer 123 made of a-Si carbide-hydride [a-Si1-xCx(H), 0<x<1] is formed in a thickness of 0.03-1mum to electrically match the photoconductive layer 122 to the surface layer 130, and this surface layer made of a-C hydride contg. 10-40atom% H is formed on the buffer layer 123 to ensure humidity resistance and printing resistance, thus permitting humidity resistance and printing resistance to be enhanced and photosensitivity and spectral sensitivity to be improved by the presence of the specified buffer layer and the specified surface layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to an electrophotographic photoreceptor having an amorphous silicon-based photosensitive layer.

[Prior art and its problems]

Conventionally, for example, amorphous Be was used as an electrophotographic photoreceptor.
, Maku is amorphous Be KAII , To +
Photoreceptors using photoconductive materials doped with impurities such as 13b have problems in terms of mechanical strength, environmental contamination, and mechanical strength.

In recent years, amorphous silicon (--
A technique has been proposed to solve the drawbacks of these conventional electrophotographic photoreceptors by using St. A-8i produced by vapor deposition or sputtering has a low specific resistance of 100 cm in the dark and extremely low photoconductivity, so it is not desirable as a photoconductive material for electrophotographic photoreceptors.

In this more a-8i, the 5i-191 bond was broken,
So-called dangling bonds are generated, and many localized levels exist within the energy gap due to these defects. For this reason, hopping conduction of thermally excited carriers occurs, which reduces the dark specific resistance, and photoconductivity deteriorates because photoexcited carriers are captured in localized levels.

On the other hand, in hydrogenated amorphous silicon (a-8i(H)) produced by glow discharge decomposition of silica/gas (5tH4) or photoCVD, the above defects are removed by hydrogen atoms (
6) and by H'i bonding to Sl, the number of dangling bonds can be greatly reduced, resulting in extremely good photoconductivity), and p-type and n-type valence electron control is also possible. However, the dark specific resistance value is 10 8 to 10 Ω·mm, which is still low compared to the dark specific resistance value of 10 12 Ω·mm or more, which is sufficient for an electrophotographic photoreceptor.

Therefore, a photoreceptor made of this stranded a-Si (H) has a high dark decay rate of surface potential and a low initial charging potential.

Therefore, in order to give the full charge retention ability to this a-sl (g), the dark specific resistance can be increased to more than 10120 by doping with an appropriate amount of boron, which is suitable for the Carlson method copying process. allows it to be applied.

Although a good image can be obtained initially with a photoconductor with a surface coated with A-SL, if it is stored in the atmosphere or in high humidity for a long period of time, it may be difficult to copy the image. It has been found that image defects occur.It is also known that image blurring gradually occurs as the copying process is repeated many times.Such deteriorated photoreceptors are known to cause image defects, especially in high humidity environments. It has been confirmed that the critical humidity at which blurring tends to occur, and as the number of copies increases, the critical humidity at which image blur begins to occur tends to decrease significantly.

As mentioned above, a photoreceptor with a surface of a-sl ( It is believed that the outermost surface of the photoreceptor is susceptible to exposure to nascent oxygen (e.g., oxygen during the nascent stage) and that some kind of chemical alteration causes image blurring, but the mechanism of this deterioration has not yet been fully investigated. In order to prevent the occurrence of such image defects and improve printing durability, a method has been attempted in which a protective layer is provided on the surface of the a-8i (H) photoreceptor to achieve chemical stabilization. There is.

For example, hydrogenated amorphous silicon carbide (a-BlxCx-!(H)-0<x<1) or hydrogenated amorphous silicon nitride (a-SiNx
(H, OH), 0<x(1) is known to prevent deterioration of the surface layer of a photoreceptor due to the copying process or environmental atmosphere (% 1985-115559
Publication No.). However, if the carbon concentration or nitrogen concentration in the surface protective layer is selected to an optimal value, printing durability can be considerably improved, but moisture resistance cannot be maintained in a high humidity atmosphere (RH 80 degrees or higher). After undergoing the process of copying tens of thousands of sheets, image blurring occurs at relative humidity levels of 60 degrees, and even with the addition of these surface protective layers, printing durability and moisture resistance cannot be significantly improved. be.

[Purpose of the invention]

It is an object of the present invention to eliminate the above-mentioned drawbacks, and to provide a photoreceptor with characteristics that does not cause deterioration phenomena even during long-term storage and repeated use, and hardly exhibits any deterioration of characteristics such as image defects even in a high-humidity atmosphere. It is an object of the present invention to provide an a-8i photoreceptor that is always stable and has excellent durability, printing durability, and moisture resistance that are hardly limited by usage environments.

Furthermore, another object of the present invention is to provide a photoreceptor having high photosensitivity and spectral sensitivity over the entire visible range.

Still another object of the present invention is to provide a photoreceptor with excellent fatigue properties and relatively low residual potential.

[Key points of the invention]

An object of the present invention is to provide an electrophotographic photoreceptor having a structure including an amorphous silicon-based photoconductive layer, an amorphous silicon-based buffer layer, and a hydrogenated amorphous carbon (hydrogenated amorphous carbon) containing 10 to 40 atoms of hydrogen on a conductive substrate. IL-(!! (
H) ) at least three layers with a surface layer consisting of 1-
This can be achieved by laminating layers to form a photoreceptor.

With this configuration, the amorphous silicon-based photoconductive layer exhibits good charging performance and photosensitivity, and the amorphous silicon-based buffer layer provides electrical and mechanical matching between the photoconductive layer and the surface layer. Printing durability and moisture resistance due to the surface layer made of hydrogenated amorphous carbon.

Storage resistance and stability of photoreceptor characteristics can be ensured.

[Embodiments of the invention]

Hereinafter, the photoreceptor of the present invention will be explained in detail with reference to the drawings.

As shown in the conceptual cross-sectional view of FIG. 1, an example of the photoreceptor according to the present invention has a blocking layer 121 formed on a conductive substrate 110.
．． Photoconductive layer 122. Buffer layer 123 and surface layer 13
0 is a stacked structure.

Here, the conductive substrate 110 may be either cylindrical or sheet-like, and its material may be metal such as aluminum or stainless steel, or glass or resin subjected to conductive treatment.

The purpose of blocking layer 121 is to prevent charge injection from conductive substrate 110. In terms of materials, A
l2O3, AIN, SiO, 510g, a-8
i1-zox(F,H)(0<x<l), a-8
iNx(H) (0<X<4/3), a 0(H)
.

Fluorinated amorphous carbon (ac(F)) 1 periodic table ■
a-0(H) doped with group V and group V elements.

A-0(F), a-81(H) doped with elements of group II, group II, etc. can be used. The film thickness is
The thinner it is, 1 μm or less, the better.

The photoconductive layer 122 is preferably made of a material that has excellent absorption ability for target light and high photoconductivity, and is a -8i(H).

a-81 (F, H) + a-S t-xcx (H
) (0<X<OlS), a-sntx@ (o<x
kuo, 2), a-stor@(o<x<o, 1).

a -5t1-xaex (m, etc., and these are group II of the periodic table.

A material doped with a group V element or the like is preferred. Film thickness is 3
Practically preferred range is from μm to 60 μm. buffer layer 1
The purpose of 23 is to alleviate material heterogeneity between layers closer to the substrate, such as the photoconductive layer 122 and the surface layer 130.

In terms of materials, a -sl, -xcx (H) (o<x
<1), a-8i1-xcx(F,H) (
o<x<1), a5iNz(H)(0(X(
4/3), a-8iOx(H) (0<x<2)
, a 5iOz(F,H) (0<X<2), etc. can be used. The thickness of the buffer layer 123 is determined based on spectral sensitivity, residual potential, electrical consistency with adjacent layers, etc., and is preferably 1 μm or less.

Next, the surface layer is an amorphous layer (a
-C(H) ), and is basically a film whose diffraction image by X-rays or electron beams is not clear, and even if it contains some crystal parts, the proportion thereof is low.

The hydrogen concentration in the a-C(■) surface layer varies from 1 to 60 atoms depending on the film-forming conditions, including the raw material gas, discharge power, gas flow rate, gas pressure, and substrate temperature. By appropriately selecting hydrogen concentration such as 10 to 40 atoms,
It is desirable to control the content to preferably 15 to 36 at.%.

Furthermore, the optical energy gap Flig of the a-C(H) surface layer is preferably 2.2 eV or more and 3.28 V or less, the refractive index is preferably 1.5 or more and 2.6 or less, and the specific resistance is 10' to 1015 Ωm is preferable, and the density is 1
．． 3 g/cm3 or more is suitable.

According to the findings of the present inventors, the bonding form between hydrogen atoms and carbon atoms contained in the a-C(H) surface layer reflects the bonding state between carbon atoms, and the formed a It has been found that the -C@ layer is one of the major factors that determines whether or not it can be applied as a surface layer of an electrophotographic photoreceptor and is important. Bonding states between carbon atoms include diamond bonds (tetracoordinated) and graphite bonds (tricoordinated).

It is known that a-C(H)$, which is mainly composed of graphite bonds and polymeric bonds (-CHx)n made of carbon and hydrogen, has poor chemical resistance and mechanical strength.
On the other hand, it is known that an a-C(H) film mainly composed of diamond bonds has excellent chemical resistance and mechanical strength.

In view of this, the present inventors have conducted extensive studies on the infrared absorption spectrum of the a-0(H) film, its chemical resistance, and mechanical strength, and have found that the a-C! It has been found that there is a unique relationship between the ratio of specific absorption coefficients in the infrared absorption spectrum of the αυ film and the chemical resistance and mechanical strength of the aO(H) film.

Original F! In order for the -0(H) surface layer formed in A to be sufficiently applied as a surface protective layer of an electrophotographic photoreceptor, the absorption at 2920 tri' of the infrared absorption spectrum of the a-0(H) surface layer is required. Coefficient α1 and 296
The ratio αa/al of the absorption coefficient α2 at 0 cm-” is 0
．． It is desirable that it be 8 or more. The theoretical basis for why the ratio of the absorption spectrum of the a-C(9) layer is limited to the above numerical range has not been clarified at the moment and remains in the realm of speculation, but we think as follows. .

In other words, even for the same four-coordinate bond, 2960cti
The CH3 type, which has an absorption at 2920 cm, is mechanically and chemically stable, but the OH type, which has an absorption at around 2920 cm, may be easier to form as a polymer.From numerous experimental results, the above Chemical resistance at absorption coefficient ratios outside the numerical range.

Although it is recognized that the mechanical strength is inferior, it is confirmed that it is a necessary condition that the absorption coefficient ratio is within the above range.

Hydrogen is not the only means of stabilizing carbon dangling bonds.
This is also possible with fluorine, oxygen, and nitrogen.

Next, a method for manufacturing the present photoreceptor will be explained using a manufacturing apparatus as exemplified as a conceptual system diagram in FIG. vacuum@
A tetraelectric substrate 22 made of an aluminum cylinder is placed inside 210.
0 to the base body holder 221. The base body 220 is heated by the heater 230 in the holding part 221 and the heater 231 of the counter electrode 252 so that the total temperature of the base body 220 reaches a predetermined temperature, for example, 50 to 350°C. Holding part 221 and conductive base 22
0 is rotated to achieve uniformity of the film in the circumferential direction.

Next, from among the pressure vessels 291 to 295 containing the various raw material gases necessary for forming each layer as described above, a pressure vessel pulp, e.g. , the stop pulp 261 is opened and fed into the vacuum chamber 210. The same applies to other gases. Next, the tank internal pressure (f - predetermined pressure, for example 0.00
1 to 5 Torr After Ic adjustment, radio frequency (RF) i
High frequency (x3.56MI(Z)) power is supplied from the lE source 250 to the counter electrode 252 via the insulating material 251.
Film formation is performed by generating glow discharge between the substrate 220 and the substrate 220.

Although five sets of pressure vessels and equipment attached thereto are shown in FIG. 2, the number of sets may be increased or decreased as appropriate depending on the type of gas used.

a-Q (H) As for the preparation conditions of the surface layer, the substrate temperature is preferably 0 to 200°C, preferably 50 to 150°C, and the energy required to decompose the gas per unit amount of gas is 300°C.
J/cc ~ 20000 J/cc is desirable. Gas pressure is o, oo~0.5 Torr + preferably 0
．． 001 to 0.2 Torr is desirable.

During film formation, applying a bias voltage from the outside is also effective in controlling film quality. Further, in the case of RF discharge, a bias is naturally generated. This is usually called self-bias, but such a bias voltage is +100 to 500
V, -100 to -4500V is suitable.

The present invention will be explained below with reference to specific examples.

Example 1 A blocking layer of 121 ft of aluminum which had been degreased and washed with trichlorethylene was formed.

stH, (xoo%) Flow rate 250cc/
min BgH6 (5000ppm, H6-su) flow i 20
cc/min Gas pressure 0.5 TorrRF power 50 W Substrate temperature 200°C Film forming time 10 minutes Furthermore, light guide was conducted under the following conditions.
It was formed to have a thickness of 25 μm.

SiH, (100 inches) Flow rate 200cc/min BaHs (20ppm, Habase) Flow rate i+t
1occ/min gas pressure 1.2 Torr
Substrate temperature: 200 C RF power: 300 W Film-forming time: 3 hours Furthermore, a buffer layer 123 tl- was formed on top of this under the following conditions.
It was formed to have a thickness of 0.1 μm.

SiH4 (100cm) Flow rate 100cc 7 minutes CH4 (100%) #, Jl 80c
c 7 minutes BaH6 (2000ppm, Hg base)
Flow rate 15cc 7 minutes Gas pressure 1.0To
rr RF power 200W Substrate temperature 200℃ Film formation time 2 minutes Furthermore, on top of this, a surface layer 130 with a thickness of 0.1 is applied under the following conditions.
μmK forms a circle.

csHa Doots) a amount 20cc
7 minutes Gas pressure 0.1 Torr RJ power
200 W Substrate temperature 100° C. Film forming time 5 minutes The substrate temperature was measured with an infrared thermometer and a thermocouple.

The photoreceptor formed as described above was designated as Sample 1. The energy gap of the photoconductive layer 122 of sample 1 is 1.8 sV
It is. Further, the composition of the buffer layer 123 is a Sio
, yCo, 5(H), and its energy gap is 2.
1 eV. Furthermore, the energy gap of the surface layer 130 is 2.7θV, and the density of the film is 1.7g/cJ.
, the refractive index is 2.1. Knoop hardness is 2000kg
f/-. moreover.

The hydrogen concentration determined from heat release was 35 atoms.

The photoreceptor of sample 1 was installed in a Carlson type plain paper copying machine and 50,000 copies were made, and extremely clear images with good resolution were obtained. Furthermore, in a copy test after copying 50,000 copies, the images were clear even when copied in an atmosphere at a temperature of 35° C. and a relative humidity of 85%.

The printing durability and moisture resistance of the photoreceptor of Sample 1 were very good.

For comparison, a photoreceptor without only a surface layer was prepared according to Example 1, and a copy test was conducted on the photoreceptor after copying 50,000 copies. When copying in an atmosphere, image resolution has already decreased and image blur has occurred.

It can be seen that the moisture resistance is significantly improved by forming the --C(H) surface layer.

For forming the surface layer 130, it is not necessarily necessary to use 03H, but various hydrocarbons, such as CH4.

CmH6, 04HIG + 02H4, Czlh 1C
Gases such as 6Hs and mixtures of these gases with hydrogen and oxygen can be used.

Example 2 Forming up to the photoconductive layer 122 by the dead force method according to Example 1,
On top of that, a buffer layer 123 with a thickness of 0.2 μm is formed under the following conditions.
K was formed.

stH, (100%) Flow rate 120cc 7 minutes NH4 (100%) Flow rate 30cc/min B
IIH6 (2000ppm, Hg base) flow rate
10cc 7 minutes Gas pressure 1.0 Tor
rRFt power: 200 W Substrate temperature: 200°C Film-forming time: 5 minutes On top of this, a surface layer 130 with a thickness of 0.1 is applied under the following conditions.
It was formed to have a thickness of 0 μm.

CsHf1 (100%) Flow rate 20cc
7 minutes gas pressure 0.1TorrRF power
Sample 1 is a photoreceptor formed at 200 W, substrate temperature: 100° C., and film formation time: 5 minutes or more.

Energy gap K of photoconductive layer 122 in sample 1
g is 1.8θV. The composition of the buffer layer 123 is a-5iNO,4(H), and its kg is 2.2a
It is V.

Furthermore, the Kg of the surface layer is 2. 'i' eV, and the film density is 1.3 to 1-7 g/cr! , the refractive index is 1.9-2.
1, and the Knoop hardness is 2000 kgf/-. Furthermore, the hydrogen concentration measured from heat release was group atoms. Even after 50,000 copies were made by installing Sample 1 in a Carlson-type plain paper copying machine, the images remained clear when copied in an atmosphere at a temperature of 35° C. and a relative humidity of 85%.

The buffer layer material is a −81NX (H) (0<x
It can be seen that the performance of <1) is dramatically improved.

In order to form the surface layer 130, it is not necessary to use csas, and as in the first embodiment, various hydrocarbons and mixed gases of these gases with hydrogen, oxygen, and nitrogen can also be used.

Example 3 A method similar to Example 1 was used to form up to the photoconductive layer 122, and thereon, a buffer layer 123 was formed to a thickness of 0.5 mm under the following conditions.
It was formed to have a thickness of 0.05 μm.

5iH4 (1oo%) flow i 7Bcc
/min02 (He based, 10%) Flow rate 5
0cc/min BAH@(Ha, 2000p
pm) flow 1 itlocc 7 minutes gas pressure
0.7 TorrRF power 200 W Substrate temperature 200 C Film forming time 3 minutes This buffer layer was a-B1Ox (H) and X was about 0.1.

On top of this, a - C! under the following conditions! (H) A surface layer 130 was formed with a thickness of 0.3 μmK.

C2H6 (purity 99.6%) Stream i 30c
c/min gas pressure 0.005 TOrrRF
'[Force: 500 W Substrate temperature: 130 C Film-forming time: 20 minutes The energy gap Kg of this surface layer is 3. Although the OaV was large, the a-B10x (b) buffer layer of this example sufficiently performed its function. A clear image was obtained.

Example 4 A method similar to Example 1 was used to form up to the photoconductive layer 122, and thereon, a buffer layer 123 was formed to a thickness of 0.5 mm under the following conditions.
It was formed to have a thickness of 15 μm.

sta, (loo%) Flow rate 50cc 7 minutes 0H4 (loo%) Flow rate 5occ/
Min0i (He based, 10%) Flow rate 10cc
7 minutes BaH6 ()! g pace, 2000ppm) Flow rate 5cc/min Gas pressure 0.7 Tor
rRF power 150W Substrate temperature 200℃ ゛ Deposition time 4 minutes This buffer layer is a -810zOy (H) i)
x = 0.3.

y = 0.05. In addition to this, Example 3
An a-C(H) surface layer 130 was formed under the same conditions as above.

An image copying test according to Example 1 was conducted on the photoreceptor prepared by the above process, and a clear image was obtained.

Example 5 The bonding state of carbon and hydrogen in the a-C(H) surface layer greatly influences the moisture resistance and printing durability of the photoreceptor. This bonding state can be determined by the absorption spectrum and reflection spectrum of infrared rays, and here, an example of the infrared absorption spectrum is shown in Fig. 3. In the spectrum, the peaks mainly observed near 2900 cm are 2saocIn12920tan, 2
There are three of them, 2920 and 2960.
cm2 heater has high strength and is suitable for determining the bonding state. Absorption coefficient a1 at 2920α and 2960
The ratio αa/α to the absorption coefficient α2 at os! We investigated the relationship between this, moisture resistance, and printing durability.

Up to the buffer layer 123 was formed according to the manufacturing method of Example 1, and in forming the a-C(H) surface layer 130 thereon, six types of photoreceptors were fabricated by changing the type of gas, gas pressure, and substrate temperature. was prepared, and the relationship between the α2/α1 value, moisture resistance, and printing durability was investigated.

The α2/α1 values of these photoreceptors are shown in Table 1.
, 2 to 1.5, but in 50,000 copies made according to Example 1, good images were obtained on all photoreceptors, and the printing durability was good. Moisture resistance is the same (Similar to Example 1, after copying 50,000 sheets, a copy test was conducted in an atmosphere at a temperature of 35° C. and a relative humidity of 85° C. The results are shown in Table 1.

The mark 0 in Table 1 indicates that a good clear image was obtained, the mark Δ indicates that a slight image defect occurred, and the mark x indicates that an extreme image defect occurred.

(If the value of IQ/a1 is 0.8 or more, good moisture resistance is achieved.

It can be seen that a photoreceptor with printing durability can be obtained.

Example 6 In the case of a structure in which a surface layer is provided on the photosensitive layer of a photoreceptor, adhesion becomes a problem. Furthermore, in terms of photoreceptor characteristics, the surface potential is difficult to disappear even when exposed to light, and a defect may occur in which the residual potential becomes large.

So 1. -0 (H) Adhesion to the buffer layer was examined by changing the hydrogen concentration of the surface layer. Furthermore, the relationship with residual potential was also investigated.

Buffer) up to -12S was formed according to the manufacturing method of Example 1, and in forming the a-0(6) surface layer 130 thereon, the type of gas, gas flow rate, gas pressure, RF power, substrate temperature, etc. Eight types of photoreceptors with different hydrogen concentrations in the a-0(H) film were prepared by changing the a-0(H) film.

Table 2 shows the results of examining the relationship between the adhesion between the a-C(H) surface layer and the buffer layer and the hydrogen concentration in the surface layer and the residual potential for these samples. Here, the mark ○ indicates that the adhesion was excellent, and the mark X indicates that the adhesion was poor.

The change in film adhesion is extremely steep when the hydrogen concentration on the second surface of the film is around 40 atoms. A high hydrogen concentration is undesirable because it is considered to reduce the number of bonds that increase adhesion.

Furthermore, if the hydrogen concentration is low, the film approaches a diamond-like film, which increases the energy gap Kg and increases the residual potential. On the other hand, when the hydrogen concentration is high, the a-C(H) film becomes polymer-like, the conductivity deteriorates, and the residual potential increases, which is not preferable.

From the viewpoint of film adhesion and residual potential value of photoreceptor characteristics, 1. −
C! The hydrogen concentration in the surface layer is preferably 10 to 40 atoms, more preferably 15 to 3611 atoms.

EXAMPLE 5 Up to the buffer layer 123 was formed in the same manner as in Example 1, and then the a-0 (silver surface layer 130) was formed. Six types of photoreceptors were manufactured. Table 3 shows the results of examining the photoreceptor characteristics and moisture resistance of these samples.

As for the residual potential in Table 3, the smaller the residual potential is, the lower the S/N ratio becomes. Sensitivity is shown in half-attenuated exposure, where light i (
The smaller the value (1ux-aθC), the higher the sensitivity, which is preferable.

Humidity resistance is the result of image copying in an atmosphere with a temperature of 35°C and a relative humidity of 85fi. A 0 mark indicates that a good image was obtained, and an X mark indicates that a defective image occurred. shows.

From the above results, 1. -C! (H) The thickness of the surface layer is 0
．． 0.005 μm or more and 1 μm or less is suitable.

Example 8 As the optical surface layer of the photosensitive layer, a-5it-xOx (H)
(0<x<Yun is known. Therefore, a −C(H
) The moisture resistance of the photoreceptor was investigated when 81 was added to the surface layer.

Sample 1' of Example 1 was designated as sample 1 without the addition of Si. Next, up to the buffer layer 123 are formed according to the method of Example 1, and an a-0(H) surface layer containing Sl is formed, for example, under the following conditions.

02H6 (100%) flow it 20CQ/
Min.5iH4 (100%) Flow It2cc/min Crab pressure 0.2 Torr1m force
300 W Substrate temperature: 100°C Film-forming time: 10 minutes Under these conditions, the addition of Sl to the a-C(H) surface layer is controlled by changing the flow rate of SiH4.
Photoreceptor samples 2 to 4 containing different amounts of 1 were prepared.

Table 4 shows the results of investigating the relationship between composition ratio 517c and moisture resistance for these four types of samples. Moisture resistance was evaluated in accordance with Example 7 by copying images in an atmosphere at a temperature of 35° C. and a relative humidity of 85%. The Δ symbol indicates that it is not preferable to contain 81 on the outermost surface in view of the moisture resistance of the photoreceptor in Table 4, and pure C is desirable, but the presence of some impurities is not a problem. Possible impurities include B and A
t, Si, P, As + C1*F +
Fe, Ni! These include Ti, Mn, Mg, etc.

Example 9 Seven types of photoreceptors with different thicknesses of a-5i1-xcz(H) buffer layers were fabricated using a method similar to Example 1, except that the film-forming time was changed only when forming the buffer layer 123.

Photoreceptor characteristics of these samples were investigated and image tests were conducted. The image test was conducted using a Carlnon plain paper copying machine. An O mark indicates a good clear image, a Δ mark indicates a slight image defect, and an x mark indicates an extreme image defect. Indicates that a has occurred.

The survey results are shown in Table 5.

If the buffer layer on the front surface of tooth 5 is too thick, the residual potential will become too strong and the sensitivity will deteriorate, which is not preferable. Furthermore, if the buffer layer is too thin, it will not be effective in alleviating heterogeneity between the surface layer 130 and the photoconductive layer 122, resulting in defects in image tests. A suitable film thickness is 0.03 to 1.0 μm.

Example 10 In Example 9, the carbon concentration in the thickness direction of the buffer layer 123 was uniform, but this is not necessarily necessary. Rather, it is effective to provide a gradient in the carbon concentration in the film thickness direction in improving the photoreceptor characteristics. For example, by setting the thickness of the buffer layer 123 to 1.0 μm, the carbon concentration can be increased from the light guide tm side toward the a-C(H) surface I- side as shown in FIG. However, in Figure 4, only the carbon-rich element (i) is shown, and the other elements are omitted.

In such a photoreceptor, its residual potential is 50V,
The defect was 0.81ux-sθC, and no defects were observed in the image test. When compared with Example 9, in which the thickness of the buffer layer was 1.0, its effectiveness is clear.

Embodiment 11 In some cases, it may be best to select the carbon concentration of the buffer layer 123 as shown in FIG.

Figure 5 shows a made from a mixed system of 02H4 and 5iJI4.
-5i1-xcx (H) Energy gap K of film
Relationship between g and composition The horizontal axis of the Nio 5 diagram, which is a circle, shows the carbon content of a -Elil-xOx (H) as the value of X [7].

If increasing the carbon concentration does not simply lead to an increase in Eg, the carbon concentration distribution as shown in FIG. 4 cannot necessarily be said to be optimal. Rather, in that case, a −0
(9) It is preferable to achieve electrical matching with the surface layer. a
The relationship between the maximum value of I, which indicates the amount of carbon in -Sil
9. Preferably, if x (0.8), there is good consistency with the a -0(6) surface layer.

Example 12 Photoreceptors of Type A were prepared in the same manner as in Example 2, except that the film formation time was changed only when forming the buffer layer 23, and the thicknesses of the &-Bi, Nx (2) buffer layers were different. Regarding these samples, the photoreceptor characteristics were investigated in the same manner as in Example 9, and an image test was performed. The results are shown in Table 6.

As in the case of the seven a-Bil xox (H) back layers in Table 6, Example 9, there is a preferred range of film thickness for the a-51yx (H) buffer layer, and the appropriate film thickness is 0.
．． 05 to 1.0 μm.

Example 13 a -81i xcx (H) As in the case of the buffer layer, a -81H! (H) In the case of seven back layers, the nitrogen concentration in the four film thickness directions does not need to be uniform; rather, from the viewpoint of photoreceptor characteristics, it is preferable that the nitrogen concentration in the film thickness direction has a gradient.

For example, in a photoreceptor in which the buffer layer 123 has a thickness t- of 0 μm and the nitrogen concentration increases monotonically from the photoconductive layer side toward the a-c (H) surface layer as shown in FIG. The potential is 50 V, the sensitivity is 0.71 ux·sec, and no abnormality is seen in the image test. Example 12
Its effectiveness is obvious when compared with the case where the buffer layer thickness is 1.0 μm. The vertical axis of Fig. 6 is the nitrogen concentration ratio of 81Ng as 100ch, and the nitrogen concentration ratio in the case of 9 is a-5sxx. Also, only the distribution of nitrogen concentration is shown and other elements are omitted.

Example 14 In the case of a buffer layer consisting of a -BINx (l,
It is not preferable to increase the amount of nitrogen at the outermost surface of the buffer layer by at. This is because the bonding force between carbon and nitrogen is weak, so the surface layer is more likely to peel off than the buffer layer.

The off table is the result of examining the composition of the outermost surface of the buffer layer and the adhesion of the surface layer. In the table, the values in the composition column are a-SiM
x is the value of X in (H).

Further, in the table, the O mark indicates good adhesion, and the X mark indicates poor adhesion.

off table The composition of the buffer layer was measured using IsCA.

The m degree of nitrogen is preferably 1 or less in terms of the value of X, that is, 50% or less in the case of 5iNi.

In the above embodiments, an a-8i buffer layer containing water*t- was described, but it may further contain oxygen. i.e. a −811-xox (H+ O)
+a-8iNX(H,O) is also effective as a material for the buffer layer of the present invention.

〔Effect of the invention〕

According to the present invention, on top of the a-8i-based photoconductive
A system buffer layer is provided, and 10% of hydrogen is added on the buffer layer.
By forming a surface layer consisting of a-0 (b) containing ~40 atoms, more preferably 15 to 36 at%,
Good photoreceptor characteristics, less susceptible to environmental pollution, moisture resistance,
An electrophotographic photoreceptor with extremely excellent printing durability can be obtained. That is, the a-8i-based photoconductivity and the a-c(a)f
By providing an a-Eli backer layer with an appropriate composition between the i-plane layer, heterogeneity between the photoconductive layer and the surface layer is alleviated, and mechanical and electrical matching between the two layers is achieved. gets better.

As a result, while maintaining the excellent properties of the a-8i photoconductive material, such as high light sensitivity, high spectral sensitivity over the entire visible light range, low fatigue, and low residual potential, the Function as a protective film of a-C(H) film of high purity (particularly free of 81) and containing appropriate amounts of hydrogen purposely combined with carbon - osine, nitrogen oxides.

Resistance to oxygen etc. during the nascent period, especially excellent moisture resistance.

Due to printing durability, there is no deterioration phenomenon even during long-term storage and repeated use, and there is almost no deterioration in characteristics such as 1-1 defects even in high-temperature atmospheres.The characteristics as a photoreceptor are always stable and can be used in almost any usage environment. It is possible to obtain a good electrophotographic photoreceptor that is not subject to any restrictions and has excellent durability, printing durability, and moisture resistance.

As a result, the life of the so-called photoreceptor is greatly extended, and the maintenance of the copying machine equipped with it is made easier, which has many benefits.

[Brief explanation of drawings]

FIG. 1 is a conceptual cross-sectional view of the photoreceptor of the present invention, FIG. 2 is a conceptual system diagram of an example of an apparatus capable of manufacturing the photoreceptor of the present invention, and FIG. 3 i shows the formation of the surface layer of the present invention. a - Infrared absorption spectrum diagram of an example of C(H) film, Figure 4 is a diagram showing an example of the carbon fIc concentration gradient in the film thickness direction in the a -811-xcx<)υ buffer layer with a film thickness of 1 μm. , Figure 5 is a −
A diagram showing an example of the relationship between energy gap and composition of 811-xcjxH film, Figure 6 is a-8 with a film thickness of 1 μm.
FIG. 2 is a diagram showing an example of a nitrogen concentration gradient in the film thickness direction within a 1Nx (H) buffer layer. 1 to 0... exclusive 11ic base layer, 121... printing layer, 122... photoconductive layer, 123... bagno layer, 130... surface layer. Toki 2 wave number (cm-ri0 0.5
1 (element 1 (L41A) Fig. 5 Fig. 6

Claims (1)

[Scope of Claims] 1) On a conductive substrate, an amorphous silicon-based photoconductive layer, an amorphous silicon-based buffer layer, and a hydrogenated amorphous carbon (a
An electrophotographic photoreceptor characterized in that it is formed by sequentially laminating at least three layers including a surface layer consisting of -C(H)). 2) An electrophotographic photoreceptor according to claim 1, wherein the surface layer is made of hydrogenated amorphous carbon (a-C(H)) containing 15 to 36 atom % of hydrogen. 3) In the photoreceptor according to claim 1, the buffer layer is made of hydrogenated amorphous silicon carbide (a-Si_
1_-_xCx (H), 0<x<1) or hydrogenated oxygenated amorphous silicon carbide (a-Si_1_-_xC
An electrophotographic photoreceptor comprising: x (H, O), 0<x<1. 4) An electrophotographic photoreceptor according to claim 3, wherein the carbon concentration of the buffer layer increases from the photoconductive layer side toward the surface layer side. 5) The electrophotographic photoreceptor according to claim 3, wherein the buffer layer has a thickness of 0.03 μm or more and 1 μm or less. 6) In the photoreceptor according to claim 1, the buffer layer is made of hydrogenated amorphous silicon nitride (a-SiN
x(H), 0<x<1) or hydrogenated oxygenated amorphous silicon nitride (a-SiNx(H,O), 0<x<1
) An electrophotographic photoreceptor comprising: 7) An electrophotographic photoreceptor according to claim 6, wherein the nitrogen concentration of the buffer layer increases from the photoconductive layer side toward the surface layer side. 8) The electrophotographic photoreceptor according to claim 6, wherein the buffer layer has a thickness of 0.05 μm or more and 1.0 μm or less. 9) In the photoreceptor according to claim 1, the buffer layer is made of hydrogenated amorphous silicon oxide (a-SiO
An electrophotographic photoreceptor characterized in that x(H), 0<x<1. 10) In the photoreceptor according to claim 1, the buffer layer is made of hydrogenated amorphous oxidized silicon carbide (a-
An electrophotographic photoreceptor comprising SiCxOy (H), 0<x<1, 0<y<1.