JPH0727246B2 - Electrophotographic photoreceptor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic photosensitive member used in an electrophotographic copying machine or printer.

2. Description of the Related Art Conventionally, hydrogenated amorphous silicon (hereinafter abbreviated as a-Si: H) has been used to provide photosensitivity to visible light and near infrared light.
And a laminated structure of hydrogenated amorphous germanium (hereinafter abbreviated as a-Ge: H) (JP-A-56-150753), a-S
Electrons such as a laminated structure of i: H and a-SiGe: H (JP-A-57-115552), a single-layer structure of a-SiGe: H doped with boron and oxygen (JP-A-57-172344) A photographic photoreceptor has been proposed.

Problems to be Solved by the Invention An electrophotographic photosensitive member composed of a-Si: H, a-SiGe: H or a-Ge: H has a large relative dielectric constant of these materials of 10 to 15, Due to the large body capacitance, a large corona current is required during charging. Also, since the surface charge amount is large,
A large amount of exposure is required to extinguish this charge, and there is a problem in that the operating speed is reduced due to restrictions on the light source used and power consumption increase, or an increase in exposure time.

Further, when the most general plasma CVD method is used for forming a-Si: H, a-SiGe: H and a-Ge: H, SiH ₄ and GeH ₄ are used as the source gas. Gas is expensive and it is difficult to reduce the manufacturing cost. In addition, a-Si: H, a-SiGe: H and a-G formed by plasma CVD method
e: H had a problem that pinholes were apt to occur and white spots appeared when the image was evaluated with the photoconductor.

Means for Solving the Problems Inorganic photoconductive layer containing at least one of silicon and germanium as main components and at least 1 of oxygen, sulfur and nitrogen
A charge-transporting layer whose main component is amorphous carbon containing titanium is laminated.

Action Amorphous carbon has a relative permittivity of 3 to 6, a-Si: H, a-Si
It is considerably smaller than the relative permittivity of Ge: H and a-Ge: H,
The electrostatic capacity of a multi-layer electrophotographic photosensitive member using amorphous carbon as a charge transport layer of a photoconductive layer composed of these materials is a-Si: H or a-SiGe: H single-layer photosensitive member. Or a laminated photoreceptor of a-Si: H and a-SiGe: H, a-Si: H and a
It is smaller than the capacitance of the laminated photoconductor of -Ge: H. Therefore, the corona current at the time of charging is reduced, and since the surface charge amount is small, the photosensitivity is increased and the operation speed can be improved. Further, when oxygen, sulfur or nitrogen is contained in the amorphous carbon, defects contained in the amorphous carbon are reduced and not only the efficiency of charge transport is improved but also the relative dielectric constant is further reduced. It is possible to further enhance the above effect.

In addition, by stacking amorphous carbon having a small relative dielectric constant, 1/3 to 1/2 of that of a photoconductor composed only of a-Si: H, a-SiGe: H or a-Ge: H can be obtained. The same thickness characteristics as those of these photoreceptors can be obtained. Furthermore, when the plasma CVD method is used for forming the amorphous carbon film, SiH ₄ ,
Inexpensive CH ₄ as compared with _{GeH 4, C 2 H 6,} C 3 H 8, for C ₂ H ₄ which can be used, such as, can be greatly reduced manufacturing cost of the photoconductor. In addition, since the amorphous carbon produced by the plasma CVD method has no pinholes, it is possible to obtain a good image without white spots.

EXAMPLE FIG. 1 is a schematic cross-sectional view of an example of the most basic electrophotographic photosensitive member according to the present invention.

The electrophotographic photosensitive member 1 shown in FIG. 1 has a charge transport layer 3 and an inorganic photoconductive layer 4 on a support 2 as an electrophotographic photosensitive member, and the inorganic photoconductive layer 4 has a free surface 5. It has one end face. The charge transport layer 3 is made of amorphous carbon [hereinafter a-C (: H:
X) (however, abbreviated as X = F, Cl, Br, I)],
The inorganic photoconductive layer 4 is made of a material containing at least hydrogen or a halogen atom and containing at least one of silicon and germanium as a main component. Further, the aC (: H: X) film constituting the charge transport layer 3 reduces the relative permittivity of aC (: H: X) and defects in the film, and eliminates the time-dependent change of the film and stabilizes it. It contains at least one of oxygen, sulfur and nitrogen to improve its properties.

In FIG. 1, the charge transport layer 3 made of aC (: H: X) and the inorganic photoconductive layer 4 are laminated in this order on the support 2, but as shown in FIG. Inorganic photoconductive layer 4, aC (:
(C: H: X) is almost transparent to visible light, even if the charge transport layer 3 composed of (H: X) is laminated in this order to form the electrophotographic photoreceptor 6. Most of the light incident from the light source can reach the inorganic photoconductive layer 4, and the characteristics similar to those of the configuration shown in FIG. 1 can be obtained.

In the present invention, the material for forming the inorganic photoconductive layer 4 containing at least hydrogen or a halogen atom and containing at least one of silicon and germanium as a main component is an a-Si (: H: X) single layer. , a−SiGe (: H: X) single layer, a−G
e (: H: X) single layer, a-Ge (: H: X) and a-Si (: H: X) stack,
Lamination of a-SiGe (: H: X) and a-Si (: H: X), a-Ge (: H: X:
X) and a-SiGe (: H: X) are laminated and used.

In the present invention, in order to further improve the electrophotographic characteristics, in FIG. 1, between the support 2 and the charge transport layer 3,
A barrier layer that effectively blocks carriers injected from the support 2 to the charge transport layer 3 may be provided. As a material for forming the barrier layer, Al ₂ O ₃ , BaO, BaO ₂ , BeO, Bi ₂ O ₃ , CaO, CeO ₂ , Ce ₂ O ₃ ,
La ₂ O ₃ ,, Dy ₂ O ₃ ,, Lu ₂ O ₃ ,, Cr ₂ O ₃ ,, CuO, Cu ₂ O, FeO, PbO, MgO, SrO ₂ ,
Ta ₂ O ₅ ,, ThO ₂ , ZrO ₂ , HfO ₂ , Y ₂ O ₃ , TiO ₂ , MgO ・ Al ₂ O ₃ , SiO ₂・ Mg
Metal oxide such as O or metal nitride such as TiN, AlN, SnN, NbN, TaN, GaN or metal carbide such as WC, SnC, TiC or
Si _1-X O _X , Si _1-X N _X , Si _1-X C _X , Ge _1-X O _X , Ge _1-X N _X , Ge _1-X C _X , B
Insulators such as _1-X N _X , B _1-X C _X (0 <X <1) or insulating organic compounds such as polyethylene, polycarbonate, polyurethane, polyparaxylene are used, and free surface 5
When a positive charge is applied to the side, a p-type semiconductor such as B,
A-Si (: H:
X), a-SiGe (: H: X), a-Ge (: H: X), a-C (: H: X), a
-SiC (: H: X), a-GeC (: H: X) may be used. When negative charges are charged on the free surface 5, an n-type semiconductor, for example, a-Si (: H: X), a-SiGe (a-SiGe ( : H: X), a−Ge (: H: X), a
The use of -C (: H: X), a-SiC (: H: X) or a-GeC (: H: X) is preferred.

Further, as shown in FIG. 2, the charge transport layer 3 has a free surface 5.
Even in the case of having the above-mentioned metal oxide, metal nitride, metal carbide, or the like between the support 2 and the inorganic photoconductive layer 4,
A barrier layer made of an insulating material or an insulating organic compound may be formed. In particular, when the free surface 5 is charged with a positive charge, the barrier layer may be formed of the above-mentioned p-type semiconductor to form the free surface 5.
When negatively charged, it is preferable to form the above n-type semiconductor.

In the present invention, a surface coating layer is formed on the free surface 5 in FIGS. 1 and 2 in order to improve the abrasion resistance, moisture resistance and cleaning property of the photoreceptor. Si can be effectively used as a surface coating layer forming material.
_1-X O _X , Si _1-X C _X , Si _1-X N _X , Ge _1-X O _X , Ge _1-X C _X , Ge _1-X N _X , B _1-X
N _X , B _1-X C _X , Al _1-X N _X , Sn _1-X N _X , Sn _1-X C _X Inorganic insulation or polyethylene terephthalate, polycarbonate, polypropylene, polyvinyl chloride, polyvinylidene chloride , Polyvinyl alcohol, polystyrene, polyamide, polytetrafluoroethylene, polytrifluoroethylene chloride, polyvinylidene fluoride, propylene hexafluoride-tetrafluoroethylene copolymer, ethylene trifluoride-vinylidene fluoride copolymer, polybutene, polyvinyl Examples include butyral and synthetic resins such as polyurethane.

To create aC (: H: X), CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₄ H ₁₀ , C
₂ H ₄ , C ₃ H ₆ , C ₄ H ₈ , C ₂ H ₂ , C ₃ H ₄ , C ₄ H ₆ , C ₆ H ₆ and other hydrocarbons, C
Alkyl halides such as H ₃ F, CH ₃ Cl, CH ₃ Br, CH ₃ I, C ₂ H ₅ Cl, C ₂ H ₅ Br, C ₂ H ₅ I, C ₃ H ₅ F, C ₃ H ₅ Cl , C ₃ H ₅ Br etc. allyl halides, CClF ₃ , CF ₄ , CHF ₃ , C ₂ F ₆ , C ₃ F ₈ etc. fluorocarbons, C ₆ H _6- mFm (m = 1-6) fluorination Plasma CVD method using C atom source gas such as benzene, or targeting graphite, Ar, H ₂ , F ₂ , Cl ₂ , CH ₄ , C ₂ H ₄ , C ₂ H ₂
The reactive sputtering method in is used. Also, a-
In order to make oxygen (O), sulfur (S) or nitrogen (N) contained in C (: H: X), O ₂ , O ₃ , CO, CO ₂ , NO, NO ₂ , N ₂ as a source gas of O atom is used.
O, as a source gas of _{N 2 O 3, N 2 O} 4, N 2 O 5, NO 3, S atom, CS _2, H ₂
S, S ₂ O, SO ₂ , SO ₃ , N N ₂ , NH ₃ , H ₂ NNH ₂ , H
Gases such as N ₃ , NH ₄ N ₃ , F ₃ N, and F ₄ N ₂ may be mixed with the above-mentioned C atom source gas in the plasma CVD method and used, and in the reactive sputtering method, Ar, H ₂ , It may be used by mixing with F ₂ , Cl ₂ or the like.

A-Si (: H: X), a-G, which is a constituent material of an inorganic photoconductive layer containing at least hydrogen or a halogen atom and containing at least one of silicon and germanium as a main component.
To create e (: H: X), a-SiGe (: H: X), first, a-Si (:
H: X), SiH ₄ ,, Si ₂ H ₆ ,, Si ₃ H ₈ ,, SiF ₄ ,, SiCl ₄ ,, SiHF ₃ ,, SiH
_{2 F 2, SiH 3 F,} SiHCl 3, SiH 2 Cl 2, SiH 3 plasma CVD method using a source gas of Si atoms, such as Cl, or polycrystalline silicon as a target Ar and H ₂ (more F ₂ or Cl ₂ may be mixed) in a mixed gas of a), and in the case of a-Ge (: H: X), GeH ₄ , Ge ₂ H ₆ , Ge ₃ H ₈ , GeF ₄ , Ge
Cl ₄ , GeBr ₄ , GeI ₄ , GeF ₂ , GeCl ₂ , GeBr ₂ , GeI ₂ , GeHF ₃ , GeH ₂ F ₂ ,
GeH ₃ F, GeHCl ₃ , GeH ₂ Cl ₂ , GeH ₃ Cl, GeHBr ₃ , GeH ₂ Br ₂ , GeH ₃ Br,
Plasma CVD method using source gas of Ge atoms such as GeHI ₃ , GeH ₂ I ₂ , GeH ₃ I, or targeting polycrystalline germanium, Ar and H ₂ (F ₂ or Cl ₂ may be mixed) )
The reactive sputtering method in the mixed gas is used. a-
Similarly, in the case of SiGe (: H: X), plasma CV using the mixed gas of the above Si atom source gas and Ge atom source gas
D method, or mixed target of Si and Ge or Si
It is formed by the reactive sputtering method in a mixed gas of Ar and H ₂ (further, F ₂ or Cl ₂ may be mixed) using two targets of Ge and Ge.

In addition, a-Si (: H: X), a-Ge which is a constituent material of the inorganic photoconductive layer
(: H: X) and a-SiGe (: H: X) containing carbon, oxygen, sulfur, or nitrogen to achieve high resistance, high photosensitivity, and high stability in the inorganic photoconductive layer. You can
Carbon, oxygen, sulfur, and nitrogen can be contained by using the above-mentioned C atom source gas, O atom source gas, S atom source gas, and N atom source gas, respectively. It may be used by mixing it with the raw material gas of Ge or the raw material gas of Ge atoms, and in the reactive sputtering method, it may be mixed with Ar or H ₂ and used (F ₂ or Cl
_May be mixed in _2. )

Further, in the present invention, the above-mentioned a-Si (: H: X), a-G
By adding impurities to e (: H: X), a-SiGe (: H: X), a-C (: H: X), conductivity can be controlled and desired electrophotographic characteristics can be obtained. it can. In particular, the carrier transport characteristics of aC (: H: X) forming the charge transport layer are significantly changed by the addition of this impurity. Examples of p-type impurities that give p-type conductivity include B, Al, Ga, and In belonging to Group III of the periodic table. B, Al, and Ga are preferably used, and n-type that gives n-type conductivity is used. Impurities include P, As, S belonging to Group V of the periodic table.
b, etc., and P and As are preferably used. As a method of adding these impurities, in the case of p-type impurities,
B ₂ H ₆ , B ₄ H ₁₀ , B ₅ H ₉ , B ₅ H ₁₁ , B ₆ H ₁₀ , B ₆ H ₁₂ , B ₆ H ₁₄ , BF ₃ , BCl ₃ , B
_{Br 3, AlCl 3, (CH} 3) 3 Al, (C 2 H 5) 3 Al, (iC 4 H 9) 3 Al, (CH
₃ ) ₃ Ga, (C ₂ H ₅ ) ₃ Ga, InCl ₃ ,, (C ₂ H ₅ ) ₃ In, in the case of n-type impurities, PH ₃ , P ₂ H ₄ , PH ₄ I, PF ₃ , PF ₅ , PCl ₃ , PCl ₅ , PBr ₃ , PBr ₅ , PI
₃ , AsH ₃ , AsF ₃ , AsCl ₃ , AsBr ₃ , AsF ₅ , SbH ₃ , SbF ₃ , SbF ₅ , SbCl ₃ ,
In the plasma CVD method, a gas of SbCl ₅ or a gas obtained by diluting these gases with H ₂ , He, and Ar is mixed with the above-mentioned source gas of C atom, Si atom, or Ge atom used for forming each material. Mixed with Ar or H ₂ in the reactive sputtering method (F ₂ or Cl ₂
May be mixed with).

Examples will be described below.

Example 1 A mirror-polished Al substrate was placed in a capacitively coupled plasma CVD apparatus, the reaction vessel was evacuated to 5 × 10 ⁻⁶ Torr or less, and then the substrate was heated to 150 to 250 ° C. C ₂ H ₄ : 10 to 80 sccm, H ₂ diluted 0.1% concentration of B ₂ H ₆ : 0.5 to 20 sccm, CO: 0.1 to 0.5 sccm was introduced into the apparatus, and the pressure in the reaction vessel was adjusted to 0.1 to 1.0 Torr. After the adjustment, an aC: H layer doped with boron and oxygen was formed to a thickness of 15 μm with a high-frequency power of 13.56 MHz of 20 to 200 W, and then SiF ₄ : 2 to 10 scc.
m, SiH ₄ : 10-40 sccm was introduced, the pressure was 0.2-1.0 Torr, the high-frequency power was 20-150 W, and the undoped a-Si: H: F layer was 0.5-2 μ.
m to form an electrophotographic photosensitive member. When this electrophotographic photosensitive member was corona-charged at +6.3 KV, a surface potential of +3500 V was obtained, and when exposed to white light, the residual potential was +20 V or less. Next, when the surface potential was charged to +400 V, the corona current at the time of charging was decreased and the photosensitivity was increased as compared with the case of only the a-Si: H: F layer having the same film thickness. This is because the aC: H layer added with boron and oxygen functions as a charge transport layer for holes and reduces the dielectric constant of the electrophotographic photoreceptor.

Example 2 A mirror-polished Al drum was placed in a capacitively coupled plasma CVD apparatus, and the reaction vessel was evacuated to 5 × 10 ⁻⁶ Torr or less.
The Al drum was heated to 150-250 ° C. Then GeF ₄ : 1-5scc
m, SiH ₄ : 100 to 200 sccm, H ₂ diluted 20 ppm PH ₃ : 1 to 5 s
Introduced ccm, pressure: 0.2 ~ 1.0Torr, high frequency power: 100 ~ 300W
The a-SiGe: H: F layer 0.5 to 1 μm in which phosphorus is added, then the introduction of GeF ₄ is stopped, CH ₄ : 5 to 20 sccm is introduced instead, and the a-SiC: H layer in which phosphorus is added is 0.5 to 1 μm Formed. _{Then, CH 4: 70~150sccm, CF 4} : 30~50sccm, N 2: 1~5sccm introduced, pressure: 0.1～1.0Torr, high frequency power: the addition of nitrogen in the 100 to 500 W a-C: H: F layer 3-5 μm is laminated, and GeH ₄ :
5 to 10 sccm, C ₂ H ₄ : 50 to 100 sccm, pressure: 0.1 to 1.0 Torr, high frequency power: 100 to 500 W Ge _1-X C _X 1000 to 5000 Å
Then, an electrophotographic photosensitive member was prepared. This photoconductor was mounted on a laser beam printer using a semiconductor laser with an oscillation wavelength of 800 nm as a light source, and it was confirmed that there was no clear printing and no white spot flaws in negative charging. It was also confirmed that the printing durability of 800,000 sheets and the absence of image deletion in a high humidity atmosphere.

Further, instead of the phosphorus-doped a-SiGe: H: F layer and the phosphorus-doped a-SiC: H layer of the photoconductive layer, an a-Ge: H (: F) single layer,
a-GeC: H (: F) single layer, a-SiGe: H (: F) single layer, or a-GeC: H (: F) and a-Si: H (: F) laminated from the support side, a−G
Stacking of e: H (: F) and a-GeC: H (: F), a-Ge: H (: F) and a
-Si: H (: F) stack, a-GeC: H (: F) and a-SiC: H: (:
F), a-GeC: H (: F) and a-SiGe: H (: F), a
-SiGe: H (: F) and a-Si: H (: F) stack, a-Ge: H (: F)
And a-SiGe: H (: F) stack, a-GeC: H (: F) and a-SiGe:
Even when the H (: F) layer was used, an electrophotographic photosensitive member having the same characteristics as described above could be formed.

Example 3 A glass substrate on which Mo is deposited is placed in a magnetron sputtering apparatus, the substrate temperature is set to 150 to 250 ° C., a Dy ₂ O ₃ sintered body is targeted, and Ar: 3 to 20 mTorr, O ₂ : 10 to 40 mTorr. , High frequency power: 1000 ~ 5000Å Dy ₂ O ₃ layer is formed under the condition of 100 ~ 300W, then target graphite and Ar: 1 ~ 10mTor
r, H ₂ : 9 to 90 mTorr, NO: 0.1 to 1 mTorr, high frequency power 100 to 600 W
Under the above conditions, an aC: H layer added with nitrogen and oxygen was formed to a thickness of 5 μm. Then, using polycrystalline silicon as a target,
r: _{2 to} 5mTorr, H ₂ : 3 to 5mTorr, NO: 0.1 to 0.5mTorr, a-Si: H with nitrogen and oxygen added under conditions of high frequency power 100 to 500W
A layer of 0.5 to 2 μm was formed to form an electrophotographic photoreceptor. When this photoreceptor was corona-charged at + 6.3KV, surface potential + 1000V was obtained, and it was highly sensitive to light with wavelength of 400-700nm.
The residual potential was also less than + 20V.

Example 4 A-Si: H doped with boron was formed as a 1000 to 5000Å barrier layer by a plasma CVD method on a glass substrate having Al vapor-deposited on its surface, and a-C: H doped with oxygen and boron was further added.
Layer 3 μm, oxygen- and boron-added a-Si: H layer 0.5-
An electrophotographic photosensitive member was prepared by sequentially laminating 2 μm and Si _1-X C _X layers 1000 to 5000 Å as a surface coating layer. + On this photoconductor
After performing corona charging of 6.3KV and exposing with white light,
The charging potential was high and the sensitivity was high.

EFFECTS OF THE INVENTION The electrophotographic photosensitive member according to the present invention has a small corona current at the time of charging, high photosensitivity, no white spots on an image, and low cost.

[Brief description of drawings]

1 and 2 are cross-sectional views of an embodiment of the electrophotographic photosensitive member according to the present invention. 1, 6 ... Electrophotographic photoreceptor, 2 ... Support, 3 ... Charge transport layer, 4 ... Inorganic photoconductive layer, 5 ... Free surface.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kyoko Onomichi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Masanori Watanabe 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 56) References Japanese Patent Laid-Open No. 62-9355 (JP, A)

Claims (5)

[Claims] 1. An inorganic photoconductive layer containing at least hydrogen or a halogen atom and having at least one of silicon and germanium as a main component, and in contact with the inorganic photoconductive layer, containing at least a hydrogen or halogen atom. And a charge transport layer containing amorphous carbon containing at least one of oxygen, sulfur and nitrogen as a main component. 2. The electrophotographic photosensitive member according to claim 1, wherein the inorganic photoconductive layer contains at least one of carbon, oxygen, sulfur, and nitrogen. 3. At least one of an inorganic photoconductive layer and a charge transport layer contains a Group III element or a Group V element of the periodic table. The electrophotographic photosensitive member according to 1. 4. The electrophotographic photosensitive member according to claim 1, which has a surface coating layer. 5. The electrophotographic photosensitive member according to claim 1, further comprising a barrier layer between the support and the inorganic photoconductive layer or the charge transport layer.