JPH0752301B2 - 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-Si:
Electrophotographic sensitizations such as a laminated structure of 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) The body is 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.

Furthermore, when the most general plasma method is used for forming a-Si: H and a-Ge: H, SiH ₄ and
GeH ₄ is used, but these gases are expensive and it is difficult to reduce the manufacturing cost.

Means for Solving the Problems An inorganic photoconductive layer containing germanium and a charge transport layer containing amorphous carbon as a main component are laminated.

Action The relative permittivity of amorphous carbon is 3 to 6, which is considerably smaller than the relative permittivity of a-Ge: H and a-SiGe: H. The dielectric constant of the multi-layer electrophotographic photosensitive member used as the charge transport layer of the: H photoconductive layer is a
-Ge: H or a-SiGe: H single layer photoreceptor, or a-G
It is smaller than the dielectric constant of the laminated photoconductor of e: H and a-SiGe: 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.

In addition, by stacking amorphous carbon having a small relative dielectric constant, the film thickness of a-Ge: H and / or a-SiGe: H is 1/10 to 1/5 that of a conventional single-layer photoconductor. The overall film thickness of the photoconductor is 1/3 compared to conventional single-layer photoconductors.
It can be reduced to about 1/2. Further, by providing a layer of a photoconductive layer such as a-Ge: H that does not contain Si and has a narrow inhibitor width, it is possible to completely absorb the exposure light even if the thickness of the photoconductive layer becomes thin, It is possible to prevent deterioration of resolution due to reflection on the surface of the support. 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.

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 photoreceptor shown in FIG. 1 comprises an amorphous carbon (hereinafter a-C (: H: X)) containing at least hydrogen or a halogen atom (X) on a support 1 as an electrophotographic photoreceptor.
(However, abbreviated as X = F, Cl, Br, I)) and an inorganic photoconductive layer 3 containing germanium. The inorganic photoconductive layer 3 has a free surface 4 on one side. It has on the end face. In FIG. 1, a charge transport layer 2 made of aC (: H: X) and an inorganic photoconductive layer 3 containing germanium are laminated in this order on a support 1, but as shown in FIG. Inorganic photoconductive layer 3 containing germanium on body 1, aC
Even if the charge transport layer 2 composed of (: H: X) is laminated in this order, a-
Since C (: H: X) is almost transparent to visible light, most of the light incident from the free surface 4 can reach the inorganic photoconductive layer 3, which is similar to the structure shown in FIG. It is possible to obtain various characteristics.

In the present invention, the inorganic photoconductive layer 3 containing germanium has a layer not containing silicon, and as a specific constitution, a-Ge (: H: X) single layer a-Ge (: H: X) And a-SiG
e (: H: X) single layer a-Ge (: H: X) and a-Si (: H: X) layered a-GeC (: H: X) single layer a-GeC (: H: X) ) And a-Si (: H:
X) laminated a-Ge (: H: X) and a-GeC (: H: C) laminated a-
Stacked a-Ge (: H: X) of GeC (: H: X) and a-SiGe (: H: X)
And a-SiC (: H: X) stack or a-GeC (H: X) and a-S
A layer of iC (: H: X) is selected for use. In addition, as an effective material other than the above as the inorganic photoconductive layer 3, a chalcogenide glass in which Ge is contained in at least Se, Te, S or a material composed of two or more of these, for example, Ge
-S, Ge-Se, Ge-Te, Ge-P-S, Ge-P-Se, Ge-P-Te, Ge
-As-S, Ge-As-Se, Ge-As-Te, Ge-Sb-Se, Ge-Te-Sb, Ge-Te-
P, Ge-Te-As, Ga-Ge-As-Te, Ge-As-S-Te, Ge-As-Se-Te, K
-Ca-Ge-S, Ge-Te-Sb-S etc. are mentioned.

In the present invention, in order to further improve the electrophotographic characteristics, in FIG. 1, between the support 1 and the charge transport layer 2,
A barrier layer may be provided to effectively block carriers injected from the support 1 into the charge transport layer 2. 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, T
a ₂ O ₅ , ThO ₂ , ZrO ₂ , HfO ₂ , GeO ₂ , Y ₂ O ₃ , TiO ₂ , MgO, MgO ・ Al ₂ O ₃ , S
Metal oxide such as iO ₂・ MgO or TiN, AlN, SnN, NbN, TaN, GaN
Such as metal nitrides such as WC, SnC, TiC, etc. or insulators such as SiO _x , SiN _x , GeC _x , GeN _x , BN _x , BC _x , polyethylene, polycarbonate, polyurethane, polyparaxylene etc. When an insulating organic compound is used and a positive charge is charged on the free surface 4 side, a-Si (: H :: H :) containing a p-type semiconductor, for example, a group III element such as B, Al, or Ga is added.
X), a-SiGe (: H: X), a-Ge (: H: X), a-C (: H: X), a
-SiC (: H: X) or a-GeC (: H: X) may be used. Further, when the free surface 4 is charged with a negative charge, an n-type semiconductor such as a-Si (: H: X) or a-SiGe (: H) added with a group V element such as N, P or As is used as a barrier layer. : X), a−Ge (: H: X), a
The use of -C (: H: X), a-SiC (: H: X) or a-GeC (: H: X) is preferred. Further, even when the charge transport layer 2 has a free surface 4 as shown in FIG. 2, between the support 1 and the inorganic photoconductive layer 3, the above-mentioned metal oxide, metal nitride, metal carbide, A barrier layer made of an insulating material or an insulating organic compound may be formed. In particular, when the free surface 4 is charged with a positive charge, the barrier layer is formed of the above p-type semiconductor and the free surface 4 is charged with a negative charge. When charging the
It is preferably formed of a mold semiconductor.

In the present invention, a surface coating layer is formed on the free surface 4 in FIGS. 1 and 2 in order to improve the wear resistance, moisture resistance and cleaning property of the photoreceptor. SiO _x , SiC _x , Si can be used effectively as surface coating materials.
Inorganic insulators such as N _x , GeO _x , GeC _x , GCM _x BN _x , BC _x , AlN _x or polyethylene terephthalate, polycarbonate,
Polypropylene, Polyvinyl chloride, Polyvinylidene chloride, Polyvinyl alcohol, Polystyrene, Polyamide, Polytetrafluoride ethylene, Polytrifluoroethylene chloride, Polyphenylidene fluoride, Hexafluoropropylene-tetrafluoroethylene copolymer, Ethylene trifluoride -Synthetic resins such as vinylidene fluoride copolymer, polybrene, polyvinyl butyral and 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, CH 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 etc. alkyl halides, 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 and} other CFC gases, C ₆ H _6-m F _m (m = 1 to 6) fluorinated benzene and other C atom source gases plasma CVD method or using a graphics site _{targeting, Ar, H 2, F 2} , Cl 2, CH 4, C 2 H 4, a reactive sputtering method in C ₂ H ₂ is used.

Materials for forming an inorganic photoconductive layer containing germanium: a-Ge (: H: X), a-Si (: H: X), a-SiGe (: H: X), a-Ge
To create C (: H: X), a-SiC (: H: X), first, a-Ge (:
H: X) GeH ₄ , Ge ₂ H ₆ , Ge ₃ H ₈ , GeF ₄ , GeCl ₄ , GeBr ₄ , GeI ₄ ,
GeF ₂ , GeCl ₂ , GeBr ₂ , GeI ₂ , GeHF ₃ , GeH ₂ F ₂ , GeH ₃ F, GeHCl ₃ , Ge
H ₂ Cl ₂ , GeH ₃ Cl, GeHBr ₃ , GeH ₂ Br ₂ , GeH ₃ Br, GeHI ₃ , GeH ₂ I ₂ , Ge
Plasma CVD method using a source gas of Ge atoms such as H ₃ I, or reaction in a mixed gas of Ar and H ₂ (F ₂ or Cl ₂ may be mixed) targeting polycrystalline germanium Reactive sputtering method is used, and in the case of a-Si (: H: X), Si
_{H 4, Si 2 H 6,} Si 3 H 8, SiF 4, SiCl 4, SiHF 3, SiH 2 F 2, SiH 3 F, SiHCl
Plasma CVD method using source gas of Si atoms such as ₃ , SiH ₂ Cl ₂ and SiH ₃ Cl, or Ar targeting polycrystalline silicon
Reactive sputtering in a mixed gas of H ₂ and H ₂ (which may be mixed with F ₂ or Cl ₂ ) is used. a-SiGe (:
In the case of (H: X), similarly, the above source gas of Ge atoms and S
Plasma CVD method using a mixed gas of i atom source gas, or a target in which Si and Ge are mixed or Si and Ge
Ar and H ₂ (additional F ₂ or Cl ₂
May be mixed) in a mixed gas of reactive sputtering method. In the case of a-GeC (: H: X), the source gas of the above Ge atom and CH ₄ , C ₂ H ₆ , C ₃ H ₈ , C ₂ H ₄ , C ₃ H ₆ , C ₂ H ₂ , CF ₄ , C ₂ F
Plasma CVD method using a mixed gas of C atom source gas such as ₆ , CHF ₃ , CClF ₃ , or Ar and H ₂ using a target mixed with Ge and C or two targets Ge and C It is formed by a reactive sputtering method in a mixed gas of (F ₂ or Cl ₂ may be further mixed), and a-SiC (: H:
Also in the case of X), as in the case of a-GeC (: H: X), a plasma CVD method using a mixed gas of the above Si atom source gas and C atom source gas, or a target in which Si and C are mixed Alternatively, it is formed by a 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 Si and C.

Further, in the present invention, the above-mentioned aC (: H: X), a-Ge (:
H: X), a-Si (: H: X), a-SiGe (: H: X), a-GeC (: H:
By adding impurities to (X), a-SiC (: H: X), the conductivity can be controlled and desired electrophotographic characteristics can be obtained. In particular, a-C (: H: X) forming the charge transport layer largely changes the carrier transport characteristics due to 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.
Ga is used, and as n-type impurities that give n-type conductivity, there are P, As, Sb belonging to Group V of the periodic table, and P, As is preferably used.

Further, as a method for 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 , BBr 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, the case of n-type _{impurity, 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 , Sb
The gas of Cl ₅ or the gas obtained by diluting these gases with H ₂ , He and Ar is used as the source gas of the above-mentioned C atom, Si atom or Ge atom in the formation of each material by the plasma CVD method. It may be mixed and used, and in the reactive sputtering method, it may be mixed and used with Ar or H ₂ or F ₂ and Cl ₂ .

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 1% concentration of B ₂ H ₆ : 0.5 to 20 sccm was introduced into the apparatus, the pressure inside the reaction vessel was adjusted to 0.1 to 1.0 Torr, and then the high frequency of 13.56 MHz. An aC: H layer doped with boron is formed to a thickness of 20 μm with an electric power of 20 to 150 W, then GeF ₄ : 0.5 to ₅ sccm, GeH ₄ : 10 to ₄₀ sccm is introduced, the pressure is 0.2 to 1.0 Torr, and the high frequency power is 20 to 100 W. undoped a-Ge: H: the F layer was 0.5~2μm formed, further SCH _4:. 20 to
40sccm, C ₂ H ₄ : 10〜40sccm was introduced, and a SiCx layer was formed by 1000〜2000Å at a pressure of 0.2〜1.0 Torr and high frequency power of 50〜150W to prepare an electrophotographic photoreceptor. This electrophotographic photoreceptor is + 6.3KV
The surface potential of + 4000V was obtained when the corona was charged with
Upon exposure to monochromatic light of 70 nm, the residual potential was +20 V or less. Next, when the surface potential was charged to + 400V,
The corona current at the time of charging was decreased and the photosensitivity was increased as compared with the case where only the a-Ge: H: F photoconductive layer having the same film thickness was used.

This is because the aC: H layer functions as a hole charge transport layer,
This is because the dielectric constant of the electrophotographic photosensitive member is reduced.

Further, instead of the 0.2 to 2 μm undoped a-Ge: H: F photoconductive layer, the a-Ge: H (: F) layer 0.1 to 1 μm from the support side.
And a-Si: H (: F) layer 0.1-1 μm are laminated, a-G
e: H (: F) layer 0.1 to 1 μm and a-SiGe: H (: F) layer 0.1 to 1
In the case of laminating an a-Ge: H (: F) layer of 0.1 to 1 µm and an a-SiC: H (: F) layer of 0.1 to 1 µm, an electrophotographic photosensitive member having the same characteristics as above. I was able to form my body.

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. GeH ₄ : 10 ~ 50sccm, H ₂
Diluted 400ppm concentration of B ₂ H _6: 10~50sccm introduced, pressure: 0.
2-1.0 Torr, high-frequency power 100-300W, p-type a as a barrier layer
Forming a Ge: H layer of 0.1-1 μm, then GeH ₄ : 10-50 sccm,
Undoped a-Ge: H layer 0.5 to 1 μm is formed at a pressure of 0.2 to 1.0 Torr and high frequency power of 100 to 300 W, and then C is added in addition to GeH _4.
H ₄ : 10 to 80 sccm introduced, undoped a-GeC: H layer 0.5 to 1
μm formed. Next, GeH ₄ was cut off, and an undoped aC: H layer of 2 to 3 μm was laminated using only CH ₄ to form an electrophotographic photosensitive member. This photoconductor is mounted on a laser beam printer that uses a semiconductor laser with an oscillation wavelength of 800 nm as its light source,
A clear print was confirmed under positive charging. Further, instead of the undoped a-Ge: H layer and the undoped a-GeC: H layer of the photoconductive layer, an a-Ge: H (: F) single layer, an a-GeC: H (: F) single layer, or , A-GeC: H (: F) and a-Si: H (: F) from the support side
, A-Ge C: H (: F) and a-Si: H (: F) stack, a-Ge
Lamination of C: H (: F) and a-SiGe: H (: F), a- (GeC: H (: F)
And a-SiC: H (: F) stack, or a-Ge: H (: F) and a
In the case of using a stack of —SiC: H :(: F), an electrophotographic photosensitive member having the same characteristics as above could be formed.

Example 3 A GeCx layer 1000 to 5000Å was formed as a surface coating layer on the electrophotographic photosensitive member manufactured in Example 2 by a plasma CVD method and mounted on the laser beam printer used in Example 2. It was confirmed that the photographic photoreceptor has excellent heat resistance and moisture resistance, and has a printing durability of 800,000 sheets.

Example 4 An a-Ge: H layer containing phosphorus of 500 to 1000 atomic ppm by plasma CVD on a glass substrate having Mo deposited on the surface of 0.5 to 0.5
2 μm and a—C: H layer 3 containing 0.5 to 50 atomic ppm of phosphorus 3
μm and SiN × 1000 to 2000Å were sequentially laminated to prepare an electrophotographic photosensitive member. When this photoreceptor was corona-charged at -6.0 KV, a surface potential of -800 V was obtained, it was highly sensitive to light having a wavelength of 400 to 700 nm, and the residual potential was -10 V or less. In this case, the phosphorus-added aC: H layer functions as an electron charge transport layer.

Example 5 A glass substrate on which Al was vapor-deposited was placed in a magnetron sputtering apparatus, the substrate temperature was set to 150 to 300 ° C., a Dy ₂ O ₃ sintered body was targeted, and Ar: 3 to 20 mTorr, O ₂ : 10 to 40 mTorr. Then, a Dy ₂ O ₃ layer of 1000 to 5000 Å is formed under the condition of high frequency power of 100 to 300 W, then graphite is targeted, and Ar: 1 to 10 mT.
orr, H _2: 9~90mTorr, under the conditions of the high-frequency power 100~600W a-
A C: H layer having a thickness of 5 μm was formed. Then, the As-Se
-Ge layer 1-2μm is formed, and As-
A polycarbonate resin was dried and uniformly applied to the Se-Ge layer so as to have a thickness of 10 μm to form an electrophotographic photoreceptor. When this photoreceptor was subjected to +6.3 KV corona charging and exposed to white light, it was confirmed that the charging potential was high and the sensitivity was high.

EFFECT OF THE INVENTION The electrophotographic photosensitive member according to the present invention has a small corona current at the time of charging, high sensitivity to visible light and near-infrared light, 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 ... Support, 2 ... Charge transport layer, 3 ... Inorganic photoconductive layer.

 ─────────────────────────────────────────────────── ─── 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 (6)

[Claims] 1. An inorganic photoconductive layer containing germanium, and a charge transport layer formed in contact with the inorganic photoconductive layer, the charge transporting layer containing amorphous carbon containing at least hydrogen or halogen atoms as a main component. An electrophotographic photoreceptor having a layer containing no silicon in the inorganic photoconductive layer. 2. The electrophotographic photosensitive member according to claim 1, wherein the inorganic photoconductive layer has a layer containing at least hydrogen or halogen atoms and containing at least carbon atoms. 3. The electrophotographic photosensitive member according to claim 1, wherein the inorganic photoconductive layer contains a chalcogen atom. 4. At least one of the inorganic photoconductive layer and the charge transport layer contains a Group III element or a Group V element of the periodic table, according to any one of claims 1 to 3.
The electrophotographic photosensitive member according to any one of items. 5. The electrophotographic photoreceptor according to claim 1, which has a surface coating layer. 6. The electrophotographic photoreceptor according to claim 1, further comprising a barrier layer between the support and the inorganic photoconductive layer or the charge transport layer.