JPS60140354A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enlarge the sensitivity region obtainable by doping of Ge without impairing photoconductivity by alternately laminating an H-contg. amorphous Si and an H-contg. amorphous germanium layer. CONSTITUTION:A 1-several atomic layers made of pure a-Si:H is formed and a pure a-Ge:H layer similar in thickness is laminated on it. In the interface of them, Si and Ge are made a Si-Ge alloy by the interaction between them. Inside the interface, both layers are made of pure a-Si:H and pure a-Ge:H, respectively, but in the laminated layer thickness direction, they become a-Si-Ge:H. For example, said unit cells are formed to a desired thickness to form the total number of high-quality photosensitive layers 2 are formed, thus forming an electrophotographic sensitive body. The high-quality-photosensitive layer 2 and the pure a-Si:H layer 3 can be laminated.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a long-life electrophotographic photoreceptor, and in particular to a laser photoreceptor.
This invention relates to an electrophotographic photoreceptor used in a beam printer.

[Background of the invention]

Photoconductive materials conventionally used as electrophotographic photoreceptors include inorganic materials such as Be, OdS, and As2Se2, and organic materials such as polyvinylcarbazole (PVX)K. Although these materials have excellent photoconductivity, their low hardness causes scratches on the surface during use.
This was deteriorating the printed image. In particular, there were many problems when used in laser beam printers, which specialize in high-speed printing. In order to improve this drawback and provide a high-quality image and a long-life photoreceptor, it was proposed to use hydrogenated amorphous silicon (hereinafter abbreviated as a-8i:H) as a photoreceptor (Japanese Patent Application Laid-Open No. 54-11101). -.78135 publication). Since the spectral sensitivity of this #light body is in the visible wavelength range of 400 to 700 nm, He-0a (wavelength 441 nm)
, Ar (55nm), He-No (633nm)
It is ideal for laser beam printers that use gas lasers as light sources. However, now that there is a pressing need for printers to be smaller and cheaper, there is an urgent need to reduce the cost of optical systems. A shift must be made to achieve this goal. However, as mentioned above, a-
Si:H has no sensitivity to this semiconductor laser.

Therefore, attempts have been made to dope Ge 2 in order to expand the sensitivity range. However, for the following reasons, expansion of the sensitivity region (higher sensitivity at long wavelengths) by doping has not been achieved.

a-8i: When H is doped with Ge, hydrogen preferentially becomes 8
Go K, which has the same 4-coordination as Sl, is S
A new unbonded hand (dangling bond) that does not bond with l or hydrogen is generated. Therefore, a large number of impurity levels are generated within the bandgap of 8l-Ge, resulting in a decrease in photoconductivity. Therefore, in the past, there has been a tendency to not only increase sensitivity at long wavelengths but also decrease sensitivity at short wavelengths.

[Purpose of the invention]

The present invention expands the sensitivity region by doping Ge without impairing the excellent photoconductivity of a-8i:H, and the a-8i:H doped with Ge has sensitivity to semiconductor lasers.
An object of the present invention is to provide an i:H (hereinafter abbreviated as a-Si-Ge:H) photoreceptor.

[Summary of the invention]

To summarize the present invention, the present invention relates to an electrophotographic photoreceptor, in which the photoreceptor has a-Eli:E as a main component, an a-8i:H layer and hydrogenated amorphous germanium (hereinafter referred to as a- Ge:H) layers are alternately laminated.

As mentioned above, the excellent photoconductivity of a-8i:H is achieved by terminating dangling bonds with hydrogen. However, in order to make the semiconductor laser sensitive (doping Ge), as mentioned above, unbonded Ge
becomes a new impurity level generation source, a-81-Go
: Impairs the photoconductivity of H. This is because during production, in the plasma OVD method, the film is decomposed in an atmosphere where 81H4 gas and GeH4 gas coexist, and in the sputtering method, 81 and Go are randomly distributed in three dimensions by co-sputtering of sl and Go targets. It is presumed that this is due to the arrangement. That is, the above production method creates a state in which hydrogen is preferentially combined with hydrogen. Therefore, in order to improve these drawbacks (i.e., hydrogen bonds preferentially to Sl and is difficult to bond to Ge), %S1 and G.

Rather than depositing Go,! on the substrate at the same time, one to several atomic layers containing Sl and ■ are first deposited, and then Go,! :)
], one to several atomic layers are sequentially laminated, resulting in a -Si-
Ge:H was produced.

A specific example of the most effective manufacturing method for manufacturing this regularly arranged a-81-Ge:H will be described later, but the gist is that when forming the Sl film, the H layer is implanted and the a-Si
The purpose of this method is to manufacture a-Go:H by implanting an H layer when forming a Ge film. In this way, a-Ge:H, which has been impossible until now, can be produced. 1 will be explained in detail below.

First, a pure a-81:H layer of one to several atomic layers is prepared,
A pure a-Go:H layer of similar thickness is laminated thereon. 81 and Ge at the interface of these two layers interact to form 5i-
It becomes GO alloy. Therefore, in the plane of these two layers, they are pure a-8i:H and a-Go:H, respectively, but in the thickness direction of the stacked layers, they are a-Bi-Ge:H.

In the above example, the ratio of Sl and Go is 1=1 in the thickness direction, but when changing this ratio, pure a-81:H layer and pure a-
This can be achieved by adjusting the thickness of the Go:H layer appropriately. By using the above two stacked layers as a unit cell and repeating this unit cell until the desired thickness, a-
Si-Ge: ■A film can be formed.

A layer in which the unit cells are formed to a desired thickness is called a high-quality photosensitive layer (hereinafter abbreviated as HGPL).

FIGS. 1 to 4 show schematic cross-sectional views of the structure of an electrophotographic photoreceptor using HGPL. In each figure, 1 means a conductive substrate, 2 means HGPL, and 3 means pure A-8 film.

FIG. 1 shows a structure in which all layers of KHGPL 2 are formed on a conductive substrate 1. From Figure 2 onwards, the function-separated photoconductor is HGPL.
2 plays the role of a charge generation layer, and pure a-Eli:H film 3
This is the case where fC is the charge transport layer. FIG. 2 shows that HGPL 2 is formed on a conductive substrate 1, and further pure a-8i:)I
It has a structure in which the film 3 is stacked, and the light that has passed through the film 3 causes H
GPL 2 generates photo-excited charges.

Figure 3 shows the structure in Figure 2, with pure a-8i between 1 and 2.
: This is a structure in which an H film is inserted.

FIG. 4 shows a structure in which a pure a-81:H film 6 is formed on a conductive substrate 1, and an HGPL 2 is further laminated thereon. In addition,
A Ge diffusion layer (that is, the composition ratio of 8l-Go is varied in the thickness direction to smoothen charge movement) may be provided at the boundary between the HGPL and the pure a-8i:H layer.

Furthermore, as a charge transport layer, in addition to pure a-8i:H, 1C,
+, F, 0, etc. may be added to a-8i:H, and Be, As2day e3, ZrxOlO (1B-04T
.

Inorganic photoconductors such as -048e or organic photoconductors typified by polyvinyl carbazole etc. [Examples of the Invention] Hereinafter, the present invention will be explained in more detail by way of Examples.
The invention is not limited to these examples.

First, a method for forming the photoreceptor will be described.

The structure of the photoreceptor was that shown in Figure 2.

Example 1 FIG. 5 shows a schematic diagram of a manufacturing apparatus using the resistance heating method. Fifth
In the figure, 5 is el, 6 is G@, 7Vi shutter,
8 is a vacuum chamber/(-19 is a resistance heating heater, 10 is a hydrogen ion gun, 11 is a substrate, 12 is a turntable, 1
3 means a quadrupole mass spectrometer. Vacuum Chang Ku-
8 contains the raw materials Si 5 and ()e 6 in a resistance heating crucible 9.
It is loaded inside. There is a shutter 7 above it.

The board 11ti and turntable 121C are set. Furthermore, an ion gun 10 for implanting hydrogen ions is attached to the vacuum chamber 8 at an angle that looks into the substrate.
i:H or a-Go:H is formed.

A quadrupole quality analyzer 13 is also installed to control the evaporation f#.

First, the inside of the vacuum chamber 8 is evacuated to 1 x 10 torr, and then Si and Go are dissolved in the resistance heating crucible 9, sufficiently degassed, and then the shutter 7 is opened to evaporate.

The turntable was heated at 300 rpm and the substrate was heated to 200°C. When the shutter is opened, hydrogen ions are irradiated from the ion gun 13. Therefore, when the substrate is on the sl rutsu, -sl: H@ is formed, and when it is on the aS rutsu, an a = Ge 2H film is formed, and the above-mentioned unit cell is formed with one rotation of the turntable. is formed. After forming a 1 pm unit cell film in this manner, only the shutter on the Go side was closed, and a 10 μm film of a-8i:H was formed.

Example 2 In Example 1, 81 and Go were evaporated by electron beam melting. The device is illustrated in FIG.

That is, FIG. 6 is a schematic diagram of a manufacturing apparatus using the electron beam melting method. In Figure 6, 5-8 and 10-13Fi 5th
The meaning is the same as in the figure, and 14 is an electron beam set and 15 and 15
' means filament. Vacuum chamber I<-8 to 1
X10-7) After evacuation to 815 or Ge 6 from cathode filament 15 or 15',
4 is irradiated to dissolve and evaporate 81 and Go. The shutter 7 is opened, and Sl 2 is first vapor-deposited onto the substrate 11 set on the rotating turntable 12. At this time, since hydrogen ions are irradiated from the hydraulic ion gun 10, a -8i:H can be formed. Similarly, a-Go
:H is stacked. After forming a film of 1 μm from this unit cell, G
After closing the 7 layers of O, a 10 pm film of Tomoe-81:H was formed.

Example 3 Different from Examples 1 and 2, 81 target and Ge
A unit cell was formed by the Takaoka wave sputtering method in which the target was irradiated with Ar ions.

The device is illustrated in FIG. In FIG. 7, reference numeral 7.
11 and 12 have the same meaning as in FIG. 5, 16 is a reaction tank, 1
8 means an Sl target, 19 means a Ge target, and 20 means a high frequency power source.

First, after evacuating the reaction tank 16 to IXf'1l-7), the substrate 11 set on the turntable 12 is
Heated to 00°C. After that, Ar and H7 are added to the reaction tank 16.
A gas mixture of 1:1 was introduced to make the volume 5×10−3). After that, 1556MHz, 1kW high frequency power supply 20
using Si target 18 and Ge target 1
9 and each shutter, and press sputtering was performed for 30 minutes. Subsequently, the shutter 7 was opened, and main sputtering was performed between the substrate 11 set on the turntable 12. The distance between the Sl, Ge target and the substrate is 150 m, and the power density applied to the target is u4W/c.
In this experiment, since hydrogen is included in the gas composition, hydrogen is ionized during discharge and reacts with sputtered Sl or Go, resulting in a-8i: 'H or a
-Ge:H is formed. This a! A unit cell consisting of several atomic layers was formed to a thickness of 0.5 μm.

After that, sputtering of Ge was stopped and a-8i:H
Only a film was formed. At this time, the distance between the board 11 and the 81 target 18 was 60 mm, and the input power density was 10 W/.
cm2, and finally formed 10 pm.

Example 4 This time, HGPL was formed using the ion beam sputtering method. FIG. 8 shows the device. In other words, FIG. 8 is a schematic diagram of a manufacturing apparatus using the ion beam sputtering method, and in FIG.
has the same meaning as in FIGS. 6 and 7, and means a 21 td target holder, 22 a reaction tank, and 23 Ar ion gas.

Each s1 target 18 is placed on the target holder 21.
and a Ge target 19 are arranged. An Ar ion gun is placed in a direction of 45 degrees from the vertical line. On the other hand, a hydrogen ion gun 10 is placed at an angle looking into the substrate 11 set on the turntable. First, the reaction tank 22 is evacuated to 10 -7 Torr, and then the substrate 11 is heated to 200°C. Thereafter, Ar ions are irradiated from the Ar ion gun 23 to the targets 18 and 19 to sputter Sl and Ge. Sputtered Sl and Go are transferred to hydrogen ion gun 1
Reacts with the ion irradiated from 0 to form a-Eli:E and a-Ge:H. When the substrate 11 on the rotating turntable is positioned directly above each target, a-8i:H or α-Gθ:H is formed on the substrate.

In this way, a unit cell can be formed. In this experiment, unit cells were formed with a thickness of 0.5 μm. He then held the substrate 11 stationary directly above the Sl target and laminated a 10 μm thick a-81:Ht layer thereon.

Next, using the photoreceptor of Example 4 as a representative example, the results of the photographic characteristics of the stain will be shown.

The evaluation device used was Paper Analyzer 8P42 manufactured by Kawaguchi Electric Co., Ltd. The corona applied voltage was -5.5 kV. Spectral sensitivity is measured from 400 to 8'00 nm, and sensitivity is defined as the reciprocal of the light energy required to halve the surface potential. FIG. 9 shows the obtained spectral sensitivity curve. In other words, Figure 9 shows the spectral wavelength (nm) (horizontal axis) and sensitivity (m2
/mJ) (vertical axis).

As shown in FIG. 9, the sensitivity is high at 400 to 800 nm. In the figure, the spectral sensitivity of the a-Eli:H single layer is also shown.

〔Effect of the invention〕

According to the present invention, an a-Eli:H photoreceptor sensitive to semiconductor lasers can be developed, and remarkable effects can be achieved, such as lowering the cost of laser beam printers and making it possible to manufacture photosensitive drums with long lifespans.

[Brief explanation of drawings]

1 to 4 are schematic cross-sectional views of an electrophotographic photoreceptor according to the present invention, FIGS. 5 to 8 are schematic views of an apparatus for producing an electrophotographic photoreceptor according to the present invention, and FIG. 9 is a diagram showing a product of the present invention and a conventional method. It is a graph showing the relationship between the spectral wavelength and sensitivity of the product. 1: Conductive substrate, 2: High quality photosensitive layer, 3: Pure a-8i:
H film, 5: silicon, 6: germanium, 7: shutter, 8: A empty chamber, 9 two-resistance heating furnace, 10: hydrogen ion gun, 11: substrate, 12: turntable, 1
3: Quadruple shoe type mass spectrometer, 14: Electron and one-piece 1.15 and 15': :y-irament, 16: Reaction tank, 18: Silicon target 1-119: Germanium target,
20: High frequency type, source, 21: Target holder, 22:
Reaction tank, 23: Argon ion gun Patent applicant Hitachi, Ltd. Agent Hiroshi Nakamoto Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Continued from page 1 0 Inventor Hanazono Masanobu 1-1, 3-chome Saiwaimachi, Hitachi, Ltd. Hitachi, Ltd. Hitachi Research Procedures Amendment (Method) April 23, 1980 Commissioner of the Patent Office Kazuo Wakasugi 1, Indication of Case 1988 Patent Application No. 245501 2
, Title of the invention Relationship to the case of person who amends electrophotographic photoreceptor 6 Patent applicant address 4-6 Kanda Surugadai, Chiyoda-ku, Tokyo Name (510) Hitachi, Ltd. Representative 3 1) Shige Katsura 1987 March 7, 2018 (Shipping date: May 27, 1982)
& Subject of amendment Full text of the specification 2 Contents of amendment Reprint of the specification (no change in content)

Claims (1)

[Claims] 1. A photoreceptor mainly composed of amorphous silicon containing hydrogen, including layers in which amorphous silicon layers containing hydrogen and amorphous germanium layers containing hydrogen are alternately laminated. Characteristic electrophotographic photoreceptor. 2. The alternately stacked layers serve as a charge generation layer, the amorphous silicon layer containing hydrogen serves as a charge transport layer, and both layers are stacked on a conductive substrate. Claim 1 The electrophotographic photoreceptor described in .