JPS61158335A - Amorphous silicon electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To obtain the sensitive body having a high reliability without giving any injury for a continuous duty during long periods by forming a fluoro- amorphous silicon layer on a surface protective layer of the amorphous silicon sensitive layer in the amorphous silicon electrophotographic sensitive body which provides said layer on the conductive substrate. CONSTITUTION:A glow discharge is induced by impressing a high frequency voltage between the electrode 16 and the drum 12 using a high frequency electric source 17. At the same time, a valve 32 of a vacuum is opened, and a gas for forming a charge holding layer is fed to a vessel 13 so as to reach 0.5torr degree of vacuum in the vessel. The fed gas makes in a plasma state by discharging, thereby adhering a decomposed product of said gas on the drum 12 to form the charge holding layer 41 on the substrate 12. Then the valves 19, 20 are closed, and then an Si2H6 gas is fed to the vessel 13 to form the amorphous silicon sensitive body layer 42 on said layer 41. Then, the valves 23, 24 are closed, and the valves 27, 28 are opened to feed an SiF4 gas to the vessel 13, thereby forming in the vessel 13 a surface protective layer 43 which has an alpha-Si:F structure and terminates an Si atom with an F atom.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvement of a surface protective layer that protects the surface of an amorphous silicon layer formed on a conductive support.

The photoconductive layer of a recording drum having a photoconductive layer formed around it is uniformly charged, and the photoconductive layer is selectively irradiated with laser light based on printed information to change the charged potential of the photoconductive layer. Electrophotographic devices such as laser printers are well known, which selectively lower the latent image to form a latent image, develop the latent image by attaching charged toner to the area where the latent image is formed, and transfer and record the developed printed image onto recording paper. be.

[Conventional technology]

Conventionally, selenium (Se) has been used as such a photoconductive layer.
Se-based materials were used, but this Se is toxic;
There is a risk of pollution problems when discarded after long-term use, and the mechanical strength is low, causing scratches on the surface of the photoconductive layer, leading to problems such as deterioration of printing quality when used for a long time. many.

Therefore, recently, a recording drum has been developed in which an amorphous silicon photoreceptor layer, which is harmless to the human body and has high mechanical strength, is formed as a photoconductive layer around a rotating drum made of aluminum (AD) instead of Se0.

By the way, as a characteristic of such an electrophotographic photoreceptor, in order to accumulate the necessary charge on the surface of the photoreceptor, the resistance when no light is irradiated, that is, the dark resistance, must be 10 to 10 Ω-1 or more. be. However, in the case of amorphous silicon, a small amount of group III rings, such as boron (B)
Even if you try to increase the resistance by doping 10
Ω - Only the resistance of the mouth can be obtained, and it is necessary as a photoreceptor.
013-10) A value of 1Ω-b cannot be obtained. Therefore, in order to use amorphous silicon as a photoreceptor, conventionally, as shown in FIG.
A charge retention layer 3.4 is provided by forming a silicon carbide compound made of a compound of Si and carbon (C), or a silicon nitride compound made of a compound of Si and nitrogen (N), and this charge retention layer N3 is formed. , 4, the conductive support 1 and the photoreceptor surface 5
This prevents charges from being injected into the amorphous silicon photoreceptor layer 2.

[Problem that the invention seeks to solve]

However, such amorphous silicon photoreceptor layer 2 is generally made of monosilane (SiH4) gas or disilane (SiH4) gas.
A hydrogen compound of Si, such as Si2Hs) gas, is formed using the plasma CVD method, and its structure is a-Si.
:H has a structure in which dangling bonds of Si atoms of amorphous silicon are terminated by H atoms. The bond energy between this H atom and Si atom is 3. It is as small as leV. Therefore, when an amorphous silicon photoreceptor layer terminated with H atoms is used as an electrophotographic photoreceptor, the air around the photoreceptor layer is decomposed by corona discharge during charging, producing ozone, oxygen ions, nitrogen ions, etc. There is a problem in that these products and the Si atoms of 4Si:H react to form Si oxide or Si nitride on the surface of the photoreceptor layer. There is also the problem that the bonds between Si atoms and H atoms are broken due to this corona discharge.

Due to this phenomenon, when an amorphous silicon photoreceptor layer having a structure such as dsi:H is used as an electrophotographic photoreceptor, there is a problem that the quality of the printed image deteriorates.

Means for Solving Problem C] The above problem lies in the fact that the surface protective layer of the amorphous silicon photosensitive layer of the amorphous silicon electrophotographic photoreceptor in which the amorphous silicon photosensitive layer is provided on a conductive support is made of fluorinated amorphous silicon. This problem is solved by the amorphous silicon electrophotographic photoreceptor of the present invention, which is formed of layers.

[Effect]

That is, the amorphous silicon electrophotographic photoreceptor of the present invention is
The bond energy between St and H is 3. leV, whereas the bond energy between Si and F is as large as 5.1 eV. Then, the surface protective layer of the amorphous silicon photoreceptor layer is made of amorphous silicon having a structure of isi:H by replacing the H atoms with fluorine (F) atoms.
-5i: A surface protective layer is formed of amorphous silicon having a structure of F to form an amorphous silicon electrophotographic photoreceptor that does not easily deteriorate even when discharged from a corona discharger.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an apparatus for manufacturing the amorphous silicon electrophotographic photoreceptor of the present invention.

As shown in the figure, a cylindrical drum 12 with a heater 11 provided therein and serving as a conductive support is placed in an airtightly sealed container 13 and rotated by a motor 14 . A cylindrical electrode 15 having a hollow center and a double structure on the sides is provided around the drum 12. Inside the double structure electrode 15, an amorphous silicon photoreceptor is placed. A forming gas is introduced into the electrode 15, and a large number of gas outlets 16 are provided on the surface of the electrode 15 facing the drum 12. The lead-out end connected to this electrode 15 is lead out to the outside of the container 13, and a high-frequency power source 17 is connected to this lead-out end.

In addition, this outlet end is a gas inlet pipe, and ammonia (
NHa) is connected to the gas cylinder 22, and further includes a valve 23,
24, connected to a disilane (Si2H6) gas cylinder 26 via a flowmeter 25, and further connected to a silicon tetrafluoride (SiF4) gas cylinder 30 via a valve 27.38 and a flowmeter 29.
It is connected to the.

Further, a mechanical booster pump 33 and a rotary pump 34 are connected to the exhaust port 31 of the container 13 via a vacuum valve 32, and a diffusion pump 36 is connected via a vacuum valve 35.
A rotary pump 38 is connected via.

The case where the amorphous silicon electrophotographic photoreceptor of the present invention is formed using such an apparatus will be described.

First, an 8-ohm support 12 that becomes a rotating body of the photosensitive drum is installed in the container 13, the vacuum valves 35 and 37 are opened, and the interior of the container 13 is vacuumed to a vacuum of 10-6 torr using the diffusion pump 36 and the rotary pump 38. Exhaust until the Next, using the heater 11, the drum 12 is
Heat until the temperature reaches 00-300°C. Furthermore, valves 19, 20, 23, and 24 are opened to supply NH, gas, and Si.
2H6 gas is introduced into the container 13, and the frequency is 13.56.
The electrode 16 and the drum 1 are connected using a MHz high frequency power source 17.
A high frequency voltage is applied between the two to generate glow discharge.

At this time, the vacuum valve 32 is opened and the container 13 is pumped using the mechanical booster pump 33 and the rotary pump 34.
A gas for forming a charge retention layer is quickly introduced into the chamber so that the degree of vacuum inside reaches 0.5 torr.

The gas introduced by this discharge is turned into a plasma state, and the decomposed components of the gas are deposited on the drum 12.
As shown in the figure, the thickness is 0.01 to 1 μm on the support 12.
A charge retention layer 41 is formed.

Then, valves 19 and 20 are closed to fill the container 13 with Si2.
H6 gas is introduced to form an amorphous silicon photoreceptor layer 42 with a thickness of 5 to 30 .mu.m on the charge retention layer 41 shown in FIG.

Furthermore, the valves 23 and 24 are closed, and the valves 27 and 28 are opened to introduce SiF4 gas into the container 13 to form an MSi:F structure on the amorphous silicon photoreceptor layer 42, with Si atoms being F atoms. Terminated surface protective layer 4
3 to a thickness of 0.01 to 1 μm.

In order to compare the amorphous silicon electrophotographic photoreceptor of the present invention formed in this way and having a surface protective layer with an a-5i:F structure, and the conventional amorphous silicon electrophotographic photoreceptor with an αSi:H structure, The two types of photoreceptors were charged by a negative corona discharge, which generates several times more ozone than a positive corona discharge, and continuous printing was performed to investigate the state in which the print density decreases.

A4 size recording paper was used as the recording paper, and 400 characters were printed continuously on one recording paper, compared to the conventional 4
When an amorphous silicon photoreceptor having a Si:H structure was used as an electrophotographic photoreceptor, a decrease in print density was observed even after printing on several hundred sheets. On the other hand, in the present invention, t
When an amorphous silicon photoreceptor having an LSi:F structure is formed on an amorphous silicon photoreceptor layer as a surface protective layer as an electrophotographic photoreceptor,
No decrease in print density was observed even when printing was performed continuously on tens of thousands of sheets of recording paper.

In addition to this embodiment, as shown in FIG. 3, an amorphous silicon electrophotograph is used in which high resistance is achieved by forming a thick amorphous silicon layer 51 directly on a conductive support without intervening a charge retention layer. Also in the structure of the photoreceptor, 4Si
A similar effect can be obtained by using :F as the surface protective layer 52.

In addition to this example, when forming dsi:F, NH3
Gas is simultaneously introduced into the container and nitrogen (N) is added.
4Si:F to which is added, or LSi:F to which carbon (C) is added may be obtained by simultaneously introducing hydrocarbon-based ethylene (C2H4) gas into the container and adding carbon (C). Both of these amorphous silicons have a high resistance value and a large band gap, making them insulator amorphous silicon.

Also, when forming LSi:F, diborane (B2H
s) Gas is simultaneously introduced into the container to prepare ■-type or P-type 4Si:F to which poron (B) is added, or phosphine (
PH3) gas may be simultaneously introduced into the container to form an N-type c5i:F to which phosphorus (P) is added.

By using such an insulator, phosphorous-doped N-type, B-doped ■-type, or P-type ASi:F, the influence of the discharge of the corona discharger is exerted on the amorphous silicon photosensitive layer below. In addition to the surface protection function of preventing the amorphous silicon photoreceptor from being damaged, it also functions as a charge retention layer that increases the charging potential of the amorphous silicon photoreceptor.

As another example, C1 or N is added between the surface protection layer 43 and the amorphous silicon photoreceptor layer 42 to form a-3i:HN with a large energy band gap.
Alternatively, a 4Si:H layer such as these may be used as a charge retention layer by sandwiching a P-type or N-type high-resistance Si:H layer doped with B, P, etc. at a high concentration.

In addition to SiF4 gas, SiH4 gas or Si2
Silane type like H6 gas (St S, +z in H layer)
A mixed gas of a gas and a carbon fluoride gas such as carbon tetrafluoride (CFa) may be used.

〔Effect of the invention〕

According to the amorphous silicon electrophotographic photoreceptor of the present invention as described above, since surface deterioration due to corona discharge can be prevented, a highly reliable electrophotographic photoreceptor that will not be damaged even when used continuously for a long time can be obtained. be.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus for forming an amorphous silicon electrophotographic photoreceptor of the present invention, FIGS. 2 and 3 are cross-sectional views showing the structure of the amorphous silicon electrophotographic photoreceptor of the present invention, and FIG. 4 is a conventional 1 is a cross-sectional view showing the structure of an amorphous silicon electrophotographic photoreceptor. In the figure, 11 is a heater, 12 is a conductive support, 13 is a container, 14 is a motor, 15 is an electrode, 16 is a gas outlet,
17 is a high frequency power supply, 18 is a gas introduction pipe, 19.20,2
3, 24° 27, 28 are valves, 21, 25.29 are flow rate needles, 22 is an ammonia gas cylinder, 26 is a disilane gas cylinder, 30 is a silicon tetrafluoride cylinder, 31 is an exhaust port, 3
2.35. 't7 is a vacuum valve, 33 is a mechanical booster pump, 34.38 is a rotary pump, 36 is a diffusion pump, 41 is a charge retention layer, 42.5
1 is an amorphous silicon photosensitive layer, and 43.52 is a surface protective layer.

Claims (1)

[Claims] An amorphous silicon electrophotographic photoreceptor comprising an amorphous silicon photosensitive layer provided on a conductive support, wherein a surface protective layer of the amorphous silicon photosensitive layer is formed of a fluorinated amorphous silicon layer. Photoreceptor.