JPS6067954A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To provide excellent stability and durability and to enable utral-high speed copying by forming an a-Si.H.F.N surface protective layer by the glow discharge made with the gas volume of an F-contg. Si compd. at a specific content with respect to the gas volume of the F-contg. Si compd. and an H-contg. Si compd. CONSTITUTION:An a-Si barrier layer 4 is preferably formed on a conductive substrate 1 and an a-Si photoconductive layer 2 and an a-Si:H:F:N surface protective layer 3 are successively formed thereon. The surface protective layer 3 is formed by the glow discharge made in an atmosphere in which the gas volume of an F-contg. Si compd., for example, SiF4 is made 20-50% with respect to the gas volume of the F- contg. Si compd. and an H-contg. Si compd., for example, SiH4. Gaseous H2 or rare gas, is incorporated as a carrier gas at 50-90% in the gas for decomposition by the glow discharge. A IIIa group element, for example, B or the like is incorporated into the surface protective layer. The stable operation characteristic and durability are further improved by providing the surface protective layer 3 on the photoconductive layer 2 in the above-mentioned way. The photosensitive body particularly adequate for ultra- high speed copying is obtd. Such photosensitive body is usable for an ultra-high speed copying machine, a laser beam printer etc.

Description

[Detailed description of the invention] The present invention uses amorphous silicon (hereinafter referred to as a-si).

) as a photoconductive layer.

In recent years, electrophotographic technology has made remarkable progress, and the development of ultra-high-speed copying machines and laser beam printers is actively underway.
Since it is used at high speed, stability and durability of operation are required. Currently, electrophotographic photoreceptors include Se, C
Photoelectric materials such as dS and ZnO are commonly used, but a-Si is preferred because it has excellent heat resistance, abrasion resistance, non-pollution, and photosensitivity characteristics. Application to electrophotographic photoreceptors has been reported.

However, in today's situation where stable operation and extremely high durability are increasingly required, the a-Si photoreceptors that have been reported so far are no longer able to adequately meet the demands, especially for ultra-high-speed copying. The properties required for photoreceptors cannot be fully satisfied.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an electrophotographic photoreceptor suitable for wholesale high-speed copying, which has extremely stable operating characteristics and extremely excellent durability.

The gist of the present invention is to provide a conductive substrate, preferably a'
-Si barrier layer is formed, and an a-Si photoconductive layer and an a-81 surface protective layer containing hydrogen and fluorine as well as nitrogen are sequentially laminated thereon by a glow discharge decomposition method. In the body, a glow discharge is generated in an atmosphere in which the gas volume of the fluorine-containing silicon compound is 20 to 50% of the gas volume of the fluorine-containing silicon compound and the hydrogen-containing silicon compound, and the a-Si surface protective layer is An object of the present invention is to provide an electrophotographic photoreceptor characterized by forming the following.

The present invention will be explained in detail below.

As shown in FIG. 1(A), the electrophotographic photoreceptor of the present invention has the following features:
Consisting of a conductive substrate (1), an a-Si photoconductive layer (2) and an a-81 surface protection layer (31) laminated in sequence,
Preferably, as shown in FIG.
) and the a-Si photoconductive layer (2), it is preferable to interpose an a-Si barrier layer (4).

The a-Si-photoconductive layer (2) contains at least one of hydrogen and fluorine, as well as oxygen and
containing boron, especially boron.

The a-Si surface protective layer (3) contains nitrogen as well as hydrogen and fluorine, and may further contain Ha group of the periodic table, particularly boron.

a-6i, the barrier layer (4) contains at least one of hydrogen and fluorine, as well as at least one of oxygen, nitrogen, and carbon, as well as a periodic system to prevent charge injection from the conductive substrate (1). Contains Ha group, especially boron.

Table 1 shows the thickness and content of each layer when the a-Si barrier layer (4) contains oxygen.

Table 1 Regarding this Table 1, even if the a-3i barrier layer (4) contains nitrogen or hydrogen instead of oxygen, the thickness of each layer and the content of other components will not change in any way. If the a-S'x barrier layer (4) contains nitrogen and carbon alone, the nitrogen content is 0.
．． 05-55 atomic%, hydrogen content is 0.05
~45 atOmi, c%.

According to the present invention, when forming the a-Si surface protective layer (3) by glow discharge decomposition method, nitrogen starting material gas (
%N3, etc.) and boron extraction source gas (e.g., B2H6, etc.) to specify the content of each in the layer, fluorine-containing silicon compounds such as SiF4, SiH4, etc. By specifying the gas volume of each of the hydrogen-containing silicon compounds, it was found that the photoreceptor had extremely stable operating characteristics and excellent durability.

In other words, when the gas volume of the fluorine-containing silicon compound is less than 20% of the gas volume of the fluorine-containing silicon compound and the hydrogen-containing silicon compound, 5i-F, which has a relatively large binding energy, decreases and the durability deteriorates. If it exceeds 50%, dangling bonds of silicon atoms will increase, leading to a decrease in charge acceptance and deterioration of photosensitivity. It's good to do that. Fluorine-containing silicon compounds include S
i, F4. There are various compounds such as Sj-gFe and 5iare, and hydrogen-containing silicon compounds include SiH
+, SigHa.

There are various compounds such as SisHg. The silicon compound gas and BRH6 gas mentioned above are rare gases such as Ar and Hθ, and H1! A gas or the like is used as a carrier gas, and according to the present invention, the carrier gas is preferably set in a range of 50 to 90% in the atmospheric gas in which the surface protective layer (3) is formed by glow discharge decomposition.

The a-81 surface protective layer (
3) The nitrogen content should be at least 1 atom, tc%,
It can be increased to 55 ato+uLQ% at the maximum, thereby achieving the intended purpose of producing 5jJN4 and increasing the durability of the photoreceptor. Preferably, the nitrogen content is preferably set in the range of 10 to 55 atomtc% in order to further improve the charge retention ability. And nitrogen is 1. □ Below atomtc%, no improvement in durability is observed, the surface potential is low, and the charge retention ability is not improved.

Further, when the thickness of the surface protection ff 1310 layer is 0.018 m or less, no improvement in durability is observed, and the surface potential is low, so that the charge retention ability is not improved. When the thickness is 0.5 μm or more, the photosensitivity tends to decrease and at the same time, the residual potential increases. Therefore, the layer thickness of the surface protective layer (3) is 0.01 to 0.5
μm, preferably in the range of 0.05 to 0.15 μm. In addition, this layer thickness is determined within the above-mentioned appropriate range, so that if the nitrogen content of the surface protective layer +31 increases, the layer thickness will be decreased, and conversely, if these contents decrease, the layer thickness will be increased. be done.

For the photoconductive layer (2), the oxygen content was 5 x 10
If it is more than 10 atoms, c%, the photosensitivity will decrease significantly, and conversely, if it is less than 10 atoms, the electrons of the dangling bonds cannot be taken in sufficiently due to the large electronegativity of the oxygen atom. Therefore, it is impossible to obtain an a-Si photoconductive layer having a dark resistance of 10 Ω or more, and the oxygen content of the photoconductive layer (2) is in the range of 10 to 5×10 atomic%.

The barrier layer (4) smoothly transports carriers generated in the photoconductive layer (2) to the conductive substrate (1), and
) serves to prevent charge injection from On the other hand, in the absence of this barrier layer (4), the conductive substrate (1)
Injection of charge from the surface of the surface is not effectively prevented, the surface potential decreases, and the dark decay rate increases.

In order for the barrier layer (4) to work effectively, oxygen, nitrogen,
The carbon content is 0.05 to 60 atom1c, respectively.
%, 0.05-55 atoms-0%, 0.05-4
If at least one of these is less than 1c% of o, o s atom, the injection of charge from the conductive substrate (1) will not be sufficiently blocked, and the surface potential will be insufficient and the dark decay rate will decrease. becomes large and each independently exceeds the above maximum value, photocarriers are trapped and the residual potential increases. Note that this barrier layer may contain a combination of two or three of oxygen, nitrogen, and carbon, and the content of each is determined as appropriate depending on the combination.

a-Sj- of the present invention [in the child photographic photoreceptor, a
-Si When a -Si containing nitrogen and a surface protective layer are laminated on the photoconductive layer by glow discharge decomposition method, the gas volume of the fluorine-containing silicon compound and the hydrogen-containing silicon compound is gas volume 2
Glow discharge is generated in an atmosphere with a concentration of 0 to 50%.
Since the -Si surface protective layer is formed, the stable operating characteristics and durability achieved by containing nitrogen are further improved, making it particularly suitable for photoreceptors for ultra-high speed copying.

Next, a capacitively coupled glow discharge decomposition apparatus for producing an a-Si layer will be described with reference to FIG.

1 in the diagram. Second. Third. 4th. 5th tank (5) +6
1 +71 +8) 19) has 5j-F+, respectively.
, SIH+, B++Ha.

Os, Ns gases are sealed. Also, SiF+
.

The carrier gas for both SiH+ and BsHa gas is hydrogen. These gases correspond to the first. Second. Third,
4th and 5th regulating valve (1 (1 (111 (13Q31 (
It is released by opening 141, and its flow rate is regulated by mass flow control acJwe times (181G!l, 1st, 2nd and 3rd tank +51 (61
Gas from 71 is sent to flf, l main pipe ■, and oxygen gas and nitrogen gas from the fourth and fifth tanks +81 +91 are sent to second main pipe QO. Note that (2) (to) is a stop valve. 1st. The gas flowing through the second main pipe (211 (21)) is sent to the reaction tube c!4.
is installed, and its own high frequency power is 50 watts.
ts to 3 kj-1owatts, and the frequency is I
MHz to several tens of MHz is suitable. Inside the reaction tube, an a-Si film is formed thereon. For example, a substrate (1) such as aluminum or NFSA glass is placed on a turntable (3) which can be rotated by a motor (5), and the substrate (1) itself is heated by a suitable heating means. 50 to 300°C, preferably about 1
It is uniformly heated to a temperature of 50 to 250°C. Also,
The interior of the reaction tube c24 is connected to a rotary pump and a diffusion pump (to) because a high degree of vacuum (discharge voltage 0.5 to 2.0 TOrr) is required during a-85- film formation.

In the glow discharge decomposition apparatus having the above configuration, for example, when forming an a-Si film containing nitrogen on the substrate, the first and/or second regulating valve α (1 (ID), the fifth Open the adjustment valve a4 and open the first and second tanks (51(
When introducing SiF+ gas and SiH+ gas from 61, nitrogen gas from the fifth tank (9), and boron as well, the third regulating valve Ilz is also opened and B is introduced from the third tank (7).
Release 9H6 gas. The amount released is mass flow control) v
x -7 (lfi (171Q9 sr , along with Si
Nitrogen gas in a constant molar ratio to F+ and/or SIH+ is supplied to the second main pipe C! It is sent to the reaction tube (goods) via υ. And the reaction chamber @inside is 0.5 to 2. OTOr
In a vacuum state of about
Due to the fact that the frequency is set to 0 MHz, a glow discharge occurs and the gas decomposes, forming an a-Si film containing fluorine, hydrogen and nitrogen on the substrate, or a suitable amount of boron in addition. The a-81 film is about lO to 2500
A: Formed at a film formation speed of 7 minutes.

Examples of the present invention will be described below.

[Example 1] An a-Si photoconductive layer and an a-Si surface protective layer were formed using the glow discharge decomposition apparatus shown in FIG. 2 described above, and the durability of this photoreceptor was tested.

That is, the turn tape /I/@ of the glow discharge decomposition device
A cylindrical aluminum substrate (1) is placed on top of the SIF 4, and hydrogen is added as a carrier gas from the first tank (5).
Gas (flow rate 130800M) was transferred from the second tank (6) to 5j-H4 gas (flow rate 1
908QOM) and B9H6 gas (flow rate f3Q BQQM) with hydrogen as carrier gas from the third tank (7).
)of.

Furthermore, oxygen gas (flow rate 1.48Q) is supplied from the fourth tank (8).
QM) is emitted, and the gas composition of the glow discharge atmosphere is determined according to the ratio of these gas flow rates. This results in
Oxygen on the aluminum substrate (1) about 10-10-8a
10 μm thick containing about 200 ppm boron and about 15 atomtc% hydrogen and fluorine in total.
An a--8j-photoconductive layer was obtained. The manufacturing conditions at this time were a discharge voltage of 0.6 Torr%, a substrate temperature of 200°C, a high frequency power of 200 watts, and a film formation rate of 14 A.
/sec. Furthermore, in the same manner, SV+ gas was applied at 20 sccM and SiH4 gas was applied at 30 secM.
, B9H6 gas at 1258QQM.

Furthermore, the above a-S was carried out under the same conditions except that nitrogen gas was released from the fifth tank (9) at a flow rate of 2080 membrane M.
An a-Si surface protective layer was formed on the i photoconductive layer.

At this time, in a glow discharge atmosphere, 5j-F+ and S
SiF4. for the gas volume of iH+. The F/S volume is approximately 4
The amount of H9 gas used as a carrier gas was about 80%. This reduces nitrogen to about 20 atoms.
, i-c%, about 200 ppm boron, and about 5 atomic% fluorine and hydrogen in total, Q, l.
/jm a-81 surface protective layer was obtained.

It has been confirmed that this electrophotographic photoreceptor has excellent photosensitivity characteristics including in the long wavelength region, and furthermore, it has been confirmed that the electrophotographic photoreceptor has excellent photosensitivity characteristics including the long wavelength region, and furthermore,
When charged with a 6 kV corona charger and following the change in surface potential over time in the dark and immediately after irradiation with 770 nm monochromatic light, the surface potential was 700 V.
It has been found that this material has significantly higher values than above, has slow dark decay, and has excellent charge retention ability.As a result, it has been found that it can be used in a wide range of future applications, such as application to laser beam printers using semiconductor lasers.

Regarding the electrophotographic photoreceptor thus obtained, 5.6 kv
After being charged by a no-corona charger, image exposure was performed and a magnetic brush phenomenon was performed.As a result, a good image with high image density and high contrast was obtained.Even after 40M repeated tests, there was no decrease in density or white background No deterioration from the initial image, such as fogging or white spots due to surface scratches, was observed, and it was confirmed that the image had good durability.

[Example 2] In the photoreceptor obtained in Example 1, a barrier layer (4) formed under the following manufacturing conditions was interposed between the aluminum substrate 11) and the photoconductive layer (2). Created an electrophotographic photoreceptor.

That is, in the glow-discharge decomposition apparatus shown in FIG.
0M, B9H6ff 125 SC0M, N
Under the conditions of Example 1, except that the R gas was used at a flow rate of 0.8 BOOM (D), about 1 c% of nitrogen and about 200 ppm of boron were deposited on an aluminum substrate (1).

An a-Si barrier layer having a thickness of about 2 μm and containing about 5 atomic Q% of fluorine and hydrogen in total was obtained. Then, on top of this, an a-Si photoconductive layer exactly the same as in Example 1 and a
-81 surface protective layers were sequentially laminated to obtain an electrophotographic photoreceptor.

The thus obtained electrophotographic photoreceptor was charged with a 55 kV corona charger, and then subjected to image exposure to perform a magnetic brush phenomenon. As a result, a good image with high image density and high contrast was obtained, and after 10,000 cycles. Even after repeated tests, no deterioration from the initial image, such as a decrease in density, fogging on white backgrounds, or white spots due to scratches on the drum surface, was observed, and durability was confirmed to be good.

Furthermore, the electrophotographic photoreceptor obtained in this example has excellent photosensitivity characteristics including the long wavelength region, and also has an excellent photosensitivity of 5.6.
According to the change in surface potential over time in the dark after charging with a kV corona charger and the change over time in the surface potential immediately after irradiation with monochromatic light of 77Q n1Tl, the surface potential was significantly higher than that in Example 1, and 850 (2) or more, and it was found that the charge retention ability was also favorable. [Example 3] When forming the surface protective layer described in Example 1, SiF+ gas with hydrogen as a carrier gas was used from the first tank (5), and hydrogen was used as a carrier gas from the second tank (6). Photoreceptors (Al (Bl) (C1 and (Dl) were fabricated by changing the release amount of each SiH4 gas and changing the gas composition of the glow discharge atmosphere as shown in Table 2. However, other fabrications The conditions were exactly the same as in Example 1.

The durability of the photoreceptor was confirmed by the method described in Example 1, and the results are shown in Table 2. Note that the evaluation of the durability test in Table 2 was based on the limit number of repetitions at which deterioration from the initial image was observed.

Table 2 As is clear from Table 2, photoreceptors (B) and (C) are 4
Even after repeating the test 0M times, the concentration decreased.

White background fog, white spots due to scratches on the drum surface, etc.

It was found that no deterioration from the initial image was observed and the durability was significantly improved, making it fully satisfactory as a photoreceptor for ultra-high speed copying. However, the photoreceptor (At
(For DJs, at most, it is 200,000 to 150,000 times,
The level was almost the same as that of a conventional a-Si photoreceptor.

As is clear from the above-described embodiments, a-
The Si photoreceptor has a surface protective layer laminated on the photoconductive layer, and when forming the surface protective layer using a glow discharge decomposition device, it is necessary to specify the gas composition of the fluorine-containing silicon compound and the hydrogen-containing silicon compound. As a result, extremely stable operating characteristics and excellent durability have been obtained, and as a result, it is expected to be used as a photoreceptor for ultra-high speed copying, which will be increasingly required in the future.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a photoreceptor according to the present invention, and FIG. 2 is a schematic diagram showing a glow discharge decomposition apparatus for forming an amorphous silicon layer. (11-... Conductive substrate (2)... Amorphous silicon photoconductive layer! 31-...
・Amorphous silicon surface protective layer + 4) - Amorphous silicon barrier layer patent applicant Takao Kawamura, Kyocera Corporation

Claims (6)

[Claims] (1) An electrophotographic photoreceptor in which an amorphous silicon photoconductive layer and an amorphous silicon surface protective layer containing hydrogen and fluorine as well as nitrogen are sequentially laminated on a conductive substrate by glow discharge decomposition method. The gas volume of the fluorine-containing silicon compound is 20 to 5% of the gas volume of the silicon compound and the hydrogen-containing silicon compound.
An electrophotographic photoreceptor characterized in that a glow discharge is generated in an atmosphere of 0% to form the amorphous silicon surface protective layer. (2) An electrophotographic image in which an amorphous silicon barrier layer, an amorphous silicon photoconductive layer, and an amorphous silicon surface protective layer containing nitrogen as well as hydrogen and fluorine are sequentially laminated on a conductive substrate by a glow discharge decomposition method. In the photoreceptor, glow discharge is generated in an atmosphere in which the gas volume of the fluorine-containing silicon compound is 20 to 50% of the gas volume of the fluorine-containing silicon compound and the hydrogen-containing silicon compound, and the amorphous silicon surface is An electrophotographic photoreceptor characterized by forming a protective layer. (3) Along with the glow discharge decomposition gas, at least one of hydrogen gas and rare gas as a carrier gas occupies the atmosphere gas of the glow discharge, and the proportion thereof is 50 to 90%. The electrophotographic photoreceptor according to item 1 or 2. (4) The electrophotographic photoreceptor according to claim 1 or 2, wherein the fluorine-containing silicon compound is SiF4. (5) The electrophotographic photoreceptor according to claim 1 or 2, wherein the hydrogen-containing silicon compound is Si or H+. (6) The electrophotographic photoreceptor according to claim 1 or 2, wherein the amorphous silicon surface protective layer contains a member of group Ma of the periodic table.