JPS60143359A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To increase electric charge receptive power to the extent of making practicable the image formation by Carlson system and to decrease residual potential by forming an a-Si barrier layer contg. oxygen and a specific amt. of the IIIb group impurity between a photoconductive substrate and an a-Si photoconductive layer. CONSTITUTION:An a-Si barrier layer contg. oxygen and about 10-20,000ppm the group IIIb impurity is formed between a conductive substrate and an a-Si photoconductor layer. The insulating characteristic of the barrier layer is improved and the excellent barrier effect is obtd. by the incorporation of an adequate amt. of oxygen into the barrier layer formed in the above-mentioned way. The dark resistant required at the least for the barrier layer can be assured without increasing the oxygen content as the IIIb group impurity is added together with the above-mentioned oxygen to the barrier layer. The adhesion to the a-Si barrier layer is good when Al is used for the substrate. Generation of exfoliation and crack is thus obviated even after reiterative use for a long period of time. The implantation of the electric charge from the conductive substrate is effectively prohibited by providing the barrier layer in the above-mentioned way, by which the surface charge receptive power of the a-Si photoconductive layer is increased and the photosensitive body is usable for image formation by Carlson system.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic photoreceptor having an amorphous silicon photoconductor layer produced by glow discharge decomposition.

Various types of electrophotographic photoreceptors have already been proposed, and among them, amorphous silicon (3-hole, 1-orpbous 5
The application of ilicon (hereinafter abbreviated as 3-81) to photoreceptors has been attracting attention. This is because a-8i is far superior to conventional selenium and CdS photoreceptors in terms of environmental pollution resistance, heat resistance, abrasion resistance, photosensitivity, etc.
-8i as a photoconductor layer is JP-A-54-
Publication No. 86341 C has been proposed.

As a result of actually researching the application of a-8i as a photoconductor for electrophotography, the present inventor found that it is ideal for non-polluting properties, heat resistance, surface hardness, and abrasion resistance, which conventional photoconductors lacked. It was discovered that it has the following characteristics. However, on the other hand, the dark volume resistance or maximum temperature of the A-8I photoconductor layer is approximately 10100 crm when the normal glow discharge decomposition method is used.
The photoreceptor cannot be charged to a predetermined surface potential that is at least suitable for image formation using the Carlson method, and is suitable for the Carlson method due to the steps of charging, image exposure, development, transfer, cleaning, and static elimination. I ran into a problem where I couldn't use it.

For this reason, conventional C is, for example, JP-A-54-1], 6930
As shown in the publication, an a-8I photoconductor layer was formed as a thin layer, and an organic compound layer was laminated on top of the thin a-8I photoconductor layer, which had the functions of holding charge and transporting carriers generated in the a-8i layer. Is this structure proposed? Either the manufacturing method for C is complicated, or the a-8i photoconductor layer is not used as a surface layer, and the above-mentioned excellent properties are not utilized at all. . Therefore, while maintaining the structure in which the A-8I photoconductor layer formed to a thickness of several tens of microns on the conductive substrate is used as the surface layer, the A-8I photoconductor layer itself contains about 0.1 to 30 atomic%. Japanese Unexamined Patent Publication No. 54-1.45539 proposes that the dark resistance be improved by incorporating oxygen or nitrogen. However, the inventor of the present application actually thinks that 0.1 atomic%
When we investigated the overall electrophotographic properties by adding oxygen to a-8i, we found that the dark resistance was more than sufficient for the Carlson method.
However, as the oxygen content increases, the photosensitivity characteristics decrease significantly, and the lowest atomic
It was confirmed that the photosensitivity was slightly inferior to that of conventional photoreceptors in the visible light region even with % oxygen content.

The present invention has been made in view of the above facts, and a-8i
Impairing the excellent properties of the photoconductor layer, such as environmental pollution resistance, heat resistance, surface hardness, and abrasion resistance; An object of the present invention is to provide an electrophotographic photoreceptor having a λ-3i photoconductor layer having a low potential as an image forming surface layer.

The gist of the present invention is that between the conductive substrate and the A-8I photodiode layer,
Periodic Table 1I of Oxygen and about 10 to 20,000 PPm
The present invention, which is an electrophotographic photoreceptor characterized by forming an amorphous silicon barrier layer containing Ib group impurities, will be described in detail below.

The electrophotographic photoreceptor having the structure according to the present invention is produced by a glow discharge decomposition method on a conductive substrate, and has a thickness of about 0.02 to 5 microns and about 0.05 to 0.5 atomic% of oxygen, provided that the film thickness is about 0.2 to 0.5 atomic%. When the layer is as thin as 0.04 microns, a-8i contains up to about 1 atomic% of oxygen.
The barrier layer and the a-3i photoconductor layer, also produced by the glow discharge decomposition process and having a thickness of about 5 to 60 microns, are laminated sequentially, or the a-Si barrier layer is formed from a conductive substrate. This effectively prevents charge injection, significantly improves the surface charge acceptance ft1g force of the λ-8i photoconductor layer, and enables image formation by the Carlson method.

That is, if the a-Si barrier layer itself is pure a-8i containing no impurities, its volume resistance is 10Ω.
・C effective for blocking charge injection from the substrate as low as an
Although there is no oxygen, about 0.05 to Q, 5 atomic%
Its insulation properties are significantly improved by adding more
Shows excellent barrier action. Oxygen content approximately 0.05 a
The reason for setting it above Lomic% is that if it is lower than that, the resistance of a8+ will not improve much and it will not function as a barrier, so it is better to set it below 0.5acomic%. It is C because it becomes impossible to obtain an excellent image. This residual potential's rise is a-8i
This is caused by a large number of carrier carriers generated in the photoconductor layer being trapped at the interface with the a-8i barrier layer or in the barrier layer, but when the oxygen content is adjusted to 0.05 to 0.
By setting the residual potential to 5 atomic %, and further by setting the layer thickness to about 0.2 to 5 microns as described later, the residual potential is at a level that poses no problem for practical use.

In addition, in the above, the oxygen content is at most 0.5 atoms.
ic%, oxygen can be contained up to about 1 atomic% only when the thickness of the a-8i barrier layer is as thin as about 0.2 to 0.04 microns, and the residual potential is also below a certain value. It has been confirmed that it will be maintained.

The thickness of the a-8i barrier layer is preferably about 0.2 to 5 microns, which is less than 0.02 microns.
C1 because the surface potential acting as a barrier layer does not change, and C1 because the residual potential of 5 microns or more exceeds a certain value and does not have a rectifying effect. In addition to oxygen, the a-81 barrier layer may be doped with an impurity of group 1IIb of the periodic table (preferably 1 element) at a maximum of about 20,000 PPm. This is because its addition improves the dark volume resistance of the 3-81 barrier layer, albeit to some extent, and increasing the oxygen content ensures the minimum required dark resistance for the barrier layer. In addition, aluminum, stainless steel, etc. can be used as the conductive substrate, but it is important to use raw aluminum because it has good adhesion to the Sl barrier layer and does not peel or crack even after repeated use over a long period of time. It was confirmed.

The thickness of the a-3i photoconductor layer formed on the barrier layer is preferably about 5 to 60 microns, and the photoconductor layer itself may be in an impurity-free form or may have a periodicity as necessary. It may contain up to 20,000 PPm of impurity (preferably boron) of Group Ill I) of the Table of Contents,
Further, a trace amount of oxygen may be contained.

Hereinafter, the glow discharge decomposition method for producing the electrophotographic photoreceptor according to the present invention will be explained. This manufacturing apparatus has an excellent manufacturing advantage in that photoreceptors can be quickly manufactured under simple manufacturing conditions.

FIG. 1 shows a glow discharge decomposition apparatus for producing an a-8i barrier layer and a photoconductor layer;
Tanks (1), (2), and (3) contain SiH4 and B2, respectively.
H6.02 Ganu is sealed. Also 5iJ (4, B
The gear gas for both 2H6 gases is hydrogen. These gases are connected to the corresponding first, second and third regulating valves (4) and (5).
, (6), and its flow rate is regulated by mass flow controllers (7), (8), (9), and the gas from the first and second tanks (1), (2) is Oxygen gas from the first raw tube Cl0) and the third tank (3) is separately sent to the second raw tube (11). In addition, (12), (13), and (14) are flowmeters, (15
), (16) are stop valves. 1st and 2nd supervisor (10)
, (11) is sent into the reaction tube (17), which is surrounded by a resonant vibration coil (
18) is wound and its own high frequency power is iQQ
watls to number k i l o w a t t s,
The frequency ranges from 1 MHz to several IQ MHz or an appropriate degree Celsius. Inside the reaction tube (17) is a turntable (for example made of aluminum) on which an A-8I barrier layer is formed (a turntable (19) whose plate (19) is rotatable by a motor (20)).
21), and the substrate (19) itself is uniformly heated to a temperature of about 50 to 300°C, preferably about 150 to 250°C, by suitable heating means. In addition, the interior of the reaction tube (17) requires a high vacuum state (discharge voltage: 05 to 2.0 Torr) when forming the λ-8i film, so the rotary pump (22) and the diffusion pump (23)
) is connected to.

In the glow discharge decomposition apparatus with the above configuration, first a -
When forming the Si barrier layer, the temperature of the diffusion pump (23) in the C reaction tube (17) is set at about 10-4 to 10-6 Torr (
D u Empty the tank, then switch to the rotary pump (22) to bring the degree of vacuum to about 10 to 10 Torre, introduce oxygen from the third tank (3), and adjust the flow controller (9). The partial pressure is maintained at a predetermined value. Subsequently, SiH4 gas is introduced from the first tank (1), and 82H6 gas is introduced from the second tank (2) as needed.

And the inside of the reaction tube (17) is 0.5 to 2. QT
orr (D K'2 state M, the substrate temperature is 50 to 300°C, the high frequency power of the resonant vibration coil is 100W to several kW, and the frequency is set to 1 to several IQMHz). This occurs, the gas decomposes, and a λ-8L barrier layer containing a predetermined amount of oxygen or an A-81 barrier layer containing an appropriate amount of boron is deposited on the substrate at a rate of approximately 0.5 to 155 microfron/6 min. formed quickly.

Once the a-8i barrier layer is formed, the glow discharge is temporarily interrupted and then the formation of the λ-51 photoconductor layer begins. At this time, when the a-5i photoconductor layer contains oxygen and further boron, the respective mass flow controllers (7) and (8)
is adjusted to set the partial pressure to a predetermined value, and glow discharge is performed in the same manner as above to form an a-5i photoconductor layer.

An experimental example will be explained below.

Experimental Example 1 In this experimental example, an a-5i
While forming a barrier layer, the initial surface potential and residual potential of the photoreceptor were measured while changing the oxygen content.

Using the glow discharge decomposition apparatus shown in Fig. 1 described above, the interior of the reaction tube (I7) is first drawn to a vacuum of about 10" Torr by the diffusion pump (23), and then the rotary pump (22) is switched to increase the vacuum level. As approximately IQ ”Torr,
In this state, the mass flow controller (9) was adjusted to set its partial pressure to Q, Q3 Torr, and oxygen was introduced from the third tank (3). Along with this, 5iH4 gas (hydrogen with 5il-
1410%) and 5iI (4
B2H6 gas corresponding to a molar ratio of 10 was released. The total pressure of the reaction chamber at this time was 0.7 Torr.
Keep r. On the other hand, the substrate temperature was maintained at 2oot, and glow discharge was performed using the high frequency power of the resonant vibration coil (18) at 300 watts, 1 frequency, and 4 MHz, to form an a-Si film at a rate of about 1 microfron/60 minutes. The glow discharge was interrupted at the end of the minute. As a result, oxygen was deposited on the aluminum substrate at a thickness of about 0.05 μm.
a-5 containing tomic% and 20PPm of boron
An i barrier layer was formed.

Next, the mass flow controller (9) is throttled to set the oxygen partial pressure to approximately 0.005 Torr, and the SiH++
Keeping the partial pressures of B2H6 and B2H6 gases the same, claw discharge was performed again for 8 hours to produce a -5i light Q with a thickness of 8 microns.

An electric layer was formed. This a-5i photoconductor layer is about OO1
Contains acomic% oxygen and 20 PPm boron.

Separately from this photoreceptor, six types of photoreceptors having the same structure were prepared using the same method except that the oxygen content of the 3-51 barrier layer was changed. That is, when forming the a-5i barrier layer, the oxygen mass flow controller (9) was adjusted to adjust the partial pressure to 005.0.09.022.035.050, Q, and 7, respectively.
Glow discharge was performed under the same conditions except that QTorr was changed, and the oxygen content was 008.0.16.03.0. /I, 05 and Q,
a-5i containing 20 ppm boron at 5aLomic%
a barrier layer and on it Q, Q1 atomic% oxygen and 2
0 P I) 8 micron thick a containing m boron
Five types of photoreceptors were prepared comprising -5i photoconductor layers.

Separately from these, a photoreceptor was prepared in which an a-5i photoconductor layer was directly formed on a substrate. This photoconductor a-5i corresponds to a barrier layer containing no oxygen at all. still,
The oxygen content of each layer was determined by spark source mass spectrometry.
In addition, boron-containing particles were measured using an ion microanalyzer.

Next, each of the photoreceptors was uniformly charged to positive and negative polarities using a corona charger connected to a voltage of ±5.6 KV, and the initial surface potential was measured to determine the charge acceptance ability. It was uniformly irradiated with a light intensity of 3 mw-sec/7 and the residual potential after decay was measured. These measurement results are shown in Figure 2, in which the horizontal axis represents the oxygen content of the 3-5i barrier layer, the left vertical axis represents the initial surface potential, and the right vertical axis represents the residual potential. (5) and (13) show the relationship between the initial surface potential and oxygen content during positive and negative charging, respectively, and the curves tq and (D+ show the relationship between the residual potential and oxygen content during positive and negative charging, respectively) .

As is clear from Fig. 2, the photoreceptor that does not contain any oxygen in the a-5i barrier layer, that is, the photoreceptor on which the a-5i barrier layer is not formed, shows almost no residual potential when charged positively or negatively. The initial surface potential is as low as 400 V when positively charged and -360 V when negatively charged (this confirms that the charge-accepting ability of the a-5i photoconductor layer is poor. However, the a-5'l
In the case of a photoconductor containing 0.05 a L-omi, c% of oxygen in the l-wall layer, the initial surface potential becomes significantly lower, as shown by curve B, especially when negatively charged, and reaches -560 V, and Even when positively charged, it is somewhat improved, and the inclusion of oxygen ensures that it is charged to a high potential to the extent that image formation by the Carlson method is made possible for the first time. Furthermore, the initial surface potential at which the oxygen content reaches Q, Q 3 atomic% is -600 V when negatively charged and +4 when positively charged.
Increased to 70V, and the residual potential is ±]0 to 20V
and low (which ensures that images with excellent contrast are obtained.

3-51 The oxygen content of the barrier layer is 0.16 and o3.0, respectively.
4.05. In the case of a 0.6aLo-mic% photoreceptor, when negatively charged, the initial surface potential is saturated around -620V to -670V, whereas when positively charged, it is 0.16a.
When the oxygen content is Lαη1c%, the voltage increases to +600V, and when the oxygen content is higher than that, it reaches approximately +620V to +620V, which is the same as when negatively charged.
It shows a tendency to saturate at 675v. On the other hand, the residual potential is -20V when the oxygen content is 0.16 atomic%.
and +35v1Q, -75V and + at 3aLomic%
90■, 0.4aLomic96 110v and +12
5■, 0.5aLomic% -145v and +160
V, and 0.6ato+nic% is -180■
and +205V, which increases as the oxygen content increases.

However, the residual potential is ±1. It has been reported that in the region above OOV, the initial surface potential is ±600V600V, and that even with a maximum residual potential of ±150V, images with sufficiently excellent contrast can be obtained. 5
The content of oxygen contained in the i barrier layer is approximately 005 to Q, 5at.
It is preferable to use omic%. That is, when the amount of oxygen contained in the a-5i barrier layer is less than about 0.05 atomic%, the layer layer does not have the function of sufficiently blocking charge injection from the substrate; When the residual potential is above 05a [omic%], the residual potential is ±150V150V, and an image with excellent contrast cannot be obtained. The reason why the initial surface potential does not improve much when the oxygen content of the a-5i barrier layer is about 0.0B atomic % or less during positive charging is thought to be due to the rectification of the layer body.

Experimental Example 2 In this experimental example, the thickness of the a-5i barrier layer containing OQ8aLOmic% oxygen was varied and the relationship between the initial surface potential and residual potential of the photoreceptor was measured. That is, the thickness of 0.05 microns prepared in Experimental Example 1 contains 0.08 aromatic oxygen.
In addition to photoreceptors with a = 5i barrier layer containing % a
-5i barrier layer (photoreceptor with a-5i photoconductor layer directly formed on the substrate, oxygen content is 0, OB ato
Photoreceptors were prepared in which the thickness of the a-8i barrier layer was 1 micron, 24 micron, 3 micron, 4 micron, 5 micron, and 6 micron in mic%.

Next, each of these photoreceptors was charged and exposed to light under the same conditions as in Experimental Example 1, and the initial surface potential and residual potential were measured.

These measurement results are shown in Figure 3, in which the horizontal axis represents the film thickness of the a-5i barrier layer, the left vertical axis represents the initial surface potential, the right vertical axis represents the residual potential, and the curve fE), fF)
are the relationship between the initial surface potential and film thickness when positively and negatively charged, respectively.
The curves (Gl, σ1) show the relationship between the residual potential and film thickness during positive and negative charging, respectively. As is clear from this figure, a-5
In the case of a photoreceptor without an i-barrier layer, the initial surface potential is as low as 400 μm when positively charged and -360 μs when negatively charged.
When O,08atomi CX) was formed, a remarkable improvement in the initial surface potential was observed, especially when negatively charged, and it was actually
It also becomes 00v. In addition, even when positively charged, it is as high as 470V.As shown above, due to the presence of the 0.5 micron thick A-5I barrier layer, the initial surface potential is improved to the extent that image formation by the Carlson method is possible. means that the initial surface potential is similarly improved even if the thickness is less than that, and as seen from FIG. 3, a minimum initial surface potential is guaranteed if the thickness is about 0.2 microns or more.

On the other hand, when the film thickness is set to 1 micron, the initial surface potential improves somewhat to +475V and -625V, respectively, but the residual potential also increases accordingly to 25V and -20V.
becomes. By making the film thicker, the initial surface potential improves somewhat, but on the other hand, the residual potential increases, and at a film thickness of 24 microns, the initial surface potential is +5
00V and -630V.

The initial surface potential is 505 V and -650 V when the residual potential is +50 V and -40 V 13 microns, and the initial surface potential is +530 V when the residual potential is 70 V and -60 V 14:: Kron.
and '-670V, residual potential is +110V and -95V
, initial surface potential of 550V and -680V at 5 microns
, the residual potentials are +155V and -145V, and the initial surface potentials at 6 microns are +570V and -700V, while the residual potentials are +210V and -185V. As mentioned above, if the residual potential is about ±150V or less, images with sufficiently excellent contrast can be obtained, so as is clear from the results in Figure 3, the thickness of the 3-51 barrier layer can be up to about 5 microns. As mentioned above, the minimum thickness may be approximately 0.2 microns or more.

Next, apart from the various photoreceptors described above, photoreceptors having the same structure were prepared except that an a-5i barrier layer was used, the thickness was 0.3 microns, and the oxygen content was 1 atomic%. This photoreceptor was charged and exposed in the same manner, and the initial surface potential and residual potential were measured. The results are shown in Figure 3 as measured values (J),
(Kl, fL+, as shown as Oka, ke), (K) are the initial surface potentials at positive and negative charging, respectively, fL+, (Foundation)
represent the residual potential when positively and negatively charged, respectively.

That is, according to the measurement results, the initial surface potential is -1-63, respectively.
Sufficiently high values for image formation, such as 0 V and -660 V, are obtained, and the residual potential is approximately ±150 V, which guarantees that images with good contrast can be obtained. This means that when the λ-5i barrier layer is made thin, for example, about 0.3 microns, the oxygen content is reduced to 0.5 atomic%.
As is clear from the above measurement values, even if 1 acomic% of oxygen is contained, the residual potential will be the maximum limit of about ±150■, so only when it is made into a thin layer. It can contain up to 1 atomic percent oxygen. Note that the exclusive layer here is limited to 0.3 microns, and if it is about 0.2 to 0.4 microns, it can similarly contain up to 1 atomic % of oxygen.

Experimental Example 3 Here, an image forming experiment was conducted for each photoreceptor produced in Experimental Example 1.2. That is, +5.6 KV for each photoreceptor.

The images were charged positively and negatively using a corona charger connected to a voltage source of -5 and 6 KV, and then imagewise exposed, developed with a two-component developer, and then transferred to transfer paper to examine the image quality.

As a result, the image obtained from the photoreceptor without the A-51 barrier layer was not clear (the image as a whole was blurred) due to the low surface potential during both positive and negative charging. , 0.6 atoms of oxygen with a thickness of 0.5 microns
Images obtained from a photoreceptor with a 1-51 barrier layer containing 0.03a tomic% gold and a photoreceptor with an a-5i barrier layer approximately 6 microns thick and containing 0.03a tomic% gold were foggy and unclear. there were. On the other hand, the thickness is 0.05 micron and the oxygen content is 0.0-1008 respectively.
．． 016.03.04.0.5 atomic destination a-
A photoreceptor with an 8i barrier layer and an oxygen content of 0.
08at ornic% thickness 1.24.3.4.
Very clear images were obtained from the photoreceptors having the 5 micron a-5i barrier layer, confirming the excellent effects of the present invention. In addition, the oxygen content is 0.05 atomic
% photoreceptor, when positively charged (ζ) images were obtained that were somewhat inferior to those of ζ and others, but there was no problem in practical use.

In addition, 1 atomic% of oxygen is added at a thickness of 0.3 microns.
Similar imaging experiments were conducted on a photoreceptor having an a-5i barrier layer, and clear images with excellent contrast were obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a glow discharge decomposition apparatus for manufacturing an electrophotographic photoreceptor according to the present invention, and FIG. 2 is a graph diagram showing the relationship between oxygen content, initial surface potential, and residual potential in an amorphous silicon barrier layer. , FIG. 3 is a graph showing the relationship between the Di thickness of the amorphous silicon barrier layer, the initial surface potential, and the residual potential. (1)・First tank sealed with 5i1-14 gas (2)
-B21 (Second tank (3) with 6 dregs sealed...0
3rd tank (4), (5), (6) in which 2 wastes are sealed
・Adjustment valve (7), (s), (9) ・Metering valve (10), (11)...Main pipe (17) Reaction tube (18)...Resonance vibration coil (19) )... Mr. Takao Kawamura, Minolta Camera Co., Ltd., Kyocera Co., Ltd. Figure 1

Claims (1)

[Claims] 1. Between the conductive substrate and the amorphous silicon photoconductor layer, oxygen and about 10 to 20,000 ppm of the periodic table n
An electrophotographic photoreceptor comprising an amorphous silicon barrier layer containing impurities of the lb group.