JPS6151154A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve the photosensitivity to coherent light of a long wavelength and to prevent the generation of interference fringes by constituting a photoconductive layer of hydrogenated amorphous silicon incorporated with a specific atomic ratio of hydrogen atoms into silicon atoms. CONSTITUTION:The photoconductive layer 2 consisting of the hydrogenerated amorphous silicon which is obtd. by incorporating the hydrogen atoms into the silicon atoms, used as a base body, at <=10atom% by with respect to the silicon atoms and has 1.55-1.66eV optical band gap and <=10<7>OMEGAcm bright resistance to light irradiation of 10<15>/cm<2> photons at 780nm wavelength is formed on a conductive substrate 1 consisting of aluminum, etc. by which the intended electrophotographic sensitive body is obtd. The resultant electrophotographic sensitive body has substantial photosensitivity even with the coherent light near 800nm wavelength and obviates the generation of the interference fringes occurring in the reflection of incident light on the surface of the substrate 1.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] [Technical Background of the Invention and Problems Thereto Conventionally, Sc, Se-T photoreceptors have been used as electronic 71 photoreceptors.
O-based, ZnO-based, Cd S-based, UN photoconductor (0
゜P, C) etc. were used. However, in some areas, the use of CdS-based substances is prohibited because they are harmful to the human body. 3c, 3e -TO type products are suitable for electrophotographic processes in terms of sensitivity and long life, but their crystallization temperature is as low as 60" CPi (in addition, the internal atmosphere at position A where leakage from the electrophotographic photoreceptor is Normally, the temperature exceeds 45°C, so even though it gradually becomes easier to form fine particles, its properties deteriorate, and the Vickers hardness is around 40, so mechanical contact with cleaning blades etc. can cause damage such as caving (easily damaged). On the other hand, ZnO-based and non-containing dielectric materials are manufactured by dispersing them in resin and coating them on electrocardiographic substrates.
Therefore, although it is easy to manufacture and non-polluting, it has poor moisture resistance and a short lifespan.

For this reason, in recent years, amorphous silicon, which can overcome the above-mentioned drawbacks, has been attracting attention as a material for electrophotographic photoreceptors. The electrophotographic photoreceptor (hereinafter also referred to as A-8I photoreceptor) using this amorphous silicon has spectral sensitivity up to a long wavelength of 800 nm, has a Vickers hardness of 1000, and has a lifespan of 1 million copies. When forming a film on a conductive substrate, the substrate temperature is as high as 200 to 250°C, so at least 1
It has many advantages such as crystallization does not occur in the operating atmosphere of 00° C. or lower, and property deterioration is unlikely to occur, and the material is harmless in terms of wood quality.

By the way, ordinary hydrogenated amorphous silicon (hereinafter also simply referred to as a-3i), which is produced by low-temperature glow discharge decomposition of raw material gas such as 5iHa or Si 2 Hs, has a specific resistance in the dark of 1010 Ωcn+, which is as small as 1. However, there was a problem in that a sufficient surface potential could not be obtained during direct current corona charging in the dark.

This problem also applies to true a-8i.

Therefore, in order to improve this point, two methods have been adopted, which correspond to the conventional number. First, a-+,
3i film is doped with bandgap increasing elements such as O, C, N, etc. and III A 1M atoms of the periodic table by a minute amount to obtain high-resistance intrinsic a-3i photosensitive light. However, if this method is adopted, 11H3
Although it is possible to achieve a high paper IA inside, a new problem arises in that the photosensitivity decreases.

The next method is to coat the surface of a conductive substrate, such as an aluminum drum, with an electrical protection shield consisting of P-type or N-type a-3i doped with about 10゛3 atomic percent of A or vA group atoms. a photoconductive layer consisting of a blocking h4 and a-3i; l-1;
A three-layer structure is obtained by sequentially laminating a surface layer made of a-8i containing atoms such as C, 0, and N. When this method is adopted, a DC corona discharge of 4 to 5 oo
It is possible to obtain a surface potential of V, and the photosensitivity is as good as that of a conventional photoconductive layer made of a-3i; It can satisfy the requirements for an electrophotographic photoreceptor used in, for example.

On the other hand, the application of the a-3i r3 light material (including those provided with a photoconductive layer consisting of a-3i:H) to devices such as semiconductor laser printers that use the a-3i laser as a light source is progressing. However, this is because semiconductor lasers have a long emission wavelength of 780 nm, which is 800 nm compared to conventional electrophotographic photoreceptors, which do not have sufficient spectral sensitivity.
This is because it has a spectral sensitivity up to around nm.

However, the a-
Although the photoconductive layer consisting of 3i;)-1 has spectral sensitivity up to 800 nm, its peak sensitivity wavelength is 650 nm.
In reality, 800 nm corresponds to the tail of the sensitivity curve, and 800 nm corresponds to the tail of the sensitivity curve.
It does not have sufficient photosensitivity for 000111. Further, although the emission wavelength of a semiconductor laser is 780 nm, in reality, due to manufacturing variations, the emission wavelength may vary to 790 nm or aeonm. Furthermore, since the conventional photoconductive layer consisting of a-3i;)-1 cannot sufficiently absorb laser light, the incident light once reaches the surface of the η-conducting substrate and then is reflected. This will cause interference fringes on the formed image due to interference with the laser beam. Therefore, even though the a-3i illumination light has various advantages, when used in a laser printer or the like that uses coherent light with an emission wavelength of about 800 nm as a light source, there is a problem that the formed image becomes unclear. , as a solution to these problems, photoconductive ii11iYi composed of a-8i:H
Conventionally, efforts have been made to dope GeD λ atoms into the optical band to further narrow the optical bandgap 1r tube to provide sufficient 4i sensitivity even at a spectral wavelength of 800 nm, but doping with Qc atoms further reduces the specific resistance in the dark. Therefore, it became impossible to obtain a sufficient surface potential, and the solution to this problem was still insufficient.

[Purpose of the invention] ゛ The invention was developed in view of the above circumstances, and its purpose is to provide a material that has a sufficient optical TA degree even for coherent light with a wavelength of around 800nrR, and that also has a conductive substrate. To prevent interference fringes caused by reflection of incident light on the surface? An object of the present invention is to provide an electrophotographic photoreceptor that can be used in various ways.

[Summary of the Invention] Considering the above-mentioned problems, the reason why the spectral sensitivity of the conventional photoconductive layer consisting of a-3i;1 is insufficient at around 780 nm is because the optical band gap of a-3i: .68
~1. This is because γOe■ cannot generate sufficient optical carriers for coherent light with a wavelength of 780 nm, and roughly speaking, when the conventional type is irradiated with coherent light with a wavelength of 780 nm, the light is Since it reaches the conductive substrate, the photocarriers generated near the conductive substrate are captured in a-3i:)-1 before being neutralized with the surface potential and do not contribute to photosensitivity. This is thought to be because it disappears. Furthermore, the appearance of interference fringes is considered to be due to the inability to sufficiently absorb light with a wavelength of 780 nll as described above.

In order to achieve such an object, the electrophotographic photoreceptor of the present invention has a photoconductive layer formed of hydrogenated amorphous silicon that uses silicon atoms as a matrix and contains 10 atomic percent or less of hydrogen atoms relative to the silicon atoms. This narrows the optical bandgap and increases the bonding between silicon atoms, thereby reducing the trap density.

’　　　[R1171゜□6, Examples of the present invention will be described below.

FIG. 1 is a schematic sectional view showing a first embodiment of an electrophotographic photoreceptor according to the present invention. In this electrophotographic photoreceptor, a film of hydrogenated amorphous silica is formed on the surface of a conductive substrate 1, such as an aluminum drum, using silicon atoms as a matrix and containing 10 atomic percent or less of hydrogen atoms relative to the silicon atoms. A photoconductive layer 2 is provided and constructed.

FIG. 2 shows a film forming apparatus for forming the photoconductive layer 2 described above.

In the figure, 11 is a base, and a reaction container 12 is installed on the upper surface of this base 11. Roughly speaking, a cylindrical gas ejection pipe 13 which also serves as a counter electrode is provided within the reaction vessel 12 .

Further, a turntable 17 is provided on the base 11 and rotates at a predetermined speed via an m-wheel mechanism 16 using a motor 14 as a driving source. 19 and this heater 1
The conductive substrate 1, such as an aluminum drum, is rotated while being fitted onto the outer surface of the conductive substrate 9.

Further, a discharge generating power [2] such as a high frequency power source is connected to the gas ejection pipe 13 which also serves as a counter electrode.

Further, the gas passage 13 of the gas ejection pipe 13 that also serves as the counter electrode
A gas gas pipe 23 equipped with a valve 22 is connected to the lower end side of a. Further, in the reaction vessel 12, exhaust ports 17a and 17b are provided in the turntable 17, and a rice base 11 is provided.
A high vacuum evacuation system (not shown) equipped with a diffusion pump, a rotary pump, etc. is connected through a gas exhaust port 11a bored in the 24A, and a mechanical booster pump 24A.

A large-flow exhaust system 25 equipped with a rotary pump 24B and the like is connected.

Further, a valve 26 is provided in the exhaust line of the large flow m exhaust system 25.
A dust trap 28 equipped with a wire mesh 27 for trapping active species is provided on the downstream side thereof. Note that the gas ejection tube 13 which also serves as a counter electrode is electrically insulated via an insulator 29.

Next, the photoconductive layer 2 using the film forming apparatus shown in FIG.
An example of a film formation experiment will be described. First, the inside of the reaction vessel 12 is evacuated to about 10'' II torr using a high vacuum evacuation system (not shown) equipped with a diffusion pump, a rotary pump, and the like.

At this time, the temperature of the conductive substrate 1 is raised to 350° C. using the heater 19. Then, open the valve 22 to
While gas is introduced into the reaction vessel 12, the exhaust system is switched from a high vacuum exhaust system (not shown) to a high flow rate exhaust system 25 equipped with a mechanical booster pump 24A and a rotary pump 2/IB, and the valve 26 is checked. At this time, a flow of J:5iHa gas of 300 m is applied to the mass flow controller 1-roller (not shown).
SCCM and W4rilF of the valve 26
The pressure inside the reaction vessel 12 is set to 1.2 torr.

In this state, a power of 300 W is applied to the gas ejection tube 13 which also serves as the counter electrode via the 13.56 MHz discharge generation power supply 2) to start forming the photoconductive FI2.

After 2 hours, the discharge generation power source 2)'
OFF, close valve 22 and supply 5iHa gas.
L second, the inside of the reaction vessel 12 is pumped to 10"41.O again by the mechanical booster pump 24A and the rotary pump 24B.
rr vacuum, turn off the heater 19 and wait for the conductive substrate 1 to cool down to 100°C or less,
Thereafter, the vacuum in the reaction vessel 12 is broken and the electrophotographic photoreceptor is taken out into the atmosphere.

The photoconductive layer of the electrophotographic photoreceptor thus formed had a thickness of 18 μm. When this electrophotographic photoreceptor was corona charged at -6.5KV, it turned out to be -200V.
We were able to obtain a surface potential of . In addition, 2. white tungsten light. Oj: 0,1y ux − in case of ux pre-irradiation
It exhibited a high sensitivity of 0.2 CII12/erg even to a laser beam with an emission wavelength of 780 rv.

On the other hand, in order to measure the hydrogen atom content, optical bandgap, and bright resistance of the photoconductive layer deposited as described above, hydrogenated amorphous silicon was deposited on Corning 7059 glass and Nesa glass under the same deposition conditions as described above. As a result of forming and measuring the film, the hydrogen atom content was 3 atomic % with respect to silicon atoms, the optical band gap was 1.62 eV, and the bright resistance had a wavelength of 78 on'1117"1015
Photon, /CllI2 (7) Te107Ωc for light irradiation
There was mr.

When the electrophotographic photoreceptor described above is used for semiconductor laser blinking, the optical bandgap of the photoreceptor is narrowed compared to conventional ones, and the bonding between silicon atoms is increased, resulting in a reduction in trap density. ,780nm
In addition to having sufficient spectral sensitivity to light of a wavelength of , it was also possible to prevent reflection on the surface of the conductive hanging body 1, and a clear image without interference fringes could be formed.

FIG. 3 is a schematic sectional view showing a second embodiment of the electrophotographic photoreceptor according to the present invention. This electrophotographic photoreceptor has a charge injection blocking layer 31 on the surface of a conductive substrate 30 such as an aluminum drum, which prevents the injection of charges from the conductive substrate 30, and a charge injection blocking layer 31 that prevents the injection of charges from the conductive substrate 30, and a layer 31 that prevents the injection of charges from the conductive substrate 30. 10
A photoconductive layer 32 made of hydrogenated amorphous silicon containing atomic percent or less of hydrogen atoms, and a surface texture 33 for the purpose of improving the charge retention ability of this photoconductive layer 32 and protecting its surface are sequentially formed. The product 1) is composed of 2i.

Next, an experimental example in which each layer of the photoreceptor shown in FIG. 3 was formed using a film forming apparatus not shown in FIG. 2 will be explained.

The charge injection blocking layer 31 lowers the temperature of the conductive substrate 30 by 230°C.
℃, 200SCCM of 5il-1a gas, 2SCCM of 02 gas, and 10'4 flow m ratio of B2 H6 gas to 5iHa gas were introduced into the reaction vessel 12, and the pressure inside the reaction vessel 12 was set to 1.0 tOrr. At the same time, the applied high-frequency power was set to 100 W, and the P-type a-3i02 :H,
A film B was formed to a thickness of 1 μm.

The photoconductive layer 32 then increases the temperature of the conductive substrate 30 to 380°C.
°C and 3i to 14 gas only 3003 CCM
introduced into the reaction vessel 12 and set the pressure to 1.2 tOrr,
Next, by applying high frequency power of 300 W, a hydrogenated amorphous silicon (a-3i:H) crotch was formed to have a thickness of 18 μm.

The surface layer 33 is then formed by lowering the temperature of the conductive substrate 30 to 230° C. and applying 3i to 14 gas to 15080 CM.

A-8iN;
It was made by forming J with a thickness of 1 μm.

After forming each layer as described above, the application of high-frequency power is turned off, the introduction of various gases is started, and the inside of the reaction vessel 12 is re-drawn to a vacuum of about 10°4tOI'r. The present electrophotographic photoreceptor was taken out after waiting for the temperature of the substrate 30 to become 100° C. or less.

The electrophotographic photoreceptor produced in this way received one toro, 5
When corona charging of KV was performed, the surface potential of +400■ was 4! We were able to. In addition, when irradiating white tungsten light at 2.02t+x, the half-reduced exposure amount is 0.0711.
It exhibited a high sensitivity of 11X-seC, and also had a high sensitivity of 0.23 cm 2 /erg to a 780 nm laser beam.

On the other hand, in order to measure the hydrogen atom content, optical band gap, and bright resistance of the photoconductive layer 32 deposited as described above, hydrogen was applied to Corning 7059 glass and Nesa glass under the same deposition conditions as described above. As a result of forming and measuring an amorphous silicon film, the hydrogen atom content is 0.09 atoms 96 per silicon atom, the optical band resistance is 1,59 cV, and the bright resistance is 1 u/A 780 nm'
clQIs photon/cm2 light! ni J ni 10
It was 6Ωam.

When the electrophotographic photoreceptor described above is used in a semiconductor laser blink, the optical band gap of the photoreceptor is narrowed compared to conventional ones, and the bonding between silicon atoms is increased, resulting in a reduction in 1-wrap density. So, 7&Onm
It had sufficient spectral sensitivity to light with a wavelength of , and was also able to prevent reflection on the surface of the conductive substrate 30, making it possible to form a clear image without interference fringes.

Furthermore, as a result of experiments using the above-mentioned glow discharge decomposition method with various film-forming conditions, it was found that it had sufficient spectral sensitivity to light with a wavelength of approximately 800 nm, and was also able to prevent reflections on the surface of the sTi substrate, resulting in interference fringes. Hydrogenated amorphous silicon (A-8
We were able to find a critical region for the composition and properties of i:H). That is, in the case of the glow discharge decomposition method, the temperature of the conductive substrate during film formation is an important factor;
℃ to deposit hydrogenated amorphous silicon.
,,8-O Lf 6,! J: lA□, ~□=0
Contains ff110 at%, optical band gap 1.66
eV.

A bright resistance of 107 Ωam against light irradiation of 1015 photons/c+e2 at a wavelength of 780 nm forms the upper limit, and the resistance to silicon atoms after forming a film of hydrogenated 7-morph silicon with the conductive substrate temperature set at 450''C. Contains hydrogen atoms @ξj 0.01 at%, optical pad gap 1.55 eV, 1015 photons/at a wavelength of 780 nm
The lower limit is 11 resistance 105 ΩCm for light irradiation of cm2.

In addition, when the film is formed with the temperature of the conductive substrate set to W>450°C or higher, the dark resistance becomes small, and even if the structure includes a charge injection blocking layer, it is not possible to obtain a sufficient surface potential. Ta.

Although the above experimental example was explained using a glow discharge decomposition method, it is also possible to form a photoconductive layer of hydrogenated amorphous silicon by sputtering. Since this sputtering is already known, a detailed explanation thereof will be omitted, but this method can also be used to produce photoconductive properties using hydrogenated amorphous silicon, which is made of silicon atoms and contains 10 at % or less of hydrogen atoms based on the silicon atoms. Similarly, the optical band gap is 1.5511 iV or more and 1.66 e■ or less, and 180
The electrophotographic photoreceptor made of hydrogenated amorphous silicon and having a photo-S-electroconductivity can have a bright resistance of less than 107 ΩcmLX for light irradiation of 1015 photons/cm2 at a wavelength of nIll. 780nm
It has sufficient spectral sensitivity to light with a wavelength of , and can prevent reflection of incident light on the surface of the conductive substrate, contributing to the formation of clear images free of interference fringes.

It goes without saying that the above description is an example, and that various modifications can be made within the scope of the gist of the present invention. Further, the electrophotographic photoreceptor of the present invention can be applied not only to semiconductor laser printers, but also to various electrophotographic devices such as copying machines and facsimile machines.

[Effects of the Invention] As is clear from the above description, the electrophotographic photoreceptor of the present invention has a photoconductive layer made of hydrogenated amorphous silicon that has silicon atoms as its matrix and contains 10 at % or less of hydrogen atoms relative to the silicon atoms. Since it has been formed, it has sufficient photosensitivity to coherent light with a wavelength of around 800 nm, and can also contribute to preventing the generation of interference fringes caused by reflection of incident light on the surface of the conductive substrate. The effect is right.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a first embodiment of an electrophotographic photoreceptor according to the present invention, FIG. 2 is a schematic cross-sectional view of a film forming apparatus using a glow discharge decomposition method, and FIG. FIG. 2 is a schematic cross-sectional view showing a second example of a photographic photoreceptor. 2...Photoconductive layer, 32...Photoconducting fG layer. −5ζ−1・

Claims (3)

[Claims] (1) An electrophotographic photoreceptor characterized by having a photoconductive layer made of hydrogenated amorphous silicon having silicon atoms as a matrix and containing hydrogen atoms in an amount of 10 atomic % or less based on the silicon atoms. (2) The electrophotographic photoreceptor according to claim 1, wherein the hydrogenated amorphous silicon has an optical band gap of 1.55 eV or more and 1.66 eV or less. (3) Hydrogenated amorphous silicon has a wavelength of 780n
The electrophotographic photoreceptor according to claim 1 or 2, which has a bright resistance of 10^7 Ωcm or less when irradiated with light of 10^1^5 photons/cm^2 in m.