JPS59109058A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To enhance speed and sensitivity as well as humidity resistance and durability, and adaptability for use in a laser printer by using a-Si.Ge having photosensitivity throughout from the visible red to the near IR region for a part of a photosensitive layer. CONSTITUTION:The first a-Si:F type layer 2, the second a-Si.Ge layer 3, and the third a-Si:F layer 4 are successively laminated on the conductive substrate 1 of an electrophotographic sensitive body. The first layer contains 5-40 atomic % F and 10<-4>-5X10<-2> atomic % O and 10<11>OMEGA.cm (rho) as well as good dark resistance and photocarrier mobility. The second layer 3 has SiH4/GeH4=6/4-9.5/0.5, and high sensitivity throughout from the visible red to the near IR region as well as good dark resistance. The third layer 4 contains 5-40 atomic % F and 10<-3>-10<-1> atomic % O, and >=5X10<12>OMEGA.cm rho, and compensates the low resistance of the second layer 3. As a result, speed and sensitivity are enhanced, humidity resistance, durability, etc. are improved, and adaptability for use in a laser printer is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to an electrophotographic photoreceptor in which a portion of the photosensitive layer is made of amorphous silicon germanium and has photosensitivity in the visible red to near-infrared region.

Currently, Seiko photo printers are making a major contribution to the information processing field of single-child computers, such as two-Japanese word processors and terminal printers, due to improvements in electrophotographic technology and performance of writing light sources.

In addition, office automation (OA) has recently spread rapidly, and intelligent copiers with multi-functionality are being developed to perform various types of information processing in the office, centering on electrophotographic printers. (Light sources used in this printer include an optical fiber tube (OFT) that uses an optical fiber on the face plate of a cathode ray tube (CRT), a gas laser, and a semiconductor laser.

However, although OFT was originally used, due to advances in laser technology, gas lasers are now the mainstream.

This type of gas laser emits light (oscillates) in the visible range.
He-Ne laser (wavelength 633 fm), H
e-Cd laser (442nm), Ar laser (488nm)
m) etc.

The light beam control system is an acousto-optic transformer with a single rotating mirror.

It is composed of an optical scanning system consisting of a lens group that corrects scanning distortion.

However, these gas lasers are generally large in size, and have drawbacks such as difficulty in making equipment compact and quantifiable, and Ar
Although it has the problem that the laser tube must be water-cooled like a laser, He-Ne lasers are often used from the viewpoint of operational stability and life expectancy.

On the other hand, semiconductor lasers are easy to excite because they are small (the size of the light emitter is 1 mm3 or less) and are injection-based.

The threshold current density required for laser oscillation is small, and continuous operation is possible at room temperature.

Unlike gas lasers, semiconductor lasers are capable of operating at low voltages (~
2V), low current (10 to 100 mA) drive, a direct modulation method that can directly change the output light by changing the injection current, and high speed (~IGHg) modulation is possible.

As a semiconductor laser, GaAs, GaAt! with a single oscillation wavelength of 700 to 900 nm are used. As, excavation wavelength 1100-16
There is one using a III-V group compound semiconductor made of 00 nm In(1-x)GaxAs(IY)PY.

The characteristics of a laser beam printer using such a laser are +i> Good coherence without loss of light intensity.

Good resolution.

(2) Light can be focused on a small spot and high brightness can be obtained.

(3) It is possible to configure a device with almost no flare light.

(4) It is possible to increase speed and increase the density of information.

(5) There is no distortion in the polarization system.

etc.

On the other hand, the problem with laser beam printers using semiconductor lasers is that they are stable at wavelengths in the maximum photosensitivity region of the photoreceptor.
This means that a semiconductor laser that oscillates in this state has not yet been realized. In other words, to make a semiconductor laser oscillate stably at a wavelength of 700 nm or less, (Ga 1-xAl
! xAs), AI! Increasing the mixed crystal ratio It is currently a big hurdle to trace the route.

Therefore, as a photoreceptor for a semiconductor laser beam printer, it is essential that the photoreceptor has high photosensitivity at wavelengths of 7QQnm or more.

From the above, the specific conditions that the photoreceptor for semiconductor laser beam printers should have are a high t7) electrophotographic sensitivity of about 0.5 μJ/cm2 or less for light with wavelengths longer than 7QQnm, and 1 mechanical This means that it is a large-area photosensitive layer that has a durability of more than one cycle.

As a photosensitive material that has the possibility of satisfying these requirements, a photoreceptor 1 using amorphous silicon (A-8I) is used, for example, as shown in FIG. The installed one has high sensitivity and has a surface hardness of 3.
It has recently attracted attention due to its excellent durability.

However, as shown in FIG. 6, the photosensitivity decreases rapidly for excitation light with a wavelength of 6000 m or more.

As an electrophotographic photoreceptor for a semiconductor laser, which requires sensitivity in the visible red to near-infrared region, the stability of sensitivity is not necessarily sufficient.

On the other hand, in applications such as Taiyo Seike, attempts have been made to add Ge to a-8i to narrow the optical bandgap, increase sensitivity to longer wavelengths, and improve efficiency.

However, in the case of electrophotographic photoreceptors, Ge-added l
This reduction in dark resistance has a large effect on the charge acceptance of the photoreceptor, making it difficult to put it into practical use.

Therefore, as shown in FIG. 2, an a-8ieGe layer is used as a counter-liquid only for the charge generation layer 3 of the functionally separated photoreceptor, which is divided into charge generation layer 3 and charge transport layer 2). Therefore, a method of reducing the dark resistance could be considered, but it could not achieve the desired effect because the first surface layer was exposed to a S+*Gel threat.

This is because the surface resistance is small, so there is a lot of charge leaking from the surface, which causes problems such as limitations on copying equipment such as shortening the time from layer formation to development, and instability of the holding potential. It is.

In addition, because the first surface layer has low resistance, it is easily affected by humidity, and when this phenomenon occurs, charge leaks easily through the magnetic brush, which has the disadvantage that the current formation process becomes extremely unstable. Was.

In order to solve the above problems, this invention uses amorphous silicon germanium in a part of the photosensitive layer to achieve high speed and high sensitivity, and is suitable for laser printers with excellent moisture resistance and durability. The purpose is to provide photographic photoreceptors.

An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG.

After coating the a-8i:l;' series photosensitive layer 2 and coating the a-8isGe series photosensitive layer 3 on the photosensitive layer 2, a-8i
:F Unexposed layer 4 is coated to form an electrophotographic photoreceptor.

Here, the a-8i:F non-photosensitive layer refers to an amorphous silicon photosensitive layer in which dangling bonds existing in amorphous silicon are bonded by F atoms.

As the conductive layer 1, A/, MO, Au, Ag
, Cu.

Ni, Cr, Ir, Nb, Ta, V, Ti, Pt, P
Examples include metals such as b and alloys thereof.

a-8j: The F unsensitized layer 2 must maintain a high potential on the surfaces of the a-8ieGe-based photosensitive layer 3 and the a-8i:F unsensitized layer 4, and itself must have high photocarrier passage efficiency. . Therefore, it is preferable that the resistivity is 100 cm or more and that no potential barrier is formed at the interface with the a-8i++Ge photosensitive layer 3.

For the purpose of
Contains 40atmq6, and 10-4 to 5X10-
Those containing 2 atm have dark resistance (1 charge receptivity)
In addition to being suitable from the viewpoint of

Further, this photosensitive layer 2 may be doped with N instead of 0, and in this case, a layer containing 10@-4 to 110@2 at of N is suitable.

The thickness of this photosensitive layer is suitably in the range of 10 to 50 μm.

Next, the a-8isGe-based photosensitive layer 3 is desired to exhibit high sensitivity to visible red to near-infrared light, which is the excitation wavelength (oscillation wavelength) of the semiconductor laser, and to have a moderate dark resistance. Therefore, the Si to GeO ratio is SiH4/Gemel = 6/4 to 9
．． A range of 510.5 is good.

The thickness of this photosensitive layer 3 is preferably 0.1 to 3 μm, and
, if it is thinner than iμm, the absorption of excitation light will not be sufficient, and if the thickness is less than 3μm,
This is because if the thickness is increased, the dark resistance of the a-8ieGe photosensitive layer 3 will be significantly lowered. a-8ieGe here
It refers to an a-8i*Ge:H film containing 5 to 4 Qatm% of H and with compensation for dangling bonds, as can be seen from the color photosensitive material gas S i t (, GeH, etc.).

The a-8i:r photosensitive layer 4 is for compensating for the low surface resistance of the a-8ieGe photosensitive layer, and for this purpose contains 5 to 40 atm% of F and 101 to 10% of O. 1
A material containing 0"at, g2% is suitable. Also.

This photosensitive layer 4 may contain N instead of O, and in this case, a layer containing 10<-3> to 101 atm% of N is suitable.

The reason why the a-8i:F-insensitive layer 4 has a higher 0 (or N) content than the a-Bi:F-based photosensitive layer 2 is to control the photosensitivity of the outermost layer. , and the specific resistance is 5X1
This is to make it 0"0cm or more.

The thickness of this a-8i:F photoinsensitive layer 4 is 0.05 to 3 μm
A range of is preferred.

The method for forming each layer of the photoreceptor formed in this way is a vacuum evaporation method (resistance heating, Seiko beam heating).

At present, there are methods such as ion blating method, sputtering method, CVD method, glow discharge method, etc.

The glow discharge method, which is effective in compensating for dangling bonds, is most suitable.

The a-8i:F photosensitive layers 2 and 4 are based on periodic table mb.
It may also contain 0 to 30,000 ppm of group elements, or 0 to 20,000 ppm of VB group elements, and control the P type and N type.

Further, the photoreceptor of the present invention is not limited to the so-called Carlson method in which exposure is performed after charging, but as shown in FIG. 4, an a-8i:F type photosensitive layer 2. a-8i
After sequentially forming the eGe-based photosensitive layer 3 and the a-8i:F photoinsensitive layer 4, the structure was such that it had an insulating layer 5 as the outermost layer that transmits at least visible red to near-infrared light. It's okay.

The thickness of the insulating layer 5 is approximately 5 to 40μTn, and the specific resistance per volume is preferably IQ-100cm or more (, a-8ixCi).
-x.

a-8ixN1-x, a-BN, a-8in2. P
ET film, acrylic resin film, urethane resin film, epoxy resin film.

An alkyd resin film, a xylene film, etc. are passed through.

In the case of such a photoreceptor, a latent image is formed mainly through a process that includes charging and simultaneous photoimage exposure.

In this case, if the entire surface is exposed at the end, latent images can be formed only above and below the uppermost insulating film, which is extremely advantageous in maintaining cardiac surgery.

FIG. 5 shows an apparatus for carrying out this invention.

A cylindrical base 12 is disposed inside the reaction tube 11, and the base 1
2 (opposed electrodes 13 are provided on both sides).

The cylindrical base body 12 is controlled by the morph 15F.

Note that 6 is a power source.

On the other hand, a waste mixer 22 and an MFC (flow controller) 23 are connected to the counter electrode 13 via a main pipe 21.

The mixer 22 has an SiH, i nH2 cylinder 24.
, GeH.

1nH2 cylinder 25.02 cylinder 26 and B, H, i
n H2 cylinders 27 are connected respectively, and the above M
A CF and a cylinder 28 are connected to the FC 23 .

An example of an experiment using the above-mentioned apparatus will be described below.

Example 1 A 20 μm thick a-8i:F film was formed on an aluminum drum under the following conditions using the high frequency glow discharge method shown in FIG.

Substrate temperature 300~350℃' Average F power 400 W (+8iF,)
/He 15% Gas pressure I Torr 02/SiF, 10' (about 10'
(atm% oxygen doping) Next, an a-8ieGe-based film was formed to a thickness of 1 μm under the following conditions.

Substrate temperature 200-250℃ RF power 400W (S tH4+Get(4)/H215%SiH,/G
eH, 7: 3 Finally, an a-8i:F film was formed to a thickness of 0.5 μm under the following conditions to obtain an electrophotographic photoreceptor for a semiconductor laser.

Substrate temperature 300-350℃ R, F power 400W (+SiF,)/He 15% Gas pressure I Torr 02/8iF, '10'' (approx. 10'' atm%)
Oxygen doping＞Photoreceptor made in this way (this 7K
After applying a roller pressure of V, scan the GaAs semiconductor laser.

After forming the latent image, it was developed and a good image with high density could be obtained.

Reference Example 1 After forming a 20 μm a-8i:F based film under the same conditions as Example 1, a 0.5 μm a-8i m Ge based film was further formed under the same conditions as Example 1. A photoreceptor having a configuration as shown in FIG. 2 was obtained.

After applying a corona voltage of 17 KV to the photoreceptor thus prepared, a GaAs semiconductor laser was scanned to form a latent image, which was then developed, but the image contrast could not be obtained at low overall density.

Example 2゜a-8i of Example 1: Instead of O doping of the F-based film, l N
was doped under the following conditions.

N2/SiF, 5X10-7 (approximately IQ!lat
m% N doping).
The photoreceptor shown in the figure was obtained.

When a latent image was formed on the photoreceptor thus prepared under the same conditions as in Example 1 and then developed, a good image almost as good as in Example 1 could be obtained.

Example 3 20μm on an aluminum drum under the same conditions as Example 1
a-8i: F-based film, 1 μm a-8ie Ge-based film.

After laminating a 0.5 .mu.m a-8i:F film, a polyparaxylene film was formed to a thickness of 10 .mu.m by vapor phase deposition to produce a three-structure photoreceptor as shown in FIG.

First, a +7KV corona discharge is applied to this photoreceptor as a -order charge, and then a -6KV corona discharge is applied to the photoreceptor.The same number of scan exposures are performed using the GaAs semiconductor laser, and then the entire surface is exposed to form a latent image. did.

When this consideration was immediately realized, a good image with high density was obtained.

I also tried developing it after leaving it for 30 seconds after latent formation, but
The image density was almost the same as that immediately after development.

As detailed above (according to the present invention, a photoreceptor for semiconductor lasers that has sensitivity in the long wavelength red to near-infrared region than only A-8I can be obtained, making it possible to achieve higher speed and higher sensitivity. .

Also, one surface layer is not a-8ieGe-based, but a-8i:F
Since it is coated with a ' system, the dark decay of charges is reduced due to the surface barrier effect, and it exhibits excellent charge acceptance as a photoreceptor.

Furthermore, this EJJl photoreceptor exhibits excellent moisture resistance, corona ion resistance, and durability, and is superior to conventional semiconductor radar photoreceptors such as As28e3 and Cd (
While S, Se) etc. have pollution problems,
The photoreceptor of this invention is completely pollution-free.

An electrophotographic photoreceptor having many excellent features can be provided.

[Brief explanation of the drawing]

1 and 2 are structural diagrams of a conventional photoconductor, and FIG. 3 is a spectral sensitivity curve diagram of the photoconductor of the present invention and a conventional photoconductor. Figure 5 Kazuo Wakasugi, Commissioner of the Patent Office 1. Display of the case Japanese Patent Application No. 57-218549 2, Name of the invention Electrophotographic photoreceptor 3, Person making the amendment Relationship to the case H person for patent (037) Olympus Optical Industry Co., Ltd. 4 Agent 6, Amendment glue 1 Specification (1) The statement “...
・From etc., f(e = N e laser is...) is changed to "...
・The gas laser He-Ne laser...
・” I corrected it. (2) "Threshold current density" stated in line 11 of the same specification
is corrected to ``Kaku-value Seiryu Density''. (3) rln(1-x)GaxAs(1
y) PyJ rIn(1-x)GaxAs(1-Y)
Correct PYJ. (4) Page 6, line 16 of the same specification
a 1-xAI xAs J to rGa (1-x)A
Correct it as l xA, s J. (5) IJi, as stated in page 6, line 19 of the specification:
"Oscillation open current density" is corrected to "Oscillation dark value current density". (6) Page 12, line 20 of the same specification
Correct it with J.

Claims (1)

[Claims] (1) On a conductive support, the first layer is an a-8i:F film, the second layer is an a-8isGe film, and the third layer is H
81: An electrophotographic photoreceptor characterized by sequentially laminating F-based films. (2) The first layer is 10 to 50 μm, the second layer is 0.1 to 3 μm
2. The electrophotographic photoreceptor according to claim 1, wherein the third layer has a thickness of 0.05 to 3 μm. (3) First layer a-8i: F content of the system layer is 5 to 40
atm%, content of 0 is 10''~5xlO-2atm%
1 volume resistivity is set to 10'tlΩan or more, and the second layer a-8iaGe-based layer is set to 8 i H4/GeHe=
The H content is 10 to 4 at a ratio of 6/4 to 9.510.5.
Qahn% binding, the third layer a-8i:F-based layer has an F content of 5 to 4 Qatm%, and a content of 0 to 10-3 to 10
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor has a specific volume resistivity of 5XIQF2Ω9m or more at 1 atm%. (4) First layer a-8i: F-based layer with an F content of 5 to 4
Qatm%, N content is 10'~10 tatm%
in. The volume resistivity is set to lQ+tΩcm or more, and the second layer a-
The 8ieGe-based layer is 8iH,/Gem(,=6/4~
At a ratio of 9.510.5, the H content is 10 to 4 Qat.
m% binding, 3rd layer (1) a-8i: F-based layer with F
The content of N is 5 to 40 atm%, and the content of N is 10''-
1 volume resistivity at 10'atm% 5 x 1012Ω
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor has a diameter of cm or more. (5) On the conductive support, a-8i:F-based layer as the first layer, a-8isGe-based layer as the second layer, and a-8i:F-based layer as the third layer.
-8i: Volume resistivity 1014Ωc that is transparent at least in the visible red to near-infrared region as the F-based layer and the fourth layer
An electrophotographic photoreceptor characterized by sequentially laminating m or more insulating film layers. The electrophotographic photoreceptor according to claim 5, characterized in that: (7) First layer a-8i: F-based layer with an F content of 5 to
40 atm%, content of 0 is 10-5xio atm%
1 volume resistivity is 1Qlli'1 cm or more, and the second layer a-8isGe layer is 8iH4/GeHe=6
H content is 10"40 at a ratio of /4 to 9.510.5
atm%, and the third layer a-8i:F-based layer has an F content of 5 to 4 Qatm and a 0 content of 10"IQ l.
The electrophotographic photoreceptor according to claim 5, wherein the electrophotographic photoreceptor has a volume resistivity of 5×10 12 Ωcm or more in ATM. (8) First layer a-8i: F-based layer with an F content of 5 to
40atm%, N content is 110-4-1O-2at
%, the 1 volume resistivity is 1011 Ωcm or more, and the second layer a-8i 1IGe-based layer is S'H4/Ge1(4
= 6/4 to 9.510.5, H content is 10
~40 atm%, and the third layer a-8i:F-based layer is F
The content of N is 5 to 40atrr + 1, and the content of N is 10-
1 volume resistivity at 3 to 1101 at% is 5×1Qf2Ω
The electrophotographic photoreceptor according to claim 5, characterized in that the photoreceptor has a thickness of cm or more.