JPS59109059A - 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:H:F type layer 2, the second a-Si.Ge layer 3, and the third a-Si:H:F layer 4 are successively laminated on the conductive substrate 1 of an electrophotographic sensitive body. The first layer contains 5-40 atomic % sum of F and H (F>H), 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 10-40 atomic % content of H, 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 % sum of F and H, (F>H) and 10<-3>-10<-2> 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, and adaptability for use in a laser printer is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present 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, photo printers are making a significant contribution to the information processing field of digital computers, such as Japanese word processors and terminal printers, due to advances in electrophotographic technology and the performance of writing light sources.

In addition, recently office automation (OA) has been rapidly increasing.
This has become popular, and intelligent copier cameras are being released that are multi-functional and can handle various types of information processing in the office, centering around Seiko photo printers. The light source used in this Kameko photo printer is a cathode ray tube (CRT).
Optical Fiber Team (OFT), which uses optical fibers on the faceplate.

There are gas lasers, semiconductor lasers, etc.

However, due to advancements in laser technology, gas lasers are now the mainstream in OFT.

Types of this gas laser include He-Ne laser (wavelength 633 nm) that emits light in the visible range (4 wavelengths), He-
Cd laser (442nm), Arlz-laser (488nm)
nm) etc.

It is configured.

However, these gas lasers are generally large in size and have the disadvantage that it is difficult to make the device smaller and lighter. However, He 7N e lasers are often used due to their operational stability and longevity.

On the other hand, semiconductor lasers are small (the light emitting body is 1 mm3 or less), easy to excite due to the injection method, the threshold current density required for laser oscillation is small, and continuous and curved operation is possible at room temperature. .

Also, unlike gas lasers, semiconductor lasers are low-voltage (
~2V), low current (10 to 100mA) drive, a direct modulation method that can directly change the output light by changing the injection current, and high speed (~1GHg) modulation.

Semiconductor lasers include GaAs and Gal? with a wavelength of 700 to 900 nm. As, oscillation wavelength 1l100-16
There is one using an iv group compound semiconductor such as 00n In(1-X) GaxAs(1-y)Py.

The characteristics of a laser beam printer using such a laser are (1) 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 the 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 that use semiconductor lasers is that a semiconductor laser that stably oscillates at a wavelength in the maximum photosensitivity region of the photoreceptor has not been realized. In other words, to make a semiconductor laser oscillate stably at a wavelength of 700 nm or less, (()a ]-xAfx
As), AI! Inhibited zone by increasing mixing ratio X; i
In my current position, I am trying to follow the route of increasing the density gg → moving from the direct to indirect transition type → the internal number efficiency decreases → the oscillation threshold '1 current density increases. Inugina problem) It's getting better.

Therefore, as a photoreceptor for a semiconductor laser beam printer, a photoreceptor having high photosensitivity at wavelengths north of 700 nm is essential.

From the above, the specific conditions that the photoreceptor for semiconductor laser beam printers must have are high electrophotographic sensitivity of about 0.5μ・T/cm2 or less for light with wavelengths longer than 7QQnm. 2. It is a large-area photosensitive layer with mechanical durability of 105 times or more.

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. These materials have recently attracted attention because they have high sensitivity, high surface hardness, and excellent durability.

However, as shown in Figure 6, the photosensitivity rapidly decreases for excitation light with a wavelength of <600 nm or more, making it difficult to use as an electrophotographic photoreceptor for semiconductor lasers, which requires sensitivity in the visible red to near-infrared region. is not necessarily sufficient in terms of stability of growth ii.

On the other hand, in the field of applications such as solar cells, attempts have been made to improve efficiency by adding Ge to a-8i to narrow the optical band gap and increase sensitivity to longer wavelengths.

However, in the case of a quadruple photoreceptor, Ge addition 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 a countermeasure to this problem, as shown in FIG. 2, a direct generation layer 3. One possible method is to use the a-8isGe layer only in the charge generation layer 3 of a functionally separated photoreceptor divided into the charge transport layer 2, thereby reducing the decrease in dark resistance. Because of the presence of the a-8i/Ge layer, the desired effect could not be achieved.

This method has a low surface resistance, so there is a lot of charge leaking from the surface, which causes problems such as limitations on copying equipment such as minimizing the time from latent image formation to development, and instability of the holding magnetic potential. Because it does.

In addition, because the first surface layer has low resistance, it is easily affected by humidity, and during development, it is difficult for charge to leak through the magnetic brush, making the development process extremely unstable. had.

In order to solve the above-mentioned problems, this invention uses amorphous silicon germanium as part of the photosensitive layer, which makes it possible to achieve high speed and high sensitivity, as well as moisture resistance and durability. The purpose is to provide photographic photoreceptors.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 3 (on top of the conductive layer 1).

a-8i: After coating the H:F-based I photosensitive layer 2 and coating the a-8isGe-based photosensitive layer 3 on the photosensitive @2, a-8i:
H: An electrophotographic photoreceptor was formed by coating the F-based photosensitive layer 4. CT: a-8i:H:F'-based photosensitive layer is an amorphous silicon photosensitive layer in which dangling bonds present in amorphous silicon are bonded with H or F atoms.

As the conductive layer 1, At, Mo, Au,
Ag, Cu.

Ni, Cr, Ir, Nb, Ta, V, Ti, Pt
, Pb, etc., or alloys thereof.

The a-8i:H:E'' photosensitive layer 2 maintains a high potential on the surface of the a-8ieGe-based photosensitive layer 3 and the a-8i:H:F-based photosensitive layer 4; Passage efficiency must be high. Therefore, specific resistance should be IQ + 1Ωcm
It is preferable that the above conditions are met and that no potential barrier is formed at the interface with the a-8i/Ge-based photosensitive layer 3.

For this purpose, a-8i:H:F'' photosensitive layer 2 is F
Contains more H than H,:! :5~4Qat at F'
Contains m%.

And there are various kinds containing O in an amount of 10-4 to 5X10-2 atm%.

It is suitable from the point of view of dark resistance (charge acceptance).
The mobility of optical carriers also maintains an appropriate level.

Further, this photosensitive layer 2 may contain O (or N). In this case, a layer containing 10 to 10 atm % 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 (emission wavelength) of a semiconductor laser, and to have an appropriate dark resistance. Therefore, the ratio of 81 and Ge is SiH, /G e t(4=
A range of 6/4 to 9.510.5 is preferable.

The thickness of this photosensitive layer 3 is preferably 0.1 to 3 μm, o,
This is because if the thickness is less than 1 μm, the absorption of excitation light is insufficient, and if the thickness is less than 3 μm, the dark resistance of the a-8isGe photosensitive layer 3 will decrease significantly. a-8i・Ge here
The system photosensitive layer refers to an a-8isGe:H film that contains 5 to 40 atm % of Ic H and has compensated for dangling bonds, as can be seen from the raw material gases S IH4, G e H4, etc.

a-8i: H:F'-based photosensitive layer 4. This is to compensate for the low surface resistance of the a-8ieGe photosensitive layer.
For the purpose of
One containing 10-1 at% is suitable. Further, this photosensitive layer 4 may be doped with N instead of O, and in this case, a layer containing 10 -3 to IQ Iatm % of N is suitable.

Compared to the a-8i:H:F'' photosensitive layer 2t, the a-8i:H:F photosensitive layer 4 has shifted to the side with a higher content of O (or N). □The one that has shifted is the outermost layer. This is to control the photosensitivity of the film and increase the specific resistance to 5 x 1012 Ωcm or more.

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

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

Ion blasting method, sputtering method, CVD
There are several methods available at this stage, including the glow discharge method and the glow discharge method.

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

The a-8i:H:F light-insensitive layer 2.4 contains O~30,000 ppm+ of elements from group MB of the periodic table or O~30,000 ppm+ of elements from group VB.
It may be contained up to 20,000 ppm and controlled to be P-type or 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 the fourth F-based photoreceptor layer 4
as the outermost layer.

However, it may have a structure having an insulating layer 5 that transmits light in the visible red to near-infrared range.

The thickness of the insulating layer 5 is about 5 to 40 μm, and the specific resistance per volume is preferably 10-14 Ωcm or more (, a-8ixCt).
-x, a-8ixNl-x, a-BN, a-8in
2. Suitable materials include PET film, acrylic resin film, urethane resin, epoxy resin film, alkyd resin film and xylene film.

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 one beam of light is applied to the entire surface at the end, latent images can be formed only above and below the uppermost insulating film, which is extremely advantageous for charge retention.

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

A cylindrical base body 12 is disposed within the reaction tube 11, and opposing poles 13 are provided on both sides of the base body 12.

The cylindrical base body 12 is controlled by a motor 15.

Note that 6 is a power source.

The reaction tube 11 includes an amend pump 17 and an MB pump 1.
A rotary pump 192o is connected to each valve 17 and 18.

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

The above mixer 22 (here is SiH, 1nH2 bore 24
, GeT(.

1nf (to 2 cylinders 25.02 cylinders 26 and B2H, r
n H2 cylinders 27 are connected to each other, and the above-mentioned MFC23I and CF4 cylinders 28 are also connected.

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

Example 1 A-8i:H:F' of 20 μm was deposited on an aluminum drum under the following conditions by the high-frequency glow discharge method shown in FIG.
A system film was formed.

Substrate temperature 300-350℃ RF power 400W (S iH, +S i F,)/H215% gas pressure I
Torr 02/8 i H410-” (approximately 105 atm% (7
) Oxygen Tope) Next, an a-8isGe-based film was formed to a thickness of 1 μm under the following conditions.

Substrate temperature 200-250℃ RF power 400W (S 1t(4+Ge1(4)/H215%S 1
) (4/G e H47: 3 Finally a Sl:H:F
A system film was formed to a thickness of 6.5 μm under the following conditions to obtain an electrophotographic sensitive element for a semiconductor laser.

Substrate temperature 250-300℃ R, F power 400W (SiH, +SiF,)/H2i 5 gas pressure I T
orr 02/S t H410' (approximately 1.00-5 μm% oxygen tope)
After applying a corona voltage of V, the GaAs semiconductor laser was scanned to form a latent image, which was then developed and a good image with high density could be obtained.

Reference Example 1 After forming a 20 μm a-8i:H:F film under the same conditions as Example 1, a 0.5 μm film was formed under the same conditions as Example 1.
An a-8iaGe-based film was formed to obtain a photoreceptor having a structure as shown in FIG. To the photoconductor created in this way,
After applying a corona voltage of KV, scan the GaAs semiconductor laser and dive! After forming the image, it was developed.

The overall density was low and almost no image contrast was obtained.

Example 2 The a-8i:H:F film of Example 1 was doped with N instead of zero doping.

N, /SiH, 5xlO''7 (approximately 1 (1'''5 atn%
The photoreceptor shown in FIG. 3 was produced under the same conditions as in Example 1 except for the N doping.

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

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

After laminating a 0.5 μm a-8i:H:F film,
Polyparaxylene was deposited to a thickness of 10 μm by vapor deposition, and a photoreceptor having the structure shown in FIG. 4 was prepared.

First, a +7 KV corona discharge was applied to this photoreceptor as a -order band gradient, and then a -6 KV corona discharge was applied, and a GaAs semiconductor laser was scanned and exposed in the same manner.

Subsequently, the entire surface was exposed to form a latent image. When this latent image was immediately developed, a good image with high density was obtained.

In addition, after developing the image form A, the image was developed even after being left for 30 seconds, and the image density was almost the same as that developed after the image was developed.

As described in detail above), as a photoconductor for a semiconductor laser according to the present invention, a photoconductor having sensitivity in the longer wavelength red to near-infrared region than that of a Si:H system can be obtained, and higher speed and higher sensitivity can be obtained. It became.

In addition, one surface layer is S a -81-Ge based (, a
Since it is coated with St, E (system), the dark decay of charge is reduced due to the surface barrier effect, and it exhibits excellent charge acceptance as a photoreceptor.

Furthermore, the photoreceptor according to the present invention exhibits excellent properties in terms of moisture resistance, corona resistance, strength, and durability, and is superior to conventional photoreceptors for semiconductor lasers such as As2Se3 and Cd(S).

While Se) and the like have pollution problems, the photoreceptor of the present invention is completely pollution-free, and it is possible to provide an electrophotographic photoreceptor with many excellent standby properties.

[Brief explanation of drawings]

1 and 2 are structural diagrams of a conventional photoconductor, and FIG. 2 is a spectral sensitivity curve diagram of the photoconductor of the present invention and a conventional photoconductor. Fig. 1 Fig. 2 Fig. 9 Fig. 3 Fig. 4 Fig. 5 Body 3, Person making the amendment Relationship to the case Patent applicant (037) Olympus Optical Industry Co., Ltd. 4 Agent 6, Supplementary IE Nujian Specification 7, Contents of the amendment (1) Specification of the present application, page 5 The ``open current density'' written in line 18 and page 7, line 6 will be corrected to ``concentrated current density.'' (2) Reminiscence, written on page 13, line 9 of the Zensho [1]
04ΩcmJ is corrected as r +o”Ω@cmJ. (3) In the same specification, page 18, line 8, "It is pollution-free, etc." is replaced with "It is pollution-free." Further, in the structure shown in FIG. 4, the latent image charge is formed only on the upper and lower portions of the insulating film, so that the charge retention property is further improved. Fourth, the photosensitive layers 2 and 41 are doped with F, which improves the heat resistance properties, so they exhibit excellent heat resistance properties.
"..." I corrected myself.

Claims (1)

[Claims] fl) a-8i as a first layer on a magnetically permeable support:
A quadruple photosensitive member characterized in that a H:F series film, an a-8iΦGe series film as a second layer, and an a-8i:H:F series film as a third layer are sequentially laminated. (2) The first layer is 10 to 50 μm, the second layer is 0.1 to 3 μm
m. The electrophotographic photoreceptor according to item 1 of the patent application, wherein the third layer has a thickness of 0.05 to 3 μm. [3) The a-8i:H:F-based layer of the first layer has a higher H content than F (the total content of F and H is 5 to 40 atm%; the content of 0 is 10-4 to 40 atm%). 5X102atm%, the 1 volume resistivity is 1011Ωcm or more, and the second layer a-8i@
Ge-based layer is SiH, /GeHe=6/4~9.510
．． 5, the H content is 10 to 40 atm%, and the third layer a-8j:H:F system layer has a higher H content than F, and the total content of F and H is 5 to 40 atm%. %, with a content of 10-3 to 110-1 at% of 0, the 2 volume resistivity is 5
The electrophotographic photoreceptor according to claim 1, characterized in that the a-8i:H:F'-based layer of the first layer contains more H than F. The total content of F and H is 5 to 4 Qatm%,
A-8i++ of 1M2 layer with a N content of 10-4 to IQ-2atm and a volume resistivity of IQIIΩcm or more
The Ge-based layer is SrH4/GeH4=6/4~9.
5/ (at a ratio of 15, the H content is 10 to 40 atm
% binding, the third layer a-8i:H:F-based layer contains more H than F (the total content of F and H is 5 to 40 atm%)
The electrophotographic photoreceptor according to claim 1, wherein the electrophotographic photoreceptor has a H content of 10 -3 to 10" atm % and a 1 volume resistivity of 5 x 10" Ωcm or more. (5) aS i :H as the first layer on the conductive support
: An electrophotographic photoreceptor characterized by sequentially laminating an F-based layer, an a-8ieGe-based layer as a second layer, a third layer, and an insulating film layer having a specific resistance I of 3140 cm or more. (6) The first layer is 10-50 ttm, the second layer is 0.1-5
μm, 3rd layer 0.05-3μm, 4th layer 5-40μm
Claim 5, characterized in that the film has a thickness of m.
The electrophotographic photoreceptor described in . (7) The a-8i:H:F system layer in the first layer has a content of
%. The content of
1 volume resistivity is set to 1011 Ωcm or more, and the second a-8isGe layer is set to S if (,/GeHe=6/4
The content of H in the ratio of ~9.510.5 is 10~40'a
tm% binding, the third layer a-8i:H:F-based layer has more H than F, and the total content of F and H is 5 to 40 atm%.
, 0 is 10'' to 101 atm, and the electrophotographic photoreceptor has a volume resistivity of 5×10 12 Ωcm or more. (8) First layer aS s: H: The F-based layer contains more H than F. The total content of F and H is slightly 5 to 4 Qatm%, the N content is 10-10" atm%, and the specific resistivity is 1Q11Ω.
cm or more, and the second layer a-8i a Ge-based layer is S
iH. / G e H4 = 6/ 4 ~ 9.5 / O85 ratio, the H content is 10 ~ 40 atm%, and the a-8i:H:F system layer of Chopsticks 3 is made with more H than F. The total content of H and H is 5 to dQatm, and the content of N is 10
'ATM volume resistivity is 5 x 10+2Ωcm
An electrophotographic photoreceptor according to claim 5, characterized by the above.