JPS61105551A - Photoconductor - Google Patents

Abstract

PURPOSE:To enable optional and dynamic variation of absorption wavelength region by forming a photosensitive layer contg. a binary amorphous material made of C and Ge on a conductive substrate, and changing these contents. CONSTITUTION:The binary amorphous material made of C and Ge without using Si can be dynamically changed in the absorption ends of the absorption wavelength region by changing the content ratio of C to Ge. Since the amorphous Ge carbide can be generally changed by 1-3.5eV as the optical forbidden band width, the whole wavelength region necessary for the photosensitive material from the near 1R rays to the near UV rays can be covered. When the photosensitive body 21 is formed in a CVD device 9, a conductive substrate 11 cleaned of grease with trichloroethylene is placed on a susceptor 13 in a reactor 10, electric discharge is caused in an atm. of argon fed from a gas feed system 17 to deposit a carrier injection barrier layer 22, and then, to form a carrier generating layer 23 and a carrier transfer layer 24, and finally a surface layer 25, in succession.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a photoconductor on which an electrostatic latent image is formed in an electrophotographic device or the like.

[Technical background of the invention and its problems]

In recent years, image forming devices such as electrophotographic devices (JC6) have been using amorphous thin film as a photoreceptor material due to diversification. Amorphous selenium/tellurium alloy, amorphous selenium/arsenic alloy, zinc oxide resin dispersion system, cadmium sulfide resin dispersion system, inorganic materials such as amorphous silicon, polyvinyl carbazole, polyvinyl carbazole/trinitrofluorenone, organic pigment resin A wide variety of organic materials such as dispersion systems have been developed.

On the other hand, photoreceptors for electrophotographic devices and the like are required to have at least three functions: light absorption ability, photoexcited carrier transport ability, and charging ability, but in recent years, with the diversification of image forming devices, light absorption ability has become particularly important. There is. In other words, for application to laser printers, for example, a material sensitive to long wavelengths of near-infrared rays is required, and for application to color copying machines, a material sensitive to any wavelength in the visible range is required to ensure color reproducibility. Materials that can set an absorption edge in the near-ultraviolet region are required, and materials that are mainly applied to window materials used in the surface layer of photoreceptors are materials that have an absorption edge in the near-ultraviolet region that almost completely transmits visible light. I am doing what is requested. To meet these ever-increasing demands, there is a need for photoreceptor materials that can have an absorption edge at any wavelength in a wide range of wavelengths, from long wavelengths in the near-infrared to short wavelengths in the near-ultraviolet. .

However, with the exception of organic pigment resin dispersion systems that are sensitive to infrared light, all of the above-mentioned photoreceptor materials have light absorption edges that are limited to the visible region. The problem is that it is not possible to meet the requirements of Furthermore, among the above-mentioned photoreceptor materials, except for amorphous silicon, they have the disadvantage of being inferior in mechanical strength and thermal stability.

[Purpose of the invention]

This invention was made based on the above circumstances, and it is possible to arbitrarily select the absorption wavelength range from the long wavelength of the near-infrared to the short wavelength of the near-ultraviolet, and furthermore, it provides light with excellent mechanical strength and thermal stability. The purpose is to provide an electrical conductor.

[Summary of the invention]

In order to achieve the above object, this invention forms a photosensitive layer using a binary amorphous material of carbon and germanium on a conductive substrate, and furthermore, by changing the content of carbon and germanium, the absorption wavelength is It is intended that the area can be arbitrarily and dynamically changed, and it can be easily applied to diversified photoreceptor applications.

[Embodiments of the invention]

Before giving a detailed explanation of this invention, the principle of this invention will first be described. Conventionally, amorphous silicon, which has excellent mechanical strength and thermal stability, has good photoconductive properties by containing hydrogen or halogen elements, or even hydrogen and halogen elements, and is suitable for this purpose. It is known that by adding impurities, it can be used as a photoreceptor for image forming devices. By the way, this amorphous silicon has the property that by adding carbon, the absorption edge of the absorption wavelength region can be shifted to the shorter wavelength side, and the transparency and electrical resistance can be increased, but by adding germanium,
It has the property of being able to move the absorption edge of the absorption wavelength region to the longer wavelength side. Therefore, by utilizing the above characteristics, a binary amorphous material of carbon, element, and germanium (hereinafter referred to as amorphous germanium carbide) can be formed without using silicon, and the content of carbon and germanium can be reduced. By changing the ratio, the absorption edge of the absorption wavelength region can be dynamically changed. Moreover, in general, amorphous germanium carbide has an optical forbidden band width of 1 to 3.5 [eV], or an absorption edge wavelength of 1200 to 350 (nm), so it is necessary as a photoreceptor material. It is possible to cover a wide range of wavelengths from near-infrared to near-ultraviolet.

Next, based on the above-mentioned principle, a first embodiment of the present invention using amorphous germanium carbide as the photoreceptor material will be described with reference to FIGS. 1 and 2. prada
v CVD (Chemical Vapor Dep.
In the reaction vessel 1 of the apparatus (9),
100X100X0.8 [home], surface roughness approximately 0.3 [S
] In order to support the conductive support (11) made of an aluminum plate, a susceptor (13) containing a heater (1) and grounded is provided.
At the position facing the susceptor α3 inside, 13.56
The discharge electrode connected to the high frequency power supply I of (MHz) and the germane gas ((ieH,) + methane gas [CH
, ] and Diporan (BzHa) 1 [vol 96
] Containing argon gas [A"] is provided as needed. A gas blowout enclosure is provided which is connected to the gas supply system η, which can supply the argon gas [A"] as needed. Cυ is a photoreceptor, and a conductive support (ID) is sequentially laminated with a charge injection blocking layer, a carrier generation layer, a carrier transporting layer, and a surface layer. However, here, the charge injection blocking layer (21)
), during corona charging of the photoreceptor c2υ, while preventing the injecting of the electrical charges opposite to the charged charges from the conductive support (1υ) into the carrier generation layer and further into the carrier transport layer 241.
During exposure to light, among the photogenerated carrier pairs generated in the carrier generation layer, the carrier having the same polarity and gender as the charged charge smoothly flows into the conductive support αυ. have. In addition, the carrier generation layer has a function of absorbing light of a desired wavelength and generating photogenerated carriers, and the carrier transport layer Q4 absorbs electrical charges and charges among the carriers generated in the carrier generation layer (2). It has the function of efficiently transporting objects of opposite polarity toward the surface using the electric field generated by charging, and requires a high resistance value of 5 x 10' [Ω] or more as a specific resistance value in the dark to retain charge. It is. Furthermore, the surface layer (to) protects the surface, improves light transmittance, and improves charging ability. However, when forming the photoreceptor (21) in the plasma CVD device (9), it is first degreased and cleaned with trichlene. After placing the conductive support αυ on the susceptor C13,
Exhaust device (2IIC to reduce the degree of vacuum in reaction vessel H to 10-
'CTorr) and heat the conductive support αυ to 230["0] using the heater α2. Next, the gas supply system (l?) supplies gas blowing holes (German gas 1501"8CCM from 18), methane gas 200(
SCCM), 10 [8 CCM] of argon gas containing 1 [vol] of diborane gas was introduced into the reaction vessel H, and the pressure in the reaction vessel Q (I was reduced to 0.7 [To
300(
W) power to the conductive support (117 and 4-pole UE for discharge)
For about 5 minutes, a discharge is generated on the conductive support (11) to form a charge injection blocking layer cla. next,
The introduction of argon gas containing diborane gas] [vol 1%] was stopped, and germane gas 270 (
8CCM), methane gas 200 [8CC'M) was introduced, and the rest was a charge injection blocking layer c! 4 under the same conditions as 2.
Film formation is performed for 0 minutes to form a carrier generation layer.

Subsequently, the pressure inside the reaction vessel and the discharge force are controlled by the two layers (2
Under the same conditions as No. 3,123, germane gas and methane gas were both introduced at 250 [8 CCM"1 in order to increase the carbon atom content and make the resistance higher than that of the carrier generation layer.
The carrier transport layers Q and D were formed for 1 hour and 45 minutes. And finally German Gas 100 [8CCM]
, methane gas 400 (SCCM) was introduced into the reaction vessel OI, and the pressure inside the reaction vessel (11) was reduced to 1.
15 from the high frequency power supply α conductor while maintaining the
0 (W) was supplied for 15 minutes to form a surface layer (c). After the end of the last discharge, the heater α2 is stopped, and the introduction of germane gas and methane gas is stopped, and then the residual gas in the reaction vessel ill is wiped out with nitrogen gas. The photoreceptor (21) formed in this way,
As a result of positive corona charging of 6.5 CKV), the photoreceptor eυ was charged to 590 (V). In addition, after charging, the photoreceptor QυK was irradiated with near-infrared laser light with an excavation wavelength of 790 (nm) from an initial potential of 540 [V], and as a result, the potential half-reduction exposure sensitivity was 0.751"μJ/d] Then,
It has been found that the potential half-reduction exposure sensitivity is far superior to that of conventional amorphous silicon, etc., which has a potential half-reduction exposure sensitivity of 2 to 5 [μJ, Icd].

With this configuration, since the carrier generation layer (c) is formed of amorphous germanium carbide, which contains relatively more germanium than carbon, the photoreceptor I211
can sufficiently absorb light with a wavelength of 790 [nm], which is near infrared, and can be sufficiently applied to laser printers and the like. In addition, amorphous germanium carbide containing a large amount of carbon is used for the surface layer, which improves the transparency of the surface layer and allows for sufficient absorption of near-ultraviolet light, while almost completely absorbing visible light. Because it is completely transparent, it is excellent as a window material.
The exposure sensitivity of the photoreceptor CD is significantly improved compared to the conventional one.

Next, a second embodiment of the present invention will be explained.

In this second embodiment, only the film forming conditions of the carrier generation layer (2) of the above-mentioned first embodiment are changed, and the other conditions are the same as in the first embodiment.
Since the photoreceptor (21J) is exactly the same as that of the first embodiment, referring to the drawings of the first embodiment, the same parts are given the same reference numerals and the explanation thereof will be omitted.

That is, in this example, after forming a charge injection blocking layer (20) on the conductive support αυ, diborane gas 1 [vo
i%]-containing argon gas was stopped, 300 [8 CCM] of germane gas and 150 [8 CCM] of methane gas were introduced into the reaction vessel 1, and the pressure inside the reaction volume 1 G (11) was reduced by the exhaust device (4). Q, 5 [Torr) K
A high frequency power source (300 W from 14) is supplied while maintaining the temperature, and a carrier generation layer (not shown) is formed. Thereafter, a carrier transport layer and a surface layer similar to those in the first embodiment are formed on the carrier generation layer. In the photoreceptor thus formed, the content of germanium relative to carbon is increased compared to that in the first example, so the light absorption edge of the photoreceptor is longer than that in the first example. As a result of positive corona charging of 6.5 (KV) on the photoreceptor as in the first embodiment, the surface potential of the photoreceptor (not shown) was 530 [V]. reached. Further, after charging, the photoconductor was irradiated with a laser beam having an oscillation wavelength of 790 (nm) from an initial potential of 500 rV), and as a result, the potential half-reduction exposure sensitivity was 0.70 (μJ/crf), which was the first example. Better sensitivity was obtained compared to the previous method.

With this configuration, compared to the first embodiment, the absorption edge of the absorption wavelength range can be brought closer to the long wavelength side, and when applied to a laser printer, etc., the wavelength range of the laser beam can be expanded, and the application The range is expanded.

The present invention is not limited to the above-mentioned embodiments and can be modified in various ways. For example, the device for forming a film on a photoreceptor may be
Any device or sputtering device may be used, and the conductive substrate may be rotated during film formation within a reactor. In addition, the carbon and germanium contents of amorphous germanium carbide can be varied depending on the required characteristics, and for those sensitive to short wavelengths, it is necessary to increase the carbon content compared to germanium. In general, the carbon/germanium atomic ratio is suitable for the carrier generation layer to be about 0.2 to 2, and for the carrier transport layer to be about 0.5 to 3. In a surface layer whose purpose is to improve light transmittance or chargeability, the carbon/germanium atomic ratio is suitably about 1 to 5. The gas specifically used for film formation is ethane gas [CtH] as a carbon-containing gas.
6], propane gas CC5Hs) = ethylene gas [cA), acetylene gas (C*H*L 7 Leon gas [C'F,), etc., and germanium-containing gas may include germanium 47tide gas [GeF, ] Other germanium compounds are optional. Furthermore, other additives may be added to the amorphous germanium carbide. For example, the photoconductive properties of the photoreceptor can be improved by incorporating hydrogen or /S rogen elements or hydrogen and /S rogen elements into the amorphous germanium carbide. It can be improved and other helium (He),
Diluent gases such as argon [Ar], neon [Ne], monosilane [8iH,], silicon 47 trouside [8
gas containing silicon such as iF4], diborane CBtHs containing elements of group IIIa of the periodic table and group Va of the periodic table that control the conductivity type of the photoreceptor ephosphine (P)1
3), a gas such as arsine (A s H3) may be added. In the charge injection blocking layer, for positively charged photoreceptors, elements from group IIIa of the periodic table are used.
Amorphous germanium carbide, which is made p-type or p+ type by containing 10' (atmPPM), is used, while germanium carbide from periodic table V is used for negatively charged photoreceptors.
10 Group A elements! 9 using amorphous germanium carbide, which is made n-type or n+-type by containing ~10'' (atmPPM), or even containing silicon (8i) to improve adhesion to the conductive support. good.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to form a photoreceptor using amorphous germanium carbide, which has excellent mechanical strength and thermal stability, and to change the content ratio of carbon and germanium in the amorphous germanium carbide. This makes it possible to dynamically change the absorption wavelength range of the photoreceptor from near-ultraviolet to near-infrared, making it possible to apply it to laser printers, etc., while improving color reproducibility because the light absorption edge of the photoreceptor can be set arbitrarily. This makes it easier to use and can be applied to color copying machines, etc.
The scope of application to increasingly diverse image forming apparatuses can be expanded.

Furthermore, depending on the content of carbon and germanium in amorphous germanium carbide, it is possible to form a photosensitive material that can completely transmit visible light, so if this is applied as a window material, the sensitivity of the photoreceptor can be significantly improved. .

[Brief explanation of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a schematic explanatory diagram showing a plasma CVD apparatus thereof, and FIG.
The figure is a partially omitted sectional view showing the photoreceptor. 10... Reaction container 11... Conductive support 1
2... Heater 13... Susceptor 14...
・High frequency power supply 16...Discharge electrode 17...Gas supply system 18...Gas blow-off hole 20...Exhaust A
Device 21...Photoreceptor 22...Charge injection blocking layer Z3...Carrier generation layer 24...Carrier transport layer 25...Surface layer agent Patent attorney Inoue - Male□Figure 1Figure 2

Claims (1)

[Scope of Claims] 1. A photoconductor having a photosensitive layer on a substrate, wherein the photosensitive layer is made of a binary amorphous material of carbon and germanium. 2. The photoconductor according to claim 1, wherein the photosensitive layer has a charge injection blocking layer, a carrier generation layer, a carrier transport layer, and a surface layer, which are sequentially laminated on the substrate. 3. The photoconductor according to claim 2, wherein the binary amorphous material of carbon and germanium in the charge injection blocking layer contains an element of group IIIa of the periodic table. 4. The photoconductor according to claim 2, wherein the binary amorphous material of carbon and germanium in the charge injection blocking layer contains an element of group Va of the periodic table.