JPS5984256A - Photosensitive body - Google Patents

Abstract

PURPOSE:To obtain a photosensitive body superior in sensitivity to the region of visible ane near infrared (IR) light by forming an amorphous silicon hydride or fluoride layer (a-Si:H or a-Si:F) on an amorphous silicon gelmanum hydride or fluoro (a-SiGe:H or a-SiGe:F) layer. CONSTITUTION:An a-Si:H or a SiGe:F layer 2 is formed on an aluminum substrate 1 or the like, and Ge is added by 0.1-50mol% to the layer 2. On the layer 2, a 100nm-5,000nm thick a-Si:F or a-Si:F layer 3 is formed to obtain a laminate photoconductive layer 4 for use in a photosensitive body. The layer 2 has good sensitivity in a near IR region, and the layer 3 has good sensitivity to the visible region and high hardness. As a result, the obtained photosensitive body has high sensitivity in the visible and near IR region and superior printing resistance, etc. A charge transfer layer may be formed between the substrate 1 and the layer 2, or on the layer 3, and a barrier layer 6 may be formed between the layer 2 and the substrate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to photoreceptors, such as electrophotographic photoreceptors.

Conventionally, electrophotographic photoreceptors have been made of Se, light, or Te.
, a photoconductor doped with Sb, and a photoconductor in which ZnO or CdS is dispersed in a resin binder are known. However, these photoreceptors have problems in terms of environmental pollution, thermal stability, and mechanical strength.

On the other hand, electrophotographic photoreceptors using amorphous silicon (a-8i) as a base material have been proposed in recent years.

a-8i has a so-called dangling bond in which the bond of 5i-81 is broken, and many localized levels exist within the energy gap due to this defect. For this reason, hopping conduction of thermally excited carriers occurs, resulting in a small dark resistance, and photoexcited carriers are trapped in localized levels, resulting in poor photoconductivity. Therefore, we replaced the above defects with hydrogen atoms (
The dangling bonds are filled by bonding H to Si with compensation with H).

Such amorphous hydrogenated silicon (hereinafter referred to as a-s
i: Referred to as i-1. ) has good photosensitivity and
It is attracting attention for its non-polluting properties and good printing durability.

It is known that ShikaL, a-8i:H is about one order of magnitude less sensitive to light with a wavelength of 750 to 800 nm (near infrared) than to light in the visible range. Therefore, when using a semiconductor laser as a recording light source in an information terminal processing machine that electrically processes information signals and outputs them as hard copies, a practical semiconductor laser for information recording is Qa Af! , As the constituent material is As, and its oscillation wavelength is 760-820 nm, so a-8i:H has insufficient sensitivity and is inappropriate for this type of information recording. In the case of a Se-based photoreceptor, although the sensitivity is higher than that of a photoreceptor made of an organic photoconductive material, the sensitivity in a long wavelength region is still insufficient to cope with an increase in processing speed.

Therefore, in order to improve the sensitivity in the long wavelength region while taking advantage of the excellent photoconductivity or photosensitivity of a-8i:H, amorphous silicon germanium hydride (hereinafter referred to as a-5i
(3e: referred to as H) may be used in the photoconductive layer. In other words, a-8iGe:H is 600~
It has good photosensitivity in the wavelength range of 85Q nm. However, conversely speaking, a-5iGe:II alone has lower sensitivity in the visible region than a-8i:H.

Recently, multifunctional devices that have a recording function using visible light as a light source (for example, a function as a normal electrophotographic copying machine) in addition to a recording function using a semiconductor laser or the like have been attracting attention. :H and a-8iGe :H cannot satisfy such requirements.

In order to solve this problem, an a-8i:0 layer with a sufficient thickness to retain charge was formed on the support, and an a-5iGe:II layer was further formed on top of this. A photoreceptor having a photoconductive layer (a layer that generates carriers in response to light irradiation) having a layered structure has been proposed. According to this structure,
The aSt:H and a-5iGe:H layers provide good sensitivity in both visible light and near-infrared light regions.

However, this photoreceptor has several problems (particularly the following two points).

(1), a-5iGe: Since it has a structure in which the 0 layer exists on the surface side, it has a weaker chemical structure compared to a-8i and a-8iC, and its printing durability deteriorates.

(2) If the a-8iGe:0 layer is thick, the sensitivity in the visible light region will be insufficient. This is a −5iQe:
This is presumably because the presence of the 0 layer inhibits the generation of photocarriers in the a-8i:0 layer in the visible light region.

As a result of various studies, the present inventor discovered a photoconductor that can withstand practical use, has excellent sensitivity in both the visible and near-infrared regions, has good printing durability, and has stable charge retention characteristics. invention has been achieved.

That is, photoreceptors according to the present invention contain amorphous hydrogenated and/or fluorinated silicon germanium (e.g. a-5
iGe: H) layer and amorphous hydrogenated and/or fluorinated silicon (e.g. a-8i
: H) It is characterized by having a photoconductive layer with a laminated structure consisting of layers.

According to the present invention, the photoconductive layer is amorphous hydrogenated and/or
Or, since it is composed of a fluorinated silicon germanium layer and an amorphous hydrogenated and/or fluorinated silicon layer, a photoreceptor that achieves both improved sensitivity in the near-infrared region by the former and improved sensitivity in the visible region by the latter. can be provided. Moreover, since the latter is formed on the former, a-8i is present on the front side, and sensitivity in the visible range is significantly improved, and at the same time, printing durability is improved due to a-84.

In the photoreceptor of the present invention, the thickness of the upper amorphous hydrogenated and/or fluorinated silicon layer is 1000 A~
The thickness is preferably 5 μm. In other words, the thickness is 1000
If it is not more than
It is enough.

Hereinafter, the photoreceptor according to the present invention will be explained in detail.

As shown in FIG. 1 or 2, for example, the photoreceptor according to the present invention has, on a conductive support substrate 1, an a-8iQe:H layer 2 and an a-8i:H layer 3 having a thickness that allows charge retention.
A photoconductive layer 4 having a laminated structure consisting of the following is provided. a-5iGe: The H layer 2 generates charge carriers in response to light irradiation,
It exhibits high sensitivity especially in the long wavelength range of 600 to 850 nm,
In the example shown in Figure 1, its thickness is 5oooA ~ so ttm
, Example in Figure 2] OOo J--5 μm (especially 1 μm
m to 2 μm). On the other hand, a-8i:H
Layer 3 functions as a carrier generation layer exhibiting high sensitivity in the visible light region and provides excellent printing durability to the photoreceptor, and is provided to a thickness of 1000 L to 5 μm.

a-si:) (Layer 3, a-5iGe: H When layer 2 is doped with an element of group ■A of the periodic table (for example, boron, M) to make it intrinsic, it is possible to increase the resistivity to about 1012Ω-I. Although it is possible, this is somewhat insufficient for charge retention.

Therefore, it is desirable to provide a separate charge transport layer above or below the photoconductive layer 4. For example, as shown in FIG.
can be provided with a thickness of 0.5 to 50 μm. This charge transport layer is composed of 'I''i02, ZnO, CdS, Zn
Inorganic substances such as amorphous substances containing S, Be or Te, polyvinylcarbazole, N-ethylcarbazole,
Tetraphenylpyrene, 1-methylpyrene, chrysene,
It may be composed of organic substances such as anthracene, polyvinylpyrene, polyvinyltetracene, polyvinylgarbazole-tetranitrofluorenone, tetranitrofluorenone, dinitroanthracene, and the like.

Note that the a-8i:H layer 3 and the a-8iGe:H layer 2 can contain carbon, nitrogen, oxygen, etc. in order to increase the resistance.

The charge transport layer 5 in FIG. 2 is a-si:) as shown in FIG.
(Even if it is provided on layer 3, the same effect as above can be obtained.

FIG. 4 shows an example in which a barrier layer 6 is formed in order to prevent injection of carriers from the support 1 and increase charge retention ability. This barrier layer is 5i02. SiO, AJ120a
, Zr0z, MgF2, etc., or organic substances such as oxadiazole derivatives, triazole derivatives, imidazole derivatives, oxazole derivatives, thiophene derivatives, triazine derivatives, styryl compounds, and pyrazoline derivatives. Further, the thickness of the barrier layer 6 is preferably set to 50 to 5000 K in order to prevent carrier injection from the support and to prevent residual potential.

In addition, for example, for use in the image forming process described in Japanese Patent Publication No. 42-23910, or for protecting the surface of a photoreceptor, it can also be used to improve charge retention and to improve photoreceptivity by exposure to corona discharge. In order to prevent the deterioration of the tissue characteristics and to reduce the influence of humidity on the electrophotographic characteristics, it is recommended to provide a composite layer or a modified layer 7 on the surface of the photoreceptor shown in FIG. 1, as shown in FIG. good. This surface modification layer can of course be provided on the surface side of the photoreceptor shown in FIG. 2, as shown in FIG. 6, or it can also be formed on the surface of the photoreceptor having the barrier layer 6, as shown in FIG. It is. Materials that can be used for the surface modification layer 7 include synthetic resins such as polyethylene terephthalate, polycarbonate, polypropylene, polyvinyl butyrane, and polyvinyl fluoride, cellulose derivatives such as triacetate, amorphous silicon carbide, semiconductors such as TiO2, and insulating materials such as 8i0zM203. One example is the body. Further, the thickness is preferably 8 to 50 μm in the case of the process shown in Japanese Patent Publication No. 42-23910, and 500× to 5 μm in other cases.

In addition, a-8iC:H and a-8i on each side above
The stacked structure with Ge:I-I is essential for making the photoreceptor according to the present invention highly sensitive in both the visible and near-infrared regions. That is, as shown in FIG.
-8iGe:H/a-8i:H), a-8iGe
:I-], the photosensitivity on the long wavelength side (half-reduced exposure amount (er
g/all). ) is good and has a-
8i:H also provides good sensitivity in the visible range, and shows high sensitivity over a wide wavelength range as a whole.

The film characteristics of the a-5iGe: H layer vary greatly depending on film forming conditions such as substrate temperature and high frequency discharge power in the manufacturing method described below. In terms of composition, the Ge content is 0.
．． It is preferable to set it to 1 to 50 atomic%. That is, if it is less than 0.1 atomic 4, the long wavelength sensitivity will not increase, and if it exceeds 50 atomic %, the sensitivity will decrease and the mechanical properties and thermal properties of the film will deteriorate. Also desirable. Specifically, the infrared absorption intensity I VS iH2 with a wave number of about 2090 cIrL" and the wave number of about 2000 cI
Infrared absorption intensity of rL'■νSiH is O≦■ν5IH2
/ IνSin ≦03. The amount of H bonded to 8i is 3.5 to 20 atomic
% is better. When these conditions are met, ρ
This is desirable because it results in a photoreceptor with a large D/ρL.

In the above, in order to compensate for dangling bonds, fluorine is introduced into a-8i instead of the above-mentioned H or in combination with H, and a-8iGe: F,
a-8iGe: H: F, a-8iCGe:
F.

a-8iCGe: H: F, a-8iC:
F, a-8iC:H:F, etc. can also be used.

In this case, the amount of fluorine is 0.01 to 20 atomic
% is good, and 0.5 to 10 atomic is even better.

An apparatus, such as a glow discharge decomposition apparatus, which can be used to manufacture photoreceptors according to the present invention will now be described with reference to FIG.

In the vacuum chamber 12 of this apparatus 11, the above-described substrate 1 is fixed on a substrate holding part 14, and the substrate 1 can be heated to a predetermined temperature by a heater 15. A high frequency electrode 17 is disposed facing the substrate 1, and a glow discharge is generated between the high frequency electrode 17 and the substrate 1. In addition, 19, ka, 21, nl in the figure
However, Ga, Ko, 34, 36, 38 are each pulp, 30 is Ge
Source of H4 or gaseous germanium compound, 31 is S
iH4 or gaseous silicon compound source, 32 is Ar
Or a carrier gas supply source such as H2. impurity gas,
For example, a source of B2H6 may also be provided. In this glow discharge device, first, the surface of a support, for example, an M substrate 1, is cleaned, and then placed in a vacuum chamber 12.
Pulp 36 so that the gas pressure inside becomes 1O-6 Torr.
is regulated and evacuated, and the substrate 1 is heated to a predetermined temperature, for example, 20
Heat and maintain at 0°C. Next, using a high-purity inert gas as a carrier gas, a mixed gas prepared by diluting an appropriate amount of SiH4 or a gaseous silicon compound, GeI(4) or a gaseous germanium compound is suitably added to the vacuum chamber 12 according to each film composition.
0, 01~]0To introduced into the interior and adjusted with pulp M
A high frequency voltage is applied by the high frequency power supply 16 under a reaction pressure of rr. As a result, each of the above reaction gases is decomposed by glow discharge, and hydrogen-containing a-5iQe; H, a-8i
: Depositing H as layer 2 (or even 3) above on substrate 1.

Note that the above manufacturing method is based on the glow discharge decomposition method, but other methods include sputtering method, ion blating method, and a-8i or a -8i Ge vapor deposition method (in particular, Japanese Patent Application Laid-Open No. 56-7841 by the present applicant)
The above-mentioned photoreceptor can also be manufactured by the method disclosed in No. 3 (Japanese Patent Application No. 152455/1982). In addition to SiH4 and Ge114, the reaction gases used include 8i 2H6, Ge
zHa, 8iF4.5iHFa or its derivative gas can be used.

Next, an example in which the present invention is applied to an electrophotographic photoreceptor will be specifically described.

Example 1 An M substrate cleaned with trichlorethylene and etched with a 0.1% NaOH aqueous solution and a 0.1% HNOx aqueous solution was set in the glow discharge device shown in FIG. 1 μm thick on a polyvinyl carbazole layer (charge transport layer) with a thickness of 1 μm (7) Ho y
A doped aS+ Ge:H layer and a 1 μm thick boron-doped a-8i:H layer were successively formed.

Comparative Example 1 In Example 1, a-5iQe:H was provided on the surface side and a-si:)I was provided as the lower layer.

Example 2 An 8i film with a thickness of 1000X was deposited on an M substrate using a sputtering method.
An Oz layer (barrier layer) is provided, and a boron-doped a-8iGe:H layer with a thickness of 1 μm and a boron-doped a-8i:H layer with a thickness of 1 μm are formed on this layer by the glow discharge method described above, and the thickness is further increased by coating. A polyvinyl carbazole layer with a thickness of 1.5 μm was provided.

Irradiate the photoreceptor on each side with a halogen lamp, 78
When we investigated the half-reduced exposure amount when irradiated with 0 nm semiconductor laser light and the image quality when it was actually applied to an electrophotographic copying machine and copied 100,000 times, it was found that the photoreceptor based on the present invention was as shown in the table below. Both showed satisfactory results.

Example 3 On the M substrate, a 4000X thick boy-doped a-Si Ge:1-1 layer and a 3000X-thick poron-doped a-8i:1-1 layer were formed by the glow discharge method described above. A polyvinyl carbazole layer with a thickness of 1.0 μm was coated.

Then, -6KV corona discharge was applied to this photoreceptor for 10
Perform image exposure of βuXmeec to form an electrostatic latent image,
When developed with positive polarity toner, transferred and fixed on transfer paper, a clear image was obtained.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIGS. 1, 2, 3, 4, 5, 6, and 7 show examples of each side of the electrophotographic photoreceptor. 8 is a graph showing a comparison of the photosensitivity of photoreceptors, and FIG. 9 is a schematic sectional view of the glow discharge device. In addition, in the symbols shown in the drawings, ■...Support (substrate) 2 a @ 1111 a-8iQe: H layer 3...
・a-8i: H layer 4 ・Photoconductive layer 5 ・・Charge transport layer 6 ・・Barrier layer 7 ・・Surface modified layer. Agent: Patent attorney Hiroshi Aisaka (1 person)
(b) 1 yen 2nd day 40th 70th Wa M, 9th

Claims (1)

[Claims] 1. A photoconductive layer having a laminated structure consisting of an amorphous hydrogenated and/or fluorinated silicon germanium layer and an amorphous hydrogenated and/or fluorinated silicon layer formed thereon. Characteristic photoreceptor. 2. The photoreceptor according to claim 1, wherein the amorphous hydrogenated and/or fluorinated silicon layer has a thickness of 1000X to 5 μm. 3. The germanium content in the amorphous hydrogenated and/or fluorinated silicon germanium layer is 0.1 ato
mic % to 50 atomic %, the photoreceptor according to claim 1 or 2.