JPS62198868A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve the electrostatic chargeability and the sensitivity in a wide wavelength region to the near infrared region by providing a laminate type structure obtd. by interposing a specified barrier layer between a specified photoconductive layer and an electrically conductive support and forming a specified charge retentive surface layer on the photoconductive layer. CONSTITUTION:The barrier layer 22 is made of microcrystalline silicon (muc-Si) and an element belonging to the group III or V of the periodic table is added to the muc-Si so as to form the layer 22 as a P- or N-type layer. The photoconductive layer 23 is made of amorphous silicon contg. hydrogen, so it has high sensitivity to light having long wavelength. The surface layer 24 is made of muc-Si contg. nitrogen, carbon or oxygen, so it has high charge reten tivity. The photoconductive layer 23 may be a separated function type layer consisting of a charge generating layer and a charge transferring layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an electrophotographic photoreceptor having excellent charging characteristics, photosensitivity characteristics, environmental resistance, etc.

(Prior Art) Conventionally, inorganic materials such as CdS, ZnO, Se, 5e-Te, or amorphous silicon, or poly-N-vinylcarbazole (PVCz) have been used as materials for forming the photoconductive layer of electrophotographic photoreceptors. Alternatively, organic materials such as trinitrofluorenone (TNF) are used. However, these conventional photoconductive materials have various problems in terms of photoconductive properties or manufacturing, and it is necessary to use these materials depending on the purpose of use, sacrificing some of the properties of the photoreceptor system. ing.

For example, Se and CdS are materials that are harmful to the human body, and special consideration must be given to safety measures when manufacturing them. Therefore, there are problems in that the manufacturing equipment becomes complicated and the manufacturing cost is high, and in particular, Se needs to be recovered, which adds to the recovery cost. Also,
For Se or 5e-Te systems, the crystallization concentration is 65°C
As a result, problems with photoconductive properties such as residual potential occur during repeated copying, resulting in a short life span and low practicality.

Furthermore, ZnO is susceptible to oxidation-reduction and is significantly affected by the environmental atmosphere, resulting in a problem of low reliability in use.

Furthermore, organic photoconductive materials such as pvcz and TNF are suspected to be carcinogens and are
In addition to the problems, Aiso materials suffer from poor thermal stability and wear resistance, and a short lifespan.

On the other hand, amorphous silicon (hereinafter abbreviated as a-3i)
has recently attracted attention as a photoconductive conversion material, and is being actively applied to solar cells, thin film transistors, and image sensors. As part of this application of a-3i, attempts have been made to use a-8i as a photoconductive material for electrophotographic photoreceptors, and photoreceptors using a-8i are collected because they are non-polluting materials. No processing required;
Compared to other materials, it has advantages such as high spectral sensitivity in the visible light region, high surface hardness, and excellent wear resistance and impact resistance.

This a-8i is being studied as a photoreceptor for electrophotography based on the Carlson method, but in this case,
High resistance and photosensitivity are required as photoreceptor characteristics. However, it is difficult to satisfy both of these characteristics with a single layer photoreceptor, so a barrier is placed between the photoconductive layer and the conductive support. -, and a layered structure in which a surface charge retention layer is provided on the light guide Nll, satisfies these requirements.

(Problems to be Solved by the Invention) By the way, a-3i is usually formed by a glow discharge decomposition method using a silane gas.
Hydrogen is incorporated into the 3ill, and the electrical and optical characteristics vary greatly due to the difference in the amount of hydrogen. That is, as the amount of hydrogen entering the a-3i increases, the optical bandgap increases and the resistance of the a-3i increases, but as a result, the photosensitivity to long wavelength light decreases. For example, it is difficult to use it in a laser beam printer equipped with a semiconductor laser. In addition, if the hydrogen content in the a-8i film is high, depending on the film formation conditions, (S
Those having a bonding structure such as iH2)n and SiH2 may occupy most of the area in the film. In this case, voids increase and silicon dangling bonds increase, resulting in deterioration of photoconductive properties and rendering the material unusable as an electrophotographic photoreceptor. Conversely, when the amount of hydrogen penetrating into a-8i decreases, the optical band gap decreases and its resistance decreases, but the photosensitivity to long wavelength light increases. However, the conventional a-3i made under normal film-forming conditions
, the hydrogen content is low.

If this happens, there will be less hydrogen to combine with and reduce silicon dangling bonds. For this reason, the mobility of the generated carriers is reduced, the life span is shortened, and the photoconductive properties are deteriorated, making it difficult to use as an electrophotographic photoreceptor.

In addition, as a technique to increase the sensitivity to long wavelength light, there is a method of mixing silane-based gas and germane GeH+ and generating a film with a narrow optical band gap by glow discharge decomposition, but in general, silane-based gas and GeH4
In this case, since the optimum substrate temperature is determined, the produced film has many structural defects and cannot obtain good photoconductive properties.

Furthermore, waste gas treatment is complicated because GeH+ waste gas becomes toxic gas when oxidized. Therefore, such technology is not practical.

This invention was made in view of the above circumstances, and has excellent charging ability, low residual potential, high sensitivity over a wide wavelength range up to the near infrared region, and good adhesion to the substrate. An object of the present invention is to provide an electrophotographic photoreceptor having good environmental resistance.

[Structure of the Invention] (Means for Solving the Problems) An electrophotographic photoreceptor according to the present invention includes an electrically conductive support, a barrier layer formed on the electrically conductive support, and a barrier layer formed on the electrically conductive support. In an electrophotographic photoreceptor having a photoconductive layer formed thereon and a surface layer formed on the photoconductive layer, the barrier layer is made of an element belonging to Group I or Group V of the periodic table. The photoconductive layer is made of microcrystalline silicon containing at least one selected element, the photoconductive layer is made of amorphous silicon containing hydrogen, and the surface layer is made of microcrystalline silicon containing at least one selected element. It is characterized by being formed of microcrystalline silicon containing elements.

<Function> In this invention, the barrier layer is formed of microcrystalline silicon (hereinafter abbreviated as μc-8i), and this μc
-S'i contains an element belonging to group Ⅰ or group V of the periodic table to make the barrier layer n-type or n-type. Also,
Since the photoconductive layer is formed of a-8i containing hydrogen, it has high sensitivity to long wavelength light. Furthermore, since the surface layer is formed of μc-3i containing nitrogen N, carbon C, or oxygen O, it has a high charge retention ability. The photoconductive layer may be structured into a functionally separated type in which the photoconductive layer is separated into a charge generation layer and a charge transport layer.

Note that μc-3i is clearly distinguished from a-8i and polycrystalline silicon (polycrystalline silicon) due to the following physical characteristics. That is, in X-ray diffraction measurements, since a-8i is amorphous, only a halo appears and no diffraction pattern can be observed, whereas μc-8i
3i shows a crystal diffraction pattern in which 2θ is around 28 to 28.5°. Also, while polycrystalline silicon has a dark resistance of 10BΩ・1, μc-8i has a dark resistance of 1Q
It has a dark resistance of 11Ω·α or more. This μc-8i is formed by an aggregation of microcrystals having a particle size of about a few angstroms or more.

(Embodiments) Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a partial sectional view of an electrophotographic photoreceptor according to an embodiment of the invention. A barrier layer 22 is formed on a conductive support 21 such as an aluminum substrate, a photoconductive layer 23 is formed on this barrier layer 22, and a surface layer 24 is formed on the photoconductive layer 23. It is formed.

The barrier 122 is made of μc-8i;
The 3i barrier layer contains at least one element selected from elements belonging to Group Ⅰ or Group V of the periodic table. The photoconductive layer 23 is made of a-8i containing hydrogen, and the surface layer 24 is made of μc-3i containing at least one element selected from C10 and N.

The barrier layer 22 suppresses the flow of carriers (electrons or holes) from the conductive support to the photoconductive layer, thereby enhancing the charge retention function on the surface of the electrophotographic photoreceptor, and increasing the charge retention function of the electrophotographic photoreceptor. Increases charging ability. In the Carlson method, when the surface of the photoreceptor is positively charged, the barrier layer is made n-type in order to prevent electrons from being injected from the support side to the photoconductive layer. On the other hand, when the surface of the photoreceptor is negatively charged, the barrier layer is made n-type in order to prevent holes from being injected from the support into the photoconductive layer. The thickness of this barrier layer is preferably 0.01 to 10 μm.

In order to make μc-8+ n-type, it is preferable to dope it with elements belonging to Group Ⅰ of the periodic table, such as boron B1 aluminum AI, gallium Ga, indium ln, and thallium T1. To make it n-type, an element belonging to Group V of the periodic table, such as nitrogen N
, phosphorus P, arsenic AS1 antimony Sb and bismuth 3i
It is preferable to dope. This n-type impurity or n-type impurity doping prevents carriers from moving from the support side to the photoconductive layer.

Furthermore, a barrier layer can also be formed by widening the band gap. This is C, O, N in μC-81.
What is necessary is to contain. This C90, μc- containing N
By doping 3i with an element belonging to group Ⅰ or group V of the periodic table, its blocking ability can be further enhanced. Furthermore, μc- containing C, O, N
A barrier layer with high charging ability and charge retention ability can also be obtained by laminating an 8i layer and μc-8ill containing an element belonging to group Ⅰ or group V of the periodic table.

The photoconductive layer 23 is made of a-8i and contains hydrogen. Preferably, this hydrogen content is 1 to 10 at.%. Ideally, the photoconductive layer has no traps for capturing carriers. However, since the silicon layer is not a single crystal, it has some irregularities and dangling bonds. In this case, when hydrogen is contained, hydrogen acts as a terminator for silicon dangling bonds, compensates for the bonds, and improves carrier mobility. The hydrogen content is 1 to 10 at.%. When the amount of hydrogen exceeds 10 at%, SiH2 or (SiH2
)n bonds become dominant, and as a result, dangling bonds increase, photoconductivity deteriorates, and desired photoreceptor characteristics cannot be obtained. On the other hand, when the amount of hydrogen is less than 1 atomic %, it becomes impossible to compensate for dangling bonds, and carrier mobility and lifetime decrease.

Light guide 1! The surface layer 24 formed on the layer 23 is C901
Alternatively, it is formed of μc-3i containing N. By providing the surface layer, the photoconductive layer is protected from damage, and at the same time, by forming the surface layer, the charging ability is improved and the charge can be easily deposited on the surface. In addition, a- of the photoconductive layer
Since 3i has a relatively large refractive index of 3 to 4, light reflection easily occurs on the surface. When such light reflection occurs, the proportion of the amount of light absorbed by the photoconductive layer decreases, increasing optical loss. For this reason, a surface layer is provided to prevent reflection.

By doping μC-8i or a-8i with at least one element selected from nitrogen N, carbon C, and oxygen 0, the dark resistance of μC-8i or a-3i is increased and the photoconductive properties are enhanced. be able to.

It is preferable that the concentration of nitrogen in a-8i and μc-3i changes in the layer thickness direction. Thereby, it is possible to improve the adhesion between each layer and to make the carrier run evenly.

FIG. 2 shows that the photoconductive layer 40 has a charge generating layer 34 and a charge transport layer 1.
This is an example of a function-separated type in which the functions are separated into 33 and 33. That is, in this embodiment, μ
a c-3i barrier layer 32, a charge transport layer 33 made of a-3i or μc-3i, and an a-3i charge generation layer 34;
A ttc-8i surface layer 35 is formed. Charge generation! ! 34 generates carriers by irradiation with light. Charge transfer [133] moves carriers generated in charge generation 1134 to the conductive support with high efficiency. Charge transfer layer 33
By doping with hydrogen, the mobility of the carrier can be improved. Furthermore, by lightly doping the charge transfer 1233 with an element belonging to Group 1 or Group V of the periodic table, its dark resistance can be increased and charging ability can be improved.

FIG. 3 is a diagram showing an apparatus for manufacturing an electrophotographic photoreceptor according to the present invention. For example, the gas cylinders 1 and 2°3.4 contain SiH+ and BzH6', respectively.

Source gases such as H2, He, Ar, CH4, and N2 are contained. The gas in these gas cylinders 1, 2, 3, 4 is supplied to a mixer 8 via a valve 6 and piping 7 for regulating the flow rate.

A pressure gauge 5 is installed in each cylinder, and by adjusting the valve 6 while monitoring the pressure gauge 5, the flow m and mixing ratio of each raw material gas supplied to the mixer 8 can be adjusted. I can do it. The gas mixed in the mixer 8 is transferred to the reaction volume 1.
9. At the bottom 11 of the reaction vessel 9, there is a rotating shaft 1.
0 is mounted rotatably around the vertical direction,
A disk-shaped support 12 is fixed to the upper end of the rotating shaft 1o with its surface perpendicular to the rotating shaft 10. Reaction container 9
Inside, a cylindrical electrode 13 is installed on the bottom 11 with its axial center aligned with the axial center of the rotating shaft 10. A drum base 14 of a photoreceptor is placed on a support base 12 with its axial center aligned with the axial center of the rotating shaft 10, and a heater 15 for heating the drum base is installed inside the drum base 14.
is installed. A high frequency power source 16 is connected between the electrode 13 and the drum base 14, so that a high frequency current is supplied between the electrode 13 and the drum base 14. The rotating shaft 10 is rotationally driven by a motor 18.

The pressure inside the reaction vessel 9 is monitored by a pressure gauge 17, and the reaction vessel 9 is connected via a gate valve 18 to an appropriate evacuation means such as a vacuum pump.

When manufacturing a photoreceptor using the apparatus configured as described above, after installing the drum base 14 in the reaction vessel 9, the gate valve 19 is opened to control the inside of the reaction vessel 9 at approximately 0.1 Torr. Evacuate to below pressure. Next, cylinder 1
, 2.3.4, the required reaction gases are mixed at a predetermined mixing ratio and introduced into the reaction vessel 9. In this case, reaction vessel 9
The gas flow mountain introduced into the reaction vessel 9 has a pressure of 0.1
Set it so that it is between 1 Torr and 1 Torr. Next, the motor 18
is activated to rotate the drum base 14, and the heater 15 heats the drum base 14 to a constant humidity, and the high frequency type 1i16 supplies a high frequency 'R current between the t pole 13 and the drum base 14, so that both A glow discharge is formed in between. As a result, a-3i 1. c.
Zc-31 or a-BN is deposited. In addition, N20゜NH3, NO2, N2, CH4, C2H4 in the raw material gas.
, 02 gas, etc., elements such as N, C, and O can be contained in μc-3i or a-3i.

Hydrogen doping to μc-3i or a-3i can be carried out using, for example, SiH+ and 5
Either a silane-based raw material gas such as i2Hs and a carrier gas such as hydrogen or helium are introduced into a reaction vessel to cause glow discharge, or a combination of silicon halides such as SiF4 and 5iC1+ and hydrogen gas or helium gas is used. A mixed gas may be used, or a mixed gas of a silane gas and a silicon halide may be used for the reaction. Furthermore, .mu.c-3t or a-3ilfi can be formed not by the glow discharge decomposition method but also by other methods such as sputtering.

As described above, since the electrophotographic photoreceptor according to the present invention can be manufactured using a closed system manufacturing apparatus,
Safe for humans. Furthermore, this electrophotographic photoreceptor has excellent heat resistance, moisture resistance, and abrasion resistance, so it has the advantage of having a long lifespan with little deterioration even after repeated use over a long period of time.

Furthermore, since a long wavelength sensitizing gas such as GeH+ is not required, there is no need to provide waste gas treatment equipment, and industrial productivity is extremely high.

Next, embodiments of the invention will be described.

The support LfL biconductive support was heated and held at approximately 300°C, 2008
CCM flow rate of S i H4 gas and this 5ft-1+
82 H6 gas having a flow rate ratio of 10-8 to gas was mixed and supplied to the reaction vessel. Thereafter, the inside of the reaction vessel was evacuated using a mechanical booster pump, a rotary pump, etc., and the reaction pressure was adjusted to 1 Torr. And 13.56M
A high frequency power of 600 W at Hz was applied to generate a plasma of SiH + and B2 Ha and N2 between the [tfi and the drum, and a barrier layer made of p-type μC-3i was formed.

Next, the SiH+ gas flow rate was set to 5008CCM, 82H
These gases were introduced into the reaction vessel with the 6 gas flow rate set at 10-7 relative to the S i H4 gas flow rate. Then, a 30 μm thick a-8i photoconductive layer was formed under the conditions that the reaction pressure was 1.2 Torr and the high frequency power was 400 W.

Thereafter, in the same manner, μc-
A surface layer consisting of 8i was formed.

When the electrophotographic photoreceptor manufactured in this manner was installed in a semiconductor laser printer and an image was formed by the Carlson process, the exposure amount on the photoreceptor surface was 25 ero /
Even with am2, clear and high resolution images could be obtained. In addition, when we investigated the reproducibility and stability of the transfer process through repeated copying, we found that the transferred images were extremely good and demonstrated excellent durability in terms of corona resistance, moisture resistance, and abrasion resistance. Ta.

[Effects of the Invention] According to the present invention, an electronic device with high resistance, delayed charging characteristics, high photosensitivity in the visible light and near-infrared light regions, easy to manufacture, and highly practical. A photographic photoreceptor can be obtained.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing an electrophotographic photoreceptor according to an embodiment of the present invention, and FIG. 3 is a diagram showing an apparatus for manufacturing an electrophotographic photoreceptor according to the present invention. 1.2.3.4; cylinder, 5; pressure gauge, 6; valve, 7
; Piping, 8: Mixer, 9; Reaction container, 10; Rotating shaft, 1
3; Electrode, 14; Drum base, 15; Heater, 16; High frequency 'R source, 19; Ge; - valve, 21. 31: Support, 22. 32: Barrier layer, 23, 40: Photoconductive layer, 2
4, 35: Surface layer, 33: Charge transfer layer, 34; Charge generation layer Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 (!I

Claims (3)

[Claims] (1) A conductive support, a barrier layer formed on the conductive support, a photoconductive layer formed on the barrier layer, and a surface layer formed on the photoconductive layer. In the electrophotographic photoreceptor, the barrier layer is formed of microcrystalline silicon containing at least one element selected from elements belonging to Group III or V of the periodic table, and the photoconductive layer is An electrophotographic photoreceptor, characterized in that it is formed of amorphous silicon containing hydrogen, and the surface layer is formed of microcrystalline silicon containing at least one element selected from nitrogen, carbon, and oxygen. (2) The electrophotographic photoreceptor according to claim 1, wherein the photoconductive layer contains 0.1 to 10 atom % of hydrogen. (3) The electrophotographic photoreceptor according to claim 1, wherein the photoconductive layer contains at least one element selected from carbon, oxygen, and nitrogen.