JP2001154388A - Electrophotographic photoreceptor and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an amorphous silicon photoreceptor to which boron is added, when the addition of boron is increased, the photosensitivity is improved, but sufficient charging ability is not obtained. An object of the present invention is to solve the problem that the charging ability is improved but sufficient light sensitivity cannot be obtained. SOLUTION: When forming an amorphous silicon photosensitive member, the amount of a diborane gas introduced together with a raw material gas into a plasma CVD apparatus is set within a predetermined range according to the thickness of the amorphous silicon photosensitive layer, and the amorphous silicon photosensitive member is formed. A method for manufacturing an amorphous silicon electrophotographic photoreceptor in which a film is formed by providing a gradient such that the boron concentration in the photosensitive layer surface side region of the layer is higher on the substrate side and lower on the surface side to solve the above-described problems. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an electrostatic charge image (hereinafter referred to as an electrostatic latent image) on a photoreceptor by utilizing a photoconductive phenomenon, and further, to a colored charged fine particle (toner). The present invention relates to an electrophotographic photoreceptor used in an electrophotographic apparatus using an electrophotographic process for obtaining a visible image by adhering an electrostatic latent image to an electrostatic latent image, and in particular, an amorphous silicon photoreceptor formed using a plasma CVD method It is about.

[0002]

2. Description of the Related Art Conventionally, as an electrophotographic apparatus using an electrophotographic process, a copying machine using a PPC (Plain Paper Copy) method for transferring a toner image formed on an electrophotographic photosensitive member to paper or the like has been put into practical use. The so-called Carlson method is generally used. Further, as the photosensitive layer of the electrophotographic photosensitive member, there are a photosensitive layer using an inorganic material such as Se, Se-Te, CdS, and amorphous silicon, and an OPC photosensitive member using an organic material. Amorphous silicon is
Attention has been paid to its excellent abrasion resistance, heat resistance and environmental resistance. For example, a laminated photoconductor 90 as shown in FIG.
Has been proposed.

The amorphous silicon photoreceptor 90 has a structure in which a blocking layer 92, an amorphous silicon photosensitive layer 93 and a surface protection layer 94 are sequentially laminated on a conductive support base 91 such as aluminum.
Numeral 2 is formed to prevent the injection of electrons from the support base 91, and the surface protective layer 94 is formed to protect the photosensitive layer 93 using a material having high hardness and to increase the durability. ing.

An example of an electrophotographic process using such an amorphous silicon photosensitive member 90 will be briefly described. First, the surface of the amorphous silicon photoreceptor 90 is uniformly charged to a positive charge 1 by corona discharge or the like in a dark place.
Next, when the exposure light 2 corresponding to a desired image is irradiated on the surface of the photosensitive member 90, the exposure light 2 is incident on and absorbed in the photosensitive layer 93, and electron-hole pairs 3 are generated. These holes flow to the ground 4 through the conductive support base 91 as shown by the arrow 5. On the other hand, the electrons travel in the direction of arrow 6 and recombine with the positive charges 1 on the surface of the photoreceptor 90 and are canceled. Thus, an electrostatic latent image corresponding to the irradiation light 2 is formed on the photoconductor 90. Next, a toner charged to a polarity opposite to that of the electrostatic latent image by a developing device (not shown) is attached to the latent image to form a visible image,
This is transferred and fixed on paper or the like to form an image. On the other hand, the photoreceptor 90 after the transfer is cleaned by irradiating light with a static eliminator (not shown) or the like. In this way, a series of electrophotographic processes is repeated.

Further, an electrophotographic photosensitive member 90 in which boron (B) is added to the amorphous silicon photosensitive layer 93 has been developed. By adjusting the concentration of boron contained in the photosensitive layer 93, the light sensitivity and the element resistance of the photosensitive member 90 can be adjusted.

[0006]

However, in the above-described amorphous silicon photosensitive member 90 in which boron is added to the photosensitive layer 93, if the concentration of boron contained in the amorphous silicon photosensitive layer is simply increased, the photosensitivity is improved. This makes it possible to reduce the amount of energy of the exposure light, that is, to expose the photoconductor 90 with a small amount of light, but the element resistance of the photoconductor 90 becomes low and sufficient charging ability cannot be obtained. In a copying machine using the photoconductor, there arise problems such as difficulty in adjusting copy density.

On the other hand, when the concentration of boron contained in the amorphous silicon photosensitive layer is reduced, the element resistance of the photosensitive member 90 is increased, and the charging ability is improved. However, since the light sensitivity is reduced, the exposure energy must be increased, the light amount of the exposure light must be increased, the exposure time must be increased, and the running cost increases. .

In view of the above, it is an object of the present invention to provide an amorphous silicon photoreceptor containing boron which has improved both photoreceptor characteristics which are in a trade-off relationship between improvement in photosensitivity and maintenance of high charging ability, and the photoreceptor. The purpose of the present invention is to provide a manufacturing method.

[0009]

According to an aspect of the present invention,
The method for producing an electrophotographic photoreceptor, wherein a photosensitive layer having a thickness of at least 20 microns or more made of a photoconductive material containing amorphous silicon containing boron as a main component is formed on a supporting substrate by a CVD method. The boron-containing gas is obtained by simultaneously supplying a boron-containing gas together with a raw material gas for forming the photosensitive layer, and the boron-containing gas is such that the amount of boron contained in the photosensitive layer is smaller than that of the support base. A method for producing an amorphous silicon electrophotographic photoreceptor, wherein the amount of addition is within the range of the following relational expression (1) at least in a region at a depth of up to 15 microns from the surface of the photosensitive layer so that the surface side is reduced. And an electrophotographic photosensitive member using the same. (1) −0.5 + 0.0173 × d <dB <0.2 + 0.0173 × d where d is the depth (micron) from the surface side of the photosensitive layer,
dB indicates the added amount (ppm) of the boron-containing gas in the raw material gas used when forming by the CVD method.
Is greater than zero.

According to the present invention, there is provided an electrophotographic photosensitive member capable of maintaining a high charging ability because the concentration of boron contained in the amorphous silicon photosensitive layer has a gradient within a predetermined range. The goal is achieved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS.

FIG. 1 is a schematic sectional view of a first embodiment of an electrophotographic photosensitive member 10 according to the present invention, and reference numeral 13 denotes an amorphous silicon photosensitive layer. The photosensitive layer 13 is laminated on the blocking layer 12 formed on the conductive support substrate 11 at a thickness of at least 20 μm or more, preferably 40 to 50 μm. A layer 14 is provided. The support base 11 may be a metal such as aluminum, or a material in which an electrically conductive layer such as aluminum is formed on an insulating material such as glass or plastic. In general, cylindrical aluminum is used. The blocking layer 12 is formed to prevent the injection of electrons from the support base 11, and includes a-Si, S
iN, SiC, a-Si obtained by adding oxygen to a-Si, or the like can be used. The surface protective layer 14 is provided to protect the photosensitive layer 13 and can be made of a high-hardness material such as SiN or SiC, but may not be formed.

The above-described structure has the same laminated structure as the structure of the conventional amorphous silicon electrophotographic photosensitive member.
The distribution of the boron concentration contained in 3 is not uniform in the prior art, and the photosensitive layer is intentionally provided in at least a region from the surface side of the photosensitive layer to a depth of 15 microns, preferably a region to a depth of 20 microns. It has a gradient of Specifically, in the present embodiment, the support base 11
The first photosensitive layer region 13a and the second photosensitive layer region 13b having the highest boron content in order from the side, and the third photosensitive layer region 13c on the photosensitive layer surface side having the lowest boron content.
It is manufactured so that it is roughly divided into the following three areas.

In the amorphous silicon photosensitive layer 13, the charge amount is increased without impairing the photosensitivity of a wavelength necessary for forming and erasing a latent image by providing a predetermined gradient in the amount of boron added on the photosensitive layer surface side. Could be able to. In particular, the outermost surface side of the photosensitive layer, that is, the third photosensitive layer region 13c
By keeping the boron content low, the charge amount is improved by about 30% or more as compared with the conventional case having a uniform boron concentration.

In particular, when boron is added to the material gas used for forming the amorphous silicon photosensitive layer by using diborane gas (B ₂ H ₆ ), at least 15 μm, preferably 20 μm from the photosensitive layer surface. When forming the amorphous silicon photosensitive layer in the region up to the depth of
Diborane gas addition amount to raw material gas dB (ppm)
Is greater than −0.5 + 0.0173 × d and 0.2
Make it smaller than + 0.0173 × d. Here, d
Indicates the thickness (micron) in the depth direction from the surface of the amorphous silicon photosensitive layer, and is set to dB> 0. An amorphous silicon photoreceptor manufactured by satisfying these conditions can improve photosensitivity and maintain high charging ability.

Hereinafter, a specific method of manufacturing the electrophotographic photosensitive member will be described.

(Example 1) Cylindrical aluminum substrate 1
1 is set in a plasma CVD apparatus (not shown), and 300
At about 0.5 ° C., and at a predetermined vacuum of about 0.5 to 5 Torr, introducing a raw material gas at 13.56 MHz.
A high-frequency plasma was generated to form an Si-based blocking layer 12 of 4 μm, then an amorphous silicon photosensitive layer 13 and a 0.5 μm SiN-based surface protection layer 14 in succession.

At this time, the amorphous silicon photosensitive layer 13
Is a silane gas (S
iH ₄ ) and a hydrogen (H ₂ ) carrier gas of 600 sccm are introduced, and further, 15 sccm in the first photosensitive layer region 13a and 1 in the second photosensitive layer region 13b.
At a flow rate of 5 sccm, diborane (B ₂ H ₆ ) gas having a concentration of 50 ppm was added to each of the third photosensitive layer region 13 c on the photosensitive layer surface side at 0 sccm to form a film. When the first photosensitive layer region 13a, the second photosensitive layer region 13b, and the third photosensitive layer region 13c are formed, the film is continuously formed except for changing the flow rate of the diborane gas. The amounts of (SiH ₄ ) and hydrogen (H ₂ ) carrier gases introduced were always the same. The thickness of each photosensitive layer region and the amount of diborane added are determined in the first photosensitive layer region 13a.
Is 0.440 ppm at 22.0 microns, 0.294 ppm at 8.5 microns for the second photosensitive layer region 13b, and 0.147 ppm at 8.5 microns for the third photosensitive layer region 13c.

FIG. 4 (a) shows the spectral sensitivity characteristics of the amorphous photoreceptor 10 prepared by providing a gradient in the amount of boron to be added. E1 / 2 is 1 when the initial potential is 450 V
E1 / 10 is obtained by the product of the time until the voltage becomes 1/10 of 45 V and the light irradiation intensity W. FIG. 4B shows a spectral sensitivity characteristic of a conventional photoconductor in which the amorphous silicon photosensitive layer has a single boron content as a comparative example. In the comparative example, 1.
Silane gas (SiH ₄ ) with 0 slm and 600 s
Amorphous silicon described above, except that diborane (B ₂ H ₆ ) was further added at a flow rate of 14 sccm to a source gas composed of a hydrogen (H ₂ ) carrier gas of ccm to form a 40 μm amorphous silicon photosensitive layer. It is created under the same conditions as the silicon 10. The light sensitivity of the electrophotographic photoreceptor 10 manufactured according to the present embodiment is 660 nm to 770.
It has characteristics equivalent to those of a conventional photoconductor having a single boron concentration in a wavelength region near nm.

FIG. 5 shows surface energy characteristics, FIG. 6 shows dark attenuation characteristics, and FIG. 7 shows temperature characteristics. In each graph, the amorphous silicon photoconductor 1 of the present embodiment is shown.
0 indicates excellent characteristics as compared with the amorphous silicon photosensitive member of the comparative example. That is, compared to the comparative example, the charge amount is 3 when the inflow current is 180 microamps.
It has improved by 0% or more. In addition, FIG. 6 shows that the decrease in surface potential before light irradiation is small. This indicates that the charge retention is good.For example, even in the case of a large-diameter electrophotographic photosensitive member having a long time required for a series of electrophotographic processes from charging to development, it is necessary to maintain high charging ability. Can be. Further, it can be seen from FIG. 7 that the decrease in the charging ability due to the temperature rise of the electrophotographic photoreceptor is small, and a stable image can be obtained even when the photoreceptor obtained by the present invention is used in a heated environment.

(Embodiment 2) The thicknesses of the first photosensitive layer region 13a, the second photosensitive layer region 13b, and the third photosensitive layer region 13c of the amorphous silicon photosensitive layer 13 of the first embodiment are set to 1 in order.
Films were formed under the same conditions except that the thicknesses were 7.0, 8.5, and 8.5 microns. When the characteristics of this amorphous silicon photoreceptor were evaluated in the same manner as in Example 1, similar evaluation results were obtained.

(Embodiment 3) In the previous embodiment, an example was shown in which the amorphous silicon photosensitive layer 13 was formed by dividing the film into three regions with a predetermined boron addition amount, but in this embodiment, it is shown in FIG. As described above, the amorphous silicon photosensitive layer 23
Was formed as four regions having different boron contents. That is, in order from the blocking layer 12 side, a 17.0 micron first diborane flow rate of 15 sccm was added.
Photosensitive layer region 23a, 8.5 micron second photosensitive layer region 23b added with 10 sccm diborane flow rate, 5.0 micron third photosensitive layer region 23c with diborane flow added at 5 sccm, and 2 sccm diborane flow rate
A 3.5 micron fourth photosensitive layer region 23d was laminated.

The amount of diborane added in each photosensitive layer region is 0.440 ppm in the first photosensitive layer region 23a,
The photosensitive layer area 23b is 0.294 ppm, the third photosensitive layer area 23c is 0.147 ppm,
The photosensitive layer area 23d is 0.059 ppm. The characteristics of this amorphous silicon photoreceptor were evaluated in the same manner as in Example 1, and almost the same evaluation results were obtained.

FIG. 3 shows the relationship between the amount of diborane added dB (ppm) and the depth d (microns) from the surface side of the amorphous silicon photosensitive layer. Here, the amount of diborane added refers to SiH used for forming an amorphous silicon photosensitive layer.
₄ , diborane (B ₂ H ₄ ) added to a material gas such as H ₂
Is expressed in ppm, and specifically, is a value converted from a flow rate when 50 ppm concentration of diborane is added to an atmosphere introduced at a flow rate of 1.0 slm of silane and 600 sccm of hydrogen. In any of the above-described embodiments, at least in the region from the photosensitive layer surface to a depth of 15 μm, further from 0 to 25 μm, the diborane addition concentration is located in the region between the straight line L1 and the straight line L2. I have. That is, the concentration of diborane added (pp
m) is −0.5 + 0.0173 × d or more and 0.2+
It is preferable to be 0.0173 × d or less, and when it exceeds this range, the above-mentioned characteristics are inferior. Where d
B is greater than zero. Further, it is preferable that the ratio of diborane gas occupied in the film formation is generally in the range of 0.1% to 1.0%. In addition, when the amount of boron contained in the amorphous silicon layer formed in Example 1 was measured by SIMS (secondary ion mass spectroscopy) analysis, it was 2 × 10 ⁻⁴ atm% or less.

The above embodiment is a preferred embodiment of the present invention, and has been described with an example in which the amorphous silicon photosensitive layer is provided with three or four layers having different boron contents. However, the present invention is not limited to this. Four or more layers having different boron contents may be provided, or a step-like or continuous gradient may be provided to form a region in which the amount of boron changes.

Further, the present invention can be similarly applied to the case where a film is formed using another boron-containing gas such as trimethylboron or triethylboron as a source gas for forming the amorphous silicon photosensitive layer.

[0027]

As described above, according to the present invention, in the amorphous silicon photoreceptor, at least in a region of 15 microns, preferably 20 microns from the surface of the photosensitive layer, a predetermined gradient is provided in the amount of boron to be added to the photosensitive layer. Has an excellent effect that it is possible to obtain an amorphous silicon photoreceptor having improved photoreceptor characteristics, which are in a trade-off relationship between improvement of photosensitivity and maintenance of high charging ability.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating an amorphous silicon photosensitive member according to the present invention.

FIG. 2 is a schematic sectional view illustrating an amorphous silicon photosensitive member according to another embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the concentration of diborane added and the depth from the surface of the amorphous silicon photosensitive layer.

FIG. 4 is a diagram illustrating spectral sensitivity characteristics of an amorphous silicon photoconductor.

FIG. 5 is a diagram showing a surface potential characteristic of an amorphous silicon photoconductor.

FIG. 6 is a drawing showing a dark decay rate of an amorphous silicon photoconductor.

FIG. 7 is a diagram showing temperature characteristics of an amorphous silicon photoconductor.

FIG. 8 is a schematic sectional view illustrating a conventional amorphous silicon photoconductor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive charge 2 Exposure light 3 Electron-hole pair 4 Ground 5, 6 Arrow 10, 20 Amorphous silicon photosensitive body 11 Support base 12 Blocking layer 13, 23 Amorphous silicon photosensitive layer 14 Surface protective layer 90 Electrophotographic photosensitive body 91 Support base 92 Blocking layer 93 Amorphous silicon photosensitive layer 94 Surface protective layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Norihiro Sakamoto 400 Soya, Hadano-shi, Kanagawa Stanley Electric Co., Ltd. Hadano Works F-term (reference) 2H068 DA28 DA35 EA02 EA24 FA12 FA13

Claims (3)

[Claims] 1. A method for manufacturing an electrophotographic photoreceptor, wherein a photosensitive layer having a thickness of at least 20 microns or more and made of a photoconductive material containing amorphous silicon containing boron as a main component is formed on a supporting substrate by a CVD method. In the above, the boron contained in the photosensitive layer is obtained by simultaneously supplying a boron-containing gas together with a raw material gas for forming the photosensitive layer, and the boron-containing gas is such that the amount of boron contained in the photosensitive layer is Amorphous silicon, characterized in that the amount of addition is within the range of the following relational expression (1) at least in a region from the surface of the photosensitive layer to a depth of 15 microns so that the surface side is smaller than the support substrate side. A method for producing an electrophotographic photoreceptor. (1) −0.5 + 0.0173 × d <dB <0.2 + 0.0173 × d where d is the depth (micron) from the surface side of the photosensitive layer,
dB indicates the added amount (ppm) of the boron-containing gas in the raw material gas used when forming by the CVD method.
Is greater than zero. 2. The photosensitive layer comprises a silane gas (Si)
When forming an amorphous silicon photosensitive layer using a source gas containing H ₄ ) and hydrogen gas (H ₂ ) as main components, approximately 5
Characterized in that it forms 0ppm concentration of diborane gas of (B 2 _{H 6)} at the same time was added, the production method of the amorphous silicon electrophotographic photosensitive member according to claim 1. 3. An electrophotographic photosensitive member obtained by the method of manufacturing an electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer has a boron content of 2 × 10 ^−4. a
tm% or less, and is an amorphous silicon electrophotographic photosensitive member.