JP2566762B2 - Electrophotographic photoreceptor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic photosensitive member, and more specifically, to an electrophotographic photosensitive member which is excellent in negative polarity charging ability and is also excellent in electrophotographic characteristics such as light attenuation and dark attenuation. The present invention relates to a body and a manufacturing method thereof.

[Prior art and its problems]

In recent years, development of ultra-high speed copying machines, laser beam printers, etc. has been actively promoted, and along with this development, stable operation characteristics and durability are required for electrophotographic photosensitive drums mounted in this equipment.

In response to this demand, hydrogenated amorphous silicon is drawing attention because it is excellent in abrasion resistance, heat resistance, pollution-free property, photosensitivity and the like.

Such amorphous silicon (hereinafter abbreviated as a-Si)
As the electrophotographic photoreceptor composed of the above, a laminated photoreceptor as shown in FIG. 2 has been proposed.

That is, according to FIG. 2, a carrier injection blocking layer (2), an a-Si photoconductive layer (3) and a surface protective layer (4) are sequentially laminated on a conductive substrate (1) such as aluminum. The carrier injection blocking layer (2) is formed to block the injection of carriers from the substrate (1) and reduce the residual potential, and the surface protection layer (4) is made of a high hardness material. It is used to increase the durability of the photoconductor.

However, according to this a-Si photoconductor, the dark resistivity of the a-Si photoconductive layer (3) itself is 10 ¹¹ Ω · cm or less, which increases the dark decay rate of the photoconductor. At the same time, it becomes difficult to increase the chargeability of itself, and as a result, when this photoconductor is used for high-speed copying, the previous image remains without being completely removed due to the optical memory effect, and the next image is formed. Along with that, the previous image appears (ghost phenomenon)
There is a problem to say.

Moreover, in the conventional photoconductor made of a-Si shown in FIG. 2, the charging potential is as low as -400 to -500V, which is
It is subject to various restrictions. Moreover, mass production is difficult because the film formation speed is high, and the cost is high.

[Object of the Invention]

Therefore, an object of the present invention is to provide a function-separated type electrophotographic photoconductor that has durability equivalent to that of a conventional a-Si photoconductor and has excellent negative charging ability.

Another object of the present invention relates to an electrophotographic photosensitive member which is excellent in mass productivity and economical efficiency by improving a film forming rate at the time of manufacturing the photosensitive member.

That is, according to the present invention, the periodic table V
A carrier injection blocking layer mainly composed of amorphous silicon having a group a element, a carrier transport layer mainly composed of amorphous silicon, a carrier generation layer mainly composed of amorphous silicon carbide, and a surface protective layer are formed in order. There is provided an electrophotographic photosensitive member that can be charged to a negative polarity.

 Hereinafter, the present invention will be described in detail.

The electrophotographic photoreceptor of the present invention is a function-separated type laminated photoreceptor based on the structure shown in FIG.

According to FIG. 1, the photoreceptor of the present invention has a conductive substrate (1).
A carrier blocking layer (2), a carrier transport layer (3a),
A carrier generation layer (3b) and a surface protection layer (4) are sequentially provided, and the carrier injection blocking layer (2) blocks carrier injection from the conductive substrate (1) to the carrier transport layer (3a). The surface protective layer (4) is provided for the purpose of improving the durability and environment resistance of the photoreceptor.

This will be described with reference to FIGS. 3A and 3B for the electrophotographic characteristics of the photoconductor having the configuration of FIG. 1 as an example.
First, negative charging is performed by charging means such as corona discharge (3rd
(See FIG. (A)). Next, when exposure is performed, electrons and holes are generated in the carrier generation layer (3b), the holes are neutralized with the negative charges on the surface of the photoconductor, and the electrons are transferred to the transport layer and injected to the substrate side and grounded. , The electric charge becomes zero in the entire exposed portion. (See FIG. 3 (b)).

According to the present invention, of the above-mentioned layer structures, amorphous silicon containing an element of Group V a of the periodic table is used as the carrier injection blocking layer (2), and amorphous silicon (hereinafter a-) is used as the carrier transport layer (3a). Abbreviated as Si),
It is important to use amorphous carbide (hereinafter abbreviated as a-SiC) as the carrier generation layer (3b).

The carrier injection blocking layer (2) is required to have a rectifying function depending on the charging polarity. In the negatively chargeable photoreceptor of the present invention, the carrier injection blocking layer has a periodic table of V a
An n-type semiconductor is formed by adding a group element.

The a-Si in the carrier injection blocking layer is added with H or a halogen element for the purpose of terminating the dangling bond, and the amount thereof is 5 to 50 atomic% with respect to the total amount.
Particularly, it is added in the range of 10 to 40 atomic%.

On the other hand, P, N, and A are added as group V a elements of the periodic table to be added.
s and Sb are mentioned and P is desirable. These are preferably contained in the carrier injection blocking layer in the range of 0.1 to 10,000 ppm, particularly 0.5 to 1000 ppm.

The carrier injection blocking layer contains oxygen and / or nitrogen in the range of 0.01 to 30 atom%,
The adhesion with the conductive substrate (1) can be improved.

A-Si in the carrier transport layer is represented by the following formula (1) Si _(1-z) A _z (1) In the formula, A is represented by H or a halogen element 0.05 ≦ z ≦ 0.5, particularly 0.1 ≦ z ≦ 0.4. Those are preferable. Also in this carrier transport layer, a group IIIa element of the periodic table such as B, Al, Ga and In can be doped in an amount of 10,000 ppm or less, particularly 1000 ppm or less. By adding the element of group V a of the periodic table, it is possible to increase the carrier mobility in the carrier transport layer, thereby improving the surface potential and sensitivity and reducing the residual potential.

Specifically, a-SiC used in the carrier generation layer is represented by the following formula (2) {Si _{(1-x) Cx} } _(1-y) A _y (2) where A is H or a halogen element 0.01 ≦ x ≦ 0.9 Especially 0.05 ≦ x ≦ 0.5 0.05 ≦ y ≦ 0.5
In particular, it is represented by 0.1≤y≤0.4.

Also in the carrier generation layer, by containing the group Va element of the periodic table in the range of 10000 ppm or less, particularly 0.5 to 1000 ppm, the carrier generation layer becomes an n-type semiconductor, and the spectral sensitivity to light wavelength in the near infrared region is increased. It is possible to improve and improve the negative charging ability.

According to the present invention, the group V a element of the periodic table added to the carrier generation layer and the carrier injection blocking layer has the above-mentioned effects in each layer, but at the same time, due to the characteristics as a semiconductor, the energy band is shifted to the n-type. Perform the action of causing.

Therefore, for the carrier injection blocking layer and the carrier generation layer,
When adding a group V a element of the periodic table, it is important to satisfy the relationship of P1> P2, where P1 and P2 are the addition amounts in each layer. If this relationship is not satisfied, an energy barrier is formed at the interface between the layers during carrier movement, making carrier injection difficult.

Further, various materials can be used for the surface protective layer as long as they have high insulation properties, high corrosion resistance and high hardness characteristics, for example, organic materials such as polyimide resin,
SiO ₂ , SiO, Al ₂ O ₃ , SiC, Si ₃ N ₄ , and amorphous carbon can be used.

The layer thicknesses of these four layers described above are determined so as to sufficiently fulfill their respective functions, and in particular, the carrier transport layer is set to be larger than the carrier generation layer. The ability is reduced and excellent charging ability cannot be obtained. Specifically, it is desirable to set the carrier injection blocking layer to 0.1 to 10 μm, the carrier transport layer to 10 to 50 μm, the carrier generation layer to 0.1 to 10 μm, and the surface protective layer to 0.1 to 10 μm.

According to the method for producing a photoreceptor of the present invention, a thin film forming technique such as glow discharge decomposition method, ion plating method, reactive sputtering method, vacuum deposition method, or CVD method can be used to generate an inorganic photoreceptor. For example, when forming the carrier generation layer as described above in the photoreceptor of the present invention,
The glow discharge decomposition method is preferred. Therefore, the production method by glow discharge decomposition method will be explained in more detail.SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , SiF ₄ , SiCl ₄ , and SiH ₂ Cl ₂ are used as the reaction gas.
Si-based gas, CH _4, C-based gas such as _{C 2 H 4, C 2 H} 2, C 2 H 6, C 3 H 8, CF 4, CCl 4 , such as, optionally H _2, He, Ne, Ar Can be used as a carrier gas, and
Contains a group a or group V a element-containing gas.

B used as a gas containing an element of Group IIIa of the periodic table used
₂ H ₆ ,, BF ₃ , Al (CH ₃ ) ₃ , Ga (CH ₃ ) ₃ , In (CH ₃ ) ₃ , Ga (CH ₃ )
_{3 and the} like, and among these, B ₂ H ₆ is preferable because of its handling and film formation rate. PH ₃ , N ₂ , AsH ₃ , AsF ₃ , SbF _{3 and the} like are given as the group V a element-containing gas of the periodic table, and among these, PH ₃ is preferable in terms of handling and film formation rate. These are preferably contained in the reaction gas in an amount of 1 mol% or less, particularly 0.1 mol% or less.

These gases are appropriately adjusted according to the formation of each layer. First, at the time of forming the carrier injection blocking layer, a film is formed by using a Si-containing gas and a gas containing a Group Va element of the periodic table at a ratio of 10 ^{−6 to} 1 mol%, particularly 10 ^{−5 to} 0.1 mol%. To do. A film is formed using a Si-containing gas when forming the carrier transport layer and further using a Si-containing gas and a C-containing gas when forming the carrier generation layer. Incidentally. When forming the carrier generation layer,
When C ₂ H ₂ gas is used as the C-containing gas, the film forming rate can be improved. In particular, the composition ratio of (C ₂ H ₂ gas: Si-containing gas) is preferably 0.05: 1 to 3: 1.

It is preferable to add the above-mentioned carrier gas to the composition of these reaction gases from the viewpoint of stabilizing the film quality. Further, if desired, it is desirable to add a group IIIa element-containing gas of the periodic table or a group Va element-containing gas of the periodic table in the above-mentioned range at the time of forming the carrier transport layer and the carrier generation layer. When a Group V a element of the Periodic Table is added to each layer, as described above, the periodic table V a at the time of forming each layer is adjusted so that the added layers of each layer have a relationship of P ₁ > P _2. It is necessary to adjust the ratio of the group element-containing gas.

Next, the capacitively coupled glow discharge decomposition apparatus used in the embodiment of the present invention will be described with reference to FIG.

In addition, PH ₃ is used as the group V a element-containing gas of the periodic table, and B ₂ H ₆ gas is used as the group III a element-containing gas of the periodic table.

In the figure, first, second, third, fourth and fifth tanks (6)
(7), (8), (9a) and (9b) contain SiH ₄ , C ₂ H ₂ and PH _{3 respectively.}
Alternatively, B ₂ H ₆ , H ₂ and NO gas are sealed, and H ₂ is also used as a carrier gas. These gases correspond to the corresponding first, second, third, fourth and fifth control valves (10) (11) (1
2) It is released by releasing (13a) (13b), and its flow rate is controlled by the mass flow controller (14) (15) (16).
It is sent to the main pipe (18) after being restricted by (17a) and (17b).

 Incidentally, (19) is a stop valve.

The gas flowing through the main pipe (18) is
0), but the capacity coupling type discharge electrode (21) is installed inside the reaction tube, the power applied to this is 50W to 3kW, and its frequency is 1MHz to 50MHz. is there. Inside the reaction tube (20), a cylindrical conductive substrate (22) for film formation made of aluminum is placed on the sample holder (2
3), the holding table (23) is rotatably driven by a motor (24), and the substrate (22) is about 50 to 400 by a suitable heating means.
C., preferably about 150 to 300.degree. C., with uniform heating.

Furthermore, the inside of the reaction tube (20) is in a high vacuum state (discharge voltage 0.1 to 2.0 Torr) when forming an a-Si film or an a-SiC film.
Is connected to the diffusion pump (25) and the rotary pump (26).

In the glow discharge decomposition apparatus configured as described above, when forming, for example, a P-doped a-SiC film, the first, second, third and fourth regulating valves (10) (11) (1
2) (13a) is released to release the 1st, 2nd, 3rd, 4th tanks (6)
From (7), (8) and (9a), SiH ₄ gas, C ₂ H ₂ gas,
It emits PH ₃ gas and H ₂ gas, and the amount of these emissions is regulated by the mass flow controllers (14) (15) (16) (17a) and sent to the reaction tube (20) through the main pump (18). And the inside of the reaction tube (20) is 0.1 to 2.0.
Vacuum condition of Torr, substrate temperature of 50 to 400 ℃, high frequency power of 50W to the capacitive discharge electrode (21) with frequency of 1MHz to 50MHz
A glow discharge occurs in conjunction with the application of 3 to 3kW,
The gas decomposes and a P-containing a-SiC film is formed on the substrate at a high speed.

In the layer structure of the photoreceptor according to the present invention, when an organic material is used, any of them can be formed by a well-known means. Specifically, a polymer material, an organic pigment, an organic dye or the like is used in a volatile solvent. It can be provided by a dipping method, a doctor blade method or the like using a coating solution dissolved or dispersed in.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

(Manufacturing Example 1 of Photoreceptor) An aluminum drum for a substrate, which has been mirror-finished by an ultra-precision lathe using diamond vide, is cleaned by ultrasonic cleaning using an organic solvent and steam cleaning, and then by drying, It was installed in the reaction tube (20) of the capacitively coupled glow discharge divider shown in FIG.

Then, the first tank (6) has SiH ₄ gas, the second tank (7) has C ₂ H ₂ gas, the third tank (8) has B ₂ H ₆ gas or PH ₃ gas, and the fourth tank (9a). H ₂ gas and NO gas in the 5th tank (9b) were installed and the reaction gas was flowed at the flow rate shown in Table 1 to form a carrier injection blocking layer a on the conductive substrate.
-Si: H: P: O: N, a-Si: H (z≈0.
2), a-SiC: H as a carrier generation layer, (x≈0.25, y
≈0.3) SiC was provided as a surface protective layer to obtain a photoconductor 1 having a thickness of 29.6 μm.

(Production Example 2) In the same manner as in Production Example 1, a reaction gas was introduced at a flow rate shown in Table 2, and a-Si: H: P: O: N carrier injection blocking layer, a-
Si: H: B (z ≈ 0.2, B: about 3 ppm) carrier transport layer, a-Si
Carrier generation layer of C: H (x≈0.25, y≈0.3) and SiC
Then, the surface protective layer of 1 was sequentially provided to obtain a photoconductor 2 having a thickness of 33.6 μm.

(Manufacturing Example 3) In the same manner as in Manufacturing Example 1, a reaction gas was introduced at a flow rate shown in Table 3, and a-Si: H: P: O: N carrier injection blocking layer, a-S.
i: H: B (z ≈ 0.2, B: about 3 ppm) carrier transport layer, a-Si
A carrier generation layer of C: H: P (x≈0.25, y≈0.3, B: about 1 ppm) and a surface protective layer of SiC were sequentially provided to obtain a photosensitive member 3 having a size of 29.6 μm.

A corona discharge of −5.6 kV was performed on the obtained three types of photoreceptors, and the surface potential, the photosensitivity to monochromatic light of 650 nm (0.3 μW / cm ² ) and the residual potential were measured.

 The results are shown in Table 4.

As is clear from the table, a high surface potential of −600 V or higher was obtained, and the excellent characteristics of a photosensitivity of 0.58 cm ² / erg or higher and a residual potential of −45 V or lower were exhibited.

〔The invention's effect〕

As described above in detail, the photoconductor of the present invention is a function-separated laminated photoconductor, and has a carrier injection blocking layer mainly composed of amorphous silicon containing a Group V a element of the periodic table on a conductive substrate. By sequentially forming a carrier transport layer mainly composed of amorphous silicon, a carrier generation layer mainly composed of amorphous silicon carbide, and a surface protective layer, it is possible to obtain a high negative chargeability and also in photosensitivity and residual potential. It is possible to obtain a photoconductor that has characteristics that are practically satisfactory and that has excellent durability.

[Brief description of drawings]

FIG. 1 is a sectional view showing the layer structure of a photoconductor used in an embodiment of the present invention, FIG. 2 is a sectional view showing the general layer structure of the photoconductor, and FIGS. 3 (a) and 3 (b) are FIG. 4 is a diagram for explaining electrophotographic characteristics of the present invention, and FIG. 4 is an explanatory diagram of a capacitively coupled glow discharge decomposition apparatus used in an embodiment of the present invention. 1 ... Substrate 2 ... Carrier injection blocking layer 3 ... Photoconductive layer 3a ... Carrier transport layer 3b ... Carrier generation layer 4 ... Surface protection layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hitoshi Takemura Hitoshi 6-16, Haseno, Jamizo-cho, Yokaichi-shi 6 Kyocera Co., Ltd. Shiga Yokaichi factory (72) Inventor Kokichi Ishikura, 1166, Haseno, Hachimi-cho, Yokaichi-shi 6 Kyocera Corporation Shiga Yokaichi Factory (56) Reference JP-A-61-94054 (JP, A) JP-A-57-105744 (JP, A) JP-A-57-105745 (JP, A) JP-A-SHO 56-62255 (JP, A) JP 61-281250 (JP, A) JP 61-59340 (JP, A) JP 59-67547 (JP, A) JP 63-85566 (JP, A)

Claims (5)

(57) [Claims] 1. A carrier injection blocking layer mainly composed of amorphous silicon containing an element of group V a of the periodic table, a carrier transport layer mainly composed of amorphous silicon, and mainly composed of amorphous silicon carbide on a conductive substrate. An electrophotographic photosensitive member capable of being charged to a negative polarity, in which a carrier generating layer and a surface protective layer are sequentially formed. 2. The amorphous silicon carbide is represented by the following formula [Si _(1-X) C _X ] _(1-Y) A _Y , where A is H or a halogen element 0.01 ≦ X ≦ 0.9 0.05 ≦ Y ≦ 0.5. The electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is provided. 3. The carrier transport layer according to claim 1, wherein A is H or an amorphous silicon represented by a halogen element 0.05 ≦ Z ≦ 0.5 in the following formula Si _(1-Z) A _Z. The electrophotographic photosensitive member according to item 1. 4. The electrophotographic photosensitive member according to claim 1, wherein the carrier transport layer contains an element of Group IIIa of the periodic table. 5. The electrophotographic photosensitive member according to claim 1, wherein the carrier generation layer contains an element of Group V a of the periodic table.