JP2562583B2 - 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 positive 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 resistance law 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 is not completely removed due to the optical memory effect and remains in the next image formation. Along with that, the previous image appears (ghost phenomenon)
There is a problem to say.

In addition, the conventional photosensitive member made of a-Si shown in FIG. 2 has a low charging potential of +400 to +500 V and insufficient charging ability, so that it is subject to various restrictions in electrophotography. In addition, since the film forming speed is slow, mass productivity is difficult, 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, has excellent positive charging ability, and has excellent sensitivity. There is.

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 II
A carrier injection blocking layer mainly composed of amorphous silicon containing a group Ia element with a content B1 and a periodic table II.
A carrier transport layer mainly composed of amorphous silicon containing a group Ia element with a content B2, and a periodic table IIIa
A carrier generation layer mainly composed of amorphous silicon carbide containing a group B element in a content B3 (however, B1 is
0.1 to 10000 ppm, B2 and B3 are 10000 ppm or less, and a positively chargeable electrophotographic photosensitive member is provided which is characterized in that B1>B2> B3) and a surface protective layer are sequentially formed.

 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 injection blocking layer (2) and a carrier transport layer (3
a), a carrier generation layer (3b) and a surface protection layer (4) are sequentially provided, and the carrier injection blocking layer (2) is a carrier from the conductive substrate (1) to the carrier transport layer (3a). It is provided to prevent injection,
The surface protective layer (4) is provided for the purpose of improving the durability and environment resistance of the photoconductor.

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, positive 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 electrons neutralize the positive charges on the surface of the photoconductor, and the holes migrate to the transport layer and are 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, among the above-mentioned layer structures, amorphous silicon containing an element of Group IIIa 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). It is important to use Si and 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 positively chargeable photoreceptor of the present invention, the carrier injection blocking layer has a periodic table
A P-type semiconductor is formed by adding a group a 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, the added Group IIIa elements of the periodic table are B and A.
l, Ga, In are mentioned, and B is preferable. 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. One is preferable. It should be noted that, also in this carrier transport layer, the above-mentioned Group IIIa element of the periodic table is added at 10000 ppm.
The following can be doped, especially in an amount of 1000 ppm or less. The addition of this group IIIa element of the periodic table can make the carrier transport layer intrinsic and increase the carrier mobility in the carrier transport layer, thereby improving the surface potential and sensitivity and reducing the residual potential. can do.

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

Also in the carrier generation layer, the periodic table IIIa described above is used.
By containing the group element in the range of 10,000 ppm or less, particularly in the range of 0.5 to 1000 ppm, the carrier generation layer becomes a p-type semiconductor, and the spectral sensitivity to the light wavelength in the near infrared region can be improved and the positive charging ability can be improved. .

According to the present invention, the group IIIa element of the periodic table added to the carrier generation layer, the carrier transport layer and the carrier injection blocking layer has the above-mentioned effects in each layer, but at the same time, in terms of the characteristics as a semiconductor, an energy band is formed. It works to shift to P type.

Therefore, when the Group IIIa element of the periodic table is added to the carrier injection blocking layer, the carrier transport layer, and the carrier generation layer, when the addition amount in each layer is B1, B2, and B3, B1> B2
It is important to satisfy the relationship of> B3. 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, the carrier injection blocking layer is 0.1
To 10 μm, the carrier transport layer is 10 to 50 μm, the carrier generation layer is 0.1 to 10 μm, and the surface protective layer is 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-containing gas such _{as, CH 4, C 2 H 4} , C 2 H 2, C 2 H 6, C 3 H 8, CF 4, CCl 4
C-containing gas such as H ₂ , He, Ne, Ar, etc. can be used as carrier gas if desired.
Group IIIa element-containing gas is included.

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.

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 Group IIIa element-containing gas of the periodic table at a ratio of 10 ^{−6 to} 1 mol%, particularly 10 ^{−5 to} 0.1 mol%. To do. When forming the carrier transport layer, Si-containing gas is used, and when forming the carrier generation layer, Si-containing gas and C-containing gas are used to form the film. 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 the B-containing gas in the same range as in forming the carrier injection blocking layer when forming the carrier transport layer and the carrier generating layer. In addition,
When Group IIIa element of the Periodic Table is added to each layer, the addition amount of each layer should be B ₁ > B ₂ > B ₃ as described above. It is necessary to adjust the ratio of the group a 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.

Note that B ₂ H ₆ gas is used as an example of the group IIIa element-containing gas of the periodic table.

In the figure, first, second, third, fourth and fifth tanks (6)
(7), (8), (9a), and (9b) have SiH ₄ , C ₂ H ₂ , and B ₂ H _{6 respectively.}
(B ₂ H ₆ is diluted to 38 ppm in H ₂ gas), H ₂ and NO gas are sealed, and H ₂ is also used as a carrier gas. These gases are released by opening the corresponding 1st, 2nd, 3rd, 4th and 5th control valves (10) (11) (12) (13a) (13b), the flow rate of which is determined by the mass flow controller. (14) (15) (16) (17a) (17b) is restricted and sent to the main pipe (18).

 Incidentally, (19) is a stop valve.

The gas flowing through the main pipe (18) is
0), the capacity coupling type discharge electrode (21) is installed inside the reaction tube, and the power applied to this is 50W to 3kW, and its frequency is 1MHz to 5MHz. is there. Inside the reaction tube (20), a cylindrical conductive substrate (22) for film formation made of aluminum is provided as a sample holder (23).
The holder (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, for example, in forming a B-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,
B ₂ H ₆ gas and H ₂ gas are released, and the amount of these released is regulated by the mass flow controllers (14) (15) (16) (17a) and is sent to the reaction tube (20) via 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 is decomposed to form a boron-containing a-SiC film 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, reference examples will be described with (manufacturing example 1) and (manufacturing example 2), and examples of the present invention will be described with (manufacturing example 3).

(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 decomposition apparatus 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, and the fourth tank
H ₂ gas was installed in the tank (9a), NO gas was installed in the fifth tank (9b), and the reaction gas was flowed at the flow rate shown in Table 1 to form a-Si: H as a carrier injection blocking layer on the conductive substrate. : B: O: N, a-Si: H (z≈0.2) as a carrier transport layer, a-SiC: H as a carrier generation layer, (x≈0.25, y≈0.3) SiC is provided as a surface protection layer, and the thickness is A photoconductor 1 of 32.6 μm was obtained.

(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: B: 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: B: N: O (B: about 800 ppm) carrier injection blocking layer, a-Si. : H: B (z≈0.2, B: about 3 ppm) carrier transport layer, a-SiC: H: B (x≈0.25, y≈0.3, B: about 1 ppm) carrier generation layer, and SiC surface protection Layer sequentially, 29.
A 6 μm photosensitive member 3 was obtained.

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 + 700V or higher was obtained, photosensitivity of 0.50 cm ² / erg or higher 3, residual potential potential of 45V.
The following excellent characteristics were shown. Particularly, the photoreceptor of Example 3 had the best surface potential and photosensitivity.

By the way, on the Al conductive substrate, a-Si: H: B: N: O carrier injection blocking layer (2.5 μm), a-Si: H: B (25 μm), and SiC surface protection layer (0.5 μm) were formed. When a similar experiment was conducted using a photoconductor, the surface potential was +410 V, the photosensitivity was 0.60 cm ² / erg, and the residual potential was 20 V, which was a low surface potential.

[Effects of the Invention] As described above in detail, the photoreceptor of the present invention is a function-separated laminated photoreceptor, which is mainly composed of amorphous silicon containing a Group IIIa element of the periodic table on a conductive substrate. By forming the carrier injection blocking layer, the carrier transport layer mainly composed of amorphous silicon, the carrier generation layer mainly composed of amorphous silicon carbide, and the surface protective layer in order, it is possible to obtain high positive chargeability and photosensitivity. In addition, it is possible to obtain a photosensitive member that has characteristics that are practically unproblematic with respect to the residual potential 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 61-94054 (JP, A) JP 57-105745 (JP, A) JP 57-105744 (JP, A) JP 56-62255 (JP, A) JP-A-56-64346 (JP, A)

Claims (3)

(57) [Claims] 1. A carrier injection blocking layer composed mainly of amorphous silicon containing a group IIIa element of the periodic table at a content B1 on a conductive substrate, and a group IIIa element of the periodic table at a content B2. A carrier transport layer mainly containing amorphous silicon and a carrier generation layer mainly containing amorphous silicon carbide containing a Group IIIa element of the periodic table at a content B3 (where B1 is 0.1 to 10000).
ppm, B2 and B3 are less than 10000ppm, B1>B2> B
An electrophotographic photosensitive member capable of being positively charged, characterized in that 3) 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 formula Si _(1-z) A _z. The electrophotographic photosensitive member according to item 1.