JPH028858A - Electrophotographic sensitive body - Google Patents

Abstract

PURPOSE:To improve sensitivity, electrostatic characteristic, nondefective rate, and film forming speed by using an a-SiN film contg. H and/or halogen at a specific % value or above as a photoconductive layer and forming said layer by an electron cyclotron resonance method. CONSTITUTION:This photosensitive body is incorporated by laminating an intermediate layer 2 for blocking the injection of charge from a base 1 side, the photoconductive layer 3 consisting of the a-Si contg. nitrogen and a surface coating layer 4 for protecting the surface and improving the electrostatic chargeability successively on the conductive base 1. The photoconductive layer 3 is formed of the a-SiN film contg. >=40atom.% H and/or halogen and is formed by the electron cyclotron resonance method. The sufficient photosensitivity and the excellent electrostatic charge holding power at the time of repeating are obtd. in this way and the nondefective rate and film forming rate are improved.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electrophotographic photoreceptor used in an image forming apparatus that forms an image using an electrophotographic method, such as an electrostatic transfer type copying machine. Used as a photoreceptor.

<Prior art> Recently, amorphous silicon nitride (referred to as a-3iN) containing hydrogen (H) has been used as a photoconductive layer as an electrophotographic photoreceptor used in image forming apparatuses that form images using electrophotography. Practical use of a photoreceptor (referred to as a-5iN photoreceptor) is desired due to the following advantages.

■Long lifespan.

■Harmless to the human body.

■High sensitivity.

At this time, the a-SiN photoreceptor is produced by plasma CVD method or metsputter method, and Hff in the film is
JP-A-54-145539 states that i is strictly 1 to 4 Q Btomic%.

<Problems to be solved by the invention> Hf in the film used as a photoconductive layer of an electrophotographic photoreceptor
The conventional a-3iN film, whose fi is strictly limited to 1 to 40 atomic%, has a photosensitivity (ημ
It has a τ of 10-' to 1 O-'cm/v), and by doping with B (boron), the dark specific resistance value is also about 10'3 Ωcm, which is sufficient for use as a photoreceptor. Ta.

However, when we measured the repetition characteristics of the photoreceptor, we found that compared to the charging potential obtained by placing a charge on the surface of the photoreceptor in the brightest light, the charging potential obtained by placing a charge anew after exposure or photostatic discharge The potential was a value that was 20% or more lower than the initial value. In other words, in that film ■] 1 is 1 to 4 Q
Conventional a-, which was strictly limited to atomic%
A photoreceptor using a SiN film as a photoconductive layer had a very low charging ability in the practical stage, and was not suitable for practical use. The reason for this is that the inclusion of N increases gap states such as dangling bonds of Si, and the charges excited by exposure and photo-neutralization are excessive compared to the amount of charge on the photoreceptor surface. , is trapped in the gap state, and is excited again by the electric field applied during the next charging, canceling out the surface charge.

Moreover, since the conventional a-3iN photoreceptor is manufactured by plasma CVD method and metsuputter method, it is unavoidable to use (Si)
H2) Polymer powder called n was generated, which adhered to the substrate of the photoreceptor during film formation, hindering normal film growth, and resulting in the photoreceptor being rejected. Furthermore, with conventional manufacturing methods, the film formation speed is extremely slow (it takes a long time to create the photoreceptor, making it impossible to reduce costs.
In order to obtain sufficient photosensitivity, the substrate must be heated.

Means for Solving the Problems> The electrophotographic photoreceptor according to the present invention is characterized in that the photoconductive layer of the photoreceptor is an a-3iN film containing 40 atomic% or more of 1 and/or halogen. be.

Further, the a-SiH layer is created by an electron cyclotron resonance method.

Effects> According to the electrophotographic photoreceptor of the present invention, the a-3iN film containing 40 atomic % or more of H and/or halogen has a very high specific resistance of 10 13 Ωcm and also has sufficient photosensitivity. Furthermore, it is possible to reduce the number of gap states that act as trap centers for excited charges. Therefore, by using this a-3iN film as a photoconductive layer of an electrophotographic photoreceptor, it is possible to create a photoreceptor that has sufficient photosensitivity and is particularly excellent in charge retention ability during repeated cycles.

Furthermore, by producing this film using the electron cyclotron resonance method, the yield rate and film forming rate can be increased, and costs can be reduced.

<Example> FIG. 1 shows a laminated structure of an electrophotographic photoreceptor according to the present invention. The figure shows a conductive support l made of AI, etc., an intermediate layer 2 to prevent charge injection from the support side, a photoconductive layer B3 made of a-3i containing nitrogen, and a photoconductive layer B3 to protect the surface and improve charging ability. This is an electrophotographic photoreceptor that is formed by sequentially laminating a surface coating layer 4 for the purpose of increasing the image quality.

FIG. 2 shows a film forming apparatus for forming an a-3iN film by the electron cyclotron resonance method. In the film forming apparatus, the plasma chamber 11 has a cavity resonator configuration, and microwaves of 2.45G and 4z are introduced through the waveguide 14. Note that the microwave introduction window 15 is made of quartz glass through which microwaves can pass.

H3 is introduced into the plasma chamber 11. Further, a magnetic coil 16 is installed around this plasma chamber, and a divergent magnetic field is applied to draw out the plasma generated here. A conductive substrate 18 made of AI or the like is installed in the deposition chamber 12, and in this embodiment, since it is drum-shaped, it is supported by a support and rotated. The deposition chamber 12 contains, for example, S+)14.5i2Ha-3iF as a raw material gas.
A silicon compound containing H or a halogen, such as aSiC1, 5iHC13, SiHyCI2, or a mixture thereof is introduced from the introduction pipe 19. Further, as a gas for supplying nitrogen (N), a gas such as NHy.N is also introduced from the introduction pipe 19. Further, an inert gas such as He or Ar is introduced through the introduction pipe 17.

First, the plasma chamber 11 and the deposition chamber 12 are evacuated, and Hff1l source gas is introduced into each chamber. The gas pressure at this time is set to 10''torr to 10-'torr.Here, microwaves generated by the microwave power source 20 are introduced into the plasma chamber 11 through the rectangular waveguide 14, and a magnetic field is also applied. is applied to excite the plasma. The plasma-formed H2 and source gas are guided to the substrate 18 by the divergent magnetic field, and a-3iN is deposited. Since the support is rotated, a uniform film is formed. Furthermore, By adjusting the position and size of the plasma extraction window 13, it is possible to improve the uniformity of the film.

In the film forming apparatus configured as described above, an experiment was conducted using SiHy gas and NHy gas as source gases. The film forming conditions at this time were such that the raw material gas was (S + H4 + N
H3) = 120 sec m-gas ratio is (S
fHy/SiHy+NHy+)~0.96, microwave power = 2.5kw, gas pressure 2.7~4,
Change to 3mTorr, A, a-3iG on one board
The e layer was laminated. Note that the substrate was not heated.

The gas pressure dependence characteristics of the attractive conductivity (lμτ) and dark specific resistivity (ρd) of this (Da S+N film) with respect to Hff 1565 nm in the film are shown in FIGS. 3, 4, and 5, respectively.

As shown in these, select the gas pressure and set Hl to 40 a
By increasing toIIlic% or more, the dark specific resistance becomes 10+ for the first time without boron doping.
An a-3iN film with a conductivity of 3 Ωcm or more and high conductivity (high photosensitivity) was created.

Furthermore, in a region where the attractive conductivity (lμτ) increases, the dark specific resistivity (ρd), which is inversely proportional to μ, increases, which indicates that τ is elongated. It is a well-known fact that there is a strong causal relationship between τ and dangling bonds (as dangling bonds decrease, τ increases). Therefore, it was found that by increasing the amount of R to 40 atomic% or more, it was possible to mainly reduce the dangling bonds of Si atoms.

In this way, the dark resistivity is 1 without doping with boron.
The a-3iN film, which has a conductivity of 0+3 Ωcm or more and has high conductivity (high photosensitivity), is the best among conventional films (the amount is 40
This could not be achieved with an a-3iN film having atomic% or less.

In the present invention, by creating a-3ill by the electron cyclotron resonance method (
s I 82) No powder was generated.

Moreover, at this time, both the film forming speed and gas utilization efficiency depended greatly on the gas pressure, and by selecting the gas pressure, we were able to obtain a film forming speed and gas utilization efficiency that were 6 to 10 times higher than with conventional methods. . More preferably, Hl is 4 Q atoms
The gas pressure is higher than c%, that is, the dark specific resistance is 10"00
m or more, and has high conductivity (high photosensitivity)
The gas pressure (2~3,
5 mtorr) showed high values for both film formation speed and gas utilization efficiency.On the other hand, a-3iN films containing less than 40 atomic% of Il prepared by the conventional method generally had a low film formation speed. There was a tendency for photosensitivity to deteriorate in areas where the area was thick.

From this point as well, it has been found that the present invention has an advantage over conventional methods.

When a silicon compound containing halogen is introduced as a raw material gas, the total amount of Hffl and halogen in the film is 40
Needless to say, it needs to be atomic% or more. As a result of further intensive experiments, Hyl and/or
Alternatively, it has been found that when the amount of halogen is 60 atomic % or more, the optical band gap of the film becomes too large, making it unsuitable as a photoconductive layer of an electrophotographic photoreceptor that requires photosensitivity to visible light. In other words, H in the film
l and/or halogen amount is preferably 40 to 60 at
omic%, most preferably 40-55 at
The value is omic%.

Next, while fixing the Hffi in the film within the range of 43 to 46 atomic%, we changed the mixing ratio of Si H4 and NH3 gas to change the amount of N in the film.
Below mic%, there is not only no effect of increasing dark resistivity, but also
It was found that the function of N as a donor was dominant and the dark resistivity was rather lowered, making it unsuitable as a photoconductive layer of an electrophotographic photoreceptor. Furthermore, it has been found that when the content is 28 atomic % or more, the sensitivity to visible light decreases rapidly, and this is also not suitable as a photoconductive layer of an electrophotographic photoreceptor. In other words, as Nil in the film, S
Normally 0.01 to 28 atomic to i atomic weight
%, preferably 0.2-28 atomic%
The value is .

In addition, in controlling the conduction type, to make it P type, B,
A gas containing an element belonging to group Ⅰ of the periodic table, such as Hy, can be converted to N-type by introducing a gas containing an element belonging to group Ⅰ, such as PHy.

The a-SiN film according to the present invention can be used in devices that convert external optical information into electrical signals, such as photoconductive layers of electrophotographic photoreceptors, photosensitive parts of image sensors, and photosensitive parts of display elements laminated with liquid crystals. Most suitable for photosensitive areas. Furthermore, it can also be applied to devices such as solar cells and thin film transistors.

Next, a-
An example in which 3iN was used as a photoconductive layer of an electrophotographic photoreceptor will be described below.

(Example 1) N atom content @(N/Si) is l l atomic%
A-3iN containing 48 atomic% of Hf1l and doped with a trace amount of boron and having a film thickness of 24 μm was used as the photoconductive layer, and the surface coating layer was prepared by the electron cyclotron resonance method. A photoreceptor for positive charging was prepared, which included an a-3iC film and an a-Si film, which was prepared by the same method and doped with a large amount of boron, as an intermediate layer. The preparation conditions at this time are summarized in Table 1.

Here, the gas for doping boron is B
Compounds of boron and H or halogen such as tHa.BCI and .BHy are preferred. Also, atoms that have the same function as boron, such as aluminum, gallium, and indium, are suitable.

However, B when creating an intermediate layer or photoconductive layer
, I-1, are each diluted in H to 3000 pprrl or 30 ppm.

At this time, (SiHy)n powder was not generated at all, and the film forming speed and gas utilization efficiency were 6 to 10 times higher than the conventional method.
I got a much higher value. Furthermore, when the characteristics of the produced photoreceptor were measured, it was found to be particularly excellent in charging characteristics during repeated cycles. In addition, when this was mounted on a commercially available positive charging tq photographic machine and an image was produced, a good image was obtained.

In addition, as a surface coating layer, electron, cyclotron,
Good results have also been obtained when using an a-3iN film or an a-SiH film produced by the resonance method.

(Example 2) When only the gas pressure during photoconductive layer formation was changed and all other conditions were the same as in Example 1, the evaluation results of charging characteristics and image characteristics during repetition are shown in Table 2. Shown below.

As shown here, select the gas pressure and set Hffi to 40
Good results have been obtained when the content is atomic% or more.

Note that the N atom content ff1(N/
Si) was fixed in the range of 9 to 12%. In other words, in this example, the N atom content does not affect the results, and the experiment allows only the influence of Hffi on the film quality to be determined.

Table 2 (Example 3) A photoreceptor for negative charging was prepared under the same conditions as in Example 2 except that the leading conductive layer and the intermediate layer were doped with phosphorus instead of boron. The preparation conditions at this time are summarized in Table 3. PHy is used as a gas for doping phosphorus.
・Pct, ・Pct.

Compounds of phosphorus and H or halogen are suitable.

At this time, (5iHy)n powder was not generated at all, and both film forming speed and gas utilization efficiency were 6 to 10 times higher than the conventional method.
I got a much higher value. Furthermore, when the characteristics of the produced photoreceptor were measured, it was found to be particularly excellent in charging characteristics during repeated cycles. In addition, when this was installed in a commercially available copying machine for negative charging and an image was produced, a good image was obtained.

In addition, as a surface coating layer, electron, cyclotron,
Good results have also been obtained when using an a-3iN film or an a-3iO film produced by the resonance method.

<Effects of the Invention> According to the electrophotographic photoreceptor of the present invention, an a-3iN film in which the amount of Hffi and/or halogen in the film is 4 Q Btomic% or more is used as a photoconductive layer, so that sufficient light can be absorbed. It has high sensitivity and a very large dark specific resistance.
It is possible to create a photoreceptor with excellent charging characteristics, especially during repeated cycles, as well as sensitivity.

In addition, by creating this photoreceptor using the electron cyclotron resonance method (S i Hy)
No powder is generated at all, and both film forming speed and gas utilization efficiency are considerably higher than those of conventional methods, and as a result, an inexpensive electrophotographic photoreceptor can be produced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of an electrophotographic photoreceptor according to the present invention, FIG. Figures 4 and 5 show the hydrogen content in the film and the electrical conductivity (η
μτ) and dark specific resistivity (ρd), which exhibit gas-dependent characteristics. 1; Conductive support 2; Intermediate layer 3; Photoconductive layer 4; Surface coating layer Agent Patent attorney Takeshi Sugiyama (and 1 other person) Edition 10 1 #Kisen Diagram 2 Procedural Amendments June 27, 1999 Day

Claims (1)

[Scope of Claims] 1. A conductive substrate, and a 40at
Amorphous silicon nitride (a-Si_1_-_
x_-_y_-_zN_x:H_y:X_zHowever, X
is a halogen). 2. The electrophotographic photoreceptor according to claim 1, wherein the amorphous silicon nitride layer is formed by an electron cyclotron resonance method.