JPH0282261A - Image carrier body - Google Patents

Abstract

PURPOSE:To enhance transfer performance of each of holes and electrons by successively laminating a first photoconductive layer, a second photoconductive layer, an interlayer, and a surface layer on a support provided with a conductive surface. CONSTITUTION:The photoconductive layer made mainly of amorphous silicon and composed of the first layers 3 having a film thickness of x, and 0.6ppm <=B/Si <= 1.4ppm, and the second layer 4 having a film thickness of y, and 1.4ppm <= B/Si <= 4.0ppm, and 1/40 <= y/L, where L = x + y, the interlayer 5, and the surface layer 6 made mainly of amorphous silicon, and containing B and N as follows; 800ppm <= B/Si <= 4,800ppm, and 30 atomic % <= N/Si are successively laminated on the support 1 provided with the conductive surface. The interlayer 5 has the B/Si content equal to that of the layer 4 at the interface and the B/Si rises continuously in the direction from the support 1 to the surface layer 6, and it has B/Si content and N content same as those of the layer 6 at the interface, and they continuously change near the interface, thus permitting each of transfer performances of holes and electrons to be improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an image carrier for recording an electrostatic latent image in an electrophotographic device, etc., and more specifically, an image carrier capable of bipolar operation. Regarding the body.

[Prior art]

An amorphous silicon (hereinafter referred to as a-3i) photoreceptor has been announced as a photoreceptor capable of bipolar operation (
For example, 1981, National Conference of the Institute of Electrical Engineers of Japan, etc.).

The photoreceptor has a photoconductive layer containing a-St as a main component formed on a support having a conductive surface.

[Problem to be solved by the invention]

By the way, the a-5i photoreceptor having a single layer structure as described above has a fatal problem of inferior basic performance as a photoreceptor, and has not been commercialized. On the other hand, a photoreceptor with a multilayer structure
Although commercially available, this is only for - polarity operation.

In other words, bipolar photoreceptors must be able to run both hole and electron carriers, but there has been no conventional photoreceptor that has good running performance for both of these carriers.

The present invention has been made in view of the above circumstances, and provides an image carrier with a multilayer structure comprising a photoconductive layer and a surface layer in which the amount of impurities added is optimized so that both hole and electron traveling performance are improved. The purpose is to provide.

[Means to solve the problem]

The image carrier according to the present invention has amorphous silicon as a main component on a support having a conductive surface, and has a content of 0.6 ppm≦B/
A first layer of film thickness X with Si≦1.4 ppm+, and 1.4
ppm≦B/S i≦4.0 ppm 2nd J of film thickness y! a photoconductive layer in which 5L=x+y is in the relationship of 1/40≦y/L, a main component of amorphous silicon, B of at least 800ppm≦B/Si≦4800ppm, and 3゜ato+ic%≦N /Si and a N-containing surface layer, with an intermediate layer interposed therebetween, and the intermediate layer is formed with the second layer near the photoconductive layer side, and the surface layer with the N-containing surface layer of Si. It is characterized in that the vicinity of the layer side contains B and N in the same B/Si and N/Si composition ratios as the surface layer, respectively, and both composition ratios are continuously changed between the two vicinity.

[Effect]

By using the composition ratio as described above, an optimal photoconductive layer and surface layer can be obtained, and the energy gap between the photoconductive layer and the surface layer via the intermediate layer can be optimized. As a result, both the running performance of holes and electrons is improved.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on drawings showing embodiments thereof. FIG. 1 is an energy band diagram of the basic structure of an image carrier according to the present invention.

In the figure, 1 is a support having a conductive surface made of a metal material such as aluminum or an insulating material such as glass, which is coated with a conductive coating. 2 is a blocking layer containing a-5i as a main component and formed on the conductive surface of the support 1;
and 4 are a photoconductive first layer with a thickness of X and a photoconductive second layer with a thickness of y, respectively, which mainly contain a-3i, and the first photoconductive layer 3 is formed on the surface of the blocking layer 2, Further, the photoconductive layers 2114 are formed on the surfaces of the photoconductive layers 1N3, respectively. Reference numeral 5 denotes an intermediate layer formed on the surface of the second photoconductive layer, on which a surface M6 containing a-3i as a main component is formed.

FIG. 2 is different from FIG. 1 in the structure of the surface layer 6,
In FIG. 1, the optical bandgap of the surface layer 6 is kept constant, but since the surface layer is required to have a high resistance, for example, by increasing the N/Si content, the surface layer 6 is
The optical band gap is larger on the surface side than on the support 1 side.

Now, in realizing the energy distribution as shown in FIGS. 1 and 2, the following study was conducted.

In conventional positively charged drums (p-type blocking 11/i-type bulk layer/insulating surface layer), the traveling carriers were mainly holes, but in double-charged drums that perform bipolar operation, both holes and electrons are transported. It is necessary to run the carrier.

Figure 3 shows the travel performance of holes and electrons in the photoconductive layer (
This is a graph showing the BtHb concentration dependence of ημτ), and the horizontal axis is the flow rate ratio [p
ρm]. The ○ mark in the figure indicates the running performance of the hole (η
μτ)e, and ・ mark is electron traveling performance (ημ
τ)h are respectively shown.

From this figure, the driving performance is good for both (atl
It can be seen that (a) = around O-4 ppm. Further, in negative charging, the pre-exposure effect (a phenomenon in which the charging ability decreases from the second time onwards due to exposure to erase light) is greater than in positive charging. FIG. 4(a) is a model diagram showing the pre-exposure effect in conventional negative charging, and when the surface layer is irradiated with light, holes ◯ are trapped. Therefore, the fourth
As shown in Figure (b), the photoconductive layer ((BzHi) = 0.4
CB on the surface side 1μm of ppm)! H&) =1.0
By inserting ppm of the photoconductive second layer, holes ○ are no longer trapped, and the pre-exposure effect during negative charging can be reduced.

The pre-exposure effect was evaluated using one photosensitive drum as shown in Figure 5.
Pre-exposure effect evaluation coefficient ΔV = V, / using the surface potential v1 of the rotation and the difference v2 between this value and the surface potential of the second rotation.
This is done by V.

Now, in order to determine the optimal photoconductive layer that minimizes the pre-exposure effect (hereinafter referred to as ΔV (-)) during negative charging, the first photoconductive layer is CBZH&) = 0.4 ppm (hereinafter referred to as ΔV (-)).
Sil unless you say no! , the flow rate ratio to , i.e., the concentration), the film thickness xpm, and the photoconductive second layer (BzHa) = 1
．． Oppm-, film thickness yum, x + y = 20μ
As a result of the experiment, when y≧0.5μm, ΔV(
−) was confirmed to take a practical value. As a result, if the film thickness of the photoconductive layer is L, then 1/40≦y/L
The following relationship is obtained.

Next, the first photoconductive layer is 19.58 m1 and the second photoconductive layer is 0.1 m long.
When the (B2H4) concentration is fixed at 5 μm and the (B2H4) concentration is varied, the B / of each layer when ΔV (-) becomes a practical value.
According to the SIMS analysis results, Si is 0.6 ppm≦B/Si≦1.4 ppm for the photoconductive layer 1rM, and 1.4 ppm≦B/Si≦4.0 ppm for the second photoconductive layer. Ta.

As an example of a photoconductive layer that satisfies the above conditions, (B2H
6) Concentration 0.4 ppm, film thickness 19. um photoconductive first
A photoconductive second layer with a (BJ&) concentration of 1.0 ppm and a film thickness of 1 μm was used, and as a blocking layer, (N13
) concentration 5%, (ague) concentration 20 ppm, film thickness 1
The optimal surface layer when using a μm thick a-Si film was investigated with the film thickness fixed at 0.3 μm.

Here, in the surface layer, the (NH3) concentration is changed from 80% to 400% from the photoconductive layer side to the surface layer side, and B! H,
was added uniformly to determine the optimal surface layer (B2H
4) The concentration was changed to O''10000 ppm.

As a result, the surface layer that can make ΔV(-) the lowest value is:
According to SIMS analysis results, 800 ppm ≦B /
Si≦4800ppm of B and 30atomic%≦
It has been found that it is sufficient if N of N/Si is added.

Furthermore, in order to further lower ΔV(-), an intermediate layer was provided between the second photoconductive layer and the surface layer in order to smoothly connect them. As a result of studying the optimization of this intermediate layer, it was found that the vicinity of both the photoconductive second layer and the surface layer in the intermediate layer is 0.
When the composition ratios of B/Si and N/Si of 0.001 to 0.5 μm were made equal to the respective composition ratios of the photoconductive second layer and the surface layer, and the composition ratios therebetween were continuously changed,
The thickness of the intermediate layer is 0.001 to 2 μm, preferably 0.
．． It was found to be 0.01-1 μm, and further 0.05-0
．． When the thickness was 5 μm, a lower ΔV (-) was obtained.

By fabricating a photoreceptor that satisfies each of the above conditions by optimizing the gas flow rate, pressure, substrate temperature, RF POWHR, etc. during fabrication, we can determine the electron and hole ημτ that exhibit photoconductive performance in bipolar operation. Both 5×1O-9CIII
/v or more. Typical manufacturing conditions are shown in Table 1 and FIG. 6 below. FIG. 6 is a graph showing changes in doping rate, and the vertical axis is plotted on a logarithmic scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the manufacturing procedure of an image carrier according to the present invention will be specifically explained using a schematic diagram of a manufacturing apparatus shown in FIG. In this embodiment, a plasma CVD apparatus is used in which a discharge electrode 8 on a hollow cylinder is arranged in a sealed container 7 into which raw material gas is introduced. A support l having a conductive surface and a conductive surface is rotatably inserted concentrically. In this state, first, the rotary pump 9 and the mechanical booster pump 10 are driven to evacuate the inside of the sealed container 7 to a pressure of about 1X10-''.Then, while rotating the support 1, the inside of the sealed container 7 is inserted. 27 by a heater (not shown)
At the same time as heating up to 0°C, Sil+ is placed in the sealed container 7.
Predetermined amounts of B z It h gas based on gas and H2 gas, N, 0 gas, and lh gas as a dilution gas were introduced through the flow rate setting device 11, and the inside was adjusted to 1.0 Torr. Hold. Next, in this state, a high frequency power of 200 W with a frequency of 13.56 MHz was applied from the optical frequency power supply 12 to the discharge electrode 8 at a high frequency potential, and the support l was at a ground potential to achieve a blockage of 0.3 μm. Create layers.

Thereafter, a first photoconductive layer, a second photoconductive layer, an intermediate layer, and a surface layer are sequentially laminated in the same manner.

In order to evaluate the performance of the photoreceptor manufactured in this way, we measured the ημτ of electrons and holes, and found that the ημτ of electrons was 9X10-9 cal/V, and the ημτ of holes was 6XIO-9cni/V. It was confirmed that the operation was possible.

Next, when we set this on a commercially available PPC and examined the images, we found that when positively charged, images comparable to conventional unipolar devices were obtained, and in addition, when the polarity of the RPC charger was set to negative, By replacing the film, an image in which the negative film was also reversed to positive was obtained.

〔effect〕

As described above, in the image carrier according to the present invention, in the multilayer FL image carrier, both hole and electron traveling performance are good, and bipolar operation at a practical level is possible. Even in bipolar operation, the same performance and signal chain properties as the conventional multilayer structure image carrier for unipolar operation were achieved.

Also, when this image carrier is set on PPC, P
You can rotate images in the normal direction without changing the equipment of your PC.
The present invention has excellent effects such as being able to add a reversing function.

[Brief explanation of the drawing]

Fig. 1 is an energy band diagram of the basic structure of the image carrier according to the present invention, Fig. 2 is an energy band diagram with a partially modified structure of Fig. 1, and Fig. 3 is a dependence of ημτ on the photoconductive layer B2H6 concentration. Figure 4 is a model diagram for reducing the negative charging pre-exposure effect, Figure 5 is a diagram for calculating the pre-exposure effect evaluation coefficient, Figure 6 is a graph showing changes in doping rate, and Figure 7 is a model diagram of the reduction of the negative charging pre-exposure effect. It is a schematic diagram. DESCRIPTION OF SYMBOLS 1...Support 2...Blocking layer 3...Photoconductive first
Layer 4: Photoconductive second layer 5: Intermediate layer 6: Surface layer frame Applicant: Sanyo Electric Co., Ltd. Agent
Patent attorney Noboru Kono B2HC/S・H4 ζppm) Group procedural amendment (voluntary) December-29, 1988

Claims (1)

[Scope of Claims] 1. A first layer containing amorphous silicon as a main component and having a thickness x of 0.6 ppm≦B/Si≦1.4 ppm on a support having a conductive surface; 4ppm≦B/Si≦4.0
It has a second layer with a film thickness y of ppm, and L=x+y is 1/40
A photoconductive layer having a relationship of ≦y/L, B containing amorphous silicon as a main component, B of at least 800 ppm≦B/Si≦4800 ppm, and 3
and a surface layer containing N in the range of 0 atomic%≦N/Si are laminated in order with an intermediate layer interposed therebetween, and the intermediate layer is adjacent to the second layer near the photoconductive layer side. , further characterized in that the vicinity of the surface layer side contains B and N with the same B/Si and N/Si composition ratios as the surface layer, respectively, and both composition ratios are continuously changed between the two regions. An image carrier.