JPS59131941A - Amorphous silicon photosensitive body - Google Patents

Abstract

PURPOSE:To provide a single-layered photosensitive layer which has small strain of the layer and can be laminated quickly by incorporating an element which controls the valence electron of the photosensitive layer and an element which varies an optical forbidden band and dielectric constant in the amorphous silicon photosensitive layer. CONSTITUTION:The 1st element which controls the valence electron of an amorphous silicon photosensitive layer is, for example, IIIB group elements and VB group elements, and the 2nd element which varies an optical forbidden band and dielectric constant and decreases the strain of the layer is, for example, C, N, O, etc. A conductive substrate 6 is mounted in a reaction vessel 2, and gaseous raw material having, for example, SiH4, Si2H6, etc., gas contg. the 1st and 2nd elements, and gaseous carrier such as H2 or the like are blown from an electrode 14 and plasma gas is generated by glow discharge between the electrode 14 and the substrate 6 to form the layer having such concn. gradient that the content of the elements is higher near the boundary with the substrate 6 and is smaller as said electrode and substrate separate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention belongs to the technical field of amorphous silicon photoreceptors, particularly amorphous silicon photoreceptors that can be used in image forming apparatuses.

[Technical background of the invention and its problems]

In recent years, materials with high photosensitivity and mechanical integrity have replaced conventional selenium, zinc oxide, resin-dispersed cadmium sulfide, etc. as materials necessary for forming photosensitive layers in electrophotographic photoreceptors used in image forming devices, such as electrophotographic devices. Amorphous silicon (hereinafter abbreviated as a-8i), which has physical strength and heat resistance and is harmless to the human body, is being developed. a-8
i has a lower specific resistance at room temperature than conventional photoreceptor materials.

Therefore, simply by forming a single layer of a-8i on the surface of a conductive substrate, it is not possible to exhibit the charging function as an electrophotographic photoreceptor. Therefore, a photosensitive layer consisting of multiple layers has been proposed by sandwiching the a-8i layer and forming a blocking layer on the side of the conductive substrate and a surface layer on the side opposite to the conductive substrate.

However, when a plurality of photosensitive layers are formed, large strains occur in the photolayer itself due to differences in internal stress among the layers, and the layers peel off at their interfaces. Further, since a large amount of polysilane produced as a by-product during the formation of the photosensitive layer adheres to the interface between each layer, the photosensitive characteristics are significantly deteriorated. In addition, the formation of several layers requires stopping the discharge, exhausting the gas required for the formed layer, and stabilizing the gas flow rate for forming the next layer after each layer is formed. It takes a long time to form a photosensitive layer.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an amorphous silicon photoreceptor having a single photosensitive layer that has good photosensitive characteristics, has small layer distortion, and can be layered quickly. The purpose is to

[Summary of the invention]

The outline of the present invention for achieving the above object is to provide an amorphous silicon photosensitive layer containing at least amorphous silicon formed on the surface of a conductive substrate, which is capable of controlling at least valence electrons of the amorphous silicon photosensitive layer. a first element having a phosphor and a 20th element that changes at least the optical forbidden band width and dielectric constant of the amorphous silicon photosensitive layer with a degree gradient in the thickness direction of the amorphous silicon photosensitive layer; That is.

[Embodiments of the invention]

The amorphous silicon photoreceptor according to the present invention has a single-layer amorphous silicon photosensitive layer having at least a-8i on a conductive substrate, and in the amorphous silicon photosensitive layer, at least one layer of the amorphous silicon photosensitive layer has an amorphous silicon photosensitive layer. A structure in which a first element that can be electronically controlled and a second element that changes at least the optical forbidden band width and dielectric constant of amorphous silicon M i M are distributed with a concentration gradient in the thickness direction of the amorphous silicon photosensitive layer. has.

Examples of the conductive substrate include a flat conductive substrate made of aluminum, a drum-shaped conductive substrate, and the like.

The first element and second element contained in the amorphous silicon photosensitive layer are elements excluding Si, H, and halogen.

The first element is an element that is doped to enable control of valence electrons in the amorphous silicon photosensitive layer, such as group 1iB elements such as B and Ga, P, As,
Examples include Group VB elements such as Sb. The first element has a high content near the interface between the amorphous silicon photosensitive layer and the conductive substrate, and is preferably contained in the amorphous silicon photosensitive layer with a concentration gradient similar to that on the conductive substrate. When the first element is included in the amorphous silicon photosensitive layer with such a concentration gradient, it imparts rectifying properties to the amorphous silicon photosensitive layer, makes it possible to charge the surface of the amorphous silicon photosensitive layer either positively or negatively, and to improve the amorphous silicon photosensitive layer. The transfer of charge carriers to the conductive substrate, which occurs when the body is exposed to light, is not hindered. For example, an amorphous silicon photoreceptor using an 11th group B element such as B or Ga as the first element is not a positively charging photoreceptor, and the (5) second element is 2% 8b, As, etc. An amorphous silicon photoreceptor using Group VB elements is a negative charging photoreceptor. Further, the amorphous silicon photosensitive layer containing a-8i and H or a halogen element has slightly n-type properties, and its dark resistance is as low as 10 9 to 10 11 Ωm. However, in the amorphous silicon photosensitive layer having a-8+ and H or a halogen element, B,
Group B elements such as Ga 10"~1017a tm/c
When the sonoamorphous silicon photosensitive layer is doped to about tI, the n-type property disappears, and the dark resistance becomes 101° to 101°.
As a result, the charge retention ability of the amorphous silicon photoreceptor can be increased.

Furthermore, when a trace amount of B is added to an amorphous silicon photosensitive layer containing a-Si and H or a halogen element, the amorphous silicon photosensitive layer loses its n-type properties and its dark resistance decreases to IQ 1G- 1013Ωan
In addition to increasing the optical carrier transport capacity, it is possible to form clear images. Therefore, the concentration gradient of Group 111B elements in the thickness direction (6) of the amorphous silicon photosensitive layer is, for example, 1019 to 1 in the vicinity of the interface with the conductive substrate.
It is preferable that the concentration is 0" a tm/crl, and in other regions the enemy degree is 1016 to 11017 ai/-. Also, the concentration gradient of group VB elements is as follows:
For example, the concentration may be high 1 near the interface with the conductive substrate, but the concentration may be 0 in other regions. Further, the amorphous silicon photosensitive layer may contain a group VB element at a high concentration near the interface with the conductive substrate, and a group Ill B element at a low concentration in other regions.

The second element is doped to vary the optical bandgap and electrical resistivity of the amorphous silicon photosensitive layer, further reduce the strain of the amorphous silicon photosensitive layer, and improve the chemical stability against the external atmosphere. Examples of such elements include 0, N10, etc. When the second element is contained in the amorphous silicon photosensitive layer, the optical forbidden band width of the amorphous silicon photosensitive layer can be increased and the aperture ratio and reflectance can be reduced. especially,
In the amorphous silicon photosensitive layer containing B, 0, N
, 0 can significantly reduce the strain of the amorphous silicon photosensitive layer. Furthermore, by increasing the content of the second element, the chemical stability of the amorphous silicon photosensitive layer can be significantly improved. Therefore, as the concentration gradient of the second element in the amorphous silicon photosensitive layer, it is preferable to make the content of the second element high near the free surface of the amorphous silicon photosensitive layer. In this way, the vicinity of the free surface of the amorphous silicon photosensitive layer can be made extremely chemically stable against the outside world, and light reflection on the free surface can be reduced to enable efficient light absorption. It can enable light absorption in a wide range deep in the photosensitive layer, which can reduce the probability of recombination of photogenerated charge carriers, thus making the amorphous silicon photosensitive layer highly sensitive. be able to. Further, in the amorphous silicon photosensitive layer, the content of the second element may be set to a concentration near the interface of the conductive substrate. If you do that, 2J! It is possible to reduce the strain of the amorphous silicon photosensitive layer relative to the conductive substrate, and to improve the function of preventing injection of charge carriers from the conductive substrate into the amorphous silicon photosensitive layer during charging.

The amorphous silicon photosensitive layer having a first element and a second element with a constant concentration gradient is composed of silicon atom-containing molecules such as SiH4, SilH6.

Source gas containing Smu3H@, SiF4, etc., gas containing the first element, gas containing the second element, and H2
It can be formed by a glow discharge decomposition method using a carrier gas such as @Ar%He, a reactive gas, an e-stuttering method, or the like.

Next, the amorphous silicon photoreceptor and its production according to the present invention will be explained in more detail.

EXAMPLE An amorphous silicon photoreceptor was manufactured using the amorphous silicon photoreceptor manufacturing apparatus shown in FIG.

The apparatus for manufacturing an amorphous silicon photoreceptor (9) shown in FIG. 1 includes a reaction vessel 2, a gas supply section 4, and an exhaust device (not shown). Inside the reaction vessel 2, a conductive substrate 6, for example, a mirror-polished aluminum plate of 150+w x 200 m, can be mounted, and a substrate support is provided that has a heater 8 for heating the conductive substrate 6 to a predetermined temperature, for example, 100 to 300°C. A body 10 is provided, and an electrode 14 is provided above and opposite to the substrate support 10 and has a large number of gas blowing holes 12. A high frequency power source 18 (for example, 13.56 MHz, rated 50
0W) is electrically connected.

Further, the electrode 14 as a whole also functions as a gas blowing device, and can blow gas supplied from the gas supply section 4 between the electrode 14 and the conductive substrate 6. Therefore, by applying a high frequency electric field between the electrode 14 and the conductive substrate 6 while blowing out gas from the electrode 14, it is possible to generate plasma gas excited by glow emission. Note that the electrode 14 is insulated from the reaction vessel 2 and the gas supply section 4 by an insulator 20, 22. Further, the reaction container 2 is connected to an exhaust device (not shown) via a flow rate adjustment device 24 that adjusts the flow rate of gas exhausted from inside the reaction container 2. The gas supply unit 4 is, for example, 8iH4
Gas, OH4 gas, N! Gas, B, H, 20 ppm
To H! Gas diluted with (Bz H6/Hz 20p
pm gas), B, H, diluted with H3 to 200 ppm, x, (Bl H6/H2200 ppm gas) and B! Gas diluted with H2 to 2000 ppm (
B2H6/H*2000ppm gas) 6 gas lines filled with each 26 +! : , Nonoru f28
s has a flow controller 30 and a pressure reducing valve 32,
It is configured such that various gases can be supplied into the reaction vessel 2 as desired.

Using the amorphous silicon photoreceptor manufacturing apparatus configured as described above, an amorphous silicon photoreceptor according to the present invention was manufactured under the following manufacturing conditions.

7111 Thermal temperature of electrically conductive substrate: 240°C Discharge power: Reaction chamber pressure during 75W discharge: 0.35 Torr Gas flow rate
As shown in Table 1, the thickness of the photosensitive layer of the amorphous silicon photoreceptor obtained by discharging for 240 minutes was 21.5 μm. The changes in the concentrations of B and C in the thickness direction of the amorphous silicon photosensitive material 1- corresponded to the changes in the flow rate of the supplied gas over time. When the obtained amorphous silicon photoreceptor was subjected to corona discharge at a voltage of +5 KV, the photosensitive characteristics showed that the surface potential was +520 V,
The dark resistance attenuation rate after 15 seconds after corona discharge is 28%, the amount of halogen lamp exposure to halve the surface potential is Q,
It was 8tux・sec. Further, the resulting amorphous silicon photoreceptor was corona charged to +5 KV, imagewise exposed at a light intensity of 31 uxmSec, and developed by a two-component dry magnetic brush method, resulting in a toner image of good image quality.

EXAMPLE Using the same amorphous silicon photoreceptor manufacturing equipment as used in Experimental Example 1, the flow rates of B, H, and OH gases diluted with H2 to various concentrations were changed over time as shown in Table 2. Otherwise, an amorphous silicon photoreceptor was manufactured under the same manufacturing conditions as in Experimental Example 1.

(13) Table 2 (14) The changes in the flow rate over time of the gases shown in Table 1 are also shown in FIG.

The thickness of the photosensitive layer of the amorphous silicon photoreceptor obtained by discharging for 240 minutes was 21.0 μm. Changes in the concentration of B and C in the thickness direction of the amorphous silicon photosensitive layer corresponded to changes in the flow rate of the supplied gas over time. When the obtained amorphous silicon photoreceptor was subjected to corona discharge at a voltage of +5 KV, the photosensitive characteristics were that the surface potential was +550 V, the dark resistance decay rate was 22% 15 seconds after corona discharge, and the surface potential was halved. The exposure amount of the useless halogen lamp is 0.8
It was Luxasec. Furthermore, after applying +5 KV corona charging to the obtained amorphous silicon photoreceptor @
Image exposure was carried out at a light intensity of 3 tuxasec, and development was performed by a two-component dry magnetic brush method, whereby a toner image of good quality was obtained.

〔Effect of the invention〕

According to this invention, since a single amorphous silicon photosensitive layer containing a first element and a second element with a concentration gradient in the thickness direction is simply deposited on a conductive substrate, the amorphous silicon photosensitive layer can be rapidly formed. body can be manufactured. Since the second element is contained in the amorphous silicon photosensitive layer, it is possible to form an amorphous silicon photosensitive layer with small strain. Because of this distribution, it is possible to manufacture an amorphous silicon photoreceptor with excellent photosensitivity.

[Brief explanation of drawings]

Figure m1 is an explanatory view showing an amorphous silicon photoreceptor manufacturing apparatus which is an example of a device for manufacturing an amorphous silicon photoreceptor according to the present invention, and Figure 2 is a characteristic diagram showing changes over time in the flow rate of supplied gas. . 6... Conductive substrate.

Claims (2)

[Claims] (1) In an amorphous silicon photosensitive layer formed on the surface of a conductive substrate and having at least amorphous silicon, at least a first element capable of controlling valence electrons of the amorphous silicon photosensitive layer and at least an optical element of the amorphous silicon photosensitive layer are included. 1. An amorphous silicon photoreceptor comprising: a second element that varies a forbidden band width and a dielectric constant; the amorphous silicon photoreceptor layer has a concentration gradient in the thickness direction of the amorphous silicon photoreceptor layer. (2) The amorphous silicon photosensitive material according to claim 1, wherein the first element is an element belonging to Group IB, and the second element is an element belonging to Group VB. body.