JPS59231879A - Photoconductor and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a photoconductor, resolution and sensitivity thereof are high and dark currents therefrom are small, by laminating an amorphous hydrogenated Si layer containing a large amount of hydrogen and an amorphous hydrogenated Si layer containing a small amount of hydrogen on an Si substrate through an Mo film and growing them and coating the surface with an SiO2 film by anodic oxidation. CONSTITUTION:An Mo film 12 is formed on a single crystal Si substrate 11 through a sputtering method and the substrate is entered into a magnetron sputtering device, and the inside of the device is evacuated up to 2X10<-6>Torr, the substrate 11 is kept at approximately 250 deg.C, polycrystalline Si is used as a target and an amorphous hydrogenated Si layer 13 containing a large amount of hydrogen is deposited first while bringing the pressure of Ar to 4.5X10<-3>Torr and the pressure of H2 to 5X10<-4>Torr. An amorphous hydrogenated Si layer 14 containing a small amount of hydrogen is laminated through the same method, and an SiO2 film 15 is formed on the surface of the layer 14 through anodic oxidation in oxygen plasma. A transparent electrode 16 consisting of In2O3 is formed on the film 15, and the electrode 16 is brought to negative polarity and the Mo film 12 to positive polarity and voltage is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a photoconductor, particularly a photoconductor thin film for image devices such as image pickup tube targets, solid-state imaging devices, electrophotographic photosensitive plates, and the like.

Structure and Problems of the Conventional Example The present inventors proposed a hydrogen-containing method in Japanese Patent Application No. 16508-1983 as a method for realizing a photoconductive film of amorphous hydrogenated silicon suitable for image devices with low dark current and photosensitivity. We demonstrated a structure in which a blocking layer is an amorphous hydrogenated photoconductive film with a large amount and a wide bandgap, and showed that it can be realized by reactive sputtering. A layer with a large amount of hydrogen is particularly effective as a hole blocking layer, and it is necessary to introduce acceptor impurities to reduce electron injection. However, even a layer with a large amount of hydrogen into which impurities were introduced was insufficient to prevent electron injection. Therefore, it was necessary to further reduce the dark current in storage type image devices.

Purpose of the Invention The object of the present invention is to provide a photoconductor provided with a photoconductive film that uses amorphous silicon hydride that has high resolution and high sensitivity and has a low dark current, and a method for manufacturing the same. .

Structure of the Invention The present invention provides a photoconductor comprising a first layer and a second layer having a resistivity of 109 or more layers mainly composed of amorphous silicon hydride, and wherein the second layer is A method for producing the same, characterized in that a first layer of a hole injection blocking layer having a higher hydrogen content than the first layer is sandwiched between the second layer and an electron injection blocking layer on a substrate. The target is made of silicon as the main component, and the first target with a hydrogen content of 100 or more is formed by reactive sputtering in an atmosphere containing hydrogen as a reactive gas.
Steps A and B of forming a layer and a second layer having a higher hydrogen content than the first layer and forming a silicon nitride layer or silicon oxide layer by reactive sputtering in an atmosphere containing Takarazen or oxygen as a reactive gas. layer (hereinafter referred to as oxide layer)
The first layer is sandwiched between the second layer and the oxide layer, and the first layer is formed on the substrate in the configured lamination order; The purpose is to convert a portion of one surface into a silicon nitride layer or a silicon oxide layer.

DESCRIPTION OF THE EMBODIMENTS As shown in FIG. 1, the photoconductor of the present invention has two layers of amorphous hydrogenated silicon 2, 3 and silicon nitride or It consists of a silicon oxide layer 4. The amorphous hydrogenated silicon having a high hydrogen content in the two layers acts as a hole injection blocking layer, and the silicon nitride or silicon oxide layer 4 acts as an electron injection blocking layer.

One example of a specific method for manufacturing a photoconductor will be described below.

As shown in Fig. 2 (a-j), the Mo film 12 is
is formed on a single crystal 81 weight-11 which is a substrate.

The substrate body (A) thus formed was placed in a magnetron spacing device and evacuated to 2 X 10 Torr, and then the substrate body (A) was kept at 250°C and polycrystalline silicon was targeted at an argon pressure of 4.5 X 10 Torr. To
rr.

100W in an atmosphere of hydrogen pressure 5 x 10 Torr
With the discharge power of , the thickness of 02~0
A 3 μm thick amorphous hydrogenated silicon layer 13 is formed, and the discharge power is continuously changed to 200 W to 1.5 to 1.5 μm in 90 minutes.
8 μm of amorphous hydrogenated silicon with a small amount of hydrogen] 4 is formed. Next, the surface is anodized in oxygen plasma to form silicon oxide 15 on the surface. Next, In2O,16
A thickness of about 100 OA is formed using a sputtering method. Both of these amorphous hydrogenated silicon layers 13 and 14 have a specific resistance of 10 Ωm or more. FIG. 321 shows the dark current when a voltage is applied with the transparent electrode 16 of negative polarity and the Mo film 12 of positive polarity.
The light with a wavelength of 435 nm (0.5 pvj
/cnj) is shown in 22.

For comparison, after the formation of the layer 14 in the example instead of the silicon oxide 15 as shown in the cross-sectional view of FIG.
0"' Torr, diborane (E2 Hfi) + pressure I X 10 Torr, the amount of hydrogen was increased while the discharge power was 1.200 W, and amorphous silicon 17 doped with boron was formed to a thickness of 0.1 μm. After that, the transparent electrode 16 was formed, but the dark current was 23, and the photocurrent was 24.
are shown respectively. It can be seen that the dark current was reduced by adding the surface silicon oxide layer.

Next, a cross-sectional view of an electrophotographic photoreceptor according to a second embodiment of the present invention,
(a) The figure shows the initial state, (b) shows the change state of the surface layer,
shows.

An amorphous hydrogenated silicon layer 32 containing a large amount of hydrogen is formed on the Ap substrate 3] under the same conditions as the layer 13 of the first embodiment, and then an amorphous hydrogenated silicon layer 32 containing a large amount of hydrogen is formed under the same conditions as the layer 14 of the first embodiment. A thin amorphous hydrogenated silicon layer 33 is formed to a thickness of 5 to 6 μm. When negative charges are repeatedly applied to this using a corona charger, the initial charging potential gradually increases as shown in FIG. This is A
As a result of uger analysis, it was found that a large amount of oxygen and silicon oxide were present on the surface. This oxidation is thought to be due to the amorphous hydrogenated silicon on the surface being oxidized by ozone accompanying negative charging. This silicon oxide layer reduced electron injection and increased the initial charging potential.

The second embodiment is an example in which the surface layer of amorphous hydrogenated silicon is changed to a silicon oxide layer.

FIG. 6 shows a sectional view of a third embodiment of the present invention.

The amorphous silicon hydride layer 13 in the first embodiment is placed on a stainless steel substrate 41 whose surface has been mirror-treated under an argon pressure of 4×10” Torr and a hydrogen pressure of 1×10” Torr.
The layer 42 with a high hydrogen content is formed under the same conditions except that it is formed in a Torr atmosphere. Next, argon pressure 3, force 4.5 x 10 Torr, hydrogen pressure 5 x
Create an atmosphere of 10 Torr and increase the discharge power to 3
00W and forms an amorphous hydrogenated silicon layer 43 with a low hydrogen content of 5 to 6 μm in 4 hours. Further Arrr
:, force I x 10” Torr, nitriding pressure 2 x
10" Torr, and a discharge power of 400 W to form a silicon nitride film 44 of 10,080 or more. This photosensitive plate was charged with a -6 KV corona charger using a charge tester, and the initial charging potential and dark decay time were determined. It is shown in Table 1.

For comparison, the characteristics when there is no silicon nitride film are also shown.

Improvements are seen in both the initial charging potential and dark decay characteristics. The optical attenuation characteristics are good with no significant difference.

FIG. 7 shows the structure of the third embodiment reversed, with silicon nitride 44 on the substrate, amorphous hydrogenated silicon 43 with a small amount of hydrogen, and amorphous silicon hydride 4 with a large amount of hydrogen on the substrate.
Form 2 in 5 orders. The conditions are the same as in the third embodiment. When this film is used as a photosensitive plate, it produces a positive ↑Y charge.

Table 1 In the above embodiments, forming an electron injection blocking layer using silicon nitride and silicon oxide has the effect of reducing dark current, increasing the charging potential of the photoreceptor, and reducing dark decay. The first layer responsible for this electron injection is S
A similar effect can be obtained even with an intermediate composition of Nx0y and Nx0y.

Amorphous hydrogenated silicon Si H4 by sputtering method
0 decomposition results in high resistance due to glow discharge, and even if a denser and higher resistance high-quality silicon nitride or silicon oxide is used, the amorphous silicon hydride layer will have a sufficient distribution of type [[], resulting in deterioration of optical attenuation characteristics. , the increase in residual potential is not large.

Furthermore, due to the same effect, silicon nitride or silicon oxide can be made thicker than amorphous hydrogenated silicon produced by the glow discharge method, resulting in superior surface stability and wear resistance.

Such a structure increases the charging potential even if it is thin, and is advantageous in terms of productivity.

Effects of the Invention With the above configuration, the present invention prevents the injection of holes by using high resistance amorphous silicon hydride with a wide forbidden band of 1iJ≈adult, or by using a silicon nitride or silicon oxide layer. Since the structure is such that the injection of electrons is stopped at N1, the effects of high resolution, high sensitivity, and low dark current are produced. On the other hand, it has excellent stability and abrasion resistance as an electrophotographic photoreceptor.

The manufacturing method of the present invention allows amorphous silicon hydride with a resistance of 10ΩI7n or more to be obtained without doping, making it easy to control the hydrogen meter, and using the reactive sputtering method, silicon nitride and silicon oxide can be easily produced by simply changing the reaction gas. The silicon nitride and silicon oxide that are formed can be easily realized by reacting amorphous hydrogenated silicon in nitrogen or oxygen activated by plasma or the like.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the structure of the photoconductor of the present invention, and FIG.
) is a sectional view of the first embodiment of the photoconductor of the present invention, (b)
) is a sectional view of a photoconductor (hereinafter referred to as a comparative example) for comparing the characteristics with the first example, and FIG. 3 is a characteristic diagram of the first example of the present invention and the comparative example. , FIG. 4 is a sectional view of an electrophotographic photoreceptor according to a second embodiment of the present invention, (a) is an initial state, (b) is a diagram of changes in the surface layer, and FIG. 5 is a diagram of a state of change in the surface layer. FIG. 6 is a sectional view of the electrophotographic photosensitive plate according to the third embodiment of the present invention, and FIG. FIG. 2 shows an inverted cross-sectional view of the structure of the embodiment. l, 11.31.41: Substrate 2, 3, 1
3.14.32゜33,42.44: Amorphous hydrogen silicon layer 4: Silicon nitride or silicon oxide layer -V) Fig. 3 (Ref Fig. 4 Pregnancy Goginbin (d) Fig. 5 IJ Fig. 6

Claims (1)

[Claims] 1. Consisting of first and second layers containing amorphous hydrogenated silicon as a main component and having a specific resistance of 0 10 Ωm or more, the second layer
A first layer of a hole injection blocking layer having a hydrogen content higher than that of the first layer is sandwiched between the second layer and an electron injection blocking layer on a substrate. conductor. 2. The photoconductor according to claim 1, wherein the electron injection blocking layer is a silicon nitride layer. 4. Processing using reactive sputtering in an atmosphere containing silicon as the main component and hydrogen as a reactive gas.
Step A1 Step B of forming a first layer with a hydrogen content of Ωm or more and a second layer with a higher hydrogen content than the first layer
and Step C of forming a silicon nitride layer or a silicon oxide layer (hereinafter referred to as an oxide layer) by a reactive sputtering method in an atmosphere containing nitrogen or oxygen as a reactive gas, A method for manufacturing a photoconductor, comprising sandwiching the photoconductor with a layer and an oxide layer, and forming the photoconductor on a substrate in the above-described laminated order. 5 The target is made of silicon as the main component, and 10
Step A1 Step B of forming a first layer with a hydrogen content of Ωm or more and a second layer with a hydrogen content higher than the first layer
and Step C of forming a silicon nitride layer or an oxide layer (hereinafter referred to as an oxide layer) by a reactive sputtering method in an atmosphere containing nitrogen or oxygen as a reactive gas, forming a second layer, and changing a part of the first layer into a silicon nitride layer or a silicon oxide layer in an atmosphere containing active nitrogen or oxygen in the C step; 1. A method of manufacturing a photoconductor, comprising forming the photoconductor on a substrate in this order.