JPS6270857A - Electrode material for semiconductor - Google Patents

Abstract

PURPOSE:To inhibit an electrochemical reaction on the interface between an electrode material and a semiconductor by using a material consisting of 5-30wt% Mo, 4-25wt% Fe and the balance Ni with inevitable impurities as the electrode material. CONSTITUTION:This electrode material for a semiconductor consists of 5-30wt% Mo, 4-25wt% Fe and the balance Ni with inevitable impurities or further contains <=25wt% Cr, <=3wt% Co, <=6wt% W and <=2wt% C. The material can ensure satisfactory electrical characteristics and durability as an electrode material in a wide composition range. The material is relatively easily formed into a film, hardly causes an electrochemical reaction on the interface between it and a semiconductor, undergoes no deterioration in the characteristics by anodic oxidation and has superior fundamental characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to semiconductors, particularly electrode materials for electrophotographic photoreceptors.

Prior Art In an electrophotographic method generally called xerography, a metal or metal film is coated with a photoconductive insulating layer (hereinafter referred to as a photosensitive layer) on a surface conductive support, ie, an electrode, such as glass or plastic, on which a conductive layer is provided with a conductive paint. ) is used.

The material and form of the above-mentioned electrodes are appropriately selected depending on the characteristics of the photosensitive material and the manufacturing method.

When a photosensitive layer is made of Se-based material, a drum-shaped member made of A1 or an A1 alloy itself is often used. When the photosensitive layer is in the form of a solution or dispersion during coating, the electrode is often a plastic film coated with a gold WA layer by vapor deposition or sputtering. In particular, A
A polyethylene terephthalate film metallized with 1 is widely used as an electrode for an organic photoreceptor.

The reason why AI is widely used as a conductive material for electrodes is that it is relatively easy to form a film on a film.
and that AI can easily create a certain rectification property at the interface with the photosensitive layer, making it easy to obtain a high acceptance potential without impairing electrical properties;
Furthermore, it is a relatively inexpensive metal material.

A typical form of an organic semiconductor (hereinafter referred to as OPC) is a so-called functionally separated type in which a charge generation layer is laminated on the electrode side and a charge transfer layer is laminated thereon. That is, a structure in which a polyethylene terephthalate film, an A1 layer, a charge generation layer, and a charge transfer layer are laminated in this order is currently the most widely used form as an organic photoreceptor for electrophotography.

By the way, the charge transfer layer is generally made of a polymer in which a hole transfer substance such as triphenylamine or hydrazone is dissolved. Since no organic compound has been found that exhibits practically effective electron mobility, a functionally separated electrophotographic photoreceptor using OPC is usually used with a negative charge.

However, the inventors have discovered that some metals have serious drawbacks, particularly as electrodes for photoreceptors used for negative charging. Moreover, it has been found that A1, which is the most widely used, has extremely significant drawbacks. Specifically, it has been confirmed that the charge passing through the supporting electrode through repeated charging and exposure gradually oxidizes the metal of the electrode, significantly increasing the resistance value of the electrode. This reaction corresponds to anodic oxidation when used with negative charge.

It goes without saying that the passage of charge at the photosensitive layer-electrode interface is essential for the function of the photoreceptor, and that the above problem cannot be solved by blocking the charge. Furthermore, with the exception of extremely expensive precious metals, it is inevitable that most metals undergo oxidation reactions to varying degrees.

Despite high currents, some materials are limited in performance by relatively large oxidation processes. AI, Ti
Typical examples are SNb, Ta, Fe, W, etc. In general, oxidation is unavoidable for single metals, except for noble metals.

On the other hand, there are materials that are undesirable due to their slow oxidation progress but low current values. NiCr alloy, Kanthal alloy (F
e Cr Co At alloy) has a strong tendency to do so.

It is well known that stainless steel alloys containing Fe as the main component have a certain level of performance as photoreceptor substrates; IFJ formation is not easy and has limited morphology.

Purpose The present invention aims to provide a novel electrode material that hardly causes an electrochemical reaction at the interface with a semiconductor. Particularly, it is an object of the present invention to provide a novel material for electrodes of electrophotographic photoreceptors used for negative charging, which does not suffer from property deterioration due to anodic oxidation and has excellent basic properties.

Composition The present invention was made with the above object in mind, as a result of studying various metals and alloys from both the basic electrical properties and the oxidation of electrodes.
It is an electrode material for semiconductors characterized by containing other unavoidable impurities and Ni, and in addition to the above, Cr 25% by weight or less, Co 3% by weight or less, W 6% by weight or less, C 2% by weight or less It is an electrode material for semiconductors containing

The above-mentioned material of the present invention can ensure good electrical properties and durability as an electrode material over a wide composition range, and is also relatively easy to form a film.

The composition of the material of the present invention may be determined within the above-mentioned range, taking into consideration the electrode film-forming process, the photoreceptor film-forming process including cleaning and drying, and the usage conditions of the photoreceptor.

Note that the material of the present invention may contain impurities such as Sl, Mn, and S to the extent that metal materials for ordinary industrial products contain.

More specifically, as mentioned above, the electrode in contact with the semiconductor must satisfy two requirements: (1) to have desired rectification properties, and (2) to have a sufficiently small electrochemical reaction.

As far as the support conductive layer of an electrophotographic photoreceptor is concerned, it is related to three electrical properties. In other words, ■ Acceptance potential (higher is better), ■ Dark decay (lower is better), however, the evaluation is based on the absolute value of the decay rate △V/△D), ■ Residual potential (lower is better) It is one.

The performance of electrode materials can be ranked based on these three properties. However, in normal corona charging in electrophotography, the charge passing through the photoreceptor is 10-7 Courons/cm2.
/l cycle (1) t-tert Even in the case of materials that are susceptible to oxidative deterioration, it is necessary to repeat charging and exposure several thousand to tens of thousands of times to see the degree of deterioration. (This corresponds to the lifespan determined by the electrode material of the photoreceptor.) The present inventors have developed a method in which a metal electrode is pressed against the surface of the photoreceptor, and by exposing it to light while applying a bias charge, the reaction of the electrode proceeds for several minutes. I found out.

The performance of the electrode material discovered in the present invention was confirmed using this method.

To explain the above test method in detail below, in Fig. 1, 1 is a photoreceptor base, for example, a 75 μm polyester film, 2 is an electrode material to be evaluated, and 3 is a charge generation layer, for example, represented by the following formula (I). Bisazo pigment dispersed in butyral resin (pigment/resin, weight ratio 2.5/1) L/
The layer was 0.3 μm thick.

Formula (T-4) is a charge transport layer made by dissolving a styryl compound represented by the following formula (II) in a polycarbonate resin (styryl compound/resin, weight ratio 9/10) and having a thickness of 20 μm.
This is the layer of

5 is a positive electrode, for example, a mirror-polished brass plate.

6 is a bias power supply, for example 700V S current capacity 50
mA.

7 is an ammeter with an external output.

When a voltage is applied to this while exposing it to 100 μW/m 2 tungsten white light from a light source R, a photocurrent flows, and the current shows a time change. FIG. 2 shows a current pattern when the electromagnetic material is A1. In this current pattern, the magnitude indicates the ease with which light attenuates during exposure of the photoreceptor, and it is desirable that the value be large to some extent. On the other hand, temporal decay indicates that the passage of charge oxidizes the electrode, increasing its resistance and suppressing the flow of charge. It is desirable that this decrease be small. Therefore, by setting the case in FIG. 2 as a standard and obtaining and comparing current patterns for each material, it is possible to determine whether the material is suitable as an electrode material.

The photoreceptor with A1 in Figure 2 as a conductive layer is about 50,000.
After repeating the charging exposure several times, A1 was completely oxidized and lost its function as a photoreceptor.

Examples will be described below, and the above current pattern will be tested.

Example 66% Ni, 28% MO, 6% Fe and other trace amounts of M
An electrode material made of an alloy containing n, Si, and C was formed on a support by sputtering.

When this electrode material was tested as a photoreceptor using electrode material 2 in FIG. 1, it showed a current pattern as shown in FIG. 3. No change was observed in this photoreceptor even after 200,000 repetitions.

Effects The electrode material of the present invention causes almost no electrochemical reaction at the interface with the semiconductor, does not cause property deterioration due to anodic oxidation, and is a material with excellent basic properties.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the layer structure of the photoreceptor used in the test of the present invention, FIG. 2 is a graph showing the current pattern of A1, and FIG. 3 is a graph showing the electrode pattern of the electrode material of the present invention. DESCRIPTION OF SYMBOLS 1... Photoreceptor base, 2... Electrode material, 3... Charge generation layer, 4... Charge transport layer, 5... Positive electrode, 6...
...Bias power supply, 7...Ammeter. Figure 1 Figure 2 Figure 3 Time (minutes) Procedural amendment (1 issue) November 14, 1985 Michibe Uga, Commissioner of the Patent Office 1, Indication of Case Patent Application No. 1987-210087 2, Invention Relationship with the name case Patent applicant name (674) Ricoh Co., Ltd. 4, agent 5, date of amendment order (voluntary) Description, detailed description of the invention column 7, content of amendment 7
．． --1~, /"'-,,' 72, -1 (1) Correct "metal coating" in line 19 of page 1 of the specification to "metal coating?" (2) In page 6, line 16, change “(smaller is better)” to “
(The smaller the better,” he corrects.) ;1 -.1

Claims (2)

[Claims] (1) A semiconductor electrode material comprising 5 to 30% by weight of Mo, 4 to 25% by weight of Fe and other unavoidable impurities, and Ni. (2) Mo5-30% by weight, Fe4-25% by weight, Cr
25% by weight or less, Co3% by weight or less, W6% by weight or less,
An electrode material for a semiconductor, characterized in that the content is 2% by weight or less of C, and the remainder is unavoidable impurities and Ni.