JP3416495B2 - Electroless indium oxide plating aqueous solution and electroless plating method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroless plating solution capable of forming indium oxide applicable to optical elements such as photoelectric conversion elements, self-luminous elements, liquid crystal elements and the like, and indium oxide using the same. Related to electroless plating method.

[0002]

2. Description of the Related Art Indium oxide exhibits conductivity because oxygen defects act as donors to generate excess carriers, and has a large band gap and excellent light transmission properties. Therefore, its thin film is suitable for optical devices such as liquid crystal displays and solar cells. Firstly, it is used as a major material in many applications.

Conventionally, the indium oxide thin film has been formed by using the vacuum evaporation method, the electron beam evaporation method, the sputtering method, and the CVD method.

In the vacuum vapor deposition, a tungsten heater is used as a heating source to vaporize indium and indium oxide placed on a crucible or a boat and deposit them on a substrate. In order to supplement oxygen deficient in the thin film, oxygen gas is introduced into a vacuum container (usually called reactive), or after film formation, annealing is performed in the atmosphere or oxygen atmosphere. However, the annealing temperature is as high as several hundred degrees.

In the sputtering method, a target of indium oxide or indium and a gas of argon or oxygen are used for DC or R.
It is hit with plasma generated by being excited by electric energy of F, and indium oxide is deposited on the opposing substrate.

[0006] The CVD method is a method in which alkyl indium and oxygen are introduced into a vacuum container, and gas is decomposed by heat or plasma to deposit indium oxide on a substrate.

Industrially, the sputtering method is preferably used because of its stable characteristics and high throughput.

However, in general, the vacuum device is complicated and expensive, and there is a possibility that the range of industrialization is narrowed. Further, in the sputtering method, a high vacuum pump is required and the utilization efficiency of the target is not high, so that the material cost becomes high. Also, C using an organic metal
The VD method requires a facility for treating waste gas. Even though it is a material with a wide range of use as described above, the film forming method is expensive and complicated, so that it has only been applied to applications with limited momentum.

A sol-gel method is also proposed in which a solution containing indium alkoxide as a main component is thinly applied on a substrate without using a vacuum device, and a solvent is removed by heating in a furnace to obtain an indium oxide film. However, since the heating temperature exceeds 100 ° C., the range of selection of the substrate is narrowed, and pin holes are formed when the solvent escapes as a gas, so a thick film cannot be formed at one time. Due to the inconvenience of overcoating an extremely thin film, it has not yet been widely industrialized.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for forming an indium oxide film which can be applied in various ways at low cost.

The present inventors have found that indium oxide is electrolytically deposited from an aqueous solution containing nitrate ions and indium ions.

However, this method requires the use of an electrically conductive substrate as it requires the application of electrical energy to the growth surface of the thin film. No film growth was observed when the substrate was simply immersed in a solution that could be electrodeposited (in this case, an aqueous solution of indium nitrate). Therefore, it cannot be said that it has a particularly superiority on a specific substrate with respect to a vacuum film forming technique capable of depositing a film on an insulator.

However, it has been found by the present inventors that deposition can be carried out from a solution obtained by adding a tartrate salt to the above solution without electrolysis.

[0014]

The present invention based on the above findings provides an electroless indium oxide plating solution containing at least nitrate ion, indium ion and tartrate salt, and at least nitrate ion, indium ion and tartaric acid. The substrate is immersed in an aqueous solution containing a salt, and the temperature is 10 ° C.
The electroless plating method is characterized by depositing indium oxide on a substrate at 60 ° C.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below.

(1) Electroless Indium Oxide Plating Aqueous Solution (Nitrate Ion) The nitrate ion source is not particularly limited, but in addition to nitric acid, for example, indium nitrate, sodium nitrate, potassium nitrate, lithium nitrate, aluminum nitrate,
A nitrate such as ammonium nitrate can be used, and indium nitrate is preferable.

Although the concentration of nitrate ion is not particularly limited,
It is preferably 0.001 to 0.5 mol / l, more preferably 0.01 to 0.1 mol / l. 0.001m
When it is ol / l or more, indium hydroxide is preferably prevented from precipitating in the solution. Further, if it is 0.5 mol / l or less, film deposition proceeds in a practical time, which is preferable.

(Indium ion) The indium ion source is not particularly limited, but for example, indium nitrate,
Indium salts such as indium sulfate and indium chloride can be used, with indium nitrate being preferred.

The concentration of indium ions is not particularly limited, but is preferably 0.001 to 0.5 mol / l, more preferably 0.01 to 0.1 mol / l. 0.0
When it is at least 01 mol / l, the film formation effectively proceeds, which is preferable. Further, if it is 0.5 mol / l or less, unnecessary precipitation can be prevented from occurring in the solution, and aggregates are preferable because they do not adhere to the film.

(Tartrate) The tartrate is not particularly limited, but for example, sodium tartrate, potassium tartrate,
Sodium potassium tartrate, sodium hydrogen tartrate, potassium hydrogen tartrate, calcium tartrate and the like,
Of these, sodium tartrate and sodium potassium tartrate are preferably used.

The concentration of the tartrate salt is not particularly limited, but it is preferably 0.00001 to 0.1 mol / l, more preferably 0.001 to 0.01 mol / l. 0.0
If it is 0001 mol / l or more, an indium oxide thin film can be formed, which is preferable. Further, if it is 0.1 mol / l or less, there is no problem that the solution becomes cloudy and the deposited film becomes like an opaque powder aggregate, which is preferable.

Further, in order to stabilize the aqueous solution without clouding, it is more preferable that the concentration of indium ion is 1/200 to 1/5. It is speculated that this is because when the tartrate salt dissociates the carboxylic acid group or alcohol group of the tartrate ion that contributes to the oxidation of the indium ion, if it is too much, it precipitates in the solution. In particular, in the electroless process, it is preferable to control the solution, because it is not possible to apply energy for external oxidation such as electrodeposition.

(2) Electroless plating method The temperature of the plating aqueous solution during electroless plating is 20 ° C. to 60 ° C.
It is necessary to set the temperature to 30 ° C, preferably 30 ° C to 50 ° C. It is preferable to set the temperature higher, but if it exceeds 60 ° C., the plating aqueous solution tends to become cloudy and the film will not grow uniformly. Further, if the temperature is lower than 20 ° C., the adhesion of the deposited film is poor,
The mechanical strength is insufficient.

The pH of the plating solution during electroless plating is
Although it varies depending on the solute and the temperature, it is preferably controlled to 3-9. By controlling the pH, there is no problem that a film is not formed or a precipitate is not formed to form a uniform film, which is preferable. A small amount of acids such as sulfuric acid, nitric acid, hydrochloric acid and acetic acid, and bases such as sodium hydroxide, potassium hydroxide and ammonium hydroxide are used to control the pH.

The film formation rate of the obtained film is 0.01 to 10Å
/ S. In particular, it shows a large value in the initial stage of film formation, but gradually converges to a constant value with time.

(Aqueous Solution Holding Container) Stainless steel, glass, etc. are preferably used as the container for holding the plating aqueous solution, but copper and aluminum are not preferable when the pH is low. In order to prevent formation of an unnecessary film, it is preferable that an oxide other than indium oxide or a passivation material covers the surface.

(Substrate) The substrate is not particularly limited, but examples thereof include metals such as stainless steel, iron, platinum and nickel, glass, plastics, ceramics and the like.

The substrate preferably has a clean surface or a highly active surface as a trigger for film formation. Therefore, depending on the type of substrate, it is preferable to remove the oxide layer by acid cleaning, alkaline bath cleaning, or the like, or to perform sensitizer / activator treatment. As the sensitizer / activator treatment, a known method using stannous chloride or palladium chloride (for example, "Electroless plating" edited by Denki Kagaku Kenkyukai, Nikkan Kogyo Shimbun, page 134) can be applied. As the Tizer / Activator, for example, commercially available products such as S-1 and P-1 (trade name) manufactured by Kojundo Chemical Co., Ltd. can be obtained.

(3) Application of Electroless Plating Method Although the indium oxide according to the present invention can be applied to antistatic treatment, solar cells, electrophotographic photoreceptors, etc., by using the present invention, it is possible to obtain the following conventional techniques. Can be solved.

(Antistatic treatment) In the antistatic treatment, a high voltage is generated due to the phenomenon that dust is less likely to adhere to the glass material due to electrostatic force, or electrostatic charge is generated inside the electronic equipment to call dust and the static electricity is charged. This is a technique used in order to prevent the electronic parts from being damaged and to prevent the electronic parts and the peripheral members from being easily charged.
Since the main constituent material of the glass material is silicon oxide, and plastics are often used in recent electronic parts and their peripheral members, they themselves are extremely easily charged. For this reason,
The surface is subjected to a substitution treatment with a hydrophilic group such as a metal alkoxide, or a conductive carbon, a metal or the like is coated to conduct the conduction treatment.

However, in many cases, these antistatic treatments are accompanied by coloring. This is not a problem for the parts used in the invisible part, but it is not preferable for the parts used in the display part, especially the cover. In addition, IT doped with indium oxide or tin in a few%
The method of coating a transparent conductive film such as O is generally a method using a vacuum apparatus, usually a sputtering method. As described above, the cost of the apparatus becomes large, and it is not practical for small parts. Therefore, a small amount of conductivity is sacrificed and a thin coating is applied so that the coloring is not noticeable.

The electroless plated indium oxide thin film according to the present invention can be realized at a low cost because the apparatus is inexpensive and can be easily processed, and since the transparency of the film is good, it is particularly suitable for the cover member of the display section of electronic equipment. Is preferred. Further, since the processing temperature is not high, many members can be applied.

(Solar Cell) Except for a special type of solar cell of the point contact type, a solar cell uses the surface on which light is incident as an electrode. However, in the point contact type, the semiconductor material must have a long life and mobility for both electrons and holes, and cannot be practically used in practice other than high grade single crystal Si. Polycrystalline Si, amorphous Si, amorphous SiGe, which are often used,
Materials such as microcrystalline Si and polycrystalline CuInSe require a transparent conductive film as an electrode on the surface on which light is incident.

Since this transparent conductive film also serves as an optical antireflection layer, it is usually made to have an optical thickness of 1/4 of the wavelength having the maximum value of the sensitivity spectrum of the semiconductor. That is, since the maximum sensitivity wavelength is about 500 nm to 1 μm, the optical thickness is about 1200 Å to about 2500 Å, and the refractive index of the transparent conductive film is usually about 2, so the film thickness is 6
It ranges from 00Å to 1300Å. Currently known transparent conductive materials include indium oxide and ITO, zinc oxide, tin oxide, or alloys thereof, or gallium oxide or nitride introduced. Higher indium oxide and IT
O, which is the highest, shows a conductivity of less than 1 × 10 ⁴ S / cm. Conversely, no higher conductivity can be expected, which necessitates the provision of grids or integrated connections with a width of a few mm to at most a few cm or less. However, since the grid does not transmit light, it forms a shadow of sunlight, resulting in a loss that reduces the conversion efficiency of the solar cell. As described above, in order to fully utilize the sunlight, the transparent conductive film must be sufficiently transparent and at the same time highly conductive.

On the other hand, it is said that the cost of solar cells is currently the bottleneck for their widespread use. A film forming system using a vacuum device has a large depreciation cost, which is far from the cost desired in the market. The indium oxide film according to the present invention exhibits conductivity comparable to that formed by sputtering, and since the formation process thereof is simple and can be handled by an inexpensive device, the distance to the cost desired in the market can be shortened. .

(Electrophotographic Photoreceptor) In the electrophotographic photoreceptor, a photosensitive layer is formed on a conductive substrate, the surface is charged to a specific potential by corona discharge, and an electrostatic latent image is formed by imagewise exposure. It is a thing. That is, photocarriers are generated where light is applied and move so as to cancel the charging potential. Generally used light-sensitive materials or carrier-transporting materials are mainly composed of holes or electrons. For example,
In most organic photoconductors, holes act as transport carriers.

Further, for application to a laser printer, it is necessary to form a sufficient latent image in the red region in order to make the semiconductor laser sensitive, but with a layer structure in which charge generation and charge transport are functionally separated. Doing so increases stability and life.

Here, since the surface to be charged is a free surface, it is possible to prevent the intrusion of charges relatively easily, but the substrate side usually requires some ingenuity. When negative charging is preferable due to the characteristics of the toner, the charge-generating layer having the functions separated is formed on the substrate side, and the charge-transporting layer is formed on the substrate. Here, if holes enter from the substrate side, the surface potential is neutralized, and the contrast of the electrostatic latent image is drastically reduced. In order to prevent this, it is necessary to provide a hole injection prevention layer between the substrate and the charge generation layer. On the other hand, the electron, which is another carrier, causes a ghost when it accumulates in the photosensitive layer or the transport layer, and thus it is necessary to escape to the base electrode side.

The hole injection preventing layer, that is, the blocking layer is extremely effective when it is an n-type semiconductor having a large band gap. However, as described above, there are very few n-type semiconductors among organic substances, and inorganic materials, particularly oxide transparent conductive films, are stable and suitable. However, like the solar cell, if it is formed by a vacuum process such as sputtering, the cost of the photoconductor will increase significantly.
Although the sol-gel method and the like have been proposed, there are still problems to be solved such as the stability of the film.

By applying the electroless indium oxide according to the present invention, an effective blocking layer can be stably formed at low cost. In particular, the indium oxide film according to the method of the present invention is not altered or melted out in the coating process of the subsequent step, so that it can be preferably used.

[0041]

EXAMPLES The present invention will be described in more detail below with reference to examples.

(Example 1) Indium nitrate 0.08mo
1 / l, 0.003 mol / l of sodium tartrate was dissolved in pure water to form an aqueous solution, which was placed in a heat-resistant glass container, the liquid temperature was kept at 30 ° C., and the steel sheet coated with nickel was immersed for 2 hours. , About 1000Å of indium oxide thin film was deposited.

The deposited indium oxide film exhibits a sheet resistance of 100 to 10 kΩ / □ at a film thickness of 1000 Å, and the light transmittance of the film of 1000 Å formed on the reflective substrate is 85% or more. Exhibited a color. The XMA evaluation confirmed the presence of oxygen and indium.

(Example 2) A glass substrate treated with sensitizer / activator using stannous chloride and palladium chloride was immersed in an aqueous solution similar to that of Example 1, and exhibited an interference color in 4 hours. We saw the formation of an indium oxide thin film.

The deposited indium oxide film exhibits a sheet resistance of 100 to 10 kΩ / □ at a film thickness of 1000 Å, and the light transmittance of the film of 1000 Å formed on the reflective substrate is 85% or more. Exhibited a color. The XMA evaluation confirmed the presence of oxygen and indium.

(Comparative Example 1) Instead of indium nitrate,
The same procedure as in Example 1 was carried out except that indium sulfate was used, but no film was formed. This strongly suggests the involvement of nitrate ions in the aqueous solution.

(Comparative Example 2) Instead of indium nitrate,
The same procedure as in Example 1 was carried out except that indium chloride was used, but no film was formed. This strongly suggests the involvement of nitrate ions in the aqueous solution.

(Example 3: Application to antistatic glass) A stainless steel tank having an inner rectangle of 350 × 500 × 150 mm was prepared by
2 mol / l indium nitrate and 0.001 mol / l
It was filled with an aqueous solution containing sodium tartrate and kept at 50 ° C. A 400 × 300 mm sensitizer / activator-treated soda lime glass was immersed in the solution, and the solution was held for 5 hours while stirring. As a result, about 15
A 00Å indium oxide film was formed. By performing atmospheric annealing at 90 ° C. for 2 hours, the adhesion of the film was improved, and an indium oxide thin film for antistatic could be easily formed. Compared with the vacuum evaporation / sputtering method, the equipment cost, labor and process are greatly improved.

On the formed antistatic glass, +5.5.
Connected to a high voltage power source of kV, charging width 30mm, length 330
Scanning was performed at a speed of 50 mm / s while charging with a corona charger of mm. When the residual potential of the surface was measured using a surface electrometer after 30 seconds of charging, it showed a very good antistatic ability of + 2V (error range ± 5V), compared to + 200V in the case of soda lime glass that does not form indium oxide. It was

The glass that can be used is, in addition to soda-lime glass,
Examples include white plate glass, borosilicate glass, phosphosilicate glass, and barium aluminum silicate glass (Corning 7059: trade name).

This antistatic glass can be favorably used as a surface protection glass for displays and a display protection glass for ornaments because it is less prone to dust.

(Example 4: Application to solar cell) SUS4
An example of application as an upper electrode layer of a solar cell formed on 30BA is shown.

The solar cell used is a SUS430BA ferritic stainless steel substrate whose surface is 0.1 mm thick and is bright annealed.
16000Å zinc oxide using magnetron sputter using a zinc oxide sintered target, 200Å n-type amorphous Si by plasma CVD, 2000Å i-type amorphous Si by plasma CVD, and 150Å p-type microcrystalline silicon by plasma CVD It was done.

The ferritic stainless steel used for the substrate of the solar cell is selected because of the ease of device design in the subsequent step because it adheres to the magnet, and martensitic or austenitic stainless may be used. It may be non-corrosion resistant platinum. Further, the bright annealing treatment was used because a relatively smooth surface can be obtained by a simple method, but rough surface finishing typified by 2D treatment or a mirror surface by mechanical or electrolytic polishing can be used.

The DC magnetron sputter used for Al and zinc oxide was selected because of its ease of control.
RF sputtering can also be used. Further, when a metal target such as Al is used, it is possible to use DC sputtering without the aid of a magnet. Since Al has a wavelength of light having a wavelength close to the energy of the forbidden band width of the semiconductor material formed therethrough, it partially passes through the semiconductor layer, and thus Al plays a role of a reflective layer which is efficiently reflected and returned to the semiconductor layer. It is important that this layer is highly reflective to light having a wavelength longer than red light in an amorphous Si material, and gold, silver, copper, etc. can be used in addition to Al. The zinc oxide layer allows the reflected light to be sufficiently scattered so as to pass through a long distance of the semiconductor layer, and is formed to have irregularities on the surface by making it thick to some extent. Since zinc oxide can have conductivity, it forms a part of an electric circuit particularly when a solar cell is formed, but does not cause deterioration of characteristics.

The semiconductor of the solar cell used here basically has a pin junction structure, but if the carrier has a long life, it may be a pn junction. Amorphous S
In the case of the pin junction structure of i, even if light is absorbed in the p layer or the n layer to generate carriers, it cannot contribute to the generated current.
It is preferable to make the joint as thin as possible. pin
As is well known, the plasma-enhanced plasma CVD is a method in which a gas mainly containing a silane gas is flowed between electrodes to which RF is applied to form plasma, and a film is formed while causing a chemical reaction on a substrate. Is. Introducing a Group III element such as boron or aluminum to make it p-type,
An element such as phosphorus or arsenic is introduced for forming the mold. Since the p-layer of this embodiment is formed on the side on which light is incident, it is made of fine crystals to increase the transmittance. It is known that the open-circuit voltage is also improved by using the microcrystalline layer for the p-type layer. To form microcrystals, in plasma CVD, a gas diluted with a large amount of hydrogen is used, and the plasma power to be input is set high.

This solar cell was immersed in an aqueous solution containing 0.01 mol / l indium nitrate and 0.0001 mol / l sodium tartrate at 40 ° C. for 1 hour to deposit 600 liters of indium oxide. The deposited indium oxide was well wrapped around to form a thin film. Therefore, the indium oxide film was formed also in the portion where there was a local short circuit such as a pinhole.

Subsequently, in order to perform local etching of the amorphous Si defect portion (forming an electrical short circuit portion) to electrically localize it, a saturated aluminum sulfate solution having a conductivity of 60 S / cm is used. Then, a voltage pulse of −5 V and 0.1 s was applied 5 times between the stainless steel counter electrode and the electrode separated by 3 cm. As a result, the indium oxide in the minute periphery of the local short-circuited portion such as the pinhole is etched, so that the influence of the local short-circuited such as the pinhole can be neglected. Then, a gold grid electrode was vapor-deposited to form an upper electrode terminal.

Such a solar cell is AM 1.5, 100 m
When the characteristics were measured under simulated sunlight of W / cm ² ,
Short circuit current density 14 mA / cm ² , release voltage 0.97 V,
A form factor of 0.68, that is, a conversion efficiency of 9.23% was obtained. Furthermore, in order to evaluate the transparency of the upper transparent electrode, 40
The collection efficiency for 0 nm light (abbreviated as Q400) was 62%. These conversion efficiency and collection efficiency are equivalent to those of a transparent conductive film formed by vacuum deposition or sputtering, and have sufficiently excellent conductivity because they show sufficient solar cell characteristics, and at the same time, they have an excellent upper conductivity of the solar cell. It is shown that the indium oxide according to the present invention as a film has sufficient properties in both light transmission and conductivity. On the other hand, this method provides an extremely simple and inexpensive transparent conductive film of indium oxide.

The indium oxide of this system is not limited to the solar cell exemplified here, but has an i layer of amorphous SiGe.
P of crystal such as Si / CuInSe / GaAs / InP
Solar cell with n-junction, two or three pin structure
It can be applied to a stack of cells (stack cells).

(Example 5: Application to solar cell) An example of application as a light incident side electrode layer of a solar cell formed on glass will be shown.

A Corning 7059 glass substrate having a polished surface with a thickness of 0.9 mm was subjected to a sensitizer / activator treatment, and then treated with an aqueous solution containing 0.5 mol / l indium nitrate and 0.01 mol / l sodium potassium tartrate at 60 ° C. Then, it was immersed in the solution for 10 hours to deposit indium oxide having a film thickness of 2 μm. The surface of the deposited film was uneven and formed a scattering surface. The scattering surface scatters the incident light and obliquely enters the semiconductor layer, which makes it possible to increase the number of optical carriers generated by the optical path and thereby increase the conversion efficiency.

Then, leaving the electrode extraction portion,
220 p-type amorphous SiC by plasma CVD
Å, 180 i-type amorphous Si by plasma CVD
0 Å, 200 Å of n-type amorphous silicon was formed by plasma CVD. Silane, methane, BF3, and hydrogen were used as starting material gases for p-type amorphous SiC, silane and hydrogen for i-type amorphous Si, and silane, phosphine, and hydrogen for n-type amorphous silicon.

Next, 5000 Å Al was sputter deposited to form a back reflection layer. Since the unevenness grows as the film is deposited, the reflecting surface has a size of about 1 μm and is a reflecting and scattering surface that can sufficiently scatter incoming light.

The electrode lead-out portion of the indium oxide film,
A lead was formed on each of the Al back reflective layers, and the entire back surface was sealed with urethane resin to obtain a solar cell.

Such a solar cell is AM1.5, 100 m
When the characteristics were measured under simulated sunlight of W / cm ² ,
Short circuit current density 14.5 mA / cm ² , release voltage 0.92
V, a form factor of 0.67, that is, a conversion efficiency of 8.94% was obtained. Further, in order to evaluate the transparency of the light incident side transparent electrode, Q400 was measured and found to be 58%. Both the conversion efficiency and the collection efficiency are equal to or higher than those of the transparent conductive film formed by vacuum deposition or sputtering, and it has sufficiently excellent conductivity because it shows sufficient solar cell characteristics, and at the It is shown that the indium oxide according to the present invention as a conductive film has sufficient characteristics in both light-transmitting property and conductivity. In particular, the short circuit current density shows a larger value than in the case of a transparent conductive film formed by vacuum deposition or sputtering,
It was shown that the unevenness of the transparent electrode on the light incident side is extremely effective. On the other hand, this method provides an extremely simple and inexpensive transparent conductive film of indium oxide.

The indium oxide of this system is not limited to the solar cell exemplified here, but has an i layer of amorphous SiGe.
The pin structure can be applied to a stack of two or three layers (stack cell).

(Example 6: Application to electrophotographic photoreceptor) φ
A 30 mm × 260 mm Al cylinder drum is subjected to pickling treatment with nitric acid, and then electrolytically plated with Ni in a Watt bath, and then contains 0.05 mol / l indium nitrate and 0.001 mol / l sodium potassium tartrate. Immerse in aqueous solution at 40 ° C for 10 hours and 10,000
Å Indium oxide was deposited. Since this indium oxide film exhibits n-type characteristics, it is used as a blocking layer that blocks injection of holes from the Al substrate side and prevents holes generated in the charge generation layer from escaping to the drum side. Is. Since this blocking layer stably exhibits blocking characteristics with respect to the environment, the environmental characteristics of the entire photoreceptor are improved. After that, the copper phthalocyanine is dispersed in polyvinyl butyral and then applied and dried to form a 1-micron charge generation layer. Next, carbazole is dissolved in polycarbonate and applied and dried. A 10 micron charge transport layer was formed. In this way, an electrophotographic photosensitive drum was produced.

This electrophotographic photosensitive drum was held at 25 ° C. at a holding dark potential / bright residual potential with a laser printer.
A comparison was made between a normal environment of 60% RH and a high temperature and high humidity environment of 35 ° C. and 85% RH. The results were excellent at 680 V / 10 V in the normal environment and 670 V / 12 V in the high temperature and high humidity environment.

In addition to the function-separated type layer structure of the charge generation layer and the charge transport layer shown here, a single layer type is also applicable. In addition to copper phthalocyanine, photosensitive charge generating substances include quinone pigments, perylene pigments and azurenium salt pigments, and as charge transporting substances other than carbazole, anthracene, pyrene, indole, hydrazone compounds and the like can be used. .

(Example 6: Application to base layer for electrodeposition) 50
After covering the back surface of mm-square non-alkali glass (barium aluminum silicate glass: Corning 7059) with masking tape and subjecting it to sensitizer / activator processing,
0.05 mol / l indium nitrate and 0.001 mo
40 in an aqueous solution containing 1 / l sodium potassium tartrate
It was immersed at ℃ for 1 hour to deposit 1000Å indium oxide. Then, it was dried and annealed at 150 ° C. for 2 hours.

Next, the glass coated with the indium oxide film was used as a substrate in an aqueous solution containing 0.01 mol / l of indium nitrate at 50 ° C. with a current of 10 mA as the counter electrode to cause oxidation. Indium was electrolytically deposited at 8000Å. The film thickness is uniform and is 0.5
An image of indium oxide having a grain size of μm was confirmed by SEM.

The electroless indium oxide of the present invention can be used as a substrate for electrodeposition. When the underlayer for electrodeposition according to the present invention is formed in this manner, the particle size and orientation can be controlled even with indium oxide of the same material formed on the underlayer, so that the range of application of indium oxide is significantly increased. be able to.

[0074]

As described above, according to the present invention,
It is possible to fabricate a large-area indium oxide thin film having translucency and conductivity, which is much lower in cost than a vacuum device and can be applied to various applications.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP 62-274508 (JP, A) JP 62-211385 (JP, A) JP 62-180740 (JP, A) JP 60- 121614 (JP, A) JP 59-177357 (JP, A) JP 57-67048 (JP, A) PHYSICA STATUS SO LIDI, VOL. 87, NO. 1, P. 79-83 (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 18/52 C23C 20/08

Claims (16)

(57) [Claims] 1. An electroless indium oxide plating aqueous solution containing at least nitrate ions, indium ions, and tartrate salts. 2. The electroless indium oxide plating aqueous solution according to claim 1, wherein the tartrate salt is sodium tartrate or potassium sodium tartrate. 3. The concentration of nitrate ions is 0.001 to 0.5.
It is mol / l, The electroless indium oxide plating aqueous solution of Claim 1 or 2 characterized by the above-mentioned. 4. The indium ion concentration is 0.001 to
It is 0.5 mol / l, It is characterized by the above-mentioned.
The electroless indium oxide plating aqueous solution described in. 5. A tartrate concentration of 0.00001 to 0.
It is 1 mol / l, The electroless indium oxide plating aqueous solution of Claims 1-4 characterized by the above-mentioned. 6. The tartrate concentration is 1/200 to 1/5 of the indium ion concentration.
The electroless indium oxide plating aqueous solution according to any one of claims 1 to 5. 7. The ion source of nitrate ions and indium ions is indium nitrate.
The electroless indium oxide plating solution according to any one of items 1 to 6. 8. The concentration of indium nitrate is 0.001 to
It is 0.5 mol / l, The electroless indium oxide plating aqueous solution of Claim 7 characterized by the above-mentioned. 9. A substrate is immersed in an aqueous solution containing at least nitrate ions, indium ions, and tartrate salts, and the substrate is heated at 10 ° C.
An electroless plating method comprising depositing indium oxide on a substrate at 60 ° C. 10. The electroless plating method according to claim 9, wherein the tartrate salt is sodium tartrate or potassium sodium tartrate. 11. The concentration of nitrate ion is 0.001 to 0.
It is 5 mol / l, It is characterized by the above-mentioned.
The electroless plating method described in. 12. The indium ion concentration is 0.001.
~ 0.5mol / l is, characterized in that 9 ~.
11. The electroless plating method according to item 11. 13. The tartrate concentration is from 0.00001 to.
It is 0.1 mol / l, It is characterized by the above-mentioned.
2. The electroless plating method of indium oxide according to 2. 14. The electroless plating method according to claim 9, wherein the concentration of the tartrate salt is 1/200 to 1/5 of the indium ion concentration. 15. The electroless plating method according to claim 9, wherein the ion source of nitrate ions and indium ions is indium nitrate. 16. The concentration of indium nitrate is 0.001 to 0.001.
It is 0.5 mol / l, The electroless-plating method of Claim 15 characterized by the above-mentioned.