JP3373898B2 - Transparent conductive film and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent conductive film and its manufacturing method.

[0002]

2. Description of the Related Art A liquid crystal display device can be made lighter and thinner, and has a low driving voltage, so that it is actively introduced into OA equipment such as personal computers and word processors. Then, the liquid crystal display device having the above-mentioned advantages inevitably has a large area,
There is a demand for high-quality liquid crystal display devices having no display defects in the direction of increasing the number of pixels and increasing the definition. One of the important factors for obtaining a high quality liquid crystal display element is a transparent electrode, and an ITO film is currently the mainstream of this transparent electrode.

[0003]

However, the ITO is
The film has a relatively low moisture resistance, and has a drawback that its transparency is easily deteriorated by moisture. Further, in order to obtain an element or device having a high electric field response, it is desired to use a transparent conductive film having a high electron mobility. It is an object of the present invention to provide a transparent conductive film having a higher electron mobility and a higher moisture resistance than an ITO film, and a method for manufacturing the same.

[0004]

The transparent conductive film of the present invention which achieves the above object is characterized by being substantially composed of a compound having a spinel structure (hereinafter, this transparent conductive film is referred to as a transparent conductive film I). That).

Another transparent conductive film of the present invention which achieves the above object is Sn, Al, Sb, Ga, In and Ge.
Consisting essentially of a spinel structure compound doped with at least one element selected from the group consisting of, and the doping amount of said element being 20 at% or less based on the total amount of the cation elements constituting said spinel structure compound. (Hereinafter, this transparent conductive film is referred to as a transparent conductive film).
II).

On the other hand, in the method for producing a transparent conductive film of the present invention which achieves the above object, a coating solution in which a predetermined amount of a basic starting material of a spinel structure compound is dissolved is prepared, and the coating solution is applied to a substrate and baked. Then, reduction treatment is performed (hereinafter, this method is referred to as method I).

Another method for producing a transparent conductive film of the present invention that achieves the above object is to provide a predetermined amount of a basic starting material for a spinel structure compound, Sn compound, Al compound, Sb compound, Ga compound, In compound and A coating solution is prepared by dissolving at least one dope raw material selected from the group consisting of Ge compounds so that the ratio of the dope element to the total amount of the cation elements constituting the spinel structure compound is 20 at% or less. The coating solution is applied to a substrate, baked, and then subjected to a reduction treatment (hereinafter, this method is referred to as Method II).

The present invention will be described in detail below. First, the transparent conductive film I of the present invention will be described. The transparent conductive film I is substantially composed of a spinel structure compound as described above. Here, “substantially consisting of a spinel structure compound” means not only a pure spinel structure compound but also a substance containing impurities that are unavoidably mixed in the manufacturing process. In addition, the cation oxide or amorphous component constituting the spinel structure compound is converted to, for example, 50
The content may be less than wt%, preferably less than 20 wt%. Examples of cation oxides include ZnO and In
_{2 O 3, Sb 2 O 3} , Sb 2 O 5, SnO 2 and the like. Specific examples of the spinel structure compound include ZnIn ₂
O ₄ , Sb ₂ Zn ₇ O ₁₂ , Zn ₄ InSbO ₈ , SnZ
n ₂ O _{4 and the} like can be mentioned. The transparent conductive film I may be composed of one kind of spinel structure compound or may be composed of two or more kinds of spinel structure compounds.

The transparent conductive film I substantially made of such a spinel structure compound has practically sufficient conductivity and excellent visible light transmittance. The decrease in visible light transmittance due to moisture is smaller than that in the ITO film. Further, the electron mobility is as high as about 50 cm ² / V · sec or more.
The transparent conductive film I can be manufactured by various methods such as a sputtering method and a CVD method. However, since the composition can be accurately and easily controlled, the method I of the present invention described later will be described.
It is preferable to manufacture by.

Next, the transparent conductive film II of the present invention will be described. This transparent conductive film II is composed of Sn, A as described above.
at least one element selected from the group consisting of 1, Sb, Ga, In and Ge. The spinel structure compound is substantially composed of a spinel structure compound doped with at least one element. It is characterized in that it is 20 at% or less with respect to the total amount. This transparent conductive film II may be made of one kind of spinel structure compound as in the transparent conductive film I described above, or may be made of two or more kinds of spinel structure compounds. Further, as in the case of the transparent conductive film I, the oxide or amorphous component of the cation which constitutes the spinel structure compound is, for example, 50 wt%.
The content may be 20 wt% or less, preferably.

Here, the reason why the doping amount of the element is limited to 20 at% or less as described above is that if it exceeds 20 at%, ion scattering occurs and the conductivity of the film decreases too much. The doping amount of the element is preferably 1 to 10 at%, particularly preferably 2 to 10 at%. The doping element is
It is preferable that the spinel structure compound is not a basic constituent element. For example, the spinel structure compound is Zn ₄ I.
When mainly composed of nSbO _8, it is preferable to further contain at least one element selected from the group consisting of Sn, Al, Ga and Ge, which is not a basic constituent element of the spinel structure compound.

A transparent conductive film II consisting essentially of the above compound
Has an excellent visible light transmittance, and is approximately 5
It has an electron mobility of 0 cm ² / V · sec or more. The decrease in visible light transmittance due to moisture is smaller than that in the ITO film. Further, its conductivity is substantially equal to or higher than that of the transparent conductive film I because it is substantially composed of a compound in which the transparent conductive film I described above is doped with an element having a positive trivalence or higher valence. This transparent conductive film II can also be manufactured by various methods, but for the same reason as the above-mentioned transparent conductive film I, it is preferably manufactured by the method II of the present invention described later.

Next, the method I and the method II of the present invention will be described. First, the method I of the present invention will be described.
This method I is characterized by preparing a coating solution in which a predetermined amount of the basic starting material of the spinel structure compound is dissolved as described above, applying the coating solution to a substrate, baking it, and then performing a reduction treatment. is there. Method I
The coating solution used in (1) contains a solvent and a solution stabilizer in addition to the basic starting materials for the spinel structure compound described above.

Here, the type of basic starting material for the spinel structure compound is appropriately selected according to the intended spinel structure compound. As a specific example of the spinel structure compound, Zn
In ₂ O ₄ , Sb ₂ Zn ₇ O ₁₂ , Zn ₄ InSbO ₈ ,
Examples thereof include SnZn ₂ O _{4 and the} like. For example, when the target spinel structure compound is Zn ₄ InSbO ₈ , the ratio of Zn, In and Sb is zinc compound, indium compound and antimony compound as basic starting materials. Is weighed and used so as to have a predetermined stoichiometric ratio (= 4: 1: 1). In addition, the target spinel structure compound is SnZ
In the case of n ₂ O ₄ , tin compounds and zinc compounds are weighed and used as basic starting materials so that the ratio of Sn and Zn is a predetermined stoichiometric ratio (= 1: 2).

Specific examples of the zinc (Zn) compound used as the basic starting material include zinc carboxylates such as zinc acetate, inorganic zinc compounds such as zinc chloride, zinc fluoride and zinc iodide, and zinc. Examples thereof include zinc alkoxides such as methoxide, zinc ethoxide and zinc propoxide. Specific examples of the indium (In) compound include indium acetate, indium chloride, indium ethoxide, indium propoxide and the like.

Specific examples of the antimony (Sb) compound include antimony chloride (trivalent), antimony chloride (pentavalent),
Examples thereof include trimethoxy antimony, triethoxy antimony, tripropoxy antimony, tributoxy antimony and the like. As specific examples of the tin (Sn) compound, tin acetate (divalent), dimethoxytin, diethoxytin, dipropoxytin, dibutoxytin, tetramethoxytin, tetraethoxytin, tetrapropoxytin, tetrabutoxytin,
Examples thereof include tin chloride (divalent) and tin chloride (tetravalent).

As a solvent for preparing the above coating solution, alcohols such as methanol, ethanol, isopropyl alcohol, 2-methoxyethanol and 2-ethoxyethanol, and hydrocarbons such as toluene and benzene can be used. . Further, as a solution stabilizer, monoethanolamine, diethanolamine,
Alkanolamines such as triethanolamine can be used.

The coating solution used in Method I can be prepared by mixing a predetermined amount of the basic starting material for the spinel structure compound with a predetermined amount of the solvent and the stabilizer. The mixing order at this time is not particularly limited. The mixing may be stirring and mixing by a conventional method such as a stirrer, and heating may be performed at this time. Stirring time is 0.01
~ 100 hours is preferred. If it is less than 0.01 hours, it is difficult to obtain a uniform transparent solution. On the other hand, if it exceeds 100 hours, the economy becomes poor. Particularly preferable stirring time is 0.1 to 100 hours. When heating at the time of stirring, the heating temperature is preferably 100 ° C or lower. 1
When the temperature exceeds 00 ° C, the solvent evaporates and the solution concentration changes.

The concentration of the basic starting material of the spinel structure compound in the coating solution is 0.01 to 10 mol%.
It is preferable that If it is less than 0.01 mol%, the film thickness per coating is small, and a large number of coatings are required to obtain a desired film thickness, resulting in poor economic efficiency. On the other hand, if it exceeds 10 mol%, the film thickness becomes uneven during coating. A particularly preferable concentration of the basic starting material for the spinel structure compound is 0.1 to 10 mol%.

The concentration of the stabilizer in the coating solution is preferably 0.01 to 10 mol%. 0.
If it is less than 01 mol%, it becomes difficult to dissolve the basic starting material in a solvent. On the other hand, if it exceeds 10 mol%, carbon generated by decomposition of the stabilizer during baking will remain in the film even after baking, and the conductivity of the film will be reduced. A particularly preferable concentration of the stabilizer is 0.1 to 10 mol%.

In Method I, the coating solution prepared as described above is applied to the substrate and then baked. Although various substrates can be used depending on the application, examples of the transparent substrate include alkali glass, non-alkali glass, quartz glass, and transparent polymer.
The substrate may have an undercoat layer. Specific examples of the undercoat layer include ZnO, SiO ₂ , T
A thin film such as iO ₂ may be used. The coating method is not particularly limited, and various methods that have been conventionally applied when producing a thin film from a solution can be used. Specific examples include a spray method, a dipping method, a spin coating method and the like.

As the firing method, atmospheric pressure firing, vacuum firing, pressure firing or the like can be applied. Firing temperature is 5
The temperature is preferably 00 to 1000 ° C. If the temperature is lower than 500 ° C, it is difficult to produce the target spinel structure compound. On the other hand, 1
If it exceeds 000 ° C, the film composition is likely to change. A particularly preferable firing temperature is 600 to 900 ° C. The firing time is
Although depending on the firing temperature, 0.01 to 10 hours is preferable.
If it is less than 0.01 hours, the carbon generated by the decomposition of the solvent or the stabilizer remains in the film even after firing, and the conductivity of the film is lowered. On the other hand, if it exceeds 10 hours, the economy becomes poor. A particularly preferable firing time is 0.1 to 10 hours.

When the desired film thickness cannot be obtained by performing the operation of coating and baking only once,
It is preferable to perform the operation of calcining after coating a required number of times and then performing the main calcination. The temperature for calcination is 3
The temperature is preferably 00 to 1000 ° C. If the temperature is lower than 300 ° C., the carbon generated by the decomposition of the solvent or the stabilizer remains in the film even after the calcination, which lowers the conductivity of the film. On the other hand, 1000 ° C
If it exceeds, the composition of the film changes and the intended spinel structure compound cannot be obtained. Particularly preferable calcination temperature is 300 to 6
It is 00 ° C.

The calcination time varies depending on the calcination temperature, but is preferably 0.01 to 1 hour. In less than 0.01 hours,
Since the solvent or stabilizer does not fly off and remains,
No matter how many times coating and calcination are repeated, the previously coated film will melt at the next coating and the film will not become thick. On the other hand, if it exceeds 1 hour, the economy becomes poor.

In method I, reduction treatment is performed after firing as described above. As the reduction method, reduction with a reducing gas, reduction with an inert gas, reduction by vacuum firing, or the like can be applied. Hydrogen gas as the reducing gas,
Steam or the like can be used. As the inert gas, nitrogen gas, argon gas, a mixed gas of these gases and oxygen, or the like can be used.

The reduction temperature is preferably 100 to 600 ° C.
If it is less than 100 ° C, it is difficult to perform sufficient reduction.
On the other hand, when the temperature exceeds 600 ° C., the film composition tends to change. A particularly preferred reduction temperature is 200 to 500 ° C. The reduction time depends on the reduction temperature, but is preferably 0.01 to 10 hours. If it is less than 0.01 hours, it is difficult to perform sufficient reduction. On the other hand, if it exceeds 10 hours, the economy becomes poor. Particularly preferable reduction time is 0.1 to 10 hours.

The transparent conductive film I of the present invention which can be produced by the above method I has practically sufficient conductivity and excellent visible light transmittance. The decrease in visible light transmittance due to moisture is smaller than that in the ITO film. Further, the electron mobility is as high as about 50 cm ² / V · sec or more. The transparent conductive film I can be used as an electrode for various applications such as an electrode for a liquid crystal display element and an electrode for a solar cell.

Next, the method II of the present invention will be described.
Method II is, as described above, a predetermined amount of the basic starting material of the spinel structure compound and at least one dope selected from the group consisting of Sn compounds, Al compounds, Sb compounds, Ga compounds, In compounds and Ge compounds. Raw materials and
A coating solution is prepared by dissolving so that the ratio of the dope element to the total amount of the cation elements constituting the spinel structure compound is 20 at% or less, the coating solution is applied to the substrate, baked, and then subjected to reduction treatment. It is characterized by that.

Here, the doping elements (Sn, Al, S
The ratio of (n, Ga, In, Ge) is 20 at% as described above.
The reason for limiting to the following is that if the content exceeds 20 at%, the conductivity of the obtained film is excessively lowered due to ion scattering. By setting the ratio of the above elements to 20 at% or less,
A transparent conductive film having a conductivity equal to or higher than that of the transparent conductive film I can be obtained. The ratio of the doping element is preferably 1 to 10 at%, particularly preferably 2 to 10 at%.

In this method II, in addition to the basic starting material for the spinel structure compound, at least one doping material selected from the group consisting of Sn compounds, Al compounds, Sb compounds, Ga compounds, In compounds and Ge compounds is used. This is different from Method I described above in that a predetermined amount is dissolved to prepare a coating solution. Other points, namely, the types of basic starting materials for spinel structure compounds and methods for preparing coating solutions,
The type of substrate, the firing method, and the reduction method are the same as those in Method I. The doping element is preferably not a basic constituent element of the spinel structure compound as described in the explanation of the transparent conductive film II. Further, the concentration of the total amount of the basic starting material of the spinel structure compound and the dope material in the coating solution is preferably 0.01 to 10 mol% for the same reason as in Method I, and particularly 0.1 to 0.1 mol%.
10 mol% is preferable.

As specific examples of the Sn compound as the dope raw material used together with the basic starting material for the spinel structure compound in Method II, the same as those exemplified as the basic starting material for the spinel structure compound in the explanation of Method I can be mentioned. To be Specific examples of the Al compound as the dope raw material include aluminum chloride, trimethoxy aluminum, triethoxy aluminum, tripropoxy aluminum, tributoxy aluminum and the like. Dope raw material S
Specific examples of the compound b are the same as those exemplified as the basic starting material for the spinel structure compound in the explanation of Method I.

Specific examples of the Ga compound as the dope raw material include gallium chloride (trivalent), trimethoxygallium, triethoxygallium, tripropoxygallium, tributoxygallium and the like. Specific examples of the In compound as the dope material include the same as those exemplified as the basic starting material of the spinel structure compound in the description of Method I. Then, specific examples of the Ge compound as the dope raw material include germanium chloride (tetravalent), tetramethoxygermanium, tetraethoxygermanium, tetrapropoxygermanium, tetrabutoxygermanium and the like.

The transparent conductive film II of the present invention which can be produced by the above method II has an excellent visible light transmittance and an electron mobility of about 50 cm ² / V · sec or more. ing. The decrease in visible light transmittance due to moisture is smaller than that in the ITO film. Further, its conductivity is substantially equal to or higher than that of the transparent conductive film I because it is substantially composed of a compound in which the transparent conductive film I described above is doped with an element having a positive trivalence or higher valence. This transparent conductive film II
Can also be used as electrodes for various applications such as electrodes for liquid crystal display elements and electrodes for solar cells.

[0034]

EXAMPLES Examples of the present invention will be described below. Example 1 (Production Example of Transparent Conductive Film I by Method I) Anhydrous zinc acetate and tetrapropoxy tin (Sn (OC ₃ H ₇ ) ₄ ) were used as basic starting materials for a spinel structure compound, and 2-methoxymethanol was used as a solvent. A transparent conductive film I was produced in the following manner based on Method I using monoethanolamine as a stabilizer and a quartz glass plate as a substrate. First, 2-methoxymethanol 2
To 5.5 g, 1.1 g of monoethanolamine and Sn (OC
2.2 g of ₃ H ₇ ) ₄ was added and mixed with stirring for 10 minutes.
A clear solution was obtained. While stirring the transparent solution, 1.3 g of anhydrous zinc acetate was added to the transparent solution and mixed by stirring for 10 minutes to prepare a transparent and uniform coating solution.
The molar ratio of Zn and Sn in this coating solution is Z
n: Sn = 2: 1, and the total concentration of Zn and Sn was 0.5 mol / liter (4 mol%).

Next, a quartz glass plate (70 × 20 × 1.5 mm) was dipped in the obtained coating solution to perform dip coating (coating speed: 1.2 cm / min), and then 500 ° C. using an electric furnace. It was calcined for 10 minutes. The above-mentioned operation of performing dip coating and then calcining was repeated 10 times in total, and then main firing was further performed at 800 ° C. for 1 hour. Then, vacuum (1 x 1) at 400 ° C for 2 hours.
0 ^-2 torr) was reduced to obtain the target transparent conductive film I.

X of the transparent conductive film I thus obtained
RD (X-ray diffraction, equipment used: Rotaflex RU-
When 200B (manufactured by Rigaku Corporation) was measured, it was confirmed that the compound essentially consisted of a spinel structure compound (SnZn ₂ O ₄ ). Further, when the film thickness was measured from an electron micrograph of the cross section of the obtained transparent conductive film I, the film thickness was 20.
It was 0 nm. The electron mobility of this transparent conductive film I was measured by the four-terminal method. The results are shown in Table 1. Further, this transparent conductive film I was subjected to a moisture resistance test under the conditions of 40 ° C., 90% RH and a test time of 1000 hours, and the visible light transmittances (test wavelength 380 nm) before and after the test were compared. The results are also shown in Table 1.

Example 2 (Production Example of Transparent Conductive Film I by Method I) Anhydrous zinc acetate, indium acetate and tributoxyantimony were prepared as basic starting materials for a spinel structure compound. First, 23.7 g of 2-methoxyethanol was prepared. 2.2 g of monoethanolamine and 0.9 g of indium acetate were added to and mixed with stirring for 10 minutes to obtain a transparent solution. While stirring the clear solution, 1.0 g of tributoxy antimony and 2.2 g of anhydrous zinc acetate were added to the clear solution, and 1
A transparent and uniform coating solution was prepared by stirring and mixing for 0 minutes. The molar ratio of Zn, In and Sb in this coating solution was Zn: In: Sb = 4: 1: 1 and the total concentration of Zn, In and Sb was 0.5 mol / liter (4 mol%). there were. After this, the main firing temperature is set to 90.
A target transparent conductive film I (film thickness 200 nm) was obtained in the same manner as in Example 1 except that the temperature was 0 ° C.

X of the transparent conductive film I thus obtained
When RD was measured, a spinel structure compound (Zn ₄ I
It has been confirmed that it is substantially composed of nSbO ₈ ). The electron mobility of the transparent conductive film I was measured in the same manner as in Example 1, and the moisture resistance test was performed in the same manner as in Example 1 to determine the visible light transmittance before and after the test (test wavelength 380n).
m) were compared. The results are shown in Table 1.

Example 3 (Production Example of Transparent Conductive Film I by Method I) Anhydrous zinc acetate and tributoxyantimony were prepared as basic starting materials for a spinel structure compound. First, 24.6 g of 2-methoxyethanol was added to monoethanolamine. 1.2
g and 1.5 g of tributoxy antimony were added, and 10
After stirring and mixing for a minute, a clear solution was obtained. Next, while stirring the transparent solution, anhydrous zinc acetate 2.7 was added to the transparent solution.
g, and mixed by stirring for 10 minutes to prepare a transparent and uniform coating solution. The molar ratio of Zn to Sb in this coating solution was Zn: Sb = 7: 2, and
The total concentration of n and Sb is 0.5 mol / liter (4 mol
%)Met. After that, the target transparent conductive film I (film thickness 200 nm) was obtained in the same manner as in Example 2.

X of the transparent conductive film I thus obtained
When RD was measured, the spinel structure compound (Sb ₂ Z
n ₇ O ₁₂ ) was confirmed. Also,
The electron mobility of this transparent conductive film I was measured in the same manner as in Example 1, and the moisture resistance test was performed in the same manner as in Example 1 to measure the visible light transmittance before and after the test (test wavelength 380 nm).
Were compared. The results are shown in Table 1.

Comparative Example 1 (Production Example of ITO Thin Film) First, 4.0 g of monoethanolamine and 3.8 g of indium acetate were added to 22.2 g of 2-methoxymethanol, and mixed by stirring for 10 minutes to prepare a transparent solution. did. Next, while stirring this transparent solution, Sn is added to the transparent solution.
0.1 g of (OC ₄ H ₉ ) ₂ was added and mixed by stirring for 10 minutes to prepare a transparent and uniform coating solution. The molar ratio of In to Sn in this coating solution is I
n: Sn = 95: 5, and the concentration of the total amount of In and Sn was 0.5 mol / liter (4 mol%). After this,
An ITO thin film (film thickness 200 nm) was obtained in the same manner as in Example 1 except that the main firing temperature was 500 ° C. The electron mobility of the ITO thin film thus obtained was measured in the same manner as in Example 1, and the moisture resistance test was performed in the same manner as in Example 1 to measure the visible light transmittance before and after the test (test wavelength 380).
nm) was compared. The results are shown in Table 1.

[0042]

[Table 1]

As is clear from Table 1, each of the transparent conductive films I obtained in Examples 1 to 3 is 80 cm ² /
It has a high electron mobility of V · sec or more. Also,
The visible light transmittance of these transparent conductive films I is not changed before and after the moisture resistance test, or even if it is detected, it is slightly decreased after the test. From this, it is understood that any of the transparent conductive films I obtained in Examples 1 to 3 has excellent moisture resistance. On the other hand, the electron mobility of the ITO thin film of Comparative Example 1 is as low as 20 cm ² / V · sec. In addition, the visible light transmittance is significantly lowered after the humidity resistance test, which shows that the moisture resistance is inferior.

Example 4 (Production Example of Transparent Conductive Film II by Method II) Anhydrous zinc acetate and tetrapropoxy tin were used as basic starting materials for the spinel structure compound, and trihydrate was used as an Al compound used together with the basic starting material for the spinel structure compound. Using butoxyaluminum, 2-methoxyethanol as a solvent, monoethanolamine as a stabilizer, and a quartz glass plate as a substrate, a transparent conductive film II was produced based on Method II as follows. First, 2-
Example 1 using methoxyethanol, monoethanolamine, tetrapropoxy tin, and anhydrous zinc acetate.
30 g of a transparent and uniform solution (corresponding to the coating solution of Example 1) was prepared in exactly the same manner as in.

Next, 0.15 g of tributoxyaluminum was added to this solution and mixed by stirring for 10 minutes to prepare a transparent and uniform coating solution. The molar ratio of Zn and Sn in this coating solution is Zn: Sn = 2: 1.
And the ratio [Al / (Zn + Sn + Al)] × 1 of the doping element Al to the total amount of the cation elements (Zn, Sn and Al) constituting the target spinel structure compound.
00 was 4 at%. The total concentration of Zn, Sn, and Al in the coating solution was 0.5 mol / liter (4 mol%). Thereafter, coating, firing and reduction treatment were performed in the same manner as in Example 1 to obtain the target transparent conductive film II (film thickness 200 nm).

X of the transparent conductive film II thus obtained
As a result of measuring RD in the same manner as in Example 1, it was confirmed that the crystal structure of this transparent conductive film II was substantially the same as that of SnZn ₂ O ₄ having a spinel structure. Further, there is no diffraction attributed to other structures, which proves that Al is doped in the spinel structure. The electron mobility of this transparent conductive film II was measured in the same manner as in Example 1, and the moisture resistance test was performed in the same manner as in Example 1 to compare the visible light transmittance (test wavelength 380 nm) before and after the test. The results are shown in Table 2.

Example 5 (Production Example of Transparent Conductive Film II by Method II) Coating was carried out in the same manner as in Example 4 except that 0.13 g of Sb compound tributoxyantimony was used instead of Al compound tributoxyaluminum. Solution {Zn:
Sn = 2: 1, [Sb / (Zn + Sn + Sb)] × 10
0 = 4 at%, concentration of total amount of Zn, Sn and Sb = 0.5 m
ol / l (4 mol%)} and prepared a transparent conductive film II using this coating solution in exactly the same manner as in Example 4.
(Film thickness 200 nm) was obtained.

X of the transparent conductive film II thus obtained
As a result of measuring RD in the same manner as in Example 1, it was confirmed that the crystal structure of this transparent conductive film II was substantially the same as that of SnZn ₂ O ₄ having a spinel structure. Further, there was no diffraction attributed to other structures, which proves that Sb is doped in the spinel structure. The electron mobility of this transparent conductive film II was measured in the same manner as in Example 1, and the moisture resistance test was performed in the same manner as in Example 1 to compare the visible light transmittance (test wavelength 380 nm) before and after the test. The results are shown in Table 2.

Example 6 (Production Example of Transparent Conductive Film II by Method II) The same as Example 4 except that 0.11 g of Ga compound gallium chloride (trivalent) was used instead of tributoxyaluminum of Al compound. Coating solution {Zn: S
n = 2: 1, [Ga / (Zn + Sn + Ga)] × 100
= 4 at%, concentration of total amount of Zn, Sn and Ga = 0.5 mol
/ Liter (4 mol%)} was prepared and the transparent conductive film II was prepared in the same manner as in Example 4 using this coating solution.
(Film thickness 200 nm) was obtained.

X of the transparent conductive film II thus obtained
As a result of measuring RD in the same manner as in Example 1, it was confirmed that the crystal structure of this transparent conductive film II was substantially the same as that of SnZn ₂ O ₄ having a spinel structure. Further, there is no diffraction attributed to other structures, which proves that Ga is doped in the spinel structure. The electron mobility of this transparent conductive film II was measured in the same manner as in Example 1, and the moisture resistance test was performed in the same manner as in Example 1 to compare the visible light transmittance (test wavelength 380 nm) before and after the test. The results are shown in Table 2.

Example 7 (Production Example of Transparent Conductive Film II by Method II) Coating was carried out in the same manner as in Example 4 except that 0.15 g of tetrapropoxygermanium, a Ge compound, was used instead of tributoxyaluminum, an Al compound. Solution {Zn: Sn = 2: 1, [Ge / (Zn + Sn + G
e)] × 100 = 4 at%, the total concentration of Zn, Sn and Ge = 0.5 mol / liter (4 mol%)} was prepared, and this coating solution was used in the same manner as in Example 4. A transparent conductive film II (film thickness 200 nm) was obtained.

X of the transparent conductive film II thus obtained
As a result of measuring RD in the same manner as in Example 1, it was confirmed that the crystal structure of this transparent conductive film II was substantially the same as that of SnZn ₂ O ₄ having a spinel structure. Further, there is no diffraction attributed to other structures, which proves that Ge is doped in the spinel structure. The electron mobility of this transparent conductive film II was measured in the same manner as in Example 1, and the moisture resistance test was performed in the same manner as in Example 1 to compare the visible light transmittance (test wavelength 380 nm) before and after the test. The results are shown in Table 2.

Example 8 (Production Example of Transparent Conductive Film II by Method II) A coating solution was prepared in the same manner as in Example 4 except that 0.11 g of indium acetate of In compound was used in place of tributoxyaluminum of Al compound. {Zn: Sn =
2: 1, [In / (Zn + Sn + In)] × 100 = 4
at%, the total concentration of Zn, Sn, and In = 0.5 mol / liter (4 mol%)} was prepared, and using this coating solution, the transparent conductive film II (film) was prepared in the same manner as in Example 4. A thickness of 200 nm) was obtained.

X of the transparent conductive film II thus obtained
As a result of measuring RD in the same manner as in Example 1, it was confirmed that the crystal structure of this transparent conductive film II was substantially the same as that of SnZn ₂ O ₄ having a spinel structure. Further, there is no diffraction attributed to other structures, which proves that In is doped in the spinel structure. The electron mobility of this transparent conductive film II was measured in the same manner as in Example 1, and the moisture resistance test was performed in the same manner as in Example 1 to compare the visible light transmittance (test wavelength 380 nm) before and after the test. The results are shown in Table 2.

[0055]

[Table 2]

As is clear from Table 2, each of the transparent conductive films II obtained in Examples 4 to 8 is 79 cm ² /
It has a high electron mobility of V · sec or more. Also,
The visible light transmittance of these transparent conductive films II is not changed before and after the moisture resistance test, or even if it is observed, it is slightly decreased after the test. From this, it is understood that all the transparent conductive films II obtained in Examples 4 to 8 have excellent moisture resistance.

[0057]

As described above, the transparent conductive film of the present invention is superior to the ITO film in moisture resistance and has high electron mobility. Therefore, according to the present invention, it is possible to provide a transparent conductive film which is advantageous in obtaining an element or device having high durability and high electric field response.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-191844 (JP, A) JP-A-5-238807 (JP, A) New Ceramics, Vol. 5, No. 12, pp. 63-68, 1992 (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01B 5/00-5/16 JISST file (JOIS) CA (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. Sn, Al, Sb, Ga, In and G
spinel structure compound of at least one element is doped is selected from the group consisting of e (where the spinel structure
Except when the cation element constituting the compound is Mg
And a doping amount of the element is 20 at% or less with respect to the total amount of cationic elements constituting the spinel structure compound. 2. The transparent conductive film according to claim 1, which has an electron mobility of 50 cm ² / V · sec or more. 3. A spinel structure compound (provided that the spinel
When the cation element constituting the structural compound is Mg
(Excluding) a predetermined amount of basic starting material and Sn compound, Al compound, Sb compound, Ga compound, In compound and Ge
A coating solution is prepared by dissolving at least one dope raw material selected from the group consisting of compounds so that the ratio of the dope element to the total amount of the cation elements constituting the spinel structure compound is 20 at% or less. A method for producing a transparent conductive film, which comprises applying the coating solution to a substrate, baking the substrate, and then performing a reduction treatment.