RU2661166C2 - Method for creating transparent conductive composite nano-coatings (options) - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method for creating transparent conductive composite nano-coatings (variants). In the first variant, chemical deposition of a thin film of carbon nanotubes is preliminarily carried out on a heated substrate. Reactive magnetron sputtering of the metal target is carried out in an atmosphere of a gaseous mixture of inert and reactive gases, with an indium oxide coating deposited on the substrate. In reactive magnetron sputtering, a pure indium target is used, and a gas mixture with an inert gas content and 30 % oxygen is used as said gas mixture. According to the second variant, the nano-micronet is first applied to the substrate by the method of cracking polymer templates using liquid silica and by spraying a metal with electronic conductivity. Reactive magnetron sputtering of the metal target is carried out in an atmosphere of a gaseous mixture of inert and reactive gases, with the deposition of an indium oxide coating on the substrate. Reactive magnetron sputtering uses a pure indium target and a gas mixture containing 21 % oxygen in it.

EFFECT: decrease in the surface resistance of transparent conductive coatings with electronic conductivity, as well as the production of a transparent conductive coating with hole-type conductivity.

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Description

The invention relates to the field of technological processes associated with the application of transparent nanofilm coatings with high hole or electron conductivity, in particular to magnetron (reactive) sputtering and chemical deposition, and can be used to obtain transparent conductive composite nanocoatings on the surfaces of various substrates at a low temperature.

Currently, semiconductor transparent oxide thin films such as In ₂ O ₃ , ZnO, SnO ₂ , CdO, Ga ₂ O ₃ , TiO ₂ , and more complex binary and ternary oxides are widely used. This is due to the fact that the materials presented have both transparency (~ 90%) in the visible range and the ability to conduct electric current. The oxides presented are used in the manufacture of thin displays, organic light-emitting diodes, solar panels, thin-film transistors, gas sensors, spacecraft, etc. Today, one of the most industrially needed conducting oxides is In ₂ O ₃ doped with Sn atoms (ITO).

A known method of producing conductive transparent coatings of indium oxide [RF Patent No. 2112076, IPC С23С 14/20, publ. May 27, 1998], which uses reactive magnetron sputtering of a metal target in a reactive and inert gas environment. Oxygen is used as the reactive gas.

The main disadvantage of this method is the need for ion stimulation during the deposition process, which requires additional equipment and requires additional control when spraying the material.

There is a method of manufacturing transparent coatings of indium oxide [RU 2241065, IPC С23С 14/08, publ. November 27, 2004]. This method also uses reactive magnetron sputtering of a metal target in a reactive gas medium. The total working pressure in the chamber during sputtering of the target is 6-7 × 10 ^-3 mbar.

The disadvantage of this method is the use of a composite target: indium 95%, tin 5%, in the process of reactive magnetron sputtering. This increases the technological control of the manufacture of a target for magnetron reactive sputtering. In addition, the resistivity of the resulting coatings is relatively large.

Another analogue of the presented invention is the invention [RU 2578664, IPC C09D 1/00, publ. 03/27/2016], where carbon nanotubes (CNTs) and / or nanowire composite materials are used as a transparent conductive coating. This invention uses both single-walled and double-walled carbon nanotubes.

However, the main disadvantage is the relatively high resistivity> 100 Ohm / square with a relatively low transmittance <75%.

The closest analogue is a method of applying a conductive transparent coating, including reactive magnetron sputtering of a metal target in an atmosphere of a gas mixture of an inert and reactive gas and deposition of the coating. The reaction gas used is oxygen, air and carbon dioxide, while an indium and tin alloy is used as a metal target [RU 2564650, IPC С23С 14/12, publ. 10/10/2015].

The main disadvantages of the method are: a relatively high surface resistance, the inability to obtain a transparent conductive coating with hole conductivity.

The technical result of the invention is to reduce the surface resistance of transparent conductive coatings with electronic conductivity, as well as obtaining a transparent conductive coating with hole conductivity.

The technical result according to the first embodiment is achieved by the fact that in the low-temperature method for creating transparent conductive composite nanocoatings with high hole conductivity, including preparing the substrate, reactive magnetron sputtering of a metal target in an atmosphere of a gas mixture of inert and reactive gases, with the deposition of a coating of indium oxide on the substrate, a new is that they use preliminary chemical deposition of a thin film of carbon nanotubes on a substrate, and as a metal target Use of pure indium target, which is sprayed at elevated oxygen content.

The technical result of the second embodiment is also achieved by the fact that in the low-temperature method for creating transparent conductive composite nanocoatings with high electronic conductivity, which includes preparing the substrate, reactive magnetron sputtering of a metal target in an atmosphere of a gas mixture of inert and reactive gases, with deposition of an indium oxide coating on the substrate , it is new that a nanomicrogrid is preliminarily deposited on a substrate, and a pure indium target is used as a metal target. paradise is sprayed under a reduced oxygen content.

The claimed group of inventions meets the requirement of the unity of the invention, since the group of single-object inventions forms a single inventive concept, the application relates to objects of the invention of the same type, of the same purpose, providing the same technical result.

Comparative analysis with the prototype allowed us to identify a set of essential distinguishing features in relation to the technical result for each of the claimed objects of the group set forth in the formulas. Therefore, each of the objects of the group of inventions meets the criterion of "novelty." The features distinguishing the claimed technical solutions from the prototype are not identified in other technical solutions when studying data and related areas of technology and, therefore, provide the claimed solutions with the criterion of "inventive step".

In FIG. 1 shows a scheme for producing thin NMS films.

To achieve a technical result, variants of a method for manufacturing transparent conductive composite nanocoatings with high hole or electron conductivity on various substrates, including organic substrates, are proposed. The proposed method (options) includes chemical deposition and vacuum magnetron (reactive) sputtering.

As the substrate material using a cover glass, silicon, Al ₂ O ₃ , quartz and any other substrates, including organic substrates.

1. For the manufacture of transparent conductive composite nanofilms with high hole conductivity, single-walled carbon nanotubes (SWCNTs) are used in the form of thin films as the lower layer and thin In ₂ O ₃ films as the upper layer.

For the manufacture of thin SWCNT films as the lower layer, the spray method or another chemical deposition method with a heated substrate is used. Colloidal dispersion of SWCNTs is used as a sprayed substance.

For the manufacture of thin In ₂ O ₃ films, the reactive magnetron sputtering of a metal target using pulsed direct current in an atmosphere of a gas mixture of inert and reactive gases is used as the upper layer. For this method of manufacturing composite nanocoatings, an increased percentage of reactive gas is used.

Particularly pure oxygen and argon, respectively, are used as an inert and reactive gas. Chemically pure indium is used as a target. 2. For the manufacture of transparent conductive composite nanofilms with high electronic conductivity, metal nano and microgrids (NMS) are used in the form of thin films as the lower layer and thin In ₂ O ₃ films as the upper layer.

For the manufacture of thin NMS films as the lower layer, the method of cracking polymer templates with the subsequent deposition of pure metal is used.

The polymer used is liquid silica sol. Vacuum thermal deposition or direct current magnetron sputtering is used to spray metal onto a cracked polymer template. As the sprayed metal, silver, copper, gold and other metals with high electronic conductivity are usually used.

For the manufacture of thin In ₂ O ₃ films, the reactive magnetron sputtering of a metal target using pulsed direct current in an atmosphere of a gas mixture of inert and reactive gases is used as the upper layer. For this method of manufacturing nanocoatings, a reduced percentage of reactive gas is used.

Particularly pure oxygen and argon are used as an inert and reactive gas. Chemically pure indium is used as a target.

Examples of implementation

Example 1

Thin composite SWCNTs / In ₂ O ₃ films with high hole conductivity were produced using the following technology:

Thin films from SWCNTs were deposited using the spray method on glass substrates. The principle of the formation of SWCNT films was as follows: compressed air from the compressor was supplied to the airbrush at a pressure of 6 atm (0.6 MPa), spraying a colloidal dispersion of SWCNTs on a heated substrate. The working temperature of the substrate was 130 ° C. The heating of the substrate is necessary in order to exclude the migration of droplets and prevent their coalescence. The average aerosol droplet size was 30-50 microns. The distance from the airbrush nozzle to the substrate was 25 cm. The method made it possible to obtain uniform coatings on polymer and glass substrates with an area of 25 cm ² or more (by scanning).

The obtained thin SWCNT films were placed on glass substrates in a vacuum chamber from the side of the sprayed surface of the metal target onto the holder substrate for the subsequent deposition of thin In ₂ O ₃ films on them using reactive magnetron sputtering. A metal target from chemically pure indium (99.999%) was used. The distance from the target surface to the substrates with thin SWCNT films was set to 15 cm. A magnetic field was created with the magnitude of induction on the sprayed surface of the metal target in the middle of the closed magnetic gap of 0.035 T using a magnetron type magnetic system with permanent magnets.

Oil-free vacuum pumps were used to create a pressure of not more than 9⋅10 ^-6 Torr in the working chamber and they began to inject a mixture of argon and oxygen with a ratio of 70% and 30%, respectively, using a precision gas supply system. The vacuum gauge was measured, which amounted to 3.7 · 10 ^-3 Torr.

The magnetron power sources, turned on according to a scheme with power stabilization, were set to supply a negative pulse voltage to a metal target of 430 V relative to the walls of the working chamber. We set the repetition rate of negative voltage pulses at a magnetron power source to 100 kHz and set the duty cycle of 35%.

After the magnetron discharge was excited above the surface of the metal target, a stabilized plasma discharge power of 100 W was established. The thin films of indium oxide were deposited on thin SWCNT films for 20 minutes, moving the substrates with a swing frequency of 0.5 Hz.

As a result, we obtained transparent conducting composite SWCNTs / In ₂ O ₃ nanofilms with a surface resistance of not more than 10 kOhm / square with hole conductivity and an integral transmittance of at least 90%.

In addition, if pure glass substrates were used without thin SWCNT films, thin films of indium oxide were obtained with a specific surface resistance of> 100 MΩ / square and an integral transmittance of at least 92%.

The surface resistance of the coating was monitored by a four-point probe method. The integrated transmittance in the visible region of the spectrum was determined on an optical spectrophotometer. The type of conductivity was determined using the thermopower method.

Example 2

Thin composite SWCNTs / In ₂ O ₃ films on organic substrates with high hole conductivity were produced using the following technology:

thin films from SWCNTs were deposited using the spray method on organic substrates, including polyamide and polyethylene terephthalate (PET) substrates. Further manufacturing of composite SWCNTs / In ₂ O ₃ films was identical to Example 1 of Option 1.

OPTION 2

Example 1

Thin composite NMS / In ₂ O ₃ films with high electronic conductivity were made as follows:

thin NMS films were formed (according to the scheme in Fig. 1). The formation consisted of 4 main stages. At the first stage, a silica sol liquid film was applied by the Meyer rod method. At the second stage, the film was dried in air with the aim of evaporating the dispersion medium and initiating a sol – gel transition with further cracking of the silica gel gel film. This stage was completed by the process of forming the template. At the third stage, silver metal films were sprayed by direct current magnetron sputtering of a silver target onto cracked films of a polymer template. At the fourth stage, the clusters of the template were removed by liquid washing.

The obtained thin NMS films were placed on glass substrates in a vacuum chamber from the side of the sprayed surface of the metal target on the holder substrate for the subsequent deposition of thin In ₂ O ₃ films on them using reactive magnetron sputtering. A metal target from chemically pure indium (99.999%) was used. The distance from the target surface to the substrates with thin NMS films was set to 15 cm. A magnetic field was created with the magnitude of induction on the sprayed surface of the metal target in the middle of the closed magnetic gap equal to 0.035 T using a magnetron type magnetic system with permanent magnets.

Oil-free vacuum pumps were used to create a pressure of no more than 9⋅10 ^-6 Torr in the working chamber and they began to inject a mixture of argon and oxygen with a ratio of 79% and 21%, respectively, using a precision gas supply system. The vacuum gauge was measured, which amounted to 3.7 · 10 ^-3 Torr.

The magnetron power sources, turned on according to a scheme with power stabilization, were set to supply a negative pulse voltage to a metal target of 430 V relative to the walls of the working chamber. We set the repetition rate of negative voltage pulses at a magnetron power source to 100 kHz and set the duty cycle of 35%.

After the magnetron discharge was excited above the surface of the metal target, a stabilized plasma discharge power of 100 W was established. We applied thin films of indium oxide on thin NMS films for 20 minutes, moving the substrates with a swing frequency of 0.5 Hz.

As a result, we obtained transparent conductive composite NMS / In ₂ O ₃ nanofilms with a surface resistance of not more than 3.5 Ohm / square with electronic conductivity and an integral transmittance of at least 85%.

In addition, if pure glass substrates were used without thin NMS films, thin indium oxide films were obtained with a specific surface resistance of <60 Ω / square and an integral transmittance of at least 85%.

The surface resistance of the coating was monitored by a four-point probe method. The integrated transmittance in the visible region of the spectrum was determined on an optical spectrophotometer. The type of conductivity was determined using the thermopower method.

Example 2

Thin composite NMS / In ₂ O ₃ films on organic substrates with high electronic conductivity were made using the following technology:

thin NMS films were formed on organic substrates according to the circuit of FIG. 1, including polyamide and PET substrates. Further production of composite NMS / In ₂ About ₃ films was identical to example 1 of option 2.

Measurements showed that the use of the proposed method allows to obtain transparent conductive coatings in the form of composite SWCNTs / In ₂ O ₃ nanocoatings with high hole conductivity, and also allows to significantly reduce the surface resistance of transparent conductive coatings due to the use of composite NMS / In ₂ O ₃ nanocoatings.

Claims (2)

1. A method of creating transparent conductive composite nanocoatings, including substrate preparation, reactive magnetron sputtering of a metal target in an atmosphere of a gas mixture of inert and reactive gases with deposition of an indium oxide coating on a substrate, characterized in that a thin film of carbon nanotubes is chemically deposited onto a heated substrate while reactive magnetron sputtering, a pure indium target is used, and a gas mixture is used as said gas mixture l with an inert gas content and 30% oxygen. 2. A method of creating transparent conductive composite nanocoatings, including substrate preparation, reactive magnetron sputtering of a metal target in an atmosphere of a gas mixture of inert and reactive gases, with the deposition of indium oxide coatings on the substrate, characterized in that the nanomicroset is first applied to the substrate by the method of cracking polymer templates using liquid silica sol and sputtering a metal with electronic conductivity, while using a reactive magnetron sputtering, a target of pure indium and a gas mixture with 21% oxygen in it.

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