Terahertz transparent electrode based on nickel tellurium compound and preparation method and application thereof

Abstract

The invention relates to a terahertz transparent electrode based on a nickel tellurium compound and a preparation method and application thereof, and belongs to the technical field of terahertz electrodes. In order to solve the problem that an existing terahertz transparent electrode cannot have high transmittance and good conductivity in the terahertz wave propagation direction at the same time, the invention provides a terahertz transparent electrode based on a nickel-tellurium compound, which comprises a substrate and a nickel-tellurium compound film. The nickel-tellurium compound films with different nickel-tellurium ratios are prepared by setting the target materials with different nickel-tellurium areas, so that the conductivity, transmittance and thickness of the terahertz transparent electrode are adjusted, and the relatively high transmittance and high conductivity of the terahertz wave band of the terahertz transparent electrode are balanced; the transmittance of the obtained terahertz transparent electrode based on the nickel tellurium compound in the terahertz wave band is higher than 80%, the conductivity is larger than 1000 S / cm, and the qualified standard of a transparent conductive film is met. The preparation method is low in requirement and suitable for practical batch production of the terahertz transparent electrode.

Description

Technical Field

[0001] The present invention belongs to the technical field of terahertz electrodes, and in particular relates to a terahertz transparent electrode based on nickel telluride compounds and a preparation method and application thereof. Background Art

[0002] Terahertz waves are defined as electromagnetic waves with frequencies between 0.1 and 10 THz and wavelengths between 30 and 3000 μm, which are in the transition zone from microwave electronics to optoelectronics and photonics. Terahertz waves have broadband and high-frequency characteristics in electronics, and low photon energy, unique fingerprint spectrum, and high transmittance in photonics, which makes terahertz waves have extremely unique basic research value and important applications in the interaction between light and matter, especially in imaging sensing, 6G communications, radar detection, etc.

[0003] Terahertz band transparent electrodes refer to electrode materials that can maintain high transparency and conductivity in the terahertz band. Their key indicators are wide spectral transmittance and high conductivity. Their performance determines the application potential and application environment of terahertz transmission devices. There are currently several solutions for terahertz transparent electrodes, which have promoted the development of terahertz technology.

[0004] Single-layer graphene has high electrical conductivity, mobility and chemical stability, but only a few layers of graphene have high terahertz transmittance. Single-layer, double-layer and even multi-layer graphene have been proposed and studied, but the processing of large-area graphene is difficult and the process is complicated, which undoubtedly increases the production cost and difficulty of device processing.

[0005] Organic transparent conductive films have high conductivity and high transparency, but their conductivity is inversely proportional to terahertz transmittance, making it difficult to further regulate performance. In addition, the thickness of organic films is difficult to accurately control, they are not resistant to high temperatures, and have low compatibility with existing semiconductor processes. Among them, PEDOT:PSS has a high conductivity, but the minimum transmittance in the terahertz range is difficult to reach 80%.

[0006] The conductivity of polyvinyl alcohol-graphene mixed film is low, and the graphene dispersion makes it difficult to ensure the uniformity of conductivity of the electrode at the nanoscale. Although the transparent electrode material ITO has a high transmittance in the visible light band, its transmittance in the terahertz band is less than 10%. Its nano whiskers cannot guarantee the quality and uniformity of film formation and the conductivity is not high, which cannot meet the needs of the application. The conductivity of inorganic metal electrodes is too high, resulting in a small skin depth. Nanowire electrodes have low uniformity and are difficult to be compatible with existing semiconductor processes.

[0007] How to make terahertz transparent electrodes have both high transmittance and good conductivity in the direction of terahertz wave propagation, and make them easy to integrate and compact and light is an urgent problem that needs to be solved in response to the development of emerging terahertz optoelectronic integration technology. Summary of the invention

[0008] In order to solve the problem that the existing terahertz transparent electrodes cannot have high transmittance in the propagation direction of terahertz waves, good conductivity and compatibility with existing semiconductor processes, the present invention provides a terahertz transparent electrode based on nickel telluride compounds and its preparation method and application.

[0009] The technical solution of the present invention:

[0010] A terahertz transparent electrode based on nickel-tellurium compound comprises a substrate and a nickel-tellurium compound film, wherein the atomic number ratio of nickel to tellurium in the nickel-tellurium compound film is 0.3-3.5.

[0011] Furthermore, the substrate is a quartz film, silicon wafer or polytetrafluoroethylene film with a thickness of 0.1 to 1 mm and transparent in the terahertz band, and the thickness of the nickel-tellurium compound film is 5 to 20 nm.

[0012] A method for preparing a terahertz transparent electrode based on nickel telluride compounds comprises the following steps: fixing a substrate on a sample stage so that the substrate is located directly below a sputtering target head; placing a nickel sheet and a telluride target material arranged in a plurality of fan-shaped intervals in a target holder slot, wherein the ratio of the total exposed area of ​​the nickel sheet and the telluride target material is 1 to 15:10; evacuating a sputtering chamber as a back vacuum, flushing the chamber with argon gas and adjusting the sputtering gas pressure in the chamber, starting a sample stage rotating device, applying a radio frequency current to the nickel telluride target material, and growing a nickel telluride compound thin film on the substrate by plasma sputtering, thereby obtaining a terahertz transparent electrode based on nickel telluride compounds.

[0013] Furthermore, the substrate is a quartz film, silicon wafer or polytetrafluoroethylene film with a thickness of 0.1 to 1 mm and transparent in the terahertz band.

[0014] Furthermore, before use, the substrate is cleaned in sequence with deionized water, anhydrous ethanol, acetone, and anhydrous ethanol ultrasonic cleaning, and then blown dry with nitrogen.

[0015] Furthermore, the nickel-tellurium target is made of a plurality of sector-shaped nickel sheets fixedly and symmetrically arranged on the tellurium target, the purity of the tellurium target is 99.99%, the purity of the nickel sheets is 99.999%, and the distance between the target surface of the nickel-tellurium target and the sleeve is fixed at 2 mm; pre-sputtering is performed before plasma sputtering to remove impurities on the target surface.

[0016] Furthermore, the back vacuum is 2Pa, the sputtering gas pressure in the cavity is 4Pa, the RF current is 45mA, the magnetic field strength is 40mT, the sample stage rotation speed is 8rad / min; the plasma sputtering time is 20 to 60s, and the thickness of the nickel tellurium compound film is 5 to 20nm.

[0017] Furthermore, when the substrate is a quartz film or a silicon wafer, the method further includes a processing step of placing the obtained terahertz transparent electrode based on nickel tellurium compound in an argon atmosphere and annealing at normal pressure.

[0018] Furthermore, the normal pressure annealing is to raise the temperature to 150-300° C. at a rate of 30° C. / min, keep the temperature for 1 hour, and then naturally cool down to room temperature.

[0019] The terahertz transparent electrode based on nickel tellurium compounds provided by the present invention is applied in the field of photovoltaic devices, the field of flexible displays, the field of biomedical imaging or the field of high-speed communications.

[0020] Beneficial effects of the present invention:

[0021] In the process of preparing a terahertz transparent electrode by plasma sputtering, a nickel-tellurium compound film with different nickel-tellurium ratios is prepared by setting a target material with different nickel-tellurium areas, and the conductivity, transmittance and thickness of the terahertz transparent electrode are adjusted by combining the plasma sputtering growth time and the thermal annealing process. The thermal annealing treatment can reduce the defects generated during the growth of the film, reduce the carrier scattering while keeping the thickness unchanged, and further improve the conductivity of the terahertz transparent electrode, so that the higher transmittance and high conductivity in the terahertz band are balanced. The terahertz transparent electrode based on nickel-tellurium compounds obtained by the present invention has a transmittance of more than 80% in the terahertz band and a conductivity of more than 1000S / cm, which meets the qualified standards of transparent conductive films.

[0022] The terahertz transparent electrode prepared by plasma sputtering in the present invention also has considerable transmittance in the visible light band, and can be used as a transparent electrode in a visible light and terahertz dual-band system. The terahertz transparent electrode based on a terahertz band transparent polytetrafluoroethylene film in the present invention has outstanding anti-bending performance, and still maintains excellent conductivity after being bent ten thousand times, and can be used for flexible applications of electrode materials.

[0023] The terahertz transparent electrode based on nickel telluride compound of the present invention has uniform and flat thickness and low roughness, and will not cause changes in the waveform in terahertz transmission when used; the nickel telluride compound film has high room temperature air stability, and the performance of the sample remains unchanged after one week of preparation and two months of storage, and the long-term use temperature range is 0-300°C, which can meet the use requirements in different environments.

[0024] The plasma sputtering preparation method provided by the present invention has extremely low requirements, and only requires a low back-end vacuum of 2Pa to prepare a terahertz transparent electrode with high quality, stable performance and high repetition rate. The transparent electrode is an inorganic material film. Based on the sputtering process, the transparent electrode film can be successfully grown on the surface of a wide range of objects such as quartz, silicon wafers, polytetrafluoroethylene, etc., and can be directly combined with photolithography stripping technology to prepare a patterned electrode structure. Therefore, it perfectly solves the problem of compatible integration of terahertz transparent electrodes with existing semiconductor process devices, and is suitable for practical mass production of terahertz transparent electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the nickel sheet and the tellurium target material on the nickel-tellurium target material in Example 1 being arranged in a plurality of fan-shaped intervals;

[0026] Figure 2 A comparison diagram of terahertz frequency domain transmission spectra of terahertz transparent electrodes prepared in Example 5 and Example 6 after annealing and without annealing;

[0027] Figure 3 This is an elemental composition analysis spectrum of the terahertz transparent electrode based on nickel tellurium compound prepared in Example 7;

[0028] Figure 4 This is a graph showing the results of a flexible bending test of a flexible terahertz transparent electrode based on nickel telluride compounds prepared in Example 7;

[0029] Figure 5 These are actual photos of the terahertz transparent electrodes prepared in Example 1 and Example 7, wherein the upper film is the terahertz transparent electrode on a quartz substrate prepared in Example 1, and the lower film is the flexible terahertz transparent electrode prepared in Example 7. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below in conjunction with the embodiments, but it is not limited thereto. Any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be included in the protection scope of the present invention. The process equipment or devices not specifically noted in the following embodiments are all conventional equipment or devices in the art. If not specifically specified, the raw materials used in the embodiments of the present invention can be obtained commercially; if not specifically specified, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0031] Example 1

[0032] This embodiment provides a terahertz transparent electrode based on nickel telluride compounds and a preparation method thereof.

[0033] In this embodiment, the terahertz transparent electrode based on nickel telluride compound includes a substrate and a nickel telluride compound film, wherein the substrate is a quartz film with a thickness of 0.5 mm, and the atomic number ratio of nickel to tellurium in the nickel telluride compound film is 33:67.

[0034] The method for preparing a terahertz transparent electrode based on nickel telluride compounds in this embodiment comprises the following steps:

[0035] Step 1: Ultrasonic cleaning of the substrate:

[0036] A quartz substrate with a thickness of 0.5 mm was placed in a polytetrafluoroethylene cleaning basket, and ultrasonically cleaned in deionized water for 15 min, anhydrous ethanol for 15 min, acetone for 15 min, and anhydrous ethanol for 15 min, and then dried with nitrogen.

[0037] Step 2: Low vacuum plasma sputtering coating:

[0038] (i) Sample fixation: The cleaned substrate is fixed on top of a horizontal metal sample stage, with the substrate located directly below the sputtering target head. The bottom of the sample stage is connected to a vertical mechanical shaft, which is driven by an independent drive power supply and has a shaft speed set to 8 rad / min.

[0039] (ii) Target fixation: Place a 50 mm diameter tellurium target with a purity of 99.99% bound to a copper back target in the target holder slot. Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a sector with a radius of 25 mm, and the sector-shaped nickel sheet is evenly, symmetrically and spacedly fixed on the tellurium target with a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet and the tellurium target is 1:10, and the distance between the target surface of the obtained nickel tellurium target and the sleeve is 2 mm.

[0040] (III) Thin film growth: Use a mechanical pump to evacuate the sputtering chamber to 2Pa as the back vacuum, turn on the flow meter to release argon to flush the chamber, adjust the argon flow rate until the sputtering pressure in the chamber reaches 4Pa, turn on the RF power supply to a current of 45mA, pre-sputter for 4min to remove debris on the target surface, turn on the sample rotation power supply, remove the target baffle, start plasma sputtering, the magnetic field strength is 40mT, the plasma sputtering time is 30s, and a nickel telluride compound thin film with a thickness of 13nm is grown on the substrate to obtain a terahertz transparent electrode based on nickel telluride compounds.

[0041] Example 2

[0042] This embodiment provides a terahertz transparent electrode based on nickel telluride compounds and a preparation method thereof.

[0043] In this embodiment, the terahertz transparent electrode based on nickel telluride compound includes a substrate and a nickel telluride compound film, wherein the substrate is a quartz film with a thickness of 0.5 mm, and the atomic number ratio of nickel to tellurium in the nickel telluride compound film is 42:58.

[0044] The method for preparing a terahertz transparent electrode based on nickel telluride compounds in this embodiment comprises the following steps:

[0045] Step 1: Ultrasonic cleaning of the substrate:

[0046] A quartz substrate with a thickness of 0.5 mm was placed in a polytetrafluoroethylene cleaning basket, and ultrasonically cleaned in deionized water for 15 min, anhydrous ethanol for 15 min, acetone for 15 min, and anhydrous ethanol for 15 min, and then dried with nitrogen.

[0047] Step 2: Low vacuum plasma sputtering coating:

[0048] (i) Sample fixation: The cleaned substrate is fixed on top of a horizontal metal sample stage, with the substrate located directly below the sputtering target head. The bottom of the sample stage is connected to a vertical mechanical shaft, which is driven by an independent drive power supply and has a shaft speed set to 8 rad / min.

[0049] (ii) Target fixation: Place a 50 mm diameter tellurium target with a purity of 99.99% bound to a copper back target in the target holder slot. Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a sector with a radius of 25 mm, and the sector-shaped nickel sheet is evenly, symmetrically and spacedly fixed on the tellurium target by a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet and the tellurium target is 2:10, and the distance between the target surface of the obtained nickel-tellurium target and the sleeve is 2 mm.

[0050] (III) Thin film growth: Use a mechanical pump to evacuate the sputtering chamber to 2Pa as the back vacuum, turn on the flow meter to release argon to flush the chamber, adjust the argon flow rate until the sputtering pressure in the chamber reaches 4Pa, turn on the RF power supply to a current of 45mA, pre-sputter for 4min to remove debris on the target surface, turn on the sample rotation power supply, remove the target baffle, start plasma sputtering, the magnetic field strength is 40mT, the plasma sputtering time is 30s, and a nickel telluride compound film with a thickness of 12nm is grown on the substrate to obtain a terahertz transparent electrode based on nickel telluride compounds.

[0051] Example 3

[0052] This embodiment provides a terahertz transparent electrode based on nickel telluride compounds and a preparation method thereof.

[0053] In this embodiment, the terahertz transparent electrode based on nickel telluride compound includes a substrate and a nickel telluride compound film, wherein the substrate is a quartz film with a thickness of 0.5 mm, and the atomic number ratio of nickel and tellurium in the nickel telluride compound film is 45:55.

[0054] The method for preparing a terahertz transparent electrode based on nickel telluride compounds in this embodiment comprises the following steps:

[0055] Step 1: Ultrasonic cleaning of the substrate:

[0056] A quartz substrate with a thickness of 0.5 mm was placed in a polytetrafluoroethylene cleaning basket, and ultrasonically cleaned in deionized water for 15 min, anhydrous ethanol for 15 min, acetone for 15 min, and anhydrous ethanol for 15 min, and then dried with nitrogen.

[0057] Step 2: Low vacuum plasma sputtering coating:

[0058] (i) Sample fixation: The cleaned substrate is fixed on top of a horizontal metal sample stage, with the substrate located directly below the sputtering target head. The bottom of the sample stage is connected to a vertical mechanical shaft, which is driven by an independent drive power supply and has a shaft speed set to 8 rad / min.

[0059] (ii) Target fixation: Place a 50 mm diameter tellurium target with a purity of 99.99% bound to a copper back target in the target holder slot. Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a sector with a radius of 25 mm, and the sector-shaped nickel sheet is evenly, symmetrically and spacedly fixed on the tellurium target by a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet and the tellurium target is 3:10, and the distance between the target surface of the obtained nickel-tellurium target and the sleeve is 2 mm.

[0060] (III) Thin film growth: Use a mechanical pump to evacuate the sputtering chamber to 2Pa as the back vacuum, turn on the flow meter to release argon to flush the chamber, adjust the argon flow rate until the sputtering pressure in the chamber reaches 4Pa, turn on the RF power supply to a current of 45mA, pre-sputter for 4min to remove debris on the target surface, turn on the sample rotation power supply, remove the target baffle, the magnetic field strength is 40mT, the plasma sputtering time is 30s, and a nickel telluride compound thin film with a thickness of 10nm is grown on the substrate to obtain a terahertz transparent electrode based on nickel telluride compounds.

[0061] Example 4

[0062] This embodiment provides a terahertz transparent electrode based on nickel telluride compounds and a preparation method thereof.

[0063] In this embodiment, the terahertz transparent electrode based on nickel telluride compound includes a substrate and a nickel telluride compound film, wherein the substrate is a quartz film with a thickness of 0.5 mm, and the atomic number ratio of nickel to tellurium in the nickel telluride compound film is 77:22.

[0064] The method for preparing a terahertz transparent electrode based on nickel telluride compounds in this embodiment comprises the following steps:

[0065] Step 1: Ultrasonic cleaning of the substrate:

[0066] A quartz substrate with a thickness of 0.5 mm was placed in a polytetrafluoroethylene cleaning basket, and ultrasonically cleaned in deionized water for 15 min, anhydrous ethanol for 15 min, acetone for 15 min, and anhydrous ethanol for 15 min, and then dried with nitrogen.

[0067] Step 2: Low vacuum plasma sputtering coating:

[0068] (i) Sample fixation: The cleaned substrate is fixed on top of a horizontal metal sample stage, with the substrate located directly below the sputtering target head. The bottom of the sample stage is connected to a vertical mechanical shaft, which is driven by an independent drive power supply and has a shaft speed set to 8 rad / min.

[0069] (ii) Target fixation: Place a 50 mm diameter tellurium target with a purity of 99.99% bound to a copper back target in the target holder slot. Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a sector with a radius of 25 mm, and the sector-shaped nickel sheet is evenly, symmetrically and spacedly fixed on the tellurium target by a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet and the tellurium target is 8:10, and the distance between the target surface of the obtained nickel-tellurium target and the sleeve is 2 mm.

[0070] (III) Thin film growth: Use a mechanical pump to evacuate the sputtering chamber to 2Pa as the back vacuum, turn on the flow meter to release argon to flush the chamber, adjust the argon flow rate until the sputtering pressure in the chamber reaches 4Pa, turn on the RF power supply to a current of 45mA, pre-sputter for 4min to remove debris on the target surface, turn on the sample rotation power supply, remove the target baffle, start plasma sputtering, the magnetic field strength is 40mT, the plasma sputtering time is 60s, and a nickel telluride compound thin film with a thickness of 5nm is grown on the substrate to obtain a terahertz transparent electrode based on nickel telluride compounds.

[0071] Example 5

[0072] This embodiment provides a terahertz transparent electrode based on nickel telluride compounds and a preparation method thereof.

[0073] In this embodiment, the terahertz transparent electrode based on nickel telluride compound includes a substrate and a nickel telluride compound film, wherein the substrate is a quartz film with a thickness of 0.5 mm, and the atomic number ratio of nickel to tellurium in the nickel telluride compound film is 33:67.

[0074] The method for preparing a terahertz transparent electrode based on nickel telluride compounds in this embodiment comprises the following steps:

[0075] Step 1: Ultrasonic cleaning of the substrate:

[0076] A quartz substrate with a thickness of 0.5 mm was placed in a polytetrafluoroethylene cleaning basket, and ultrasonically cleaned in deionized water for 15 min, anhydrous ethanol for 15 min, acetone for 15 min, and anhydrous ethanol for 15 min, and then dried with nitrogen.

[0077] Step 2: Low vacuum plasma sputtering coating:

[0078] (i) Sample fixation: The cleaned substrate is fixed on top of a horizontal metal sample stage, with the substrate located directly below the sputtering target head. The bottom of the sample stage is connected to a vertical mechanical shaft, which is driven by an independent drive power supply and has a shaft speed set to 8 rad / min.

[0079] (ii) Target fixation: Place a 50 mm diameter tellurium target with a purity of 99.99% bound to a copper back target in the target holder slot. Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a sector with a radius of 25 mm, and the sector-shaped nickel sheet is evenly, symmetrically and spacedly fixed on the tellurium target with a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet and the tellurium target is 1:10, and the distance between the target surface of the obtained nickel tellurium target and the sleeve is 2 mm.

[0080] (III) Thin film growth: Use a mechanical pump to evacuate the sputtering chamber to 2Pa as the back vacuum, turn on the flow meter to release argon to flush the chamber, adjust the argon flow rate until the sputtering pressure in the chamber reaches 4Pa, turn on the RF power supply to a current of 45mA, pre-sputter for 4min to remove debris on the target surface, turn on the sample rotation power supply, remove the target baffle, start plasma sputtering, the magnetic field strength is 40mT, the plasma sputtering time is 20s, and a nickel telluride compound film with a thickness of 6nm is grown on the substrate to obtain a terahertz transparent electrode based on nickel telluride compounds.

[0081] Step 3: Normal pressure atmosphere annealing:

[0082] Half of the obtained terahertz transparent electrode based on nickel telluride compound was selected and placed in a tube furnace, the air was evacuated to 1 Pa, argon was filled in and maintained at normal pressure, the temperature was raised to 150°C at a rate of 30°C / min, and after keeping warm for 1 hour, the temperature was naturally cooled to room temperature and then taken out.

[0083] Example 6

[0084] This embodiment provides a terahertz transparent electrode based on nickel telluride compounds and a preparation method thereof.

[0085] In this embodiment, the terahertz transparent electrode based on nickel telluride compound includes a substrate and a nickel telluride compound film, wherein the substrate is a quartz film with a thickness of 0.5 mm, and the atomic number ratio of nickel to tellurium in the nickel telluride compound film is 33:67.

[0086] The method for preparing a terahertz transparent electrode based on nickel telluride compounds in this embodiment comprises the following steps:

[0087] Step 1: Ultrasonic cleaning of the substrate:

[0088] A quartz substrate with a thickness of 0.5 mm was placed in a polytetrafluoroethylene cleaning basket, and ultrasonically cleaned in deionized water for 15 min, anhydrous ethanol for 15 min, acetone for 15 min, and anhydrous ethanol for 15 min, and then dried with nitrogen.

[0089] Step 2: Low vacuum plasma sputtering coating:

[0090] (i) Sample fixation: The cleaned substrate is fixed on top of a horizontal metal sample stage, with the substrate located directly below the sputtering target head. The bottom of the sample stage is connected to a vertical mechanical shaft, which is driven by an independent drive power supply and has a shaft speed set to 8 rad / min.

[0091] (ii) Target fixation: Place a 50 mm diameter tellurium target with a purity of 99.99% bound to a copper back target in the target holder slot. Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a sector with a radius of 25 mm, and the sector-shaped nickel sheet is evenly, symmetrically and spacedly fixed on the tellurium target with a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet and the tellurium target is 1:10, and the distance between the target surface of the obtained nickel tellurium target and the sleeve is 2 mm.

[0092] (III) Thin film growth: Use a mechanical pump to evacuate the sputtering chamber to 2Pa as the back vacuum, turn on the flow meter to release argon to flush the chamber, adjust the argon flow rate until the sputtering pressure in the chamber reaches 4Pa, turn on the RF power supply to a current of 45mA, pre-sputter for 4min to remove debris on the target surface, turn on the sample rotation power supply, remove the target baffle, start plasma sputtering, the magnetic field strength is 40mT, the plasma sputtering time is 40s, and grow a nickel telluride compound film with a thickness of 17nm on the substrate to obtain a terahertz transparent electrode based on nickel telluride compounds.

[0093] Step 3: Normal pressure atmosphere annealing:

[0094] Half of the obtained terahertz transparent electrode based on nickel telluride compound was selected and placed in a tube furnace, the air was evacuated to 1 Pa, argon was filled in and maintained at normal pressure, the temperature was raised to 150°C at a rate of 30°C / min, and after keeping warm for 1 hour, the temperature was naturally cooled to room temperature and then taken out.

[0095] Example 7

[0096] This embodiment provides a flexible terahertz transparent electrode based on nickel telluride compounds and a preparation method thereof.

[0097] In this embodiment, the terahertz transparent electrode based on nickel telluride compound includes a substrate and a nickel telluride compound film, wherein the substrate is a polytetrafluoroethylene film with a thickness of 0.1 mm and transparent to the terahertz band, and the atomic number ratio of nickel to tellurium in the nickel telluride compound film is 33:67.

[0098] The method for preparing a terahertz transparent electrode based on nickel telluride compounds in this embodiment comprises the following steps:

[0099] Step 1: Ultrasonic cleaning of the substrate:

[0100] A 0.1 mm thick terahertz-band transparent polytetrafluoroethylene film was placed in a polytetrafluoroethylene cleaning basket, and ultrasonically cleaned in deionized water for 15 min, anhydrous ethanol for 15 min, acetone for 15 min, and anhydrous ethanol for 15 min, and then dried with nitrogen.

[0101] Step 2: Low vacuum plasma sputtering coating:

[0102] (i) Sample fixation: The cleaned substrate is fixed on top of a horizontal metal sample stage, with the substrate located directly below the sputtering target head. The bottom of the sample stage is connected to a vertical mechanical shaft, which is driven by an independent drive power supply and has a shaft speed set to 8 rad / min.

[0103] (ii) Target fixation: Place a 50 mm diameter tellurium target with a purity of 99.99% bound to a copper back target in the target holder slot. Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a sector with a radius of 25 mm, and the sector-shaped nickel sheet is evenly, symmetrically and spacedly fixed on the tellurium target with a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet and the tellurium target is 1:10, and the distance between the target surface of the obtained nickel tellurium target and the sleeve is 2 mm.

[0104] (III) Thin film growth: Use a mechanical pump to evacuate the sputtering chamber to 2Pa as the back vacuum, turn on the flow meter to release argon to flush the chamber, adjust the argon flow rate until the sputtering pressure in the chamber reaches 4Pa, turn on the RF power supply to a current of 45mA, pre-sputter for 4min to remove debris on the target surface, turn on the sample rotation power supply, remove the target baffle, start plasma sputtering, the magnetic field strength is 40mT, the plasma sputtering time is 20s, and a nickel telluride compound film with a thickness of 13nm is grown on the substrate to obtain a flexible terahertz transparent electrode based on nickel telluride compounds.

[0105] The electrical properties were characterized by the thin film four-probe method, the film transmittance was tested by terahertz time-domain spectroscopy, the terahertz frequency-domain transmission spectrum was obtained by Fourier transform, and the film thickness and uniformity were tested by atomic force microscopy. The results are shown in Table 1.

[0106] Table 1

[0107]

[0108] From the data comparison in Table 1, it can be seen that for films of the same thickness, the higher the conductivity, the lower the terahertz wave transmittance; for films with the same growth conditions, below the skin depth range, the thinner the film, the lower the terahertz wave transmittance. When considering the conductivity and transmittance comprehensively, films with a conductivity in the range of 800 to 1200 S / cm have both high conductivity and high transmittance.

[0109] Figure 2 The terahertz frequency domain transmission spectrum comparison diagram of the terahertz transparent electrodes prepared in Example 5 and Example 6 after annealing and without annealing; Figure 2 It can be seen that compared with the untreated film, the conductivity of the annealed film is significantly improved, so its transmittance decreases; keeping other conditions the same, the film with a deposition time of 40s is thicker than that of 20s, and the transmittance also decreases. From the figure, it can be seen that the transparent electrode in the terahertz band is limited by the skin depth of the film, and the improvement of conductivity and terahertz wave transmittance is a pair of contradictory factors. This type of transparent electrode material can effectively control the transparent electrode parameters through the nickel-telluride ratio and annealing degree according to the emphasis on conductivity and transmittance indicators in actual applications.

[0110] Figure 3 This is an elemental composition analysis spectrum of a terahertz transparent electrode based on nickel tellurium compounds prepared using a nickel tellurium target material having a total exposure area ratio of the nickel sheet to the tellurium target material of 1:10 in Example 7. The specific data are shown in Table 2.

[0111] Table 2

[0112]

[0113] Depend on Figure 3It can be seen from the data in Table 2 that plasma sputtering under low vacuum conditions can stably produce flexible nickel-telluride compound transparent electrode films without obvious impurity elements, which greatly reduces the production cost of transparent electrodes in the terahertz band and improves product quality.

[0114] Figure 4 The figure is a graph showing the results of the flexible bending test of the flexible terahertz transparent electrode based on nickel telluride compound prepared in Example 7; Figure 4 It can be seen that in order to verify the superiority of the mechanical fatigue resistance of this type of film in extreme environments, the resistance-bending number curve of the film is tested by a bending machine. The film on the polytetrafluoroethylene base is fixed on the bending machine, and the maximum bending radius is set to 5mm. The square resistance value after different bending cycles is recorded. Figure 4 There is no obvious change after 1000 cycles, and the square resistance change is less than 50Ω after 10000 cycles. It can be seen that the transparent electrode has strong mechanical bending fatigue resistance.

[0115] Figure 5 The actual photographs of the terahertz transparent electrodes prepared in Example 1 and Example 7, wherein the upper film is the terahertz flexible transparent electrode with a polytetrafluoroethylene substrate prepared in Example 7, and the lower film is the terahertz transparent electrode with a quartz substrate prepared in Example 1. Figure 5 It can be seen that different substrates can achieve uniform transparent electrodes, and have considerable transmittance in the visible light range.

Claims

1. A terahertz transparent electrode based on nickel telluride compounds, characterized in that: The invention comprises a substrate and a nickel-tellurium compound film, wherein the atomic number ratio of nickel to tellurium in the nickel-tellurium compound film is 0.3-3.

5.

2. A terahertz transparent electrode based on nickel telluride compounds according to claim 1, characterized in that: The substrate is a quartz film, silicon wafer or polytetrafluoroethylene film with a thickness of 0.1 to 1 mm and transparent in the terahertz band, and the thickness of the nickel-tellurium compound film is 5 to 20 nm.

3. A method for preparing a terahertz transparent electrode based on nickel telluride compounds as claimed in claim 1, characterized in that: The substrate is fixed on the sample stage so that it is located directly below the sputtering target head, and the nickel sheet and the tellurium target are arranged in a plurality of fan-shaped intervals in the target holder slot, wherein the ratio of the total exposed area of ​​the nickel sheet and the tellurium target is 1 to 15:10; the sputtering chamber is evacuated as a back vacuum, argon gas is flushed into the chamber and the sputtering gas pressure in the chamber is adjusted, the sample stage rotating device is started, a radio frequency current is applied to the nickel tellurium target, and a nickel tellurium compound thin film is grown on the substrate by plasma sputtering to obtain a terahertz transparent electrode based on nickel tellurium compounds.

4. The method for preparing a terahertz transparent electrode based on nickel telluride compounds according to claim 3, characterized in that: The substrate is a quartz film, a silicon wafer or a polytetrafluoroethylene film with a thickness of 0.1 to 1 mm and transparent in the terahertz band.

5. The method for preparing a terahertz transparent electrode based on nickel telluride compounds according to claim 4, characterized in that: Before use, the substrate is cleaned in sequence with deionized water, anhydrous ethanol, acetone, and anhydrous ethanol ultrasonic cleaning, and then blown dry with nitrogen.

6. The method for preparing a terahertz transparent electrode based on nickel telluride compounds according to claim 5, characterized in that: The nickel-tellurium target is made of a plurality of sector-shaped nickel sheets fixedly and symmetrically arranged on the tellurium target. The purity of the tellurium target is 99.99%, the purity of the nickel sheets is 99.999%, and the distance between the target surface of the nickel-tellurium target and the sleeve is fixed at 2 mm. Pre-sputtering is performed before plasma sputtering to remove impurities on the target surface.

7. The method for preparing a terahertz transparent electrode based on nickel telluride compounds according to claim 6, characterized in that: The back vacuum is 2Pa, the sputtering gas pressure in the cavity is 4Pa, the radio frequency current is 45mA, the magnetic field strength is 40mT, the rotation speed of the sample stage is 8rad / min; the plasma sputtering time is 20 to 60s, and the thickness of the nickel tellurium compound film is 5 to 20nm.

8. The method for preparing a terahertz transparent electrode based on nickel telluride compounds according to claim 7, characterized in that: When the substrate is a quartz film or a silicon wafer, the method further comprises a processing step of placing the obtained terahertz transparent electrode based on nickel tellurium compound in an argon atmosphere for annealing at normal pressure.

9. The method for preparing a terahertz transparent electrode based on nickel telluride compounds according to claim 8, characterized in that: The normal pressure annealing is to raise the temperature to 150-300° C. at a rate of 30° C. / min, keep the temperature for 1 hour, and then naturally cool down to room temperature.

10. An application of the terahertz transparent electrode based on nickel telluride compound as claimed in claim 1 or 2 in the field of photovoltaic devices, flexible displays, biomedical imaging or high-speed communications.

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