A terahertz transparent electrode based on nickel tellurium compound, its preparation method and application

Abstract

This invention relates to a terahertz transparent electrode based on a nickel-tellurium compound, its preparation method, and its application, belonging to the field of terahertz electrode technology. To address the problem that existing terahertz transparent electrodes cannot simultaneously achieve high transmittance and good conductivity in the terahertz wave propagation direction, this invention provides a terahertz transparent electrode based on a nickel-tellurium compound, comprising a substrate and a nickel-tellurium compound thin film. This invention prepares nickel-tellurium compound thin films with different nickel-tellurium ratios by setting targets with different nickel-tellurium areas, achieving adjustment of the conductivity, transmittance, and thickness of the terahertz transparent electrode. This balances high transmittance and high conductivity in the terahertz band, resulting in a nickel-tellurium compound-based terahertz transparent electrode with a transmittance exceeding 80% and a conductivity greater than 1000 S / cm in the terahertz band, meeting the qualification standards for transparent conductive thin films. The preparation method of this invention has low requirements and is suitable for practical mass production of terahertz transparent electrodes.

Description

Technical Field

[0001] This invention belongs to the field of terahertz electrode technology, and particularly relates to a terahertz transparent electrode based on nickel telluride compound, its preparation method and application. Background Technology

[0002] Terahertz waves are defined as electromagnetic waves with frequencies between 0.1 and 10 THz and wavelengths between 30 and 3000 μm, situated in the transitional region between microwave electronics and optoelectronics. Terahertz waves possess broadband and high-frequency characteristics in electronics, and low photon energy, a unique fingerprint spectrum, and high transmittance in photonics. This makes terahertz waves extremely valuable for fundamental research and important applications in the interaction of light and matter, particularly in imaging sensing, 6G communication, and radar detection.

[0003] Terahertz transparent electrodes are electrode materials that maintain high transparency and conductivity within the terahertz frequency band. Their key indicators are broad-spectrum transmittance and high conductivity, and their performance determines the application potential and environment of terahertz transmission devices. Several terahertz transparent electrode schemes are currently available, promoting the development of terahertz technology.

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

[0005] Organic transparent conductive films possess high conductivity and high transparency, but their conductivity and terahertz transmittance are inversely proportional, making further performance tuning difficult. Furthermore, the thickness of organic films is difficult to control precisely, they are not heat-resistant, and they have low compatibility with existing semiconductor processes. Among them, PEDOT:PSS has relatively high conductivity, but its minimum transmittance in the terahertz range is difficult to reach 80%.

[0006] Polyvinyl alcohol-graphene hybrid films exhibit low conductivity, and the graphene dispersion makes it difficult to ensure uniform conductivity at the nanoscale. While ITO, a transparent electrode material, has high transmittance in the visible light band, its transmittance in the terahertz band is less than 10%. Its nanocrystals cannot guarantee film quality and uniformity, and its conductivity is low, failing to meet application requirements. Inorganic metal electrodes have excessively high conductivity, resulting in insufficient skin depth. Nanowire electrodes suffer from low uniformity, making them incompatible 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, while also being easy to integrate, compact and lightweight, is a problem that urgently needs to be solved in order to meet the development needs of emerging terahertz optoelectronic integration technology. Summary of the Invention

[0008] To address the issue that existing terahertz transparent electrodes cannot simultaneously achieve high transmittance, good conductivity, and compatibility with existing semiconductor processes, this invention provides a terahertz transparent electrode based on a nickel tellurium compound, its preparation method, and its applications.

[0009] The technical solution of the present invention:

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

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

[0012] A method for fabricating a terahertz transparent electrode based on a nickel tellurium compound involves fixing a substrate to a sample stage directly below a sputtering target. Nickel sheets and tellurium targets, spaced in a fan shape, are placed in a target holder slot. The ratio of the total exposed area of ​​the nickel sheets to the tellurium targets is 1–15:10. The sputtering chamber is evacuated to create a back-bottom vacuum. The chamber is then flushed with argon gas, and the sputtering pressure is adjusted. The sample stage rotation device is activated, and a radio frequency current is applied to the nickel tellurium targets. A nickel tellurium compound thin film is grown on the substrate via plasma sputtering to obtain the terahertz transparent electrode based on the nickel tellurium compound.

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

[0014] Furthermore, the substrate is ultrasonically cleaned sequentially with deionized water, anhydrous ethanol, acetone, and anhydrous ethanol before use, and then dried with nitrogen gas.

[0015] Furthermore, the nickel-tellurium target is made by fixing several fan-shaped nickel sheets symmetrically spaced on a 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 and the sleeve of the nickel-tellurium target is fixed at 2mm. Before plasma sputtering, pre-sputtering is performed to remove impurities from the target surface.

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

[0017] Furthermore, when the substrate is a quartz thin film or a silicon wafer, the process also includes a step of annealing the resulting terahertz transparent electrode based on a nickel tellurium compound under an argon atmosphere at atmospheric pressure.

[0018] Furthermore, the atmospheric pressure annealing involves raising the temperature to 150–300°C at a rate of 30°C / min, holding it at that temperature for 1 hour, and then allowing it to cool naturally to room temperature.

[0019] The terahertz transparent electrode based on nickel telluride compound provided by this invention has applications in the fields of photovoltaic devices, flexible displays, biomedical imaging, and high-speed communication.

[0020] The beneficial effects of this invention are:

[0021] This invention employs plasma sputtering to prepare terahertz transparent electrodes. By using targets with different nickel-tellurium areas, nickel-tellurium compound films with varying nickel-tellurium ratios are obtained. Combining plasma sputtering growth time with thermal annealing, the conductivity, transmittance, and thickness of the terahertz transparent electrode are adjusted. Thermal annealing reduces defects generated during film growth, decreases carrier scattering while maintaining the same thickness, and further improves the conductivity of the terahertz transparent electrode, achieving a balance between high transmittance and high conductivity in the terahertz band. The nickel-tellurium compound-based terahertz transparent electrode obtained by this invention exhibits a transmittance exceeding 80% and a conductivity greater than 1000 S / cm in the terahertz band, meeting the qualification standards for transparent conductive films.

[0022] The terahertz transparent electrode prepared by plasma sputtering in this invention also exhibits considerable transmittance in the visible light band, making it suitable for use as a transparent electrode in dual-band systems of visible light and terahertz. The terahertz transparent electrode based on a transparent polytetrafluoroethylene film in the terahertz band of this invention demonstrates outstanding bending resistance, maintaining excellent conductivity even after tens of thousands of bends, and can be used for flexible applications of electrode materials.

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

[0024] The plasma sputtering preparation method provided by this invention has extremely low requirements, requiring only a low background vacuum of 2 Pa to prepare high-quality, stable, and highly reproducible terahertz transparent electrodes. Moreover, the transparent electrode is an inorganic material thin film. Based on the sputtering process, this transparent electrode thin film can be successfully grown on a wide range of objects such as quartz, silicon wafers, and polytetrafluoroethylene. It can be directly combined with photolithography lift-off technology to prepare patterned electrode structures. Therefore, it perfectly solves the problem of compatibility and integration of terahertz transparent electrodes with existing semiconductor process devices, and is suitable for the practical mass production of terahertz transparent electrodes. Attached Figure Description

[0025] Figure 1 This is a schematic diagram showing that the nickel sheet and tellurium target on the nickel-tellurium target are arranged in several fan-shaped intervals in Example 1;

[0026] Figure 2 Comparison of terahertz frequency domain transmission spectra of annealed and unannealed terahertz transparent electrodes prepared in Examples 5 and 6;

[0027] Figure 3 The elemental composition analysis spectrum of the terahertz transparent electrode based on nickel telluride compound prepared in Example 7;

[0028] Figure 4 The image shows the flexible bending test results of the flexible terahertz transparent electrode based on nickel telluride compound prepared in Example 7.

[0029] Figure 5 The images show actual photographs of the terahertz transparent electrodes prepared in Examples 1 and 7, where 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 Implementation

[0030] The technical solution of the present invention will be further described below with reference to embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention. In the following embodiments, the process equipment or apparatus not specifically specified are all conventional equipment or apparatus in the art. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commercially available; unless otherwise 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 a nickel tellurium compound and its preparation method.

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

[0034] The method for preparing the terahertz transparent electrode based on nickel telluride compound in this embodiment includes 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 sequence with deionized water for 15 minutes, anhydrous ethanol for 15 minutes, acetone for 15 minutes, and anhydrous ethanol for 15 minutes, and then dried with nitrogen.

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

[0038] (a) Sample fixation: Fix the cleaned substrate above the horizontal metal sample stage. The substrate is located directly below the sputtering target. The bottom of the sample stage is connected to a vertical mechanical shaft. The shaft is driven by an independent power supply and the shaft speed is set to 8 rad / min.

[0039] (II) Target Fixing: Place a 50mm diameter, 99.99% pure tellurium target with a copper backing into the target holder slot, such as... Figure 1 As shown, a nickel sheet with a thickness of 0.1 mm and a purity of 99.999% is cut into a fan shape with a radius of 25 mm. The fan-shaped nickel sheet is fixed evenly, symmetrically and with intervals on the tellurium target material using a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet to the tellurium target material is 1:10. The distance between the target surface of the resulting nickel-tellurium target material and the sleeve is 2 mm.

[0040] (III) Thin film growth: The sputtering chamber was evacuated to 2 Pa using a mechanical pump as a back vacuum. Argon gas was released from the flow meter to flush the chamber. The argon gas flow rate was adjusted to the sputtering pressure in the chamber to 4 Pa. The RF power supply was turned on to the current of 45 mA. Pre-sputtering was performed for 4 min to remove impurities from the target surface. The sample rotation power supply was turned on. The target baffle was removed. Plasma sputtering was started with a magnetic field strength of 40 mT and a plasma sputtering time of 30 s. A nickel tellurium compound thin film with a thickness of 13 nm was grown on the substrate, resulting in a terahertz transparent electrode based on the nickel tellurium compound.

[0041] Example 2

[0042] This embodiment provides a terahertz transparent electrode based on a nickel tellurium compound and its preparation method.

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

[0044] The method for preparing the terahertz transparent electrode based on nickel telluride compound in this embodiment includes 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 sequence with deionized water for 15 minutes, anhydrous ethanol for 15 minutes, acetone for 15 minutes, and anhydrous ethanol for 15 minutes, and then dried with nitrogen.

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

[0048] (a) Sample fixation: Fix the cleaned substrate above the horizontal metal sample stage. The substrate is located directly below the sputtering target. The bottom of the sample stage is connected to a vertical mechanical shaft. The shaft is driven by an independent power supply and the shaft speed is set to 8 rad / min.

[0049] (II) Target Fixing: Place a 50mm diameter, 99.99% pure tellurium target with a copper backing into the target holder slot, such as... Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a fan shape with a radius of 25 mm. The fan-shaped nickel sheet is fixed evenly, symmetrically and at intervals on the tellurium target material using a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet to the tellurium target material is 2:10. The distance between the target surface of the resulting nickel-tellurium target material and the sleeve is 2 mm.

[0050] (III) Thin film growth: The sputtering chamber was evacuated to 2 Pa using a mechanical pump as a back vacuum. Argon gas was released from the flow meter to flush the chamber. The argon gas flow rate was adjusted to the sputtering pressure in the chamber to 4 Pa. The RF power supply was turned on to the current of 45 mA. Pre-sputtering was performed for 4 min to remove impurities from the target surface. The sample rotation power supply was turned on. The target baffle was removed. Plasma sputtering was started with a magnetic field strength of 40 mT and a plasma sputtering time of 30 s. A nickel tellurium compound thin film with a thickness of 12 nm was grown on the substrate, resulting in a terahertz transparent electrode based on the nickel tellurium compound.

[0051] Example 3

[0052] This embodiment provides a terahertz transparent electrode based on a nickel tellurium compound and its preparation method.

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

[0054] The method for preparing the terahertz transparent electrode based on nickel telluride compound in this embodiment includes 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 sequence with deionized water for 15 minutes, anhydrous ethanol for 15 minutes, acetone for 15 minutes, and anhydrous ethanol for 15 minutes, and then dried with nitrogen.

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

[0058] (a) Sample fixation: Fix the cleaned substrate above the horizontal metal sample stage. The substrate is located directly below the sputtering target. The bottom of the sample stage is connected to a vertical mechanical shaft. The shaft is driven by an independent power supply and the shaft speed is set to 8 rad / min.

[0059] (II) Target Fixing: Place a 50mm diameter, 99.99% pure tellurium target with a copper backing into the target holder slot, such as... Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a fan shape with a radius of 25 mm. The fan-shaped nickel sheet is fixed evenly, symmetrically and at intervals on the tellurium target material using a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet to the tellurium target material is 3:10. The distance between the target surface of the resulting nickel-tellurium target material and the sleeve is 2 mm.

[0060] (III) Thin film growth: The sputtering chamber was evacuated to 2 Pa using a mechanical pump as a back vacuum. Argon gas was released from the flow meter to flush the chamber. The argon gas flow rate was adjusted to the sputtering pressure in the chamber to 4 Pa. The RF power supply was turned on to the current of 45 mA. Pre-sputtering was performed for 4 min to remove impurities from the target surface. The sample rotation power supply was turned on. The target baffle was removed. The magnetic field strength was 40 mT and the plasma sputtering time was 30 s. A nickel tellurium compound thin film with a thickness of 10 nm was grown on the substrate, resulting in a terahertz transparent electrode based on the nickel tellurium compound.

[0061] Example 4

[0062] This embodiment provides a terahertz transparent electrode based on a nickel tellurium compound and its preparation method.

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

[0064] The method for preparing the terahertz transparent electrode based on nickel telluride compound in this embodiment includes 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 sequence with deionized water for 15 minutes, anhydrous ethanol for 15 minutes, acetone for 15 minutes, and anhydrous ethanol for 15 minutes, and then dried with nitrogen.

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

[0068] (a) Sample fixation: Fix the cleaned substrate above the horizontal metal sample stage. The substrate is located directly below the sputtering target. The bottom of the sample stage is connected to a vertical mechanical shaft. The shaft is driven by an independent power supply and the shaft speed is set to 8 rad / min.

[0069] (II) Target Fixing: Place a 50mm diameter, 99.99% pure tellurium target with a copper backing into the target holder slot, such as... Figure 1 As shown, a 0.1 mm thick nickel sheet with a purity of 99.999% is cut into a fan shape with a radius of 25 mm. The fan-shaped nickel sheet is fixed evenly, symmetrically and with intervals on the tellurium target material using a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet to the tellurium target material is 8:10. The distance between the target surface of the resulting nickel-tellurium target material and the sleeve is 2 mm.

[0070] (III) Thin film growth: The sputtering chamber was evacuated to 2 Pa using a mechanical pump as a back vacuum. Argon gas was released from the flow meter to flush the chamber. The argon gas flow rate was adjusted to the sputtering pressure in the chamber to 4 Pa. The RF power supply was turned on to the current of 45 mA. Pre-sputtering was performed for 4 min to remove impurities from the target surface. The sample rotation power supply was turned on. The target baffle was removed. Plasma sputtering was started with a magnetic field strength of 40 mT and a plasma sputtering time of 60 s. A nickel tellurium compound thin film with a thickness of 5 nm was grown on the substrate, resulting in a terahertz transparent electrode based on the nickel tellurium compound.

[0071] Example 5

[0072] This embodiment provides a terahertz transparent electrode based on a nickel tellurium compound and its preparation method.

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

[0074] The method for preparing the terahertz transparent electrode based on nickel telluride compound in this embodiment includes 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 sequence with deionized water for 15 minutes, anhydrous ethanol for 15 minutes, acetone for 15 minutes, and anhydrous ethanol for 15 minutes, and then dried with nitrogen.

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

[0078] (a) Sample fixation: Fix the cleaned substrate above the horizontal metal sample stage. The substrate is located directly below the sputtering target. The bottom of the sample stage is connected to a vertical mechanical shaft. The shaft is driven by an independent power supply and the shaft speed is set to 8 rad / min.

[0079] (II) Target Fixing: Place a 50mm diameter, 99.99% pure tellurium target with a copper backing into the target holder slot, such as... Figure 1 As shown, a nickel sheet with a thickness of 0.1 mm and a purity of 99.999% is cut into a fan shape with a radius of 25 mm. The fan-shaped nickel sheet is fixed evenly, symmetrically and with intervals on the tellurium target material using a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet to the tellurium target material is 1:10. The distance between the target surface of the resulting nickel-tellurium target material and the sleeve is 2 mm.

[0080] (III) Thin film growth: The sputtering chamber was evacuated to 2 Pa using a mechanical pump as a back vacuum. Argon gas was released from the flow meter to flush the chamber. The argon gas flow rate was adjusted to the sputtering pressure in the chamber to 4 Pa. The RF power supply was turned on to the current of 45 mA. Pre-sputtering was performed for 4 min to remove impurities from the target surface. The sample rotation power supply was turned on. The target baffle was removed. Plasma sputtering was started with a magnetic field strength of 40 mT and a plasma sputtering time of 20 s. A nickel tellurium compound thin film with a thickness of 6 nm was grown on the substrate, resulting in a terahertz transparent electrode based on the nickel tellurium compound.

[0081] Step 3: Annealing at atmospheric pressure:

[0082] Half of the obtained terahertz transparent electrode based on nickel telluride compound was placed in a tube furnace, the air was evacuated to 1 Pa, argon was introduced and maintained at atmospheric pressure, the temperature was raised to 150 °C at a rate of 30 °C / min, held at the temperature for 1 hour and then allowed to cool naturally to room temperature before being taken out.

[0083] Example 6

[0084] This embodiment provides a terahertz transparent electrode based on a nickel tellurium compound and its preparation method.

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

[0086] The method for preparing the terahertz transparent electrode based on nickel telluride compound in this embodiment includes 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 sequence with deionized water for 15 minutes, anhydrous ethanol for 15 minutes, acetone for 15 minutes, and anhydrous ethanol for 15 minutes, and then dried with nitrogen.

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

[0090] (a) Sample fixation: Fix the cleaned substrate above the horizontal metal sample stage. The substrate is located directly below the sputtering target. The bottom of the sample stage is connected to a vertical mechanical shaft. The shaft is driven by an independent power supply and the shaft speed is set to 8 rad / min.

[0091] (II) Target Fixing: Place a 50mm diameter, 99.99% pure tellurium target with a copper backing into the target holder slot, such as... Figure 1 As shown, a nickel sheet with a thickness of 0.1 mm and a purity of 99.999% is cut into a fan shape with a radius of 25 mm. The fan-shaped nickel sheet is fixed evenly, symmetrically and with intervals on the tellurium target material using a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet to the tellurium target material is 1:10. The distance between the target surface of the resulting nickel-tellurium target material and the sleeve is 2 mm.

[0092] (III) Thin film growth: The sputtering chamber was evacuated to 2 Pa using a mechanical pump as a back vacuum. Argon gas was released from the flow meter to flush the chamber. The argon gas flow rate was adjusted to the sputtering pressure in the chamber to 4 Pa. The RF power supply was turned on to the current of 45 mA. Pre-sputtering was performed for 4 min to remove impurities from the target surface. The sample rotation power supply was turned on. The target baffle was removed. Plasma sputtering was started with a magnetic field strength of 40 mT and a plasma sputtering time of 40 s. A nickel tellurium compound thin film with a thickness of 17 nm was grown on the substrate, resulting in a terahertz transparent electrode based on the nickel tellurium compound.

[0093] Step 3: Annealing at atmospheric pressure:

[0094] Half of the obtained terahertz transparent electrode based on nickel telluride compound was placed in a tube furnace, the air was evacuated to 1 Pa, argon was introduced and maintained at atmospheric pressure, the temperature was raised to 150 °C at a rate of 30 °C / min, held at the temperature for 1 hour and then allowed to cool naturally to room temperature before being taken out.

[0095] Example 7

[0096] This embodiment provides a flexible terahertz transparent electrode based on a nickel tellurium compound and its preparation method.

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

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

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

[0100] A 0.1 mm thick transparent polytetrafluoroethylene film in the terahertz band was placed in a polytetrafluoroethylene cleaning basket and ultrasonically cleaned sequentially with 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] (a) Sample fixation: Fix the cleaned substrate above the horizontal metal sample stage. The substrate is located directly below the sputtering target. The bottom of the sample stage is connected to a vertical mechanical shaft. The shaft is driven by an independent power supply and the shaft speed is set to 8 rad / min.

[0103] (II) Target Fixing: Place a 50mm diameter, 99.99% pure tellurium target with a copper backing into the target holder slot, such as... Figure 1 As shown, a nickel sheet with a thickness of 0.1 mm and a purity of 99.999% is cut into a fan shape with a radius of 25 mm. The fan-shaped nickel sheet is fixed evenly, symmetrically and with intervals on the tellurium target material using a pressure ring, so that the ratio of the total exposed area of ​​the nickel sheet to the tellurium target material is 1:10. The distance between the target surface of the resulting nickel-tellurium target material and the sleeve is 2 mm.

[0104] (III) Thin film growth: The sputtering chamber was evacuated to 2 Pa using a mechanical pump as a back vacuum. Argon gas was released from the flow meter to flush the chamber. The argon gas flow rate was adjusted to the sputtering pressure in the chamber to 4 Pa. The RF power supply was turned on to the current of 45 mA. Pre-sputtering was performed for 4 min to remove impurities from the target surface. The sample rotation power supply was turned on. The target baffle was removed. Plasma sputtering was started with a magnetic field strength of 40 mT and a plasma sputtering time of 20 s. A nickel tellurium compound thin film with a thickness of 13 nm was grown on the substrate, resulting in a flexible terahertz transparent electrode based on the nickel tellurium compound.

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

[0106] Table 1

[0107]

[0108] The data comparison in Table 1 shows 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 their skin depth, the thinner the film, the lower the terahertz wave transmittance. When considering both conductivity and transmittance, films with conductivity in the range of 800–1200 S / cm have both high conductivity and high transmittance.

[0109] Figure 2 The terahertz frequency domain transmission spectra of the annealed and unannealed terahertz transparent electrodes prepared in Examples 5 and 6 are compared. Figure 2 It can be seen that compared with the untreated film, the conductivity of the annealed film is significantly improved, thus its transmittance decreases. Keeping other conditions the same, the film with a deposition time of 40s is thicker than that with 20s, and its transmittance also decreases. In summary, the terahertz transparent electrode is limited by the skin depth of the film; the improvement of conductivity and terahertz wave transmittance are a pair of contradictory factors. This type of transparent electrode material allows for effective control of transparent electrode parameters by adjusting the nickel-tellurium ratio and the degree of annealing, based on the emphasis placed on conductivity and transmittance in practical applications.

[0110] Figure 3 The elemental composition analysis spectrum of the terahertz transparent electrode based on nickel tellurium compound prepared by nickel tellurium target material with a total exposed area ratio of nickel sheet to tellurium target material of 1:10 in Example 7 is shown in Table 2.

[0111] Table 2

[0112]

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

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

[0115] Figure 5 Photographs of the terahertz transparent electrodes prepared in Example 1 and Example 7. The upper film is the terahertz flexible transparent electrode on the polytetrafluoroethylene substrate prepared in Example 7, and the lower film is the terahertz transparent electrode on the quartz substrate prepared in Example 1. Figure 5 It can be seen that uniform transparent electrodes can be achieved on different substrates, and there is also a considerable transmittance in the visible light range.

Claims

1. A terahertz transparent electrode based on a nickel tellurium compound, characterized in that, The electrode comprises a substrate and a nickel-tellurium compound thin film, wherein the atomic ratio of nickel to tellurium in the nickel-tellurium compound thin film is 33:

67. The method for preparing the terahertz transparent electrode based on the nickel-tellurium compound is as follows: the substrate is fixed on the sample stage so that it is directly below the sputtering target head; nickel sheets and tellurium targets are arranged in several fan-shaped intervals and placed in the target holder slot; the ratio of the total exposed area of ​​the nickel sheets and tellurium targets is 1~15:10; the sputtering chamber is evacuated as a back vacuum; the chamber is flushed with argon gas and the sputtering gas pressure in the chamber is adjusted; the sample stage rotation device is started; 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 the terahertz transparent electrode based on the nickel-tellurium compound. The background vacuum is 2 Pa, the sputtering pressure inside the cavity is 4 Pa, the radio frequency current is 45 mA, the magnetic field strength is 40 mT, the sample stage rotation speed is 8 rad / min, the plasma sputtering time is 20~60 s, and the thickness of the nickel tellurium compound film is 13~17 nm. When the substrate is a quartz thin film or a silicon wafer, the process also includes a step of annealing the obtained terahertz transparent electrode based on nickel tellurium compound under an argon atmosphere at atmospheric pressure; the atmospheric pressure annealing is to raise the temperature to 150~300℃ at a rate of 30℃ / min, hold it at that temperature for 1 hour, and then allow it to cool naturally to room temperature.

2. The terahertz transparent electrode based on nickel tellurium compound according to claim 1, characterized in that, The substrate is a transparent quartz film or silicon wafer with a thickness of 0.1 to 1 mm in the terahertz band.

3. The terahertz transparent electrode based on nickel tellurium compound according to claim 2, characterized in that, Before use, the substrate is ultrasonically cleaned sequentially with deionized water, anhydrous ethanol, acetone, and anhydrous ethanol, and then dried with nitrogen.

4. The terahertz transparent electrode based on nickel tellurium compound according to claim 3, characterized in that, The nickel-tellurium target is made by fixing several fan-shaped nickel sheets symmetrically spaced on a 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 and the sleeve of the nickel-tellurium target is fixed at 2mm. Before plasma sputtering, pre-sputtering is performed to remove impurities from the target surface.

5. An application of a terahertz transparent electrode based on a nickel tellurium compound as described in claim 1 or 2 in the fields of photovoltaic devices, flexible displays, biomedical imaging, or high-speed communications.

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