CN103361614A - Method for preparing Terahertz modulator film material based on flexible substrate - Google Patents

Abstract

The invention discloses a preparation method of a terahertz modulator film material based on a flexible substrate. Polyimide is used as a flexible substrate, and a metal vanadium nano-film with a thickness of 50-300 nm is deposited on the surface after cleaning, and then the metal vanadium is The nano film is subjected to rapid heat treatment to form a metal vanadium film with a thickness of 100-600nm. The invention realizes the modulation of the terahertz wave by changing the properties of the material itself by means of laser excitation, realizes the operability of the modulator film material on the flexible substrate, and provides an application basis for the new device of the flexible substrate integrated circuit.

Description

A preparation method of terahertz modulator film material based on flexible substrate

technical field

The invention relates to the technical field of microelectronics and semiconductors, in particular to a method for preparing a terahertz modulator film material based on a flexible substrate.

Background technique

Terahertz (THz) waves (electromagnetic waves with frequencies in the 0.1-10THz band) are in a special position between millimeter waves and infrared rays, and are the last empty frequency band in the electromagnetic spectrum. It has potential applications in short-range wireless communication, biosensing, medical diagnosis, spectral detection of material properties, and non-destructive detection. To promote the further development and practical application of terahertz technology, it is necessary not only to solve the problem of reliable and stable THz source and THz detector with high sensitivity and high signal-to-noise ratio, but also to provide high-performance, high-integration and low-cost terahertz function Devices, such as THz polarization, beam splitting, filtering, switching, modulation and other new functional devices.

However, terahertz communication technology is not a transplantation of microwave communication or optical communication technology, and has many new features. Existing optical devices and electronic devices are difficult to directly control terahertz transmission. The lack of terahertz materials and devices has seriously restricted the practical development of terahertz technology, and has become one of the key problems to be solved in the terahertz field. In particular, modulation devices for terahertz communication are far from microwave and light wave communication technologies in terms of structure, size, performance, and working methods, and new research is needed. Los Alamos National Laboratory in the United States proposed a terahertz modulation device based on metal-type electromagnetic metamaterials. The device is to build a metal electromagnetic resonance unit on a Si or GaAs semiconductor substrate. The carrier concentration of the semiconductor substrate is changed by an external electric field, thereby affecting the terahertz resonance amplitude of the electromagnetic resonance unit, and realizing the modulation of the terahertz wave transmission signal. [H.T. Chen, et al, Nature, 444, 597-600, (2006)]. (CN101943803A) Quartz glass, a dielectric material highly transparent to terahertz waves, is used as a substrate, and a vanadium dioxide film is used to make an electromagnetic resonance array to realize modulation of terahertz signals. (CN102393571A) Coating a layer of vanadium dioxide film on the surface of the silicon photonic crystal column array of the wired defect waveguide, using the phase change characteristics of the vanadium dioxide film and the difference between the medium of the same structure and the conduction band of the metal photonic crystal waveguide, to achieve high-speed optical control Broadband terahertz intensity modulation and frequency modulation.

At present, there are few reports on flexible terahertz modulators, mainly because organic functional layer materials and flexible substrates are generally not compatible with CMOS processes, and are generally prepared on non-flexible substrates, which cannot achieve flexible and bendable effects. Along with the fabrication of integrated circuits on flexible substrates, new types of flexible functional devices are also required.

Contents of the invention

The purpose of the present invention is to overcome the disadvantages and deficiencies of the prior art. Based on the flexible substrate, the _VO2 nanofilm with phase transition properties was prepared by metal oxidation method, and the terahertz wave was modulated by using the photoexcited flexible substrate vanadium oxide. Provided is a method for preparing a novel terahertz modulator film material based on a flexible substrate, which is simple in the preparation process, easy to control, stable and reliable at low optical power.

The present invention is realized through the following technical solutions.

A method for preparing a terahertz modulator film material based on a flexible substrate, comprising the following steps:

(1) Cleaning of flexible substrate PI:

The flexible substrate used was polyimide, referred to as PI, which was ultrasonically cleaned in deionized water, acetone solvent and absolute ethanol for 20 minutes, and then soaked in 5% acetic acid solution for 15 minutes. Remove surface organic impurities; then wash with deionized water and dry for later use;

(2) Preparation of metal vanadium nanofilm:

Place the PI cleaned in step (1) in the vacuum chamber of the ultra-high vacuum magnetron sputtering equipment, using metal vanadium with a mass purity of 99.99% as the target material, and argon gas with a mass purity of 99.999% as the working gas , the background vacuum degree is 4～6×10 ^-4 Pa, the substrate temperature is room temperature, the argon gas flow rate is 45-48mL/min, the sputtering working pressure is 0.5～2Pa, the sputtering power is 135～150W, the sputtering time 10-60min, deposit metal vanadium nano-film on the surface of PI;

(3) Heat treatment based on flexible base metal vanadium nanofilm

The metal vanadium nanofilm that step (2) makes is placed in rapid heat treatment equipment, adopts the oxygen that mass purity is 99.999% as working gas, and oxygen gas flow rate is 30～50sccm, and heat treatment temperature is 250～300 ℃, and heat treatment time is 30～180s;

(4) A standard 8-fTHz time-domain spectrum system is used to test the modulation characteristics of the vanadium oxide film on the flexible substrate, and the laser power is 200-600mW.

The dielectric constant of the flexible substrate PI in the step (1) is 3.4, and the high temperature resistance can reach 400°C.

In the step (1), the specification of the flexible substrate PI is a rectangle of 2cm×1cm;

The metal vanadium thin film prepared in the step (2) has a thickness of 50-300nm, and the vacuum chamber of the high-vacuum target magnetron sputtering equipment is the vacuum chamber of the DPS-III ultra-high vacuum target magnetron sputtering equipment.

The film after heat treatment in the step (3) is vanadium dioxide or vanadium pentoxide.

The rapid heat treatment equipment in the step (3) is AG610 series, and the thickness of the vanadium oxide film formed after the heat treatment is 100-600 nm.

Compared with prior art, the beneficial effects of the present invention are:

1) The terahertz wave modulation film material based on the flexible substrate provided by the present invention realizes the modulation of the terahertz wave by changing the properties of the material itself by means of laser excitation.

2) Compared with the existing modulators with non-flexible substrates, the present invention realizes the operability of modulator film materials on flexible substrates, and provides an application basis for new devices with flexible substrate integrated circuits.

Description of drawings

Fig. 1 is the scanning electron micrograph of vanadium dioxide thin film on the flexible substrate in embodiment 1;

Fig. 2 is the terahertz modulation spectrogram of the vanadium dioxide thin film on the flexible substrate in embodiment 1;

FIG. 3 is a terahertz modulation spectrum diagram of a vanadium dioxide thin film on a flexible substrate in Example 2. FIG.

Detailed ways

Example 1

(1) The flexible substrate used is polyimide (Polyimide), referred to as PI, put it in deionized water, acetone solvent, and absolute ethanol for 20 minutes, and then put it in acetic acid with a mass fraction of 5%. Soak in the solution for 15 minutes to remove surface organic impurities; then wash with deionized water, and finally dry the PI for later use;

The size of the PI flexible substrate is a rectangle of 2cm×1cm;

(2) The metal vanadium film was prepared by the magnetron beam sputtering method, the metal vanadium with a mass purity of 99.99% was used as the target material, and the argon gas with a mass purity of 99.999% was used as the working gas, and the background vacuum degree was 4×10 ^-4 Pa, the substrate temperature is room temperature, the argon gas flow rate is 45mL/min, the sputtering working pressure is 2Pa, the sputtering power is 135W, the sputtering time is 10min, and the metal vanadium nano film deposited on the surface is 50nm;

(3) Put the metal vanadium nanofilm in the rapid heat treatment equipment AG610, use oxygen with a mass purity of 99.999% as the working gas, the oxygen gas flow rate is 30 sccm, the heat treatment temperature is 300 ° C, and the heat treatment time is 180 s; The thickness of the vanadium oxide film is 100nm. From the electron micrograph of the vanadium oxide film in Figure 1, it can be seen that the prepared film has a smooth surface and uniform particle size.

(4) The standard 8-fTHz time-domain spectrum system is used for testing. The vanadium dioxide film on the flexible substrate prepared in Example 1 has a stable modulation effect on the terahertz wave, and the frequency is 2.1THz, and the laser power is 600mW. It is measured that the change of its modulation amplitude is 40%, as shown in Figure 2.

Example 2

The difference between embodiment 2 and embodiment 1 is:

The heat treatment temperature in step (3) is 250°C. The vanadium dioxide film on the flexible substrate obtained in Example 2 has a stable modulation effect on terahertz waves. When the frequency is 2.1THz and the laser power is 400mW, the variation of the modulation amplitude is 40% in multiple measurements, as shown in Figure 3 .

Example 3

The difference between embodiment 3 and embodiment 1 is:

The laser power in step (4) is 300mW. The vanadium dioxide thin film on the flexible substrate prepared in Example 3 has a stable modulation effect on terahertz waves. When the frequency is 2.1 THz and the laser power is 300 mW, the variation of the modulation amplitude is 30% in multiple measurements.

Example 4

Embodiment 4 differs from Embodiment 1 in that:

The laser power in step (4) is 400mW. The vanadium dioxide thin film on the flexible substrate prepared in Example 4 has a stable modulation effect on terahertz waves. When the frequency is 2.1 THz and the laser power is 400 mW, the variation of the modulation amplitude is 35% in multiple measurements.

The present invention is not limited to the above-mentioned embodiments, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (6)

1. A method for preparing a terahertz modulator membrane material based on a flexible substrate, comprising the following steps: (1) Cleaning of flexible substrate PI: The flexible substrate used was polyimide, referred to as PI, which was ultrasonically cleaned in deionized water, acetone solvent and absolute ethanol for 20 minutes, and then soaked in 5% acetic acid solution for 15 minutes. Remove surface organic impurities; then wash with deionized water and dry for later use; (2) Preparation of metal vanadium nanofilm: Place the PI cleaned in step (1) in the vacuum chamber of the ultra-high vacuum magnetron sputtering equipment, using metal vanadium with a mass purity of 99.99% as the target material, and argon gas with a mass purity of 99.999% as the working gas , the background vacuum degree is 4～6×10 ^-4 Pa, the substrate temperature is room temperature, the argon gas flow rate is 45-48mL/min, the sputtering working pressure is 0.5～2Pa, the sputtering power is 135～150W, the sputtering time 10-60min, deposit metal vanadium nano-film on the surface of PI; (3) Heat treatment based on flexible base metal vanadium nanofilm The metal vanadium nanofilm that step (2) makes is placed in rapid heat treatment equipment, adopts the oxygen that mass purity is 99.999% as working gas, and oxygen gas flow rate is 30～50sccm, and heat treatment temperature is 250～300 ℃, and heat treatment time is 30～180s; (4) A standard 8-fTHz time-domain spectrum system is used to test the modulation characteristics of the vanadium oxide film on the flexible substrate, and the laser power is 200-600mW. the 2. A method for preparing a flexible substrate-based terahertz modulator film material according to claim 1, characterized in that the flexible substrate PI in the step (1) has a dielectric constant of 3.4 and can withstand high temperatures up to 400°C. the 3 . The method for preparing a terahertz modulator film material based on a flexible substrate according to claim 1 , wherein in the step (1), the specification of the flexible substrate PI is a rectangle of 2 cm×1 cm. 4 . the 4. the preparation method of a kind of terahertz modulator film material based on flexible substrate according to claim 1, it is characterized in that, the metal vanadium film thickness of described step (2) preparation is 50～300nm, and high vacuum is to target magnetron The vacuum chamber of the sputtering equipment is the vacuum chamber of the DPS-Ⅲ ultra-high vacuum target magnetron sputtering equipment. the 5 . A method for preparing a flexible substrate-based terahertz modulator film material according to claim 1 , wherein the film after the heat treatment in step (3) is vanadium dioxide or vanadium pentoxide. the 6. according to a kind of preparation method of the terahertz modulator membrane material based on flexible substrate according to claim 1, it is characterized in that, the rapid heat treatment equipment of described step (3) is AG610 series, the vanadium oxide film thickness that forms after heat treatment is 100~600nm. the

Images