CN103981501B - Ripple struction vanadium dioxide film and preparation method thereof - Google Patents

Abstract

A vanadium dioxide film with a corrugated structure and a preparation method thereof, the invention relates to a vanadium dioxide film and a preparation method thereof. The present invention will solve the technical problem that the existing VO thin film has low transmittance in the visible light region. The corrugated vanadium _dioxide thin film of the present invention is made up of a substrate and a vanadium dioxide layer attached to the substrate surface, wherein The surface morphology of the vanadium dioxide layer is corrugated. Preparation method: 1. Use radio frequency magnetron sputtering method to prepare V ₂ O ₅ film on the surface of the substrate; 2. Heat treatment to convert V ₂ O ₅ into VO ₂ film; 3. Ion beam sputtering self-assembly to obtain corrugated structure _VO2 film. The highest visible light transmittance of the vanadium dioxide thin film of the invention is close to 70%, can be used as an intelligent window, and the thin film has the characteristics of high repetition rate and simple method, and is suitable for industrial production.

Description

Corrugated structure vanadium dioxide thin film and preparation method thereof

technical field

The invention relates to a vanadium dioxide thin film and a preparation method thereof.

Background technique

Sunlight energy is an inexhaustible source of energy, of which 45% is visible light and 49% is infrared light. Due to the lag in the development of intelligent and controllable high-performance materials, the development and utilization of visible light is not very high, so To effectively discover a functional material that utilizes sunlight energy has become an urgent task in the development of new material technology. In addition, nearly 30-40% of the energy in today's society is used for building heating, cooling, ventilation and lighting, and the use of air conditioners is the most energy-consuming part. Indoor-outdoor energy exchange through glass is a key area for effective energy conservation, and coating thin-film materials on building glass to control the input of solar radiation under different conditions is an effective energy-saving strategy. VO ₂ is a metal oxide with thermally induced phase transition properties. It has the characteristics of transition between monoclinic structure and tetragonal structure during phase transition, and this transition is a high-speed reversible phase transition. An important property of VO ₂ film is that the reversible metal-semiconductor phase transition (MS phase transition for short) occurs at a low temperature (68°C), and the electrical and optical properties undergo a sudden change when the phase transition occurs. At low temperature, the infrared transmittance of the semiconductor phase reaches 70%, while at high temperature the infrared transmittance of the metal phase is close to 0%, making it an ideal smart glass coating material. In order to be able to be applied practically, the visible light transmittance of VO ₂ thin film should reach more than 60%. However, the visible light transmittance of existing VO ₂ thin films is generally less than 45%, which limits its application. In recent years, a large number of researchers have improved the visible light transmittance by doping Mg, F and other elements, and adding anti-reflection coating SiO ₂ or TiO ₂ on the surface of VO ₂ , and some researchers have also prepared VO ₂ films with holes to improve Visible light transmittance. However, the above methods for increasing visible light transmittance are too complicated and increase the manufacturing cost.

Contents of the invention

The invention aims to solve the technical problem of low transmittance of the existing VO2 film in the visible light region, and provides a method for preparing a corrugated structure vanadium _dioxide film.

The vanadium dioxide film with a corrugated structure of the invention is composed of a substrate and a vanadium dioxide layer attached to the surface of the substrate, wherein the surface morphology of the vanadium dioxide layer is corrugated.

The preparation method of the above-mentioned corrugated structure vanadium dioxide film is carried out according to the following steps:

1. Prepare a V ₂ O ₅ thin film on the surface of the substrate by radio frequency magnetron sputtering;

2. The V ₂ O ₅ film prepared in step 1 is subjected to heat treatment to obtain VO ₂ film;

3. Send the VO ₂ thin film to the ion beam sputtering chamber, evacuate to a vacuum degree of 5.0×10 ^-4 ~9.0×10 ^-4 Pa, and then pass in argon gas to make the vacuum degree 2.0×10 ^-2 ~8.0× 10 ^-2 Pa, the temperature of the VO ₂ film is room temperature, the discharge voltage is 60-70V, the discharge current is 0.1A, the particle beam current voltage is 0.8-1Kv, the accelerating voltage is 200-260V, the accelerating current is 2-4mA, and the filament current is 6- Ion beam sputtering under the condition of 8A, the sputtering time is 20min-40min, and the vanadium dioxide film with corrugated structure is obtained.

In the present invention, a VO2 film with thermally induced phase transition properties is firstly prepared by radio frequency magnetron sputtering technology, and then a VO2 film with a corrugated structure is self _- assembled using low _- energy ion beam irradiation technology, and the film has thermally induced phase transition properties , its phase transition temperature is 55-57°C, and its visible light transmittance is close to 70%. The corrugated vanadium dioxide film with high visible light transmittance can meet the application of smart windows, and the film has a high repetition rate. The preparation method is simple and suitable for industrialized production.

Description of drawings

Fig. 1 is the XRD spectrogram of the corrugated structure vanadium dioxide film that test 1 prepares;

Fig. 2 is the AFM picture of the corrugated structure vanadium dioxide thin film that test 1 prepares;

Fig. 3 is the autocorrelation diagram of Fig. 2;

Fig. 4 is the VO prepared in the step ₂ of test 1 The AFM photograph (before ion beam irradiation) of thin film;

Fig. 5 is the variable temperature resistance curve diagram of the corrugated structure vanadium dioxide thin film prepared in test 1;

Fig. 6 is the transmittance curve of the corrugated structure vanadium dioxide thin film prepared in test 1;

Fig. 7 is the XRD spectrogram of the corrugated structure vanadium dioxide thin film prepared in test 2;

Fig. 8 is the AFM picture of the corrugated structure vanadium dioxide thin film prepared in test 2;

Fig. 9 is the variable temperature resistance curve diagram of the corrugated structure vanadium dioxide thin film prepared in test 2;

Figure 10 is the transmittance curve of the corrugated vanadium dioxide film prepared in Experiment 2.

detailed description

Embodiment 1: A vanadium dioxide film with a corrugated structure in this embodiment is composed of a substrate and a vanadium dioxide layer attached to the surface of the substrate, wherein the cross section of the vanadium dioxide layer is corrugated.

Embodiment 2: This embodiment is different from Embodiment 1 in that the substrate is glass, quartz or silicon. Others are the same as in the first embodiment.

Specific embodiment three: the preparation method of the corrugated structure vanadium dioxide film described in specific embodiment one is carried out according to the following steps:

1. Prepare a V ₂ O ₅ thin film on the surface of the substrate by radio frequency magnetron sputtering;

2. The V ₂ O ₅ film prepared in step 1 is subjected to heat treatment to obtain VO ₂ film;

3. Send the VO ₂ thin film to the ion beam sputtering chamber, evacuate to a vacuum degree of 5.0×10 ^-4 ~9.0×10 ^-4 Pa, and then pass in argon gas to make the vacuum degree 2.0×10 ^-2 ~8.0× 10 ^-2 Pa, the temperature of the VO ₂ film is room temperature, the discharge voltage is 60-70V, the discharge current is 0.1A, the particle beam current voltage is 0.8-1Kv, the accelerating voltage is 200-260V, the accelerating current is 2-4mA, and the filament current is 6- Ion beam sputtering under the condition of 8A, the sputtering time is 20min-40min, and the vanadium dioxide film with corrugated structure is obtained.

Embodiment 4: The difference between this embodiment and Embodiment 3 is that the preparation of the V ₂ O ₅ thin film in step 1 is as follows:

a. Fix the V ₂ O ₅ target with a purity of 99.99% on the cathode of the radio frequency magnetron sputtering equipment, place the clean substrate on the anode facing the target surface, and the distance between the target and the substrate is 4-7cm ;

b. After the system is evacuated to 6.0×10 ^-4 Pa, the mixed gas of argon and oxygen is filled to make the vacuum degree of the system 1.2-2.4Pa, and the O ₂ /Ar is 0.5%-2%;

c. Heating the substrate to 350-450° C., sputtering for 60-180 min under the conditions of sputtering power of 90-150 W and bias voltage of 100-150 V to obtain a V ₂ O ₅ film. Others are the same as in the third embodiment.

Specific embodiment five: the difference between this embodiment and specific embodiment three or four is that the specific steps of heat treatment in step two are as follows:

a. Put the V ₂ O ₅ film into the heat treatment chamber, evacuate to 0-10Pa, and then pass through nitrogen protection with a purity of 99.995%, and the nitrogen flow rate is 10 sccm;

b. Heat the V ₂ O ₅ film at a heating rate of 5-15° C./min to 400-450° C. for heat treatment, keep it for 2-6 hours, and cool it down to room temperature naturally to obtain a VO ₂ film. Others are the same as the third or fourth specific embodiment.

Embodiment 6: This embodiment differs from Embodiment 3 to Embodiment 5 in that the discharge voltage is 65V during ion beam sputtering in step 3. Others are the same as one of the third to fifth specific embodiments.

Embodiment 7: This embodiment differs from Embodiment 3 to Embodiment 6 in that the particle beam current voltage is 0.9KV during ion beam sputtering in Step 3. Others are the same as one of the third to sixth specific embodiments.

Embodiment 8: The difference between this embodiment and one of Embodiments 3 to 7 is that the acceleration voltage is 250V during ion beam sputtering in step 3. Others are the same as one of the third to seventh embodiments.

Embodiment 9: This embodiment differs from Embodiment 3 to Embodiment 8 in that the acceleration current is 3mA during the ion beam sputtering in Step 3. Others are the same as one of the third to eighth specific embodiments.

Embodiment 10: This embodiment differs from Embodiment 3 to Embodiment 9 in that the filament current is 7A during ion beam sputtering in step 3. Others are the same as one of the third to ninth specific embodiments.

Verify beneficial effect of the present invention with following test:

Experiment 1: In this experiment, FJL560 high vacuum magnetron sputtering and ion beam combined sputtering equipment was used to study the preparation of corrugated structure vanadium dioxide film. The specific method is as follows:

1. The V ₂ O ₅ thin film is first prepared by radio frequency magnetron sputtering method:

a. Fix the V ₂ O ₅ target with a purity of 99.99% on the cathode of the FJL560 high-vacuum magnetron sputtering and ion beam combined sputtering equipment, and place the clean glass substrate on the sample stage facing the target surface , the distance between target and substrate is 5cm;

b. Evacuate the sputtering chamber to 6.0×10 ^-4 Pa and then fill it with argon and oxygen mixed gas to make the vacuum of the system 1.2 Pa, where O ₂ /Ar is 1%;

c. Heating the glass substrate to 450°C, sputtering for 120min under the condition of sputtering power of 120W and bias voltage of 100V, stop sputtering, let it cool down to room temperature naturally, and obtain V ₂ O ₅ film;

2. Transform the V ₂ O ₅ film prepared in step 1 into a VO ₂ film by heat treatment:

a. Evacuate the sputtering chamber of the FJL560 high-vacuum magnetron sputtering and ion beam combined sputtering equipment to 6Pa, and then pass through nitrogen protection with a mass purity of 99.995%, and the nitrogen flow rate is 10 sccm;

b. Raise the temperature of the V ₂ O ₅ thin film on the sample stage to 450°C at a heating rate of 5°C/min and keep it for 4 hours, then naturally cool to room temperature to obtain a VO ₂ thin film;

3. Under the same vacuum conditions in the sputtering chamber and the ion beam chamber, the VO ₂ thin film is sent into the ion beam sputtering chamber through the transfer device, and the vacuum is evacuated to make the vacuum degree reach 9.0×10 ^-4 Pa, and then argon gas is introduced. The vacuum degree is 6.0×10 ^-2 Pa, the temperature of the VO ₂ film is room temperature, under the conditions of discharge voltage 60V, discharge current 0.1A, particle beam current voltage 1Kv, acceleration voltage 200V, acceleration current 2mA, filament current 8A , the irradiation time is 20min, and the vanadium dioxide film with corrugated structure is obtained.

The XRD spectrogram of the corrugated vanadium dioxide film prepared in this test is shown in Figure 1, as can be seen from Figure 1, the sample has an obvious diffraction peak at 18.3 °, which is the same as the diffraction peak of the VO ₂ (M) standard card , indicating that the prepared thin film is a VO ₂ thin film with obvious preferred orientation growth. The AFM image of the corrugated vanadium dioxide film prepared in this test is shown in Figure 2. It can be seen from Figure 2 that the vanadium dioxide layer on the substrate has a corrugated structure. In order to see the corrugated structure more clearly, the The AFM autocorrelation diagram in Figure 2 is shown in Figure 3, and its corrugated structure can be seen more clearly.

At the same time, the AFM photo of the VO2 thin film prepared in this test step _two is shown in Figure 4. As can be seen from Figure 4, the particles on the surface of the VO2 thin film obtained through heat treatment are arranged chaotically. Compare Figure 4 and Figure ₂ It can be known from and 3 that, through low-energy ion beam irradiation treatment, the vanadium dioxide particles on the surface of the glass substrate are self-assembled to obtain this corrugated structure.

For the vanadium dioxide thin film with corrugated structure prepared in this test, the thickness of the vanadium dioxide film layer is 300nm.

The variable temperature resistance curve of the corrugated vanadium dioxide film prepared in this test is shown in Figure 5, where a is the resistance change when the temperature is raised, and b is the resistance change when the temperature is lowered. It can be seen from Figure 5 that the film has obvious Thermally induced phase transition characteristics, the phase transition temperature is 55°C, and the resistance mutation is close to 2 orders of magnitude at the phase transition temperature.

The transmittance curve of the corrugated vanadium dioxide film prepared in this experiment is shown in Figure 6. From Figure 6, it can be seen that the transmittance of the film in the visible light region reaches 55% to 70%.

Test 2: Test 1: This test uses FJL560 high vacuum magnetron sputtering and ion beam combined sputtering equipment to study the preparation of corrugated vanadium dioxide thin films. The specific method is as follows:

1. The V ₂ O ₅ thin film is first prepared by radio frequency magnetron sputtering method:

a. Fix the V ₂ O ₅ target with a purity of 99.99% on the cathode of the radio frequency magnetron sputtering equipment, place the clean substrate on the anode facing the target surface, and the distance between the target and the substrate is 6cm;

b. After the system is evacuated to 6.0×10 ^-4 Pa, the mixed gas of argon and oxygen is filled to make the vacuum degree of the system 2.0 Pa, and the O ₂ /Ar is 1.5%;

c. Heating the substrate to 400°C, sputtering for 160min under the conditions of sputtering power of 150W and bias voltage of 150V, to obtain a V ₂ O ₅ film;

2. Transform the V ₂ O ₅ film prepared in step 1 into a VO ₂ film by heat treatment:

a. Evacuate the sputtering chamber of the FJL560 high-vacuum magnetron sputtering and ion beam combined sputtering equipment to 9Pa, and then pass through nitrogen protection with a mass purity of 99.995%, and the nitrogen flow rate is 10 sccm;

b. Raise the temperature of the V ₂ O ₅ thin film on the sample stage to 430°C at a heating rate of 5°C/min and keep it for 5h, then naturally cool to room temperature to obtain a VO ₂ thin film;

3. Under the same vacuum conditions in the sputtering chamber and the ion beam chamber, send the VO ₂ thin film into the ion beam sputtering chamber through the transfer device, evacuate to make the vacuum degree reach 8.0×10 ^-4 Pa, and then pass in argon gas. The vacuum degree is 8.0×10 ^-2 Pa, the temperature of the VO ₂ film is room temperature, and the discharge voltage is 70V, the discharge current is 0.1A, the particle beam current voltage is 0.8Kv, the acceleration voltage is 260V, the acceleration current is 3mA, and the filament current is 8A. Under the irradiation time of 30min, a corrugated vanadium dioxide film was obtained.

The XRD spectrum of the corrugated vanadium dioxide film prepared in this test is shown in Figure 7, as can be seen from Figure 7, the sample has an obvious diffraction peak at 18.3 °, which is the same as the diffraction peak of the VO2 ₍ M) standard card , indicating that the prepared thin film is a VO ₂ thin film with obvious preferred orientation growth.

The AFM image of the vanadium dioxide film with corrugated structure prepared in this test is shown in Fig. 8. It can be seen from Fig. 8 that the vanadium dioxide layer on the substrate has a corrugated structure.

The variable temperature resistance diagram of the corrugated vanadium dioxide film prepared in this test is shown in Figure 9, where a is the resistance change when the temperature is raised, and b is the resistance change when the temperature is lowered. It can be seen from Figure 9 that the film has obvious Thermally induced phase transition characteristics. The phase transition temperature is 57°C. When the temperature is close to the phase transition temperature, the resistance undergoes a sudden change, and the magnitude of the sudden change is close to 2.

The transmittance curve of the corrugated vanadium dioxide film prepared in this experiment is shown in Figure 10. It can be seen from Figure 10 that the transmittance of the film in the visible light region reaches 60% to 70%.

Claims (8)

1. a preparation method of corrugated structure vanadium dioxide thin film is characterized in that the method is carried out according to the following steps: 1. Prepare a V ₂ O ₅ thin film on the surface of the substrate by radio frequency magnetron sputtering; 2. The V ₂ O ₅ film prepared in step 1 is subjected to heat treatment to obtain VO ₂ film; 3. Send the VO ₂ thin film to the ion beam sputtering chamber, evacuate to a vacuum degree of 5.0×10 ^-4 ~9.0×10 ^-4 Pa, and then pass in argon gas to make the vacuum degree 2.0×10 ^-2 ~8.0× 10 ^-2 Pa, the temperature of the VO ₂ film is room temperature, the discharge voltage is 60-70V, the discharge current is 0.1A, the particle beam current voltage is 0.8-1kV, the accelerating voltage is 200-260V, the accelerating current is 2-4mA, and the filament current is 6- Ion beam sputtering under the condition of 8A, the sputtering time is 20min-40min, and the vanadium dioxide film with corrugated structure is obtained. 2. the preparation method of a kind of corrugated structure vanadium dioxide thin film according to claim ₁ is characterized in that the V in the step one O _The preparation method of the thin film is carried out according to the following steps: a. Fix the V ₂ O ₅ target with a purity of 99.99% on the cathode of the radio frequency magnetron sputtering equipment, place the clean substrate on the anode facing the target surface, and the distance between the target and the substrate is 4-7cm ; b. After the system is evacuated to 6.0×10 ^-4 Pa, the mixed gas of argon and oxygen is filled to make the vacuum degree of the system 1.2-2.4Pa, and the O ₂ /Ar is 0.5%-2%; c. Heating the substrate to 350-450° C., sputtering for 60-180 min under the conditions of sputtering power of 90-150 W and bias voltage of 100-150 V to obtain a V ₂ O ₅ film. 3. the preparation method of a kind of corrugated structure vanadium dioxide thin film according to claim 1 is characterized in that heat treatment is carried out in the following steps in step 2: a. Put the V ₂ O ₅ film into the heat treatment chamber, evacuate to 0-10Pa, and then pass through nitrogen protection with a purity of 99.995%, and the nitrogen flow rate is 10 sccm; b. Heat the V ₂ O ₅ film at a heating rate of 5-15° C./min to 400-450° C. for heat treatment, keep it for 2-6 hours, and cool it down to room temperature naturally to obtain a VO ₂ film. 4. The method for preparing a corrugated vanadium dioxide film according to claim 1, 2 or 3, wherein the discharge voltage is 65V during ion beam sputtering in step 3. 5 . The method for preparing a corrugated vanadium dioxide thin film according to claim 1 , 2 or 3, characterized in that during ion beam sputtering in step 3, the particle beam current voltage is 0.9 kV. 6. The method for preparing a corrugated vanadium dioxide thin film according to claim 1, 2 or 3, wherein the acceleration voltage is 250V during ion beam sputtering in step 3. 7. The method for preparing a corrugated vanadium dioxide thin film according to claim 1, 2 or 3, wherein the acceleration current is 3mA during ion beam sputtering in step 3. 8. The method for preparing a corrugated vanadium dioxide film according to claim 1, 2 or 3, wherein the filament current is 7A during ion beam sputtering in step 3.