Method for synchronously controlling optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films

Abstract

Method for synchronously controlling optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films. The present invention aims to solve the problem of VO2 thin film preparation process using magnetron sputtering technology. x The composition of the mixed phase is very sensitive to the oxygen flow rate, and the technical problem of poor stability of the VO2 thin film preparation process. Control method: 1. Ultrasonic cleaning of the substrate; 2. Cleaning of the metal target; 3. Connecting the V metal target to a DC power supply and the W metal target to an RF power supply; 4. Vacuuming; 5. Heating the substrate; 6. Ignition; 7. Pre-sputtering the target; 8. Controlling the oxygen flow rate so that the coating state is in a poisoning mode for thin film deposition; 9. Cooling; 10. Vacuuming in an annealing furnace; 11. Annealing. The present invention introduces W atoms to regulate the crystal structure and band structure of VO2 while making full use of the difference in electronegativity and atomic radius between W and V elements, thereby achieving synchronous regulation of microscopic electronic polarization response and optical frequency dielectric properties.

Description

Technical Field

[0001] The invention relates to a method for preparing a vanadium dioxide film with adjustable optical frequency dielectric constant and phase transition temperature. Background Art

[0002] VO2 can undergo phase transitions driven by external physical fields such as light, electricity, force, and heat, and its optical and electrical properties change dramatically before and after the phase transition. It has a wide range of applications in storage, metasurfaces, microelectronic devices, thermal radiation regulation, smart windows, photonic chips, and other fields. VO2 thin films can undergo a structural phase transition between two different crystal structures at around 68°C. At low temperatures, VO2 is an insulating phase (or semiconductor phase) with a monoclinic crystal structure. It has high infrared transmittance and a wide transmission band, but poor conductivity. When VO2 is heated to around 68°C, the crystal structure gradually transforms from the monoclinic phase to the tetrahedral rutile phase, and completely transforms into the tetrahedral rutile phase after the temperature exceeds 68°C. The high-temperature tetrahedral rutile phase can also be called a metallic phase. Its infrared transmittance decreases rapidly, but its conductivity is greatly improved.

[0003] Because VO2 thin films have a phase transition temperature closest to room temperature and exhibit high cyclic stability and long cycle life, they have attracted widespread attention and have been widely used in the optical and electromagnetic fields. However, when applying VO2 thin films to optical devices, it is necessary to simultaneously consider the phase transition temperature, optical properties, and phase transition characteristics. On the one hand, while lowering the VO2 phase transition temperature, it is necessary to maintain a certain phase transition capability. On the other hand, when regulating the phase transition temperature, the effect on the dielectric constant of VO2 must be considered. The optical frequency dielectric constant is a key parameter for the interaction between the material and photons. Therefore, while regulating the VO2 phase transition temperature, considering the simultaneous regulation of optical properties such as the optical frequency dielectric constant and optical constant is of great significance for further expanding the application of VO2.

[0004] Due to the limitations of VO2 material properties, the preparation of high-purity VO2 thin films has become another key issue that everyone is concerned about. Using magnetron sputtering technology, VO2 thin films can be directly prepared, but the purity of VO2 is not ideal and the optical modulation performance needs to be improved. Through a two-step method, first, VO2 is prepared by magnetron sputtering. x Mixed phase, then high temperature annealing, using VO x The thermal transition between different phases in VO2 can produce high-purity VO2 thin films. x The composition of the mixed phase is very sensitive to the oxygen flow rate during magnetron sputtering, and VO x The transition conditions of different phases are different, so the two-step preparation process has different effects on oxygen flow rate, VO x The composition and annealing conditions of the mixed phase are strictly required. If it is possible to achieve VO through certain coating technology innovationsx Precise control of the composition of the mixed phase can improve the stability of the VO2 thin film preparation process and reduce the time and economic cost required for VO2 thin film preparation. Although a large number of preliminary process controls can be performed by adjusting the oxygen flow rate, the appropriate oxygen flow rate can be found to achieve VO2 thin film preparation. x The control of the mixed phase composition, but repeated experiments require a lot of time and economic costs, which reduces the efficiency and has certain disadvantages.

[0005] Therefore, it is an important task to achieve controllable VO2 thin film preparation process, improve the stability of the preparation process, and achieve synchronous regulation of VO2 phase transition temperature and optical frequency dielectric constant through certain technical means. Summary of the Invention

[0006] The present invention aims to solve the problem of VO2 thin film preparation process using magnetron sputtering technology. x The composition of the mixed phase is very sensitive to the oxygen flow rate, the stability of the VO2 thin film preparation process is poor, and there are technical problems such as how to achieve synchronous regulation of the VO2 phase transition temperature and optical frequency dielectric constant. A method for synchronously regulating the optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films is provided.

[0007] The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of a vanadium oxide thin film according to the present invention is implemented by the following steps:

[0008] 1. performing ultrasonic cleaning on the substrate to obtain a cleaned substrate;

[0009] 2. Grinding and cleaning the V metal target and the W metal target respectively to obtain cleaned V metal target and W metal target;

[0010] 3. Install the cleaned V metal target and W metal target in the cabin of the magnetron sputtering device, place the substrate on the sample stage, connect the V metal target to the DC power supply, and connect the W metal target to the RF power supply;

[0011] 4. Turn on the mechanical pump to vacuum the cavity of the magnetron sputtering device. When the vacuum degree reaches below 10Pa, turn on the molecular pump to continue vacuuming to complete the vacuuming process.

[0012] 5. Heat the substrate to 300-500°C and keep it warm;

[0013] 6. Turn on the RF power supply and DC power supply, set the power of both to 80-120W, the argon flow rate to 10-30sccm, adjust the chamber pressure to 3.0-5.0Pa, and start the ignition.

[0014] 7. After the ignition is successful, adjust the chamber pressure to 1.0 Pa and perform pre-sputtering treatment on the V metal target and the W metal target;

[0015] 8. After the pre-sputtering is completed, the RF power supply is controlled to 1-10W, the argon flow rate is 10-30sccm, the DC power supply power is 80-120W, and the oxygen flow rate is controlled to make the coating state in the poisoning mode for thin film deposition;

[0016] 9. After the deposition is completed, the temperature is lowered in an argon atmosphere until the temperature drops to room temperature to obtain a W-doped vanadium oxide film;

[0017] 10. Place the W-doped vanadium oxide film in an annealing furnace, evacuate the furnace, and then introduce argon gas;

[0018] 11. The annealing temperature was controlled at 450-600°C, the holding time was 30-60 minutes, the argon flow rate was 40-80 seem, and high-temperature post-treatment was performed in a flowing argon atmosphere. After heating, the temperature was cooled to obtain a vanadium oxide film with synchronous regulation of optical frequency dielectric properties and phase transition temperature.

[0019] The present invention is used to synchronously control the optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films. In the method, W atoms with a low doping ratio of 0.5% to 1% are used to achieve synchronous control of VO2 phase transition temperature and optical frequency dielectric constant. By testing W doping W x V 1-x The phase transition temperature, relative dielectric constant and optical constant of the O2 film confirmed the effectiveness of the control method.

[0020] The method for determining the oxygen flow rate in the poisoning mode during the preparation of vanadium dioxide thin films using the magnetron sputtering process of the present invention is as follows:

[0021] 1. performing ultrasonic cleaning on the substrate to obtain a cleaned substrate;

[0022] 2. Grind and clean the V metal target;

[0023] 3. Install the cleaned V metal target in the chamber of the magnetron sputtering device, place the substrate on the sample stage, and connect the V metal target to the DC power supply;

[0024] 4. Turn on the mechanical pump to vacuum the cavity of the magnetron sputtering device. When the vacuum degree reaches below 10Pa, turn on the molecular pump to continue vacuuming to complete the vacuuming process.

[0025] 5. Heat the substrate to 300-500°C and keep it warm;

[0026] 6. Turn on the DC power supply, set the power to 80-120W, the argon flow rate to 10-30sccm, and adjust the chamber pressure to 3.0-5.0Pa for ignition.

[0027] 7. After the ignition is successful, adjust the cabin pressure to 1.0 Pa and perform pre-sputtering treatment on the V metal target;

[0028] 8. After the pre-sputtering is completed, the DC power supply power is controlled to 80-120W, the argon flow rate is 10-30sccm, the oxygen flow rate is initially set to 0, and the test is started. The oxygen flow rate is continuously increased at fixed intervals, and then the oxygen flow rate is reduced at the same intervals. The discharge voltage / discharge current parameters on the DC power supply are recorded during the entire test process, and the hysteresis loop of the magnetron sputtering reaction is obtained by plotting;

[0029] 9. In the high oxygen flow stage, the overlapping area of ​​discharge voltage / discharge current in the oxygen flow increase stage and the oxygen flow decrease stage in the magnetron sputtering reaction hysteresis loop is determined to be the poisoning mode, thereby determining the oxygen flow rate under the poisoning mode.

[0030] The preparation of the vanadium oxide film that synchronously controls the optical frequency dielectric properties and phase transition temperature adopts a two-step method, that is, the first step is to prepare VO by reactive DC magnetron sputtering. x Mixed phase, the second step is VO x The mixed phase is annealed at high temperature to prepare high-purity VO2 thin film. x In order to solve the problems of mixed phase being sensitive to oxygen flow, difficult to control composition and high process cost, reactive DC magnetron sputtering technology was used to establish the oxygen flow, discharge parameters (target discharge voltage, target discharge current), coating mode, VO x The relationship between the mixed phase components is realized by real-time feedback of the current coating state through oxygen flow and discharge parameters, and timely adjustment of coating parameters, which realizes the VO x The precise control of the mixed phase (mainly generating V2O5 phase) greatly improves the coating stability and reduces the sensitivity of the subsequent annealing process to annealing conditions.

[0031] When DC magnetron sputtering is used for reactive sputtering coating, as the oxygen flow rate increases, the coating state will gradually go through the metal mode, transition mode and poisoning mode. As the oxygen flow rate changes, the coating state will show regular changes, and the discharge voltage and discharge current on the target surface will also change accordingly. The changes in the above parameters are very sensitive to changes in oxygen flow rate. In addition, VO x The composition of the mixed phase is also very sensitive to the oxygen flow rate.

[0032] Therefore, the present invention makes full use of reactive DC magnetron sputtering and VO xThe composition of the mixed phase is synchronously sensitive to oxygen. By real-time monitoring the changes of discharge parameters such as discharge voltage and discharge current on the target surface with the oxygen flow rate, the corresponding magnetron sputtering coating state is obtained, and the relationship between oxygen flow rate, discharge parameters and coating mode is established, which realizes real-time monitoring and control of the coating state, and finally achieves the goal of VO x The effect of controlled regulation of the mixed phase composition is beneficial to reducing the complexity and difficulty of the subsequent annealing process.

[0033] The present invention tests the primary reaction hysteresis loop to find the oxygen flow rate corresponding to the poisoning mode, and directly controls the magnetron sputtering coating state in the poisoning mode. By utilizing the highly oxidized state of the target surface in the poisoning mode, VO is directly x The mixed phase composition is controlled to be a high-purity V2O5 film, eliminating the tedious preliminary process exploration and further simplifying the annealing process to the transformation of V2O5 to VO2, greatly reducing the time cost and improving the controllability of the process and the film quality.

[0034] The method of the present invention for synchronously regulating the dielectric properties and phase transition temperature of vanadium oxide thin films has the following beneficial effects:

[0035] 1. Taking advantage of the large radius of W atoms, W atoms are doped to occupy the lattice sites of V atoms and introduce a large lattice distortion in the VO2 lattice. At the same time, W+6 in the +6 valence state acts as a shallow donor doping, introducing free electrons, synchronously regulating the crystal structure and band structure of VO2 and lowering the phase transition temperature.

[0036] 2. By introducing W atoms, while regulating the crystal structure and band structure of VO2, the differences in electronegativity and atomic radius between W and V elements are fully utilized to affect the atomic bonding and electronic state in the lattice, thereby achieving synchronous regulation of the microscopic electronic polarization response of VO2.

[0037] 3. Dielectric properties refer to the ability of an object to polarize under the influence of an external electric field. The microscopic mechanism underlying the optical-frequency dielectric properties of VO2 is an electronic polarization response, while the macroscopic response is a change in the dielectric constant and optical constants (n and k). Therefore, the present invention modulates the microscopic electronic polarization response of VO2 through low-concentration W atom doping, thereby successfully controlling the optical-frequency dielectric properties of VO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a curve diagram showing changes in target surface discharge voltage and discharge current along with oxygen flow rate during DC magnetron sputtering in Example 1;

[0039] Figure 2 is the XRD pattern of the vanadium oxide film at different oxygen flow rates in Example 1;

[0040] Figure 3 is W in Example 2 x V 1-x Test diagram of the phase transition temperature of O2 changing with W doping content;

[0041] Figure 4 is W in Example 2 x V 1-x The real part (a) and imaginary part (b) of the dielectric constant of O2 change with the W doping content;

[0042] Figure 5 In the embodiment 2 W x V 1-x Test graph of the optical constants n(a) and k(b) of O2 as a function of W doping content. DETAILED DESCRIPTION

[0043] Specific embodiment 1: The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films in this embodiment is implemented according to the following steps:

[0044] 1. performing ultrasonic cleaning on the substrate to obtain a cleaned substrate;

[0045] 2. Grinding and cleaning the V metal target and the W metal target respectively to obtain cleaned V metal target and W metal target;

[0046] 3. Install the cleaned V metal target and W metal target in the cabin of the magnetron sputtering device, place the substrate on the sample stage, connect the V metal target to the DC power supply, and connect the W metal target to the RF power supply;

[0047] 4. Turn on the mechanical pump to vacuum the cavity of the magnetron sputtering device. When the vacuum degree reaches below 10Pa, turn on the molecular pump to continue vacuuming to complete the vacuuming process.

[0048] 5. Heat the substrate to 300-500°C and keep it warm;

[0049] 6. Turn on the RF power supply and DC power supply, set the power of both to 80-120W, the argon flow rate to 10-30sccm, adjust the chamber pressure to 3.0-5.0Pa, and start the ignition.

[0050] 7. After the ignition is successful, adjust the chamber pressure to 1.0 Pa and perform pre-sputtering treatment on the V metal target and the W metal target;

[0051] 8. After the pre-sputtering is completed, the RF power supply is controlled to 1-10W, the argon flow rate is 10-30sccm, the DC power supply power is 80-120W, and the oxygen flow rate is controlled to make the coating state in the poisoning mode for thin film deposition;

[0052] 9. After the deposition is completed, the temperature is lowered in an argon atmosphere until the temperature drops to room temperature to obtain a W-doped vanadium oxide film;

[0053] 10. Place the W-doped vanadium oxide film in an annealing furnace, evacuate the furnace, and then introduce argon gas;

[0054] 11. The annealing temperature was controlled at 450-600°C, the holding time was 30-60 minutes, the argon flow rate was 40-80 seem, and high-temperature post-treatment was performed in a flowing argon atmosphere. After heating, the temperature was cooled to obtain a vanadium oxide film with synchronous regulation of optical frequency dielectric properties and phase transition temperature.

[0055] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that in step 1, the substrate is sequentially placed in acetone, anhydrous ethanol, and deionized water for ultrasonic cleaning.

[0056] Specific embodiment three: This embodiment differs from specific embodiments one or two in that the material of the substrate in step one is sapphire, quartz glass or silicon wafer.

[0057] Specific embodiment 4: The difference between this embodiment and specific embodiments 1 to 3 is that in step 4, the molecular pump is turned on to continue vacuuming, so that the vacuum degree reaches 1×10 -4 Pa.

[0058] Specific embodiment 5: The difference between this embodiment and any one of specific embodiments 1 to 4 is that in step 5, the substrate is heated to 300-500° C. and the heat preservation treatment time is 30-50 minutes.

[0059] Specific embodiment 6: The difference between this embodiment and any one of specific embodiments 1 to 5 is that the pre-sputtering treatment time in step 6 is 10 to 20 minutes.

[0060] Specific embodiment seven: This embodiment differs from any one of specific embodiments one to six in that the thickness of the W-doped vanadium oxide film in step nine is 80 nm to 200 nm.

[0061] Specific embodiment eight: This embodiment differs from any one of specific embodiments one to seven in that the heating rate of the annealing in step ten is controlled to be 5° C. / min.

[0062] Specific embodiment 9: The difference between this embodiment and specific embodiments 1 to 8 is that in step 11, the annealing temperature is controlled to be 500-550° C. and the holding time is 30-40 minutes.

[0063] Specific embodiment ten: This embodiment differs from specific embodiments one to nine in that the atomic doping amount of W in the vanadium oxide film for synchronously regulating the optical frequency dielectric properties and the phase transition temperature is 0.5%-1%.

[0064] Example 1: In this example, the method for determining the oxygen flow rate in the poisoning mode during the preparation of a vanadium dioxide thin film using a magnetron sputtering process is as follows:

[0065] 1. performing ultrasonic cleaning on the substrate to obtain a cleaned substrate;

[0066] 2. Grind and clean the V metal target;

[0067] 3. Install the cleaned V metal target in the chamber of the magnetron sputtering device, place the substrate on the sample stage, and connect the V metal target to the DC power supply;

[0068] 4. Turn on the mechanical pump to vacuum the cavity of the magnetron sputtering device. When the vacuum degree reaches below 10Pa, turn on the molecular pump to continue vacuuming to complete the vacuuming process.

[0069] 5. Heat the substrate to 500°C and keep it warm for 30 minutes;

[0070] 6. Turn on the DC power supply, set the power to 100W, the argon flow rate to 20sccm, adjust the chamber pressure to 4.0Pa, and start the ignition.

[0071] 7. After the ignition is successful, adjust the cabin pressure to 1.0 Pa and perform pre-sputtering treatment on the V metal target;

[0072] 8. After the pre-sputtering is completed, the DC power supply power is controlled to 100W, the argon flow rate is 20sccm, and the oxygen flow rate is initially set to 0. The test is started, and the oxygen flow rate is increased at fixed intervals, and then the oxygen flow rate is reduced at the same intervals. The discharge voltage / discharge current parameters on the DC power supply are recorded during the entire test process, and the magnetron sputtering reaction hysteresis loop is plotted;

[0073] 9. In the high oxygen flow stage, the overlapping area of ​​discharge voltage / discharge current in the oxygen flow increase stage and the oxygen flow decrease stage in the magnetron sputtering reaction hysteresis loop is determined to be the poisoning mode, thereby determining the oxygen flow rate under the poisoning mode.

[0074] The time interval and oxygen flow rate controlled in step eight of this embodiment are shown in Table 1.

[0075] Table 1 Oxygen flow parameter setting values ​​and setting time of the hysteresis loop corresponding to the oxygen flow increase process

[0076]

[0077] like Figure 1 As shown in the figure, during the reactive DC magnetron sputtering process, the discharge voltage and discharge current on the target surface change regularly with the change of oxygen flow rate, and show a certain hysteresis when the oxygen flow rate decreases. Figure 1 The curve shown is also called a hysteresis loop. As the oxygen flow rate increases, the oxygen flow rate is in the transition mode in the range of 0-2.5 sccm, in the poisoning mode in the range of 2.5-4.0 sccm, and the metal mode is not significant.

[0078] like Figure 2 The XRD patterns of vanadium oxide films at different oxygen flow rates are shown. When the oxygen flow rate is 2.0, 2.5, and 3.0 sccm, all signal peaks belong to the characteristic peaks of V2O5. Figure 1 It can be seen that when the oxygen flow rate is ≥2.5sccm, the coating state is in the poisoning mode. Figure 1 and Figure 2 The results show that by using reactive DC magnetron sputtering, by adjusting the oxygen flow rate ≥ 2.5sccm and controlling the coating state directly in the poisoning mode, high-purity V2O5 thin films can be successfully prepared. Using the hysteresis loop of reactive DC magnetron sputtering, the VO2O5 film in the magnetron sputtering process can be quickly x The regulation of the mixed phase composition eliminates the process control stage, improves process stability and reduces production costs.

[0079] Example 2: The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of a vanadium oxide thin film in this embodiment is implemented according to the following steps:

[0080] 1. Place the quartz glass substrate in acetone, anhydrous ethanol, and deionized water in sequence for ultrasonic cleaning to remove contaminants on the substrate surface to obtain a cleaned substrate;

[0081] 2. Grinding and cleaning the V metal target and the W metal target respectively to obtain cleaned V metal target and W metal target;

[0082] 3. Install the cleaned V metal target and W metal target in the cabin of the magnetron sputtering device, place the substrate on the sample stage, connect the V metal target to the DC power supply, and connect the W metal target to the RF power supply;

[0083] 4. Turn on the mechanical pump to vacuum the cavity of the magnetron sputtering device. When the vacuum degree reaches below 10Pa, turn on the molecular pump to continue vacuuming to 1×10 -4 Pa, complete vacuum treatment;

[0084] 5. Heat the substrate to 500°C and keep it warm for 30 minutes to ensure that the substrate is heated evenly;

[0085] 6. Turn on the RF power supply and DC power supply, set the power of both RF power supply and DC power supply to 100W, the argon flow rate to 20sccm, adjust the chamber pressure to 4.0Pa, start the DC and RF power supplies for ignition, and after successful ignition, adjust the chamber pressure to 1.0Pa and pre-sputter the target surface for 10 minutes;

[0086] 7. After the pre-sputtering is completed, the DC power supply is controlled to 100 W, the RF power supply is controlled to 5 W, the argon flow rate is controlled to 20 sccm, and the oxygen flow rate is controlled to 5 sccm, and the film deposition is carried out for 60 minutes;

[0087] 8. After the deposition is completed, the temperature is lowered in an argon atmosphere until the temperature drops to room temperature, thereby obtaining a W-doped vanadium oxide film with a thickness of 100 nm;

[0088] 9. Place the W-doped vanadium oxide film in an annealing furnace, evacuate the chamber, and introduce high-purity argon gas until the pressure in the chamber returns to atmospheric pressure, ensuring that the quartz tube is in an argon atmosphere;

[0089] 10. Control the annealing temperature to 550°C, the heating rate to 5°C / min, the holding time to 30 minutes, and the argon flow rate to 60 seem. Perform high-temperature post-treatment in a flowing argon atmosphere. Cool down after heating to obtain a vanadium oxide film with synchronously controlled dielectric properties and phase transition temperature.

[0090] This embodiment utilizes a reactive multi-target DC co-sputtering process, using a metal V target and a metal W target as target materials, to deposit a thin film on a substrate.

[0091] Figure 3-Figure 5 The graphs show how the phase transition temperature, dielectric constant, and optical constants of VO2 change with W doping content. It can be seen that W doping effectively regulates the phase transition temperature, dielectric constant, and optical constants of VO2 simultaneously, with this regulation becoming increasingly pronounced with increasing W doping content. In the figure, the W doping content of both the W1-VO2 and W2-VO2 samples is less than 1%, with W2 > W1.

[0092] The corresponding relationship between the curve labels and the preparation process is shown in Table 2 below. In the curve labels, M represents the low-temperature monoclinic phase and R represents the high-temperature metallic phase. The sputtering power of the fixed V target remains unchanged. As the sputtering power of the W target increases, the W doping content gradually increases. It can be seen that as the W doping content increases, the phase transition temperature of the film gradually decreases, and the real part of the dielectric constant of the M and R phases ( Figure 4 a) shows a downward trend, the imaginary part of the dielectric constant of the M and R phases ( Figure 4 b) shows a decreasing trend in the visible light band, while in the infrared band, the imaginary part of the dielectric constant of the M phase ( Figure 4 b) shows an upward trend, the imaginary part of the dielectric constant of the R phase ( Figure 4b) first decreases and then increases. For the optical constants n and k, as the W doping content increases, the refractive index n of the M and R phases ( Figure 5 a) shows a downward trend, and the extinction coefficient k( Figure 5 b) shows a decreasing trend in the visible light band, while in the infrared band, the extinction coefficient k of the M phase ( Figure 5 b) shows an upward trend, and the extinction coefficient k of the R phase ( Figure 5 b) first decrease and then increase.

[0093] Table 2 Correspondence between curve labels and preparation processes

[0094] Curve Label V target sputtering power (W) W target sputtering power (W) <![CDATA[VO2]]> 100 0 <![CDATA[W1-VO2]]> 100 5 <![CDATA[W2-VO2]]> 100 10 .

Claims

1. A method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films, characterized in that The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of a vanadium oxide thin film is implemented by the following steps:

1. performing ultrasonic cleaning on the substrate to obtain a cleaned substrate; 2. Grinding and cleaning the V metal target and the W metal target respectively to obtain cleaned V metal target and W metal target; 3. Install the cleaned V metal target and W metal target in the cabin of the magnetron sputtering device, place the substrate on the sample stage, connect the V metal target to the DC power supply, and connect the W metal target to the RF power supply; 4. Turn on the mechanical pump to vacuum the cavity of the magnetron sputtering device. When the vacuum degree reaches below 10 Pa, turn on the molecular pump to continue vacuuming to complete the vacuuming process.

5. Heat the substrate to 300~500℃ and keep it warm; 6. Turn on the RF power supply and DC power supply, set the power of both to 80-120 W, the argon flow rate to 10-30 sccm, and adjust the chamber pressure to 3.0-5.0 Pa for ignition.

7. After the ignition is successful, adjust the chamber pressure to 1.0 Pa and perform pre-sputtering treatment on the V metal target and the W metal target; 8. After the pre-sputtering is completed, control the RF power supply power to 1-10 W, the argon flow rate to 10-30 sccm, the DC power supply power to 80-120 W, and control the oxygen flow rate to make the coating state in the poisoning mode for thin film deposition; 9. After the deposition is completed, the temperature is lowered in an argon atmosphere until the temperature drops to room temperature to obtain a W-doped vanadium oxide film; 10. Place the W-doped vanadium oxide film in an annealing furnace, evacuate the furnace, and then introduce argon gas; 11. By controlling the annealing temperature between 450°C and 600°C, holding time between 30 and 60 minutes, and argon flow rate between 40 and 80 sccm, high-temperature post-treatment was performed in a flowing argon atmosphere. After heating, the temperature was cooled to obtain a vanadium oxide film with synchronous control of optical frequency dielectric properties and phase transition temperature. The method for determining the oxygen flow rate in poisoning mode in step 8 is as follows: a. performing ultrasonic cleaning on the substrate to obtain a cleaned substrate; b. Grind and clean the V metal target; c. Install the cleaned V metal target in the cabin of the magnetron sputtering device, place the substrate on the sample stage, and connect the V metal target to a DC power supply; d. Turn on the mechanical pump to vacuum the cavity of the magnetron sputtering device. When the vacuum degree reaches below 10 Pa, turn on the molecular pump to continue vacuuming to complete the vacuuming process; e. Heat the substrate to 300~500℃ and keep it warm; f. Turn on the DC power supply, set the power to 80-120 W, the argon flow rate to 10-30 sccm, and adjust the chamber pressure to 3.0-5.0 Pa for ignition. g. After the ignition is successful, the cabin pressure is adjusted to 1.0 Pa and the V metal target is pre-sputtered; h. After pre-sputtering is completed, control the DC power supply power to 80-120 W, the argon flow rate to 10-30 sccm, and the oxygen flow rate to 0 initially. Start the test, increase the oxygen flow rate at fixed intervals, and then decrease the oxygen flow rate at the same intervals. Record the discharge voltage / discharge current parameters on the DC power supply during the entire test process, and draw the hysteresis loop of the magnetron sputtering reaction; i. In the high oxygen flow stage, the overlapping area of ​​discharge voltage / discharge current in the oxygen flow increase stage and the oxygen flow decrease stage in the magnetron sputtering reaction hysteresis loop is determined as the poisoning mode, thereby determining the oxygen flow rate under the poisoning mode.

2. The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films according to claim 1, characterized in that The material of the substrate in step 1 is sapphire, quartz glass or silicon wafer.

3. The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films according to claim 1, characterized in that In step 4, open the molecular pump and continue to evacuate until the vacuum reaches 1×10 -4 Pa.

4. The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of a vanadium oxide thin film according to claim 1, characterized in that In step 5, the substrate is heated to 300-500° C. and the heat preservation time is 30-50 minutes.

5. The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of vanadium oxide thin films according to claim 1, characterized in that The pre-sputtering treatment time in step six is ​​10 to 20 minutes.

6. The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of a vanadium oxide thin film according to claim 1, characterized in that The thickness of the W-doped vanadium oxide film in step nine is 80 nm to 200 nm.

7. The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of a vanadium oxide thin film according to claim 1, characterized in that In step 10, the heating rate of annealing is controlled to be 5°C / min.

8. The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of a vanadium oxide thin film according to claim 1, characterized in that In step 11, the annealing temperature is controlled to be 500-550°C, and the holding time is 30-40 min.

9. The method for synchronously controlling the optical frequency dielectric properties and phase transition temperature of a vanadium oxide thin film according to claim 1, characterized in that The atomic doping amount of W in the vanadium oxide film that synchronously controls the optical frequency dielectric properties and phase transition temperature is 0.5%~1%.

Images