A narrow hysteresis width film material and its preparation method and application

Abstract

This application relates to the field of sensor technology, and mainly to a narrow hysteresis width thin film material and its preparation method and application. This application introduces magnetic rare earth elements gadolinium (Gd) and titanium (Ti) into the vanadium dioxide film as impurity ions, which can effectively replace or destroy the V 4+ ‑V 4+ Covalent bonds are formed, thereby increasing the defects in the film to regulate the phase change characteristics of the vanadium dioxide film. The provided film material also has a narrow hysteresis width, which helps to achieve a breakthrough in the wide application of zero hysteresis width. At the same time, it also has excellent reversible phase change and cycle stability as well as ultra-sensitive temperature response and fast switching characteristics, which can provide strong support for the development of the sensor field.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and mainly to a narrow hysteresis width thin film material and a preparation method and application thereof. Background Art

[0002] In today's rapidly advancing technology, sensor technology plays a vital role in many fields, and its application in environmental monitoring is particularly crucial. As a core component of environmental monitoring systems, temperature sensors require precise measurement and rapid response to temperature changes, crucial for effective monitoring. Environmental monitoring scenarios such as temperature monitoring at urban air quality monitoring stations and monitoring of heat emissions from industrial production place extremely stringent performance requirements on temperature sensors. However, existing temperature sensors suffer from numerous drawbacks, including a significant lack of response speed. In early warning scenarios such as forest fires, sensors must react instantly to rapid temperature changes and provide accurate temperature data in a timely manner, enabling effective fire prevention and extinguishing measures. However, due to limitations in materials and structures, existing sensors often experience signal response delays, making them unable to quickly capture rapid temperature fluctuations, leading to misjudgments of disaster situations and delaying optimal response times. Their long-term stability also poses a pressing challenge. Long-term exposure to complex and harsh environments can lead to corrosion and interference, which can easily cause measurement errors or even failure. This not only increases replacement costs but also threatens the reliability and effectiveness of monitoring operations.

[0003] Vanadium dioxide (VO2), due to its unique metal-semiconductor phase transition properties, undergoes a high-speed, reversible phase transition under the influence of external factors such as heat, lasers, and electric fields. Prior to the phase transition, VO2 exhibits a high resistance value, similar to typical semiconductor materials. However, when the temperature exceeds 68°C or other external stimuli trigger the phase transition, its resistance drops dramatically by orders of magnitude, rapidly transforming into a low-resistance state similar to that of a metallic conductor. This large resistance change and rapid, reversible phase transition capability enable sensors to react instantly and provide early warning of fires experiencing rapid temperature fluctuations. However, when used in temperature sensors, VO2 has a significant drawback: the phase transition temperatures for heating and cooling do not coincide, resulting in a phase transition hysteresis. This temperature difference creates a phase transition hysteresis width that, when used in temperature sensors, can cause measurement errors near the phase transition point, reducing the sensor's response speed and preventing it from accurately reflecting actual temperature changes. This error can accumulate, especially in environments with frequent temperature fluctuations, seriously affecting accurate ambient temperature assessment. During long-term monitoring, the phase change process may be inconsistent due to the influence of hysteresis width in different measurements, making the measurement results unstable and repeatable, making it difficult to provide reliable continuous monitoring data.

[0004] In summary, the defects of existing temperature sensor technology and the drawbacks of vanadium oxide with hysteresis width when used in sensors have greatly limited its effective application in key areas such as environmental monitoring. Therefore, there is an urgent need to develop a preparation method that can effectively eliminate or significantly reduce the hysteresis width of the vanadium oxide phase transition. This is of immeasurable significance for comprehensively improving the performance of temperature sensors and effectively promoting the development of environmental monitoring technology. Therefore, it is necessary to provide an innovative and practical solution to overcome this key technical problem and provide higher quality and more reliable temperature sensor technology for environmental monitoring and related fields. Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of this application is to provide a narrow hysteresis width thin film material and its preparation method and application, aiming to solve the problems of low sensitivity, poor long-term stability, and easy measurement deviation due to hysteresis width in existing temperature sensors.

[0006] The technical solution of this application is as follows:

[0007] In a first aspect, the present application provides a narrow hysteresis width thin film material, which includes a vanadium dioxide thin film; the vanadium dioxide thin film is doped with gadolinium and titanium.

[0008] Furthermore, the doping amount of gadolinium in the narrow hysteresis width thin film material is 1 at %-7.5 at %, and the doping amount of titanium in the narrow hysteresis width thin film material is 1 at %-10 at %.

[0009] The present invention introduces magnetic rare earth elements gadolinium (Gd) and titanium (Ti) into the vanadium dioxide film by doping, which effectively replaces or destroys the V of vanadium ions as impurity ions. 4+ - V 4+ Covalent bonds are formed, thereby increasing the defects in the film to regulate the phase change characteristics of the vanadium dioxide film. The provided thin film material has a narrow hysteresis width, which helps to achieve a breakthrough in the wide application of zero hysteresis width. At the same time, it also has excellent reversible phase change and cycle stability as well as ultra-sensitive temperature response and fast switching characteristics, providing strong support for the development of the sensor field.

[0010] In a second aspect, the present application further provides a method for preparing the narrow hysteresis width thin film material as described in the first aspect, comprising the following steps:

[0011] Placing the substrate on a substrate holder in a vacuum chamber of a three-axis magnetron sputtering device, evacuating the chamber, and preheating the substrate;

[0012] Argon and oxygen are introduced, the vacuum degree is adjusted to the deposition pressure, the substrate negative bias voltage and duty cycle are set, the oxygen content is adjusted, and a vanadium target is magnetron sputtered using a DC power supply pulse to grow vanadium dioxide on the substrate;

[0013] Using the three-axis co-sputtering mode, gadolinium target and titanium target were added to co-sputter with vanadium target;

[0014] After the sputtering is completed, an inert gas is introduced to perform an in-situ annealing treatment, and the heating is turned off and the mixture is cooled to room temperature to obtain the narrow hysteresis width thin film material.

[0015] Furthermore, the sputtering distance between the substrate and the target is 4-10 cm; the vacuum degree of the vacuum pump is 2×10 -4 Pa -5×10 -4 Pa; the rotation speed of the substrate rack is 10-30 Hz.

[0016] Furthermore, the preheating condition is heating to 400-600°C and maintaining for 0.5-1h;

[0017] The flow rate of the argon gas is 30-150 sccm, and the content of the oxygen gas is 4%-15%.

[0018] Furthermore, the deposition pressure is 0.3-1 Pa, the substrate negative bias voltage is 50-400 V, the duty cycle is 10%-80%, the power supply power of the DC power pulse magnetron sputtering vanadium target is 50-400 W, the pulse frequency is 40-100 KHz, the interval time is 1-10 μs, and the sputtering time is 0.5-1 h;

[0019] The oxygen content is adjusted to maintain the oxygen content between 4% and 20%.

[0020] Furthermore, after the vanadium dioxide is grown for 5-20 minutes, a gadolinium target and a titanium target are added and sputtered together with the vanadium target, and the power of the radio frequency power supply for sputtering the gadolinium target and the titanium target is 5-300W.

[0021] Furthermore, the vanadium target is pre-sputtered for 5-30 minutes before growing vanadium dioxide on the substrate;

[0022] Before sputtering the gadolinium target and the titanium target, the gadolinium target and the titanium target are pre-sputtered for 5-10 minutes.

[0023] Furthermore, the inert gas has an inlet flow rate of 10-40 sccm, and the inert gas is one or both of argon and nitrogen;

[0024] The in-situ annealing treatment is carried out at a temperature of 400-600° C. for 5-60 minutes.

[0025] In a third aspect, the present application further provides an application of the narrow hysteresis width thin film material as described in the first aspect, wherein the narrow hysteresis width thin film material is applied to a temperature sensor.

[0026] Beneficial effect: The present invention introduces magnetic rare earth elements gadolinium (Gd) and titanium (Ti) into the vanadium dioxide film by doping, which effectively replaces or destroys the V of vanadium ions as impurity ions. 4+ - V 4+ Covalent bonds are formed, thereby increasing the defects in the film to regulate the phase change characteristics of the vanadium dioxide film. The provided thin film material has a narrow hysteresis width, which helps to achieve a breakthrough in the wide application of zero hysteresis width. At the same time, it also has excellent reversible phase change and cycle stability as well as ultra-sensitive temperature response and fast switching characteristics, providing strong support for the development of the sensor field. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a curve showing the change of film resistance with temperature during the heating and cooling process of the vanadium dioxide thin film material of Comparative Example 1 of the present application.

[0028] Figure 2 This is a Raman test image of the vanadium dioxide thin film material of Comparative Example 1 of the present application.

[0029] Figure 3 This is the curve of the change of film resistance with temperature during the heating and cooling process at different gadolinium single doping concentrations in comparative example 2 of the present application.

[0030] Figure 4 This is a curve showing the change of film resistance with temperature during the heating and cooling process of the film material of Comparative Example 3 of the present application.

[0031] Figure 5 This is a curve showing the change of film resistance with temperature during the heating and cooling process of the narrow hysteresis width film material of Example 1 of the present application.

[0032] Figure 6 This is a curve showing the change of film resistance with temperature during the heating and cooling process of the narrow hysteresis width film material of Example 2 of the present application.

[0033] Figure 7 This is a Raman test graph of the narrow hysteresis width thin film material of Example 2 of the present application.

[0034] Figure 8 This is a curve showing the change of film resistance with temperature during the heating and cooling process of the narrow hysteresis width film material of Example 3 of the present application.

[0035] Figure 9 This is a Raman test graph of the narrow hysteresis width thin film material of Example 3 of the present application.

[0036] Figure 10This is a comparison chart of the Raman tests of the comparative example, Example 2, and Example 3 of this application. DETAILED DESCRIPTION

[0037] This application provides a narrow hysteresis width thin film material and its preparation method and application. To make the purpose, technical solution and effect of this application clearer and more specific, this application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0038] The present application provides a thin film material with a narrow hysteresis width, which includes a vanadium dioxide thin film; the vanadium dioxide thin film is doped with gadolinium and titanium.

[0039] The present invention introduces magnetic rare earth elements gadolinium (Gd) and titanium (Ti) into the vanadium dioxide film by doping, which effectively replaces or destroys the V of vanadium ions as impurity ions. 4+ -V 4+ Covalent bonds are formed, thereby increasing the defects in the film to regulate the phase change characteristics of the vanadium dioxide film. The provided thin film material has a narrow hysteresis width, which helps to achieve a breakthrough in the wide application of zero hysteresis width. At the same time, it also has excellent reversible phase change and cycle stability as well as ultra-sensitive temperature response and fast switching characteristics, providing strong support for the development of the sensor field.

[0040] In the present application, when Gd and Ti are doped into vanadium dioxide at the same time, their effects on the lattice structure and electronic structure synergize with each other. The lattice expansion and adjustment of the overall electronic structure caused by Gd are combined with the changes in the local lattice distortion and electron scattering mechanism caused by Ti. The presence of Gd provides a more favorable lattice environment for the doping of Ti, enabling Ti to better exert its regulatory effect on the local structure, and the local structural changes of Ti can further promote the influence of Gd on the overall electronic structure and phase transition energy. The combined effect of the two makes the atomic motion of vanadium dioxide more coordinated and the electronic behavior more orderly during the phase transition process, thereby significantly reducing the energy hysteresis of the phase transition and further narrowing the hysteresis width.

[0041] Specifically, when gadolinium and titanium are ion-doped into vanadium dioxide (VO2) materials, the ionic radius is different from that of vanadium ions, which will cause changes in the lattice structure of vanadium dioxide. 3+ (93.8 pm) radius is greater than V 4+(63 pm), entering the lattice will cause the lattice to expand and distort. This change in the lattice structure will change the distance and direction of magnetic interactions between atoms. The distortion of the lattice will affect the strength and mode of magnetic coupling between Gd ions and the surrounding V atoms and oxygen atoms. Lattice expansion may weaken the original magnetic exchange interaction and derive some additional magnetic interactions. Lattice distortion will change the interaction distance and bond angle between atoms, thereby affecting the distribution of the electron cloud. Gd doping narrows the band structure of vanadium dioxide and changes the state density. During the phase transition, the energy barrier that electrons need to cross also changes. The energy barrier that needs to be overcome by atomic rearrangement during the phase transition is adjusted, and the energy change is smoother and the phase transition is easier to occur, thereby reducing the energy hysteresis phenomenon and causing the hysteresis width to narrow. When Ti is doped into vanadium dioxide, it mainly changes the hysteresis width by affecting the crystal structure. Ti 4+ The ionic radius (about 61 pm) and V 4+ The proximity of the two phases will cause local lattice distortion, breaking the octahedral symmetry in the vanadium dioxide (R) phase and affecting the interatomic forces, making atomic displacement easier during the phase transition and reducing the energy barrier of the phase transition. During the phase transition, the atomic vibration mode and energy transfer method change, making the energy input and release required for the phase transition more continuous, reducing the jump-like changes in energy, and thus narrowing the hysteresis width.

[0042] In addition, whether vanadium dioxide is doped with one or more rare earth elements, it ultimately destroys or replaces part of the crystal structure on a small scale. That is, the effect of single ion doping (titanium or gadolinium) is limited, and the regulation of the phase change performance of vanadium dioxide from a single crystal structural destruction or substitution is limited. Moreover, while changing the hysteresis width, it is often accompanied by a decrease in electrical performance. Therefore, the present application adjusts the hysteresis width through the dual effects of Ti and Gd, so that it retains some of the original characteristics while having new changes. The co-doped ions achieve a reduction in the hysteresis width while minimizing the phase change amplitude under the multiple effects of two different ion radii (one large and one small) and magnetism.

[0043] Furthermore, the gadolinium doping amount in the thin film material with a narrow hysteresis width is 1 at%-7.5 at%, and the titanium doping amount in the thin film material with a narrow hysteresis width is 1 at%-10 at%. In the present application, by introducing gadolinium and titanium to replace or destroy the structure of a small amount of vanadium dioxide, excessively high or low doping levels will affect the hysteresis performance and phase change properties. By controlling the doping amounts of gadolinium and titanium, a narrow hysteresis width can be achieved.

[0044] By precisely controlling the type, concentration, and doping method of impurity ions, the present application can adjust key parameters such as the phase transition temperature and hysteresis width of the film, so that it has a narrow hysteresis range to achieve a fast and sensitive response.

[0045] The narrow hysteresis width thin film material provided by this application exhibits ultra-sensitive temperature response and fast switching characteristics. Under normal operating conditions, sensors using this thin film material can stably monitor ambient temperature changes. In the event of a sudden temperature change, such as in a fire warning scenario, when the ambient temperature rises rapidly to or above the phase transition temperature of vanadium dioxide, it can instantly undergo a phase transition from semiconductor to conductor, acting like a precise temperature-triggered switch. Compared to traditional temperature sensors, its response speed is significantly superior. While traditional sensors may take several seconds or even longer to react, the thin film material of this application has a microsecond-level reaction time at the moment of temperature-induced phase change, significantly improving the monitoring efficiency and early warning capabilities of sudden temperature changes. This rapid phase transition allows the sensor to convert temperature changes into electrical signal changes in an extremely short time (milliseconds or even faster), enabling immediate response to temperature anomalies and issuing timely alarm signals. This buys valuable time to respond to emergencies and effectively avoids significant losses caused by delayed responses.

[0046] The narrow hysteresis width thin film material provided by the present application also has excellent reversible phase change and cyclic stability. During multiple temperature rise and fall cycles, the thin film material can stably switch back and forth between the semiconductor phase and the conductor phase, and the phase change performance will not show obvious attenuation. Whether it is after the phase change caused by temperature increase, it can be restored to the initial semiconductor phase as the temperature decreases, or in a repeated temperature fluctuation environment, it always maintains good phase change reversibility. This feature allows the sensor to be reused many times and has extremely high reliability in long-term environmental monitoring applications. For example, temperature monitoring in industrial production processes may experience frequent temperature fluctuations, but the sensor after application can continue to work stably and provide accurate temperature data feedback for the production process, greatly reducing maintenance costs and replacement frequency, and ensuring efficient and stable operation of the production process.

[0047] The present application also provides a method for preparing the above-mentioned narrow hysteresis width thin film material, which comprises the following steps:

[0048] S1. Place the substrate on a substrate holder in a vacuum chamber of a three-axis magnetron sputtering device, evacuate the chamber, and preheat the substrate.

[0049] S2, introducing argon and oxygen, adjusting the vacuum degree to the deposition pressure, setting the substrate negative bias voltage and duty cycle, adjusting the oxygen content, and using a DC power supply pulsed magnetron sputtering vanadium target to grow vanadium dioxide on the substrate;

[0050] S3, using the three-axis co-sputtering mode, adding gadolinium target and titanium target and vanadium target co-sputtering;

[0051] S4. After the sputtering is completed, an inert gas is introduced to perform in-situ annealing treatment, and the heating is turned off and the film is cooled to room temperature to obtain a thin film material with a narrow hysteresis width.

[0052] Magnetron sputtering can achieve precise control of the type and content of doping elements, depositing uniform thin films and achieving film performance regulation. Through the preparation process provided in this application, a layer of vanadium dioxide film is first selectively generated on the substrate as a seed layer, and then gadolinium and titanium elements are introduced. Using a three-axis co-sputtering mode, the doping concentration is adjusted by changing the sputtering power. During sputtering, the reaction oxygen content inside the cavity is maintained constant by adjusting the intake flow rate. All processes are completed in one go inside the cavity, without the formation of a multilayer structure. The resulting vanadium dioxide film is doped with gadolinium and titanium, thereby achieving regulation of the narrow hysteresis width of vanadium dioxide.

[0053] Specifically, the substrate is cleaned before deposition, including the following steps:

[0054] S0. Ultrasonic cleaning of the substrate was performed in acetone, alcohol and deionized water in sequence, with each cleaning time being 10-30 minutes, and then dried with nitrogen.

[0055] Among them, by cleaning the substrate, impurities and pollutants on the substrate surface can be effectively removed, ensuring that the substrate surface is clean, providing excellent conditions for the smooth growth of the thin film, and then placed on the substrate rack in the vacuum chamber of the three-axis magnetron sputtering equipment after drying.

[0056] Furthermore, the substrate is one of silicon wafer, sapphire, mica, and quartz glass. The selected substrate material has the characteristics of smooth surface and good thermal stability, laying a solid foundation for subsequent high-quality thin film growth.

[0057] Furthermore, the vanadium target is vanadium trioxide. Other vanadium source-containing target materials (vanadium targets) can also be used as alternative options to meet different experimental requirements and conditions.

[0058] Furthermore, this application uses a three-axis magnetron sputtering device, with the sputtering distance between the substrate and the three targets (vanadium, gadolinium, and titanium) set at 4-10 cm. The atoms produced by magnetron sputtering have higher energy, which allows them to better bond with each other when deposited on the substrate, forming a dense film structure and reducing porosity and defects in the film.

[0059] Furthermore, in step S1, the vacuum degree of the vacuum pump is 2×10 -4 Pa -5×10 -4 Pa; the rotation speed of the substrate rack is 10-30 Hz. In this application, the vacuum degree of the chamber is 2×10 -4 Pa -5×10 - 4Pa. This high vacuum environment can significantly reduce the adverse effects of external impurities on thin film growth. At the same time, the substrate holder rotates at a constant speed of 10-30Hz to ensure uniform coating, allowing the film to evenly receive sputtered materials during growth, thereby improving the quality and performance of the film.

[0060] Furthermore, in step S1, the preheating condition is to heat to 400-600°C and maintain for 0.5-1 hour. This step helps to remove adsorbents and moisture on the substrate surface and creates suitable temperature conditions for subsequent thin film growth.

[0061] Furthermore, in step S2, the flow rate of argon gas is 30-150 sccm, and the oxygen content is 4%-15%. The argon gas can be high-purity argon gas, and the oxygen content can be set by an oxygen flow sensor to maintain an appropriate oxygen content in the chamber.

[0062] Furthermore, in step S2, after introducing argon and oxygen, the vacuum is adjusted to a deposition pressure of 0.3-1 Pa, the substrate negative bias is set to 50-400 V, and the duty cycle is set to 10%-80%; the power of the DC pulsed magnetron sputtering vanadium target is 50-400 W, the pulse frequency is 40-100 kHz, the interval time is 1-10 μs, and the sputtering time is 0.5-1 h. After adjusting the parameters, the baffle is opened to start sputtering the vanadium target. The sputtering process is oxidized and a vanadium dioxide film is grown on the substrate. When the substrate is biased, the oxygen ions are more likely to reach the substrate surface under the action of the bias electric field and react with vanadium atoms, titanium atoms, and gadolinium atoms. The reaction process can change the combination ratio of oxygen and vanadium in the film, thereby precisely controlling the stoichiometric ratio of the vanadium oxide film and the ratio of titanium and gadolinium atoms, affecting the distribution and content of the doping elements in the film, and optimizing the composition of the film by adjusting the bias voltage to obtain a film with specific properties.

[0063] Specifically, simply ensuring that vanadium dioxide, gadolinium, and titanium can be sputtered together will certainly not achieve the effect of reducing the hysteresis width. It is necessary to control the parameters so that the doped atoms replace and destroy the original structure. Simply sputtering together will have a dominant effect. In a stable environment, a small number of vanadium atoms will be forcibly seized by titanium or gadolinium atoms when they are combined with oxygen atoms and impersonate them (for example, it was originally VOV, and after the oxygen atoms were taken away, it became VO-Ti / Gd), losing part of the original structure and gaining new properties. Moreover, since there are many types and phases of vanadium oxides, only the monoclinic phase has the ability to change phase among the multiple phases of vanadium dioxide, while others do not. Common ones such as vanadium trioxide and vanadium pentoxide do not have the ability to change phase under conditions close to room temperature. This application prepares vanadium dioxide with low-valent vanadium, creates an environment for the stable generation of vanadium dioxide for the vanadium dioxide matrix by controlling reasonable parameters, and introduces gadolinium and titanium through in-situ growth to ensure the control effect of doping on performance.

[0064] Furthermore, during the deposition process in step S2, the air intake is adjusted to maintain the oxygen content between 4% and 20%. By creating an oxidizing atmosphere conducive to the growth of vanadium dioxide, the stability and consistency of the film growth are ensured. Throughout the co-sputtering process, the oxygen atmosphere inside the chamber is closely monitored to ensure that the required oxygen content is maintained, thereby ensuring that the oxidation state and phase change characteristics of the film are not affected.

[0065] Specifically, in step S3, after 5-20 minutes of vanadium dioxide growth, the gadolinium target and titanium target baffles are opened, and biaxial co-sputtering of the gadolinium target and titanium target is newly introduced. The RF power of the gadolinium target and titanium target is 5-300 W. If the gadolinium target and titanium target are sputtered using a DC power supply, the deposition rate will be much faster than that of vanadium dioxide, resulting in vanadium dioxide becoming the doped element. The RF power supply is relatively slow, ensuring stable deposition.

[0066] By controlling the power supply, the doping amount of gadolinium and titanium can be controlled. The selected radio frequency power supply has a slow deposition rate and does not cause excessive doping. This application first grows a vanadium dioxide film on the substrate as a seed layer, and then introduces gadolinium and titanium elements during the continued growth process. Among them, the oxygen content is kept stable by triaxial co-sputtering. The gadolinium target and titanium target provide the source. The doping content of the gadolinium target and titanium target is controlled by power, and no other condition parameters are required. The ignition provides a certain amount of elements for the reaction. During the reaction, by controlling the power, a small number of titanium atoms or gadolinium atoms bombarded by argon ion sputtering can combine with oxygen atoms in the environment to destroy or replace some of the positions originally occupied by vanadium atoms. This oxide is not a simple oxide. The oxygen originally belonging to VO2 was originally connected to vanadium or oxygen combination. Now it can connect vanadium and oxygen, and vanadium and titanium or gadolinium. By affecting the lattice structure, it is then deposited on the substrate with a large amount of vanadium dioxide, completing the doping and affecting the hysteresis width during the phase transition and achieving an improvement effect.

[0067] Furthermore, the vanadium target is pre-sputtered for 5-30 minutes before growing vanadium dioxide on the substrate; and the gadolinium and titanium targets are pre-sputtered for 5-10 minutes before magnetron sputtering them using an RF power supply. Pre-sputtering before actual deposition removes impurities and oxide layers from the target surface.

[0068] The present application controls the doping ratio by precisely controlling the amount of oxygen in the reaction and the sputtering power of titanium and gadolinium elements, ensuring that gadolinium and titanium are doped with vanadium dioxide. This can effectively adjust the phase change characteristics and hysteresis width of the vanadium dioxide film to make it more suitable for specific sensor application requirements, and avoid excessive doping that causes oxidized vanadium doping.

[0069] Furthermore, in step S4, the inert gas flow rate is 10-40 sccm, and the inert gas is one or both of argon and nitrogen. The in-situ annealing treatment is carried out at a temperature of 400-600°C for 5-60 minutes, preferably 30 minutes. In the present application, cooling to room temperature under an inert gas atmosphere can prevent thermal stress problems caused by sudden cooling. The annealing treatment can further improve the crystallinity of the film, eliminate internal stress, and promote the diffusion and uniform distribution of gadolinium and titanium elements in the vanadium dioxide film, thereby improving the performance and stability of the narrow hysteresis width film.

[0070] By providing an optimized preparation method in this application, the growth of vanadium dioxide thin films and the doping process of gadolinium and titanium elements can be more accurately controlled, thereby improving the quality and performance of the thin films and providing strong support for the development of the sensor field.

[0071] Specifically, the present application successfully reduces the hysteresis width of the vanadium dioxide film to near zero through an innovative preparation process, which can achieve a breakthrough in the widespread application of zero hysteresis width. This breakthrough completely solves the many problems that exist in the application of traditional vanadium dioxide with hysteresis width in temperature sensors. Under zero hysteresis width, the measurement accuracy of the sensor near the phase transition point is greatly improved, which can accurately reflect the actual temperature changes and avoid measurement deviations caused by hysteresis. In addition, the zero hysteresis width makes the response speed of the sensor no longer limited by the hysteresis range, further improving the timeliness and accuracy of the response. This feature broadens the application scope of vanadium dioxide films in the field of temperature sensors and opens new doors for the application of sensor technology in more key areas.

[0072] After preparation is completed, the obtained narrow hysteresis width film can be subjected to phase change characteristic tests, electrical performance tests, structural characterization, etc. to determine whether the phase change temperature and hysteresis width meet the requirements of sensor applications, measure parameters such as the resistance of the film, evaluate its performance changes under different temperature conditions, and obtain a vanadium dioxide film with a specific hysteresis range that meets the needs of sensor applications.

[0073] The following is further described by specific examples.

[0074] Comparative Example 1

[0075] The preparation method of the vanadium dioxide thin film material of Comparative Example 1 comprises the following steps:

[0076] The target material is vanadium trioxide target, the substrate is silicon wafer; the sputtering distance is set to 6cm;

[0077] The silicon wafer was ultrasonically cleaned in acetone, alcohol, and deionized water, respectively, for 20 min each time. It was then dried with nitrogen and placed on a substrate rack in a vacuum chamber of a magnetron sputtering device. The substrate rack rotated at a constant speed of 30 Hz and evacuated to a vacuum degree of 3 × 10 -4 Pa, preheat the substrate to 600℃ and keep it warm for 40min;

[0078] High-purity argon gas was introduced at a flow rate of 80 sccm, the oxygen content was kept at 8%, the deposition pressure was 0.50 Pa, the substrate negative bias voltage was set to 200 V, the duty cycle was 50%, the power of the DC power supply pulsed magnetron sputtering was 200 W, the pulse frequency was 60 kHz, the interval time was 5 μs, and after pre-sputtering for 10 minutes, vanadium dioxide was grown and the coating time was 60 minutes;

[0079] Subsequently, oxygen was turned off to maintain an argon flow rate of 20 sccm, and the mixture was kept warm for 30 minutes and then cooled to room temperature to obtain the vanadium dioxide thin film material of Comparative Example 1.

[0080] Comparative Example 1 was used as a control group experiment. The resistance-temperature characteristic test of the vanadium dioxide thin film material of Comparative Example 1 was carried out. The four-probe resistance measurement was used to control the temperature at a temperature change rate of 10°C / min. The resistance change in the temperature range of 25-100°C was measured. The test results are as follows: Figure 1 As shown in FIG, the relationship between the film resistance and temperature of the vanadium dioxide thin film material of Comparative Example 1 during the heating and cooling processes (labeled as Heat and Cool, respectively) is detected. It can be found that in the heating process (Heat), when the temperature reaches about 64.8°C, the film resistance begins to drop sharply, and the resistance decreases from 10 4 Ω / cm rapidly decreases to 10 1 The resistance of the vanadium dioxide film is about Ω / cm, which indicates that the vanadium dioxide film transforms from a semiconductor phase to a metallic phase. During the cooling process (Cool), the resistance begins to rise rapidly when the temperature drops to about 54.7°C, and the film transforms from a metallic phase back to a semiconductor phase.

[0081] By comparing the phase transition temperatures during the heating and cooling processes, the phase transition hysteresis width of the vanadium dioxide thin film material of Comparative Example 1 can be calculated. In this test, the hysteresis width is 10.1°C. A wider hysteresis width affects the sensitivity and accuracy of temperature detection.

[0082] The Raman test was performed on the vanadium dioxide thin film material of Comparative Example 1, and the Raman pattern measured was as follows: Figure 2 As shown, it can be observed that the film sample has a peak at 193 cm -1 , 224cm -1 、305cm -1 、392 cm -1 、615cm-1 There are obvious Raman peaks at all locations, which correspond to the Raman peaks of monoclinic vanadium dioxide films, among which 193.8 cm -1 and 224.6 cm -1 The nearby peaks correspond to the VV vibration peaks in vanadium dioxide, and the other vibration peaks belong to VO, which show the overall characteristics of vanadium dioxide.

[0083] Comparative Example 2

[0084] The preparation method of the four groups of thin film materials with different gadolinium contents in Comparative Example 2 includes the following steps:

[0085] Comparative Example 2: Four groups of thin film materials with different gadolinium contents were all prepared by biaxial reactive magnetron sputtering, with vanadium trioxide as the target material and sapphire as the substrate; the sputtering distance was set to 8 cm;

[0086] The sapphire was ultrasonically cleaned in acetone, alcohol, and deionized water, respectively, for 15 min each time. It was then dried with nitrogen. The silicon wafer was placed on a substrate rack in the vacuum chamber of a magnetron sputtering device. The substrate rack rotated at a constant speed of 30 Hz and evacuated to a vacuum degree of 2.5×10 -4 Pa, preheat the substrate to 550℃ and keep it warm for 30min;

[0087] High-purity argon gas was introduced at a flow rate of 60 sccm, the oxygen content was maintained at 7%, the deposition pressure was 0.55 Pa, the substrate negative bias voltage was set to 240 V, the duty cycle was 50%, the power of the DC power supply pulsed magnetron sputtering was 250 W, the pulse frequency was 50 kHz, the interval time was 2 μs, and after pre-sputtering for 10 minutes, vanadium dioxide was grown;

[0088] Using the dual-axis co-sputtering mode, a gadolinium target and a vanadium target were co-sputtered. The RF power of the gadolinium target in the four experimental groups was set to 0 W, 25 W, 50 W, and 80 W, respectively. Pre-sputtering was performed for 10 minutes (the pre-sputtering of the gadolinium target and the vanadium target can be performed simultaneously, and the shutter was opened only after the pre-sputtering was completed to officially start sputtering). After the vanadium dioxide was grown for 5 minutes, the gadolinium target and the vanadium target were co-sputtered for 55 minutes, for a total coating time of 60 minutes (in the experimental group with the gadolinium target power of 0 W, vanadium dioxide was grown for 60 minutes without gadolinium doping).

[0089] Subsequently, oxygen was turned off and an argon flow rate of 20 sccm was maintained. After the temperature was kept for 30 minutes, the mixture was cooled to room temperature to obtain four groups of thin film materials with different gadolinium contents as in Comparative Example 2. The corresponding deposited films were named VGd-0, VGd-1, VGd-2, and VGd-3.

[0090] The gadolinium content of the thin films of VGd-0, VGd-1, VGd-2 and VGd-3 of Comparative Example 2 was measured by XPS. The results are shown in Table 1:

[0091] Table 1

[0092] Group Gadolinium target RF power supply power (W) Gadolinium doping amount (at%) VGd-0 0 0 VGd-1 25 1.8 VGd-2 50 3.7 VGd-3 80 7.5

[0093] Comparative Example 2 The thin film materials with different Gd contents were subjected to the same resistance-temperature characteristic test as in Comparative Example 1. The test results are shown in FIG. Figure 3 As shown in Figure 2, the phase transition temperatures (T) of VGd-0, VGd-1, VGd-2, and VGd-3 during the heating process (Heat) and cooling process (Cool) H 、T C ) and hysteresis width (△H) data are shown in Table 2:

[0094] Table 2

[0095] Group <![CDATA[T H (℃)]]> <![CDATA[T C (℃)]]> △H（℃） VGd-0 66.2 56.9 9.3 VGd-1 60.8 52.2 8.6 VGd-2 55.4 47.9 7.5 VGd-3 -- -- --

[0096] It can be found that single doping will destroy the VV bond around the C axis of the vanadium dioxide crystal to a certain extent, change the structural integrity, and thus reduce the hysteresis width or change the phase transition temperature. Using only one element will greatly reduce the resistance ratio before and after the phase transition. Figure 3 (VGd-0 is undoped resistance, and the phase transition ability disappears when it increases to VGd-3) The resistance change of single Gd doping can be observed. With the addition of Gd, the phase transition temperature decreases and the hysteresis width decreases. Although the hysteresis width can be reduced, it can no longer meet the application requirements. Vanadium dioxide itself has certain magnetism, and its magnetism will change during the phase transition. Under certain conditions, the magnetic moment of vanadium dioxide interacts with the electrons and lattice in the material, which may affect the energy balance during the phase transition and the phase stability after the phase transition. Therefore, it is necessary to dope gadolinium (Gd 3+ ) and other elements (Ti 4+ ) jointly regulate the magnetic and phase transition properties of vanadium dioxide.

[0097] Comparative Example 3

[0098] Comparative Example 3 The method for preparing an overdoped thin film material comprises the following steps:

[0099] The target material is vanadium trioxide target, and the substrate is sapphire; the sputtering distance is set to 10 cm (Comparative Example 3 uses a higher power, increases the sputtering distance, and the end distribution is more uniform);

[0100] The sapphire was ultrasonically cleaned in acetone, alcohol, and deionized water, respectively, for 20 min each time. It was then dried with nitrogen. The silicon wafer was placed on a substrate rack in the vacuum chamber of a three-axis magnetron sputtering device. The substrate rack rotated at a constant speed of 30 Hz and evacuated to a vacuum degree of 4 × 10 -4 Pa, preheat the substrate to 550℃ and keep it warm for 30min;

[0101] High-purity argon gas was introduced at a flow rate of 50 sccm, the oxygen content was maintained at 8.5%, the deposition pressure was 0.60 Pa, the substrate negative bias voltage was set to 240 V, the duty cycle was 50%, the DC power supply pulsed magnetron sputtering power was 250 W, the pulse frequency was 50 kHz, the interval time was 2 μs, and after pre-sputtering for 10 minutes, vanadium dioxide was grown;

[0102] Using the three-axis co-sputtering mode, gadolinium target and titanium target were added for co-sputtering with the vanadium target. The RF power of the gadolinium target and titanium target was 150W and 200W respectively. The pre-sputtering was carried out for 5 minutes. After 5 minutes of vanadium dioxide coating, vanadium dioxide and gadolinium titanium were co-sputtered for 300 minutes, for a total coating time of 35 minutes. (As the power increases, the deposition rate also increases accordingly, and the time should be reduced accordingly, because the generation rate of vanadium dioxide is much slower than that of titanium and gadolinium. As time goes on, the proportion of vanadium dioxide will continue to decrease.)

[0103] Subsequently, oxygen was turned off to maintain an argon flow rate of 15 sccm, and the mixture was kept warm for 30 minutes and then cooled to room temperature to obtain the thin film material of Comparative Example 3.

[0104] The doping amount of gadolinium in the thin film material prepared in Comparative Example 3 was calculated by XPS to be 9.8 at%, and the doping amount of titanium was 11.5 at%. The same test method as in Comparative Example 1 was used to test the resistance-temperature characteristics of the thin film material prepared in Comparative Example 3. The results are as follows: Figure 4 As shown, it can be found that the doping element becomes the main component of the thin film material of Comparative Example 3 under excessive doping, which affects the characterization of the phase change performance of vanadium dioxide.

[0105] Example 1

[0106] The method for preparing the narrow hysteresis width thin film material of Example 1 comprises the following steps:

[0107] The target material is vanadium trioxide target, the substrate is sapphire; the sputtering distance is set to 8cm;

[0108] The sapphire was ultrasonically cleaned in acetone, alcohol, and deionized water, respectively, for 20 min each time. It was then dried with nitrogen. The silicon wafer was placed on a substrate rack in the vacuum chamber of a three-axis magnetron sputtering device. The substrate rack rotated at a constant speed of 30 Hz and evacuated to a vacuum degree of 4 × 10 -4Pa, preheat the substrate to 550℃ and keep it warm for 30min;

[0109] High-purity argon gas was introduced at a flow rate of 50 sccm, the oxygen content was kept at 8%, the deposition pressure was 0.55 Pa, the substrate negative bias voltage was set to 240 V, the duty cycle was 50%, the DC power supply pulsed magnetron sputtering power was 250 W, the pulse frequency was 50 kHz, the interval time was 2 μs, and after pre-sputtering for 10 minutes, vanadium dioxide was grown;

[0110] Using the three-axis co-sputtering mode, gadolinium target and titanium target were added to co-sputter with vanadium target. The RF power of gadolinium target and titanium target was 20W and 20W respectively. The pre-sputtering was 5 minutes. After vanadium dioxide coating for 5 minutes, vanadium dioxide and gadolinium titanium were co-sputtered for 60 minutes, and the total coating time was 65 minutes.

[0111] Subsequently, oxygen was turned off to maintain an argon flow rate of 15 sccm, and the mixture was kept warm for 30 minutes and then cooled to room temperature to obtain the narrow hysteresis width thin film material of Example 1.

[0112] The XPS measurement showed that the gadolinium doping amount of the narrow hysteresis width thin film material prepared in Example 1 was 1.7 at%, and the titanium doping amount was 1.42 at%. The resistance-temperature characteristic test of the narrow hysteresis width thin film material prepared in Example 1 was carried out using the same test method as in Comparative Example 1. The results are as follows: Figure 5 As shown in FIG, the relationship between the film resistance and temperature of the narrow hysteresis width film material of Example 1 during the heating and cooling processes (labeled as Heat and Cool, respectively) is detected. In the heating process (Heat), when the temperature reaches about 59.5°C, the film resistance begins to drop sharply, and the resistance decreases from 10 5 Ω / cm rapidly decreases to 10 2 The resistance of the vanadium dioxide film is about Ω / cm, which indicates that the vanadium dioxide film transforms from a semiconductor phase to a metallic phase. During the cooling process (Cool), the resistance begins to rise rapidly when the temperature drops to about 56.3°C, and the film transforms from a metallic phase back to a semiconductor phase.

[0113] By comparing the phase transition temperatures during the heating and cooling processes, the phase transition hysteresis width of the narrow hysteresis width thin film material of Example 1 can be calculated. In this test, the hysteresis width was 3.2°C. Compared with Comparative Example 1, the hysteresis width of Example 1 is significantly reduced.

[0114] Example 2

[0115] The method for preparing the narrow hysteresis width thin film material of Example 2 comprises the following steps:

[0116] The target material is vanadium trioxide target, the substrate is silicon wafer; the sputtering distance is set to 8cm;

[0117] The silicon wafer was ultrasonically cleaned in acetone, alcohol, and deionized water, respectively, for 20 min each time. It was then dried with nitrogen and placed on a substrate rack in a vacuum chamber of a three-axis magnetron sputtering device. The substrate rack rotated at a constant speed of 30 Hz and evacuated to a vacuum degree of 3.5 × 10 -4 Pa, preheat the substrate to 600℃ and keep it warm for 45min;

[0118] High-purity argon gas was introduced at a flow rate of 50 sccm, the oxygen content was maintained at 8%, the deposition pressure was 0.55 Pa, the substrate negative bias voltage was set to 240 V, the duty cycle was 50%, the DC power supply pulsed magnetron sputtering power was 250 W, the pulse frequency was 60 kHz, the interval time was 4 μs, and after pre-sputtering for 10 minutes, vanadium dioxide was grown;

[0119] Using the three-axis co-sputtering mode, gadolinium target and titanium target were added to co-sputter with vanadium target. The RF power of gadolinium target and titanium target was 50W and 75W respectively. The pre-sputtering was 5 minutes. After vanadium dioxide coating for 10 minutes, vanadium dioxide and gadolinium titanium were co-sputtered for 50 minutes, and the total coating time was 60 minutes.

[0120] Then, the oxygen gas was turned off to maintain an argon flow rate of 20 sccm, and the mixture was kept warm for 40 minutes and then cooled to room temperature to obtain the narrow hysteresis width thin film material of Example 2.

[0121] The XPS measurement showed that the gadolinium doping amount of the narrow hysteresis width thin film material prepared in Example 2 was 3.71 at%, and the titanium doping amount was 4.86 at%. The resistance-temperature characteristic test of the narrow hysteresis width thin film material prepared in Example 2 was carried out using the same test method as in Comparative Example 1. The results are as follows: Figure 6 As shown in FIG. 1 , the relationship between the film resistance and temperature during the heating and cooling processes (labeled as Heat and Cool, respectively) of the narrow hysteresis width film material of Example 2 is detected. In the heating process (Heat), when the temperature reaches about 65.6°C, the film resistance begins to drop sharply, and the resistance decreases from 10 5 Ω / cm rapidly decreases to 10 2 The resistance of the vanadium dioxide film is about Ω / cm, which indicates that the vanadium dioxide film transforms from a semiconductor phase to a metallic phase. During the cooling process (Cool), the resistance begins to rise rapidly when the temperature drops to about 64.7°C, and the film transforms from a metallic phase back to a semiconductor phase.

[0122] By comparing the phase transition temperatures during the heating and cooling processes, the phase transition hysteresis width of the narrow hysteresis width thin film material of Example 2 can be calculated. In this test, the hysteresis width was 0.9°C. Compared to Comparative Example 1, the hysteresis width of Example 2 is significantly reduced. This 0.9°C hysteresis width reduces the sensor's response speed from being limited by the hysteresis interval, further improving the timeliness and accuracy of the response.

[0123] The narrow hysteresis width thin film material of Example 2 was subjected to Raman testing, and the Raman pattern measured was as follows: Figure 7 As shown, it can be observed that the film sample has a peak at 187.3 cm -1 、219.5cm -1 、302.7cm -1 、390.4 cm -1 、613.8cm -1 There are obvious Raman peaks at all places. Compared with comparative example 1, these peaks have shifted to the left. This is because titanium or gadolinium atoms replace the positions originally belonging to vanadium, which will cause the original VV bonds and VO bonds to change, which is manifested as the shift of Raman peak positions. The result is that the peaks are shifted to the left. It can be seen that the doping of gadolinium and titanium effectively destroys the V 4+ -V 4+ Covalent bonds are used to increase defects in the film to regulate the phase change characteristics of vanadium dioxide films.

[0124] Example 3

[0125] The method for preparing the narrow hysteresis width thin film material of Example 3 comprises the following steps:

[0126] The target material is vanadium trioxide target, the substrate is silicon wafer; the sputtering distance is set to 10cm;

[0127] The silicon wafer was ultrasonically cleaned in acetone, alcohol, and deionized water, respectively, for 20 min each time. It was then dried with nitrogen and placed on a substrate rack in a vacuum chamber of a three-axis magnetron sputtering device. The substrate rack rotated at a constant speed of 30 Hz and evacuated to a vacuum degree of 4 × 10 -4 Pa, preheat the substrate to 550℃ and keep it warm for 30min;

[0128] High-purity argon gas was introduced at a flow rate of 50 sccm, the oxygen content was kept at 8%, the deposition pressure was 0.55 Pa, the substrate negative bias voltage was set to 240 V, the duty cycle was 50%, the DC power supply pulsed magnetron sputtering power was 250 W, the pulse frequency was 50 kHz, the interval time was 2 μs, and after pre-sputtering for 10 minutes, vanadium dioxide was grown;

[0129] The three-axis co-sputtering mode was used. Gd-target and titanium target were added to the vanadium target for co-sputtering. The RF power of the gadolinium target and titanium target was 40W and 80W respectively. The pre-sputtering was carried out for 5 minutes. After vanadium dioxide was deposited for 5 minutes, vanadium dioxide and gadolinium titanium were co-sputtered for 60 minutes, and the total deposition time was 65 minutes.

[0130] Subsequently, oxygen was turned off to maintain an argon flow rate of 15 sccm, and the mixture was kept warm for 30 minutes and then cooled to room temperature to obtain the narrow hysteresis width thin film material of Example 3.

[0131] The XPS measurement showed that the gadolinium doping amount of the narrow hysteresis width thin film material prepared in Example 3 was 3.12 at%, and the titanium doping amount was 5.14 at%. The resistance-temperature characteristic test of the narrow hysteresis width thin film material prepared in Example 3 was carried out using the same test method as in Comparative Example 1. The results are as follows: Figure 8 As shown in FIG, the relationship between the film resistance and temperature of the narrow hysteresis width film material of Example 3 during the heating and cooling processes (labeled as Heat and Cool, respectively) is detected. In the heating process (Heat), when the temperature reaches about 65.1°C, the film resistance begins to drop sharply, and the resistance decreases from 10 4 Ω / cm rapidly decreases to 10 2 The resistance of the vanadium dioxide film is about Ω / cm, which indicates that the vanadium dioxide film transforms from a semiconductor phase to a metallic phase. During the cooling process (Cool), the resistance begins to rise rapidly when the temperature drops to about 65.0°C, and the film transforms from a metallic phase back to a semiconductor phase.

[0132] By comparing the phase transition temperatures during the heating and cooling processes, the phase transition hysteresis width of the narrow hysteresis width thin film material of Example 3 can be calculated. In this test, the hysteresis width was 0.1°C. Compared to Comparative Example 1, the hysteresis width of Example 3 is significantly reduced. This 0.1°C hysteresis width further reduces the sensor's response speed, which is limited by the hysteresis range, significantly improving the timeliness and accuracy of the response.

[0133] The narrow hysteresis width film material of Example 3 was subjected to Raman testing, and the Raman pattern measured was as follows: Figure 9 As shown, it can be observed that the film sample has a peak at 184.6 cm -1 、217.9cm -1 、300.8cm -1 、387.9 cm -1 、609.6cm -1 There are obvious Raman peaks at all locations. Compared with comparative example 1, these peaks have shifted to the left. It can be seen that the doping of gadolinium and titanium effectively destroys the V 4+ -V 4+ Covalent bonds are used to increase defects in the film to regulate the phase change characteristics of the vanadium dioxide film, reducing the hysteresis width while minimizing the loss of electrical properties.

[0134] The Raman spectra comparison of Comparative Example 1, Example 2 and Example 3 are shown in FIG. Figure 10 As shown, it provides intuitive data support for process optimization. It can be found that these peaks have shifted to the left compared with comparative example 1. The doping of gadolinium and titanium effectively destroys the V4+ -V 4+ Covalent bonds and increasing defects in the film lead to a significant change in the phase transition hysteresis width of the vanadium dioxide film.

[0135] When gadolinium and titanium are ion-doped into vanadium dioxide (VO2) materials, they will cause lattice distortion due to the difference in ion radius from vanadium ions. 3+ (93.8 pm) radius is greater than V 4+ (63 pm) will expand the lattice and have a certain degree of magnetism. After doping, its magnetic moment interacts with the electrons and lattice in the material, which may change the energy balance during the phase transition. The magnetic interaction may promote or hinder the occurrence of phase transition, or affect the phase stability after phase transition. 4+ (61 pm) radius is smaller than V 4+ , which causes the lattice to shrink. The lattice distortion under the action of gadolinium and titanium dual ions changes the periodic potential field of the crystal, affecting the band structure and transition behavior of the electrons. In the Raman spectrum, the lattice vibration mode changes, resulting in the displacement and peak shape of the Raman peak. The Raman peak moves toward the low frequency direction, indicating that the lattice vibration frequency is reduced. This is because the lattice distortion changes the bond length and bond angle between atoms. The weakening of the interatomic interaction force will change the amplitude and speed of this resistance change, which in turn affects the electrical signal response characteristics to temperature changes in applications such as sensors.

[0136] The method of introducing gadolinium and titanium in this application is the key innovation in regulating the phase transition properties of vanadium dioxide thin films. Through a triaxial co-sputtering mode, gadolinium and titanium are introduced at specific process stages to increase the effective defects in the film. The doping concentration is regulated by varying the target's RF magnetron sputtering power within a range of 0-300W. Precise control of the doping concentration can directly influence the number and distribution of defects formed in the film, thereby adjusting the film's phase transition temperature and hysteresis width. Different application scenarios may have different requirements for phase transition temperature and hysteresis width, and the process of this invention can be flexibly adjusted according to actual needs. Maintaining a constant oxygen atmosphere within the chamber throughout the co-sputtering process is crucial. A stable oxygen content ensures a stable oxidation state of the film, preventing fluctuations in film composition and structure due to changes in the oxidizing environment, thereby ensuring predictable and stable phase transition properties. Any attempt to achieve similar vanadium dioxide film performance without adopting the Gd and Ti doping process of this application or failing to maintain the same process conditions infringes the intellectual property rights of this invention.

[0137] It should be understood that the application of this application is not limited to the above examples. For ordinary technicians in this field, they can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of this application.

Claims

1. A thin film material with a narrow hysteresis width, characterized in that: The invention comprises a vanadium dioxide film; the vanadium dioxide film is doped with gadolinium and titanium; The doping amount of gadolinium in the narrow hysteresis width thin film material is 1 at %-7.5 at %, and the doping amount of titanium in the narrow hysteresis width thin film material is 1 at %-10 at %.

2. A method for preparing a thin film material with a narrow hysteresis width according to claim 1, characterized in that: The following steps are involved: Placing the substrate on a substrate holder in a vacuum chamber of a three-axis magnetron sputtering device, evacuating the chamber, and preheating the substrate; Argon and oxygen are introduced, the vacuum degree is adjusted to the deposition pressure, the substrate negative bias voltage and duty cycle are set, the oxygen content is adjusted, and a vanadium target is magnetron sputtered by a DC power supply pulse to grow vanadium dioxide on the substrate; Using the three-axis co-sputtering mode, gadolinium target and titanium target were added to co-sputter with vanadium target; After the sputtering is completed, an inert gas is introduced to perform an in-situ annealing treatment, and the heating is turned off and the mixture is cooled to room temperature to obtain the narrow hysteresis width thin film material.

3. The method for preparing a thin film material with a narrow hysteresis width according to claim 2, characterized in that: The sputtering distance between the substrate and the target is 4-10 cm; the vacuum degree of the vacuum pump is 2×10 -4 Pa -5×10 -4 Pa; the rotation speed of the substrate rack is 10-30 Hz.

4. The method for preparing a thin film material with a narrow hysteresis width according to claim 2, wherein: The preheating condition is to heat to 400-600°C and maintain for 0.5-1h; The flow rate of the argon gas is 30-150 sccm, and the content of the oxygen gas is 4%-15%.

5. The method for preparing a thin film material with a narrow hysteresis width according to claim 2, characterized in that: The deposition pressure is 0.3-1 Pa, the substrate negative bias voltage is 50-400 V, the duty cycle is 10%-80%, the power of the DC power pulse magnetron sputtering vanadium target is 50-400 W, the pulse frequency is 40-100 KHz, the interval time is 1-10 μs, and the sputtering time is 0.5-1 h; The oxygen content is adjusted to maintain the oxygen content between 4% and 20%.

6. The method for preparing a thin film material with a narrow hysteresis width according to claim 2, wherein: After growing vanadium dioxide for 5-20 minutes, a gadolinium target and a titanium target are added and sputtered together with the vanadium target. The radio frequency power of the gadolinium target and the titanium target is 5-300W.

7. The method for preparing a thin film material with a narrow hysteresis width according to claim 2, characterized in that: Pre-sputtering the vanadium target for 5-30 minutes before growing vanadium dioxide on the substrate; Before sputtering the gadolinium target and the titanium target, the gadolinium target and the titanium target are pre-sputtered for 5-10 minutes.

8. The method for preparing a thin film material with a narrow hysteresis width according to claim 2, characterized in that: The inert gas has an inlet flow rate of 10-40 sccm, and the inert gas is one or both of argon and nitrogen; The in-situ annealing treatment is carried out at a temperature of 400-600° C. for 5-60 minutes.

9. An application of the narrow hysteresis width film material according to claim 1, characterized in that: The narrow hysteresis width thin film material is applied to a temperature sensor.

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