用随机阻抗网络模拟纳米热致变色VO2薄膜的电阻温度特性

SIMULATION OF TEMPERATURE DEPENDENCE OF RESISTANCE IN THERMOCHROMIC NANO-VO_2 THIN FILMS BY USING RANDOM RESISTOR NETWORKS

用反应离子束溅射法制备了低相变点（45℃）纳米二氧化钒（VO2）薄膜,并利用随机阻抗网络模型来模拟其电阻-温度特性.在模拟过程中,该薄膜被等效为一个由半导体相和金属相微粒随机分布组成的复合系统.氧化钒薄膜电阻温度特性的模拟结果与实验测量值在整个温度变化范围（10～75℃）十分吻合.这一结果表明,氧化钒薄膜在温度变化过程中发生相分离,且半导体相微粒和金属相微粒之间相互竞争导致了氧化钒薄膜电阻的突变.

Nanoploycrystalline VO2 thin films with low phase transition temperature （45℃） were fabricated by reactive ionbeam sputtering method, and random resistor network （RRN） model was employed to simulate the characteristics of temperature dependence of resistance in VO2 thin film. The thin film was modeled as a composite medium consisting of semiconducting and metallic regions randomly distributed in the microcrystals. There is a satisfactory agreement between the simulated resistance-temperature trajectories and the measured major hysteresis loops for temperature coveting the whole range （10 -75℃ ）. The physical mechanics in our simulation is that the phase segregation occurs and the phase transition in VO2 thin films is due to the competition between the semiconducting and metallic regions of these two components in the procedure of temperature changing.