Research On Thermal Radiation Properties Of Vanadium Dioxide Film Structure

Vanadium dioxide has attracted wide attention with its special characteristics of phase change. And its role in the near field of heat transfer, thermal rectif ication and far-field of smart materials, etc., is irreplaceable because of the phase change property. It also makes the vanadium dioxide have a good prospect of application in the related field. This article investigates the heat radiation characteristics of vanadium dioxide film from the near field, far field as well as modification of silver grating on vanadium dioxide film structure.Firstly, based on the fluctuation dissipation relations theory, the near-field thermal radiation characteristics of vanadium dioxide thin films are analyzed. The relationship between film thickness, separation distance and density of states of near-field radiation is also explored. We then analyze the role of photon polarization resonance played in the enhancement of local density of state. On this basis, we analyze the evanescent wave mode distribution of vanadium dioxide film and study the contribution of surface polarization photon to the near field thermal radiation enhancement. The results show that at the frequency where surface polaritons photon resonance exists local density of state enhancement is of magnitudes compared with blackbody radiation.Secondly, based on the finite difference time domain(FDTD) algorithm the radiation characteristics are analyzed in order to investigate the far field radiation characteristics of vanadium dioxide film. Then we prepare vanadium dioxide film with magnetron sputtering and characterize its absorption spectrum in infrared region to explore the influence of film thickness, temperature on the radiation characteristics of vanadium dioxide films. The results show that the phase transition properties of vanadium dioxide film have a switch effect at its absorptive frequency.Finally, we build a structure consisted composite phase of vanadium dioxide. In order to achieve control of phase, silver stripe array are involved as electrodes, we analyze influence of electrode period, duty cycle and other factors on its radiative properties. The structure of silver electrodes and vanadium dioxide film is experimentally demonstrated by the means of photolithography, electron beam deposition and magnetron sputtering. Its spectrum is also characterized in the infrared region. The results show that the width can significantly affect the resonant absorption frequency of vanadium dioxide film.