Reactive RF Sputtering of VO2
There are multiple lower oxides which exhibit metal-to-insulator transition, VO2 is one of them. What makes it unique is that the transition occurs at near room temperature, thus making the energy cost of switching very low. The material had amassed a large amount of attention from scientific community over the past few years, resulting in low power devices like phase change field-effect transistor with switching times on the order of picoseconds. The deposition of VO2 can be approached from multiple perspectives: chemical vapour deposition, evaporation, sputtering and sol-gel. The focus of my work is the reactive RF sputtering deposition of VO2 thin films and analysis of its application in RF field. The optimal deposition parameters were demonstrated to be 500degC, substrate temperature and 10.2%-10.3% partial oxygen flow using a 2'' target at 200W RF power, resulting in a growth rate of 1.5 nm/min. The quality of VO2 was studied using device level vector network analysis, more specifically coplanar waveguide series switches with 5 um VO2 gap which was activated using a global heating approach. Future plans for further improvement of the material deposited and solutions for localized heating using wave-shaped Au/Cr micro-heaters will be discussed as well.