Epitaxial VO2 thin film-based radio-frequency switches with thermal activation

In this paper, we report on the demonstration of thermally triggered “normally ON” radio-frequency (RF) switches based on epitaxial vanadium dioxide (VO2) thin films with a SnO2 template on (001) TiO2 substrates. Fast insulator-to-metal phase transition of the epitaxial VO2 at a relatively low temperature allowed RF switches made of the VO2 to exhibit sharp changes in the RF insertion loss during cooling and heating at 60 °C and 66 °C, respectively. The change of RF insertion loss due to phase transition is greater than 15 dB. The VO2 RF switches also completed the transition of S21 within less than 3 °C and showed a low-loss operation frequency of up to 24.2 GHz with a low insertion loss of −1.36 dB and isolation of 17.56 dB at 12.03 GHz, respectively. The demonstration suggests that epitaxial VO2-based RF switches can be used in switching elements up to Ku-band RF circuits.