Tuning of TCR in poly-crystalline VO2 for enhanced IR detection

Abstract

We explored the effect of Cr dopant on the transport behaviors of polycrystalline VO2 thin films in order to suppress the sharp metal-insulator transition, and tune the temperature coefficient of resistivity (TCR) value. A reactive bias target ion beam deposition was used for combinational sputtering to Cr doped VO2 thin films (~100 nm). The addition of Cr led a structural change in the semiconducting phase of VO2. With the Cr content >7 at. %, the sharp metal-semiconductor transition and the hysteresis loop was suppressed in thin film VO2. A further increase of Cr content reduced the TCR. Separately the effect of the oxygen flow rate was investigated to modulate the TCR and the resistivity value of Cr doped VO2. We demonstrated the resistivity of Cr doped VO2 was modulated by 2 orders of magnitude with a very small change in the oxygen flow rate. We obtained TCR of ~ 4.5 %/K in Cr doped VO2 grown on single crystal sapphire substrate near room temperature.