$\hbox {VO}_{2}$ Thin-Film Varistor Based on Metal-Insulator Transition

For electronic applications, we have fabricated VO₂ thin-film variable resistors (varistors) using metal-insulator transition regarded as the abrupt current jump. The increase of the number of parallel stripe patterns in the varistor leads to the increase in current below a current-jump voltage, which endures a high surge voltage with high current and short rising time. Electrostatic discharge (ESD) experiments show that the varistic coefficient of 500 is larger than 30-80, which is known for commercial ZnO varistors. In overvoltage-protection tests applying high ESD voltages up to 3.3 kV to a varistor, the maximum response voltage is lower than 200 V at an ESD voltage of 1600 V, and the electronic response time is less than 20 ns. This is sufficient to protect a device perfectly.