Abstract
Negative capacitance (NC) in a planar W-doped VO
2
micro-switch was observed at room temperature in the low-frequency range 1 kHz-10 MHz. The capacitance changed from positive to negative values as the W-doped VO
2
active layer switched from semiconducting to metallic state under applied voltage. In addition, a capacitance-voltage hysteresis was observed as the applied voltage was cycled from −35 to 35 V. These observations suggest that NC results from the increase of the electrically induced conductivity in the active layer. This NC phenomenon could be exploited in advanced multifunctional devices including ultrafast switches, field-effect transistors and memcapacitive systems.