Search for power-efficient wide-range reversible resistance modulation of VO2 single crystals

The abrupt metal insulator transition in VO2 is attracting considerable interest from both fundamental and applicative angles. We report on DC I-V characteristics measured on VO2 single crystals in the two-probe configuration at several ambient temperatures below the insulator-metal (I-M) transition. The insulator-mixed-metal-insulator transition is induced by Joule heating above ambient temperature in the range of negative differential resistivity (NDR). In this range the stability of I(V) is governed by the load resistance RL. Steady state I(V) is obtained for R-L > vertical bar dV/dI vertical bar(max) in the NDR regime. For R-L < vertical bar dV/dI vertical bar(max) there is switching between initial and final steady states associated with peaks in the Joule power, that are higher the lower R-L is. The peaks caused by steep switching are superfluous and damaging the samples. On the other hand, the large R-L needed for steady state is the main power consumer in the circuit at high currents. The present work is motivated by the need to avoid damaging switching in the NDR regime while reducing the power consumption in the circuit. Large resistance modulation can be obtained under steady state conditions with reduced power consumption by increasing the ambient temperature of the device above room temperature. Under steady state conditions, the transition to the mixed metal-insulator state is smooth and is followed closely by appearance of sliding domains.