VO[sub.x] Phase Mixture of Reduced Single Crystalline V[sub.2]O[sub.5]: VO[sub.2] Resistive Switching

The strongly correlated electron material, vanadium dioxide (VO[sub.2]), has seen considerable attention and research application in metal-oxide electronics due to its metal-to-insulator transition close to room temperature. Vacuum annealing a V[sub.2]O[sub.5](010) single crystal results in Wadsley phases (V[sub.n]O[sub.2n+1], n > 1) and VO[sub.2]. The resistance changes by a factor of 20 at 342 K, corresponding to the metal-to-insulator phase transition of VO[sub.2]. Macroscopic voltage-current measurements with a probe separation on the millimetre scale result in Joule heating-induced resistive switching at extremely low voltages of under a volt. This can reduce the hysteresis and facilitate low temperature operation of VO[sub.2] devices, of potential benefit for switching speed and device stability. This is correlated to the low resistance of the system at temperatures below the transition. High-resolution transmission electron microscopy measurements reveal a complex structural relationship between V[sub.2]O[sub.5], VO[sub.2] and V[sub.6]O[sub.13] crystallites. Percolation paths incorporating both VO[sub.2] and metallic V[sub.6]O[sub.13] are revealed, which can reduce the resistance below the transition and result in exceptionally low voltage resistive switching.