High performance electroformed Single-crystallite VO2 threshold switch
Threshold switches (TSs) is an effective approach for resolving the sneak path problem within a memristor array. VO2 is a promising material for fabricating high-performance TSs. Here we report a single crystal VO2-based TS device with high switching performance. The single crystal monoclinic VO2 channel is obtained by electroforming in a composite vanadium oxide film consisting of VO2, V2O5 and V3O7. The formation mechanism on single crystal VO2 is thoroughly investigated by means of X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. The single crystal VO2-based TS device exhibits better switching performance than polycrystalline monoclinic VO2 counterpart. The TS device based on single crystal channel with (-211) orientation exhibits a steep turn-on voltage slope of <0.5 mV dec-1, a fast switching speed of 23 ns, an excellent endurance over 109 cycles, a high Ion/Ioff ratio of 143 and a low sample-to-sample variance. Enhanced switching performance originates from single crystal feature and specified crystal orientation.