Investigation on electrically-driven semiconductor-metal transition of polycrystalline VO2 thin films on two kinds of substrates

Electrical driving is one of frequently-used stimuli for the semiconductor-metal transition (SMT) of VO2. But the driving mechanism is still under debate. We investigated the DC electrically-driven SMT features of polycrystalline VO2 thin films deposited on two kinds of substrates (quartz and silicon) with obviously-different thermal conductivity and the influence of cooling by a thermo electric cooler (TEC) on the SMT of VO2. Interestingly, the SMT doesn’t happen at a high voltage at very start, but at a relatively low one. Moreover, the SMT of VO2 thin films on silicon substrate is completely restrained by cooling through a TEC although the electric field strength across VO2 reaches 1.1×107 V/m. Our findings reveal that the Joule-heating effect plays an important role in the DC electrically-driven SMT of VO2.