Rapid local modulation of VO2 phase transition by graphene heater

Abstract

Vanadium dioxide (VO₂), a thermochromic material with a low phase transition temperature at 68℃ and the magical hysteresis property near the phase transition temperature, has been widely investigated because of its potential application as infrared detector, optical switch, memristor, and ‘smart window’. Graphene, due to its special electrical, optical and thermal properties, has been extensively studied in recent years with layered hybrid structures of other materials. In this paper, to realize flexible manipulation of VO₂ phase transition, we co-designed a graphene heater to locally modulate temperature of VO₂. Typical thermal induced phase transition by temperature control stage has been achieved through electrical measurements, which shows the resistance of VO₂ has gone through a dramatical change over 3 order of magnitude around the critical temperature (68℃). As for the in situ heating manipulation, we applied current to the graphene to generate joule heating, which would result in a hot-spot to locally modulate the temperature of VO₂ to reach the phase transition point. Meanwhile, the electrical current of graphene that results in the structural phase transition of VO₂ could be smaller by inserting Al₂O₃ capping layer between graphene and VO₂. Compared with the traditional macroscale VO₂ device, our nanosized co-designed structure shows both low power consumption and fast response, which would benefit a lot in exploring VO₂ based on-chip electronic applications. In addition, we believe that the designed composite structure has a wide range of research significance in optoelectronic devices.