Tuning the phase transitions of VO2thin films on silicon substrates using ultrathin Al2O3as buffer layers

High quality VO 2 thin films have been fabricated on silicon substrates using magnetron sputtering by introducing Al 2 O 3 thin films as a buffer. The ultrathin Al 2 O 3 deposited by plasma-assisted atomic layer deposition leads to a greatly improved crystallinity and textures in VO 2 films. Dramatic change in electrical resistivity (4 orders of magnitude) and a small thermal hysteresis loop (~4 K) are obtained across the metal–insulator phase transition (MIT). Remarkably, by applying perpendicular voltage to a VO 2 /Al 2 O 3 based metal/VO 2 /semiconductor device, electrically driven MIT switching characteristics have been observed with a tiny tunneling leakage current of ~10 μ A. These results show that an electric field alone is sufficient to trigger the MIT, and the realization of VO 2 based ultrafast electrical switching devices on a silicon substrate is possible.