Enhancement of metal-insulator transition performance of VO2 thin films by conventional furnace annealing

•VO2 thin films annealed using rapid thermal annealing (RTA) have large defect density.•Additional conventional furnace annealing (CFA) step has been used.•RTA-CFA procedure improved the metal-insulator transition of VO2 films.•VO2 crystallite size and content of V4+ in the film can be increased by CFA extra-step.•VO2 phase transformation amplitude can be increased from 90 to about 1600 times using CFA. The vanadium dioxide (VO2) thin films fabricated by rapid thermal annealing (RTA) of vanadium thin films have high defect density and low phase transition magnitude. In this manuscript, VO2 thin films were fabricated by sputtering deposition and RTA process, then the VO2 thin films were annealed by the conventional furnace to improve metal-insulator transition performance. The effect of conventional furnace annealing (CFA) on content, grain size and phase transition property of VO2 thin films were studied. From the calculations of the VO2 grain size, the CFA method effectively increases the VO2 grain size. The valence and chemical composition of vanadium before and after annealing were studied by X-ray photoelectron spectroscopy. The results show that the content of V4+ in the film is significantly increased by CFA. After CFA on the basis of RTA, the transition magnitude of VO2 film increased from 90 to about 1600. It is feasible to prepare high-quality VO2 films with enhanced metal-insulator transition performance by CFA of VO2 films after RTA, which is beneficial to the application of VO2 thin films in optoelectronic devices.