Changes in lattice parameters of VO2 films grown on c-plane Al2O3 substrates across metal-insulator transition

We demonstrated lattice parameters of vanadium dioxide (VO2) films grown on Al2O3(001) substrates across metal-insulator transition using temperature-controlled X-ray diffraction measurements. Changes in lattice length for both the monoclinic and tetragonal phases were shown against temperature. Films prepared by pulsed laser deposition (PLD) and reactive sputtering were examined to discuss the dependence of the transition properties on lattice parameters. The expansion of cm sin β due to smaller angle β was revealed to be a characteristic in the low-temperature monoclinic phase and to be transformed to a larger in-plane at length in the high-temperature tetragonal phase. We discussed the dependence of transition temperature on ct length in the tetragonal phase in relation to the am length in the monoclinic phase across metal-insulator transition. (author)