Advantages of inductively coupled plasma-assisted sputtering for preparation of stoichiometric VO2 films with metal–insulator transition

Inductively coupled plasma (ICP)-assisted sputtering with an internal coil enabled deposition of stoichiometric crystalline vanadium dioxide (VO2) films on a sapphire (Al2O3) (001) substrate under widely various deposition conditions. The films showed a metal–insulator (M–I) transition around temperatures of 68 °C with several orders of change in resistivity. Particularly, low-temperature (250 °C) growth of VO2 film with two orders transition decade was achieved in ICP-assisted sputtering, in contrast with conventional sputtering, which required 400 °C for VO2 growth. Rutherford back scattering (RBS) measurements revealed that the VO2 film prepared by ICP-assisted sputtering was exactly stoichiometric, containing no impurity atoms from the inserted coil material. The ICP-assisted sputtering was examined in comparison to conventional sputtering in view of plasma characteristics.