Stabilization of the VO 2 (M2) Phase and Change in Lattice Parameters at the Phase Transition Temperature of W X V 1- X O 2 Thin Films.

Various methods have been used to fabricate vanadium dioxide (VO) thin films exhibiting polymorph phases and an identical chemical formula suited to different applications. Most fabrication techniques require post-annealing to convert the amorphous VO thin film into the VO (M1) phase. In this study, we provide a temperature-dependent XRD analysis that confirms the change in lattice parameters responsible for the metal-to-insulator transition as the structure undergoes a monoclinic to the tetragonal phase transition. In our study, we deposited VO and W-doped VO thin films onto silica substrates using a high repetition rate (10 kHz) fs-PLD deposition without post-annealing. The XRD patterns measured at room temperature revealed stabilization of the monoclinic M2 phase by W doping VO. We developed an alternative approach to determine the phase transition temperatures using temperature-dependent X-ray diffraction measurements to evaluate the and lattice parameters for the monoclinic and rutile phases. The and lattice parameters versus temperature revealed phase transition temperature reduction from ∼66 to 38 °C when the W concentration increases. This study provides a novel unorthodox technique to characterize and evaluate the structural phase transitions seen on VO thin films.