Stress-induced VO2 films with M2 monoclinic phase stable at room temperature grown by inductively coupled plasma-assisted reactive sputtering

We report on growth of VO2 films with M2 monoclinic phase stable at room temperature under atmospheric pressure. The films were grown on quartz glass and Si substrates by using an inductively coupled plasma-assisted reactive sputtering method. XRD-sin2Ψ measurements revealed that the films with M2 phase are under compressive stress in contrast to tensile stress of films with M1 phase. Scanning electron microscopy observations revealed characteristic crystal grain aspects with formation of periodical twin structure of M2 phase. Structural phase transition from M2 to tetragonal phases, accompanied by a resistance change, was confirmed to occur as the temperature rises. Growth of VO2 films composed of M2 phase crystalline is of strong interest for clarifying nature of Mott transition of strongly correlated materials.