We investigated configuration of metallic and insulating domains in VO2 thin films, while spanning metalinsulator phase transition. Kelvin probe force microscopy, of which spatial resolution is less than 100 nm, enables us to measure local work functi...
We investigated configuration of metallic and insulating domains in VO2 thin films, while spanning metalinsulator phase transition. Kelvin probe force microscopy, of which spatial resolution is less than 100 nm, enables us to measure local work function (WF) at the sample surface. The WF of VO2 thin films decreased (increased) as increasing (decreasing) the sample temperature, during the phase transition. The higher and lower WF regions corresponded to the insulating and metallic domains, respectively. The metallic fraction, estimated from the WF maps, well explained the temperature-dependent resistivity based on the percolation model. The WF mapping also showed us how the structural defects affected the phase transition behaviors.