Evolution of local work function in epitaxial VO₂ thin films spanning the metal-insulator transition

Abstract

Transport and Kelvin probe force microscopy measurements were simultaneously conducted on epitaxial VO2 thin films. The sample's work function abruptly dropped from 4.88 eV to 4.70 eV during heating from 333 K to 353 K, suggesting a significant change in its electronic band structure spanning the metal insulator transition. The work function showed nearly no statistical deviation across the film's surface during the transition, likely due to band bending at the boundaries of the small domains. Resistance profiles confirmed that the local work function corresponded closely to the resistance of the corresponding area.