Metal-insulator transition switching in VOx−VSe2 heterojunctions

First-order metal-insulator transition (MIT) observed in strongly correlated systems such as vanadium dioxide $({\mathrm{VO}}_{2})$ holds potential in electronics, energy, to optical applications. Starting from a vanadium diselenide $({\mathrm{VSe}}_{2})$ bulk crystal, we demonstrated a direct surface conversion from ${\mathrm{VSe}}_{2}$ to ${\mathrm{VO}}_{2}$ via laser exposure in ambient condition. The process generates defects, and the heat from the laser promotes oxidation forming ${\mathrm{VO}}_{x}$. Raman spectra at room temperature suggest the resulting oxide formed is monoclinic (M1) ${\mathrm{VO}}_{2}$. Above the transition temperature $({T}_{C})$, all the phonon modes are damped indicating formation of the rutile phase (metallic). Photoluminescence (PL) intensity enhancement and peak shifts observed at ${T}_{C}$ suggest correlation to the band structure transformation. In addition, we observed electrically induced MIT in our lateral ${\mathrm{VSe}}_{2}\text{\ensuremath{-}}{\mathrm{VO}}_{x}$ heterojunction device.