Novel pulsed-laser-deposition—VO2 thin films for ultrafast applications

VO2 thin films deposited on fused quartz substrates were successfully fabricated by the pulsed-laser-deposition (PLD) technique. The obtained samples were examined by microscopy and x-ray diffraction (XRD). The films show a fast, passive thermochromic effect of semiconductor-to-metal phase transition (PT) with a characteristic hysterisis at ∼68°C. The thermochromic effect was measured as resistivity, optical transmission, and reflection versus temperature. Under pulsed laser excitation, an optically induced ultrafast PT of VO2 thin film was observed. Using the degenerate-four-wave-mixing (DFWM) technique, it was found that excited state dynamics is responsible for the induced lattice reorientation polarization, which results in the ultrafast PT.