In this paper we used Raman spectroscopy to investigate the optical properties of vanadium dioxide (VO2) thin films during the thermally induced insulating to metallic phase transition. We observed a significant difference in transition temperature in similar VO2 films grown on quartz and sapphire substrates: the film grown on quartz displayed the phase transition at a lower temperature (Tc=50C) compared a film grown on sapphire (Tc=68C). We also investigated differences in the detected Raman signal for different wavelengths and polarizations of the excitation laser. We found that for either substrate, a longer wavelength (in our case 785 nm) yielded the clearest VO2 Raman spectra, with no polarization dependence.
@article{arxiv.1210.7746,
title = {Substrate Effect on Optical Properties of Insulator-Metal Transition in VO2 Thin Films},
author = {E. Radue and E. Crisman and L. Wang and S. Kittiwatanakul and J. Lu and S. A. Wolf and R. Wincheski and R. A. Lukaszew and I. Novikova},
journal= {arXiv preprint arXiv:1210.7746},
year = {2013}
}