Polarized Raman scattering of large crystalline domains in VO2 films on sapphire

Polarized Raman scattering measurements were performed on (0 1 1)-oriented, over 10 μm-size VO2 grains on an Al2O3 (0 0 1) substrate. Angular intensity dependence of Raman active modes allowed to observe 17 modes among the 18 expected and to demonstrate the single crystalline character of the large domains. Analyses of intensity evolution have been used to correctly assign phonon modes and to calculate the Raman tensor elements. In addition, a Raman Ag mode related to the VV stretching vibration was found to have a different behavior versus angle rotation from other Ag modes, which supports the previous theoretical study and photoexcitation measurements.