Characterization of vanadium oxide thin films with different stoichiometry using Raman spectroscopy

Vanadium oxides (VOx) have been widely studied as “smart materials” because of their capability of going through a reversible metal-insulator-transition. They are of considerable technological interests for applications in optoelectronics, ultrafast optical switches, electrochomic devices, and lithium microbatteries. However, vanadium-oxygen system is complicated due to the multivalency of vanadium, which makes preparation of VOx with single stoichiometry difficult. Therefore, structural characterization of vanadium oxides of different stoichiometriesis highly desirable and would provide helpful guideline to both materials preparation and their structural characterization. In the present work, VOx thin films with different stoichiometries under various bonding states were successfully prepared by reactive sputtering with and without post oxidation or reduction and characterized using Raman spectroscopy. Characteristic Raman spectra of single and multi- valence states of VOx including V2O3, VO2, V6O13, and V2O5 are presented and discussed. The results have demonstrated that high purity VOx thin films with single stoichiometry can be obtained under well controlled conditions.