In-Situ AlN Induced Valence State Variation of V in Vanadium Oxide Films Investigated by XPS

Vanadium oxide (VOx) thin films with and without in situ AlN layer were grown on single crystal sapphire substrates by pulsed laser deposition (PLD) with V2O5 target. The significant structure and morphology transforms resulted from the insertion of in-situ AlN layer were observed by X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM). To interpret the mechanism behind these phenomena, the valence state variation of vanadium (V) in VOx films induced by in-situ AlN layer was investigated by X-ray photoelectron spectroscopy (XPS) analyses. The results indicated that the valence state of V become more complicated and VOx films with the mixed V valence state of V5+,V4+and V3+ were obtained due to the introduction of AlN interfacial stress layer. Our achievements will be helpful for understanding the physical mechanism behind the exotic characteristics of VOx films induced by stress layer