The importance of local bond order to conduction in amorphous, transparent, conducting oxides: The case of amorphous ZnSnOy

In this report, reactive and non-reactive sputtering of ZnSnOy was investigated, and extensive composition maps have been measured by X-ray Photoelectron Spectroscopy (XPS). The comprehensive analysis of ((ZnO)x(SnO2)1-x) composition reveals the best Zn/Sn ratio for high conductivity of the material can vary depending on the deposition technique utilized. Best conductivities of 225 S/cm were found to occur at x=0.32 for reactive sputtering of a Sn target and x=0.27 for non-reactive sputtering of a SnO2 target. These values correspond to unstable polymorphs of ZnSnOy, ZnSn2O5 and ZnSn3O7. Distinct local bonding arrangements have been confirmed by Raman spectroscopy.