Importance of Local Bond Order to Conduction in Amorphous, Transparent, Conducting Oxides: The Case of Amorphous ZnSnO.

In this report, reactive and nonreactive sputtering of amorphous ZnSnO (a-ZnSnO) was investigated, and extensive composition maps have been measured by X-ray photoelectron spectroscopy. The comprehensive analysis of the ((ZnO)(SnO)) composition reveals that 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 = 0.32 for reactive sputtering of a Sn target and = 0.27 for nonreactive sputtering of a SnO target. These values correspond to unstable polymorphs of a-ZnSnO, ZnSnO, and ZnSnO. Distinct local bonding arrangements have been confirmed by Raman spectroscopy.