Elevated temperature dependent transport properties of phosphorus and arsenic doped zinc oxide thin films

Elevated temperature dependent Hall effect measurements were performed in a wide temperature range from 80 to 800K to study transport properties of zinc oxide (ZnO) thin films heavily doped with phosphorus (P) and arsenic (As), and grown on sapphire substrates by RF magnetron sputtering. Double thermal activation processes in both P-and As-doped ZnO thin films with small activation energy of similar to 0.04 eV and large activation energy of similar to 0.8 eV were observed from variable temperature Hall effect measurements. The samples exhibited n-type conductivities throughout the temperature range. Based on photoluminescence measurements at 11K and theoretical results, the large activation energy observed in the temperature dependent Hall effect measurement has been assigned to a deep donor level, which could be related to oxygen vacancy (V-O) in the doped ZnO thin films. (C) 2013 AIP Publishing LLC.