The E3 center in zinc oxide: Evidence for involvement of hydrogen

Abstract

Proton implantation is shown to increase the concentration of the so called and commonly observed E3 defect level in zinc oxide (ZnO). Box and single profiles of protons with doses ranging from 6×1010 cm−2 to 4.3×1012 cm−2 were implanted into hydrothermally grown ZnO samples with original concentrations of E3 below 5×1014 cm−3. Capacitance-Voltage profiling and junction spectroscopy measurements showed that the charge carrier concentration and absolute concentration of E3 centers increase by more than one order of magnitude compared to the as-grown samples as well as control samples implanted with He ions. The results provide strong evidence for the involvement of H in the formation of the E3 center, and a complex involving interstitial H and an oxygen sub-lattice primary defect are discussed.