There has been a great interest in transition metal (TM) doped diluted magnetic semiconductors (DMSs) in recent years. This is due to possibility of manipulating their charge and spin degrees of freedom. These DMSs are potential candidates for next generation spintronic devices, such as spin-valve transistors, spin light-emitting diodes, non-volatile storage and logic devices [1–3]. DMSs can be synthesized from wide-band gap semiconductors with the replacement of the host sites of the semiconductors with magnetic impurities [1]. A wide-band gap II–IV and III–V based semiconductors doped
with metal-transition (Fe, Co, and Mn) metals have been studied widely to investigate the room temperature ferromagnetism [2–6]. ZnO was also used as a potential DMSs material, due to its wide band gap (3.3 eV) and exciton binding energy (60 meV) at room temperature.