Study on oxygen source and its effect on film properties of ZnO deposited by radio frequency magnetron sputtering

► Sputtered ZnO films are mainly formed by a chemical reaction of Zn with oxygen. ► ZnO changed O-rich to Zn-rich with decreasing rf-power and oxygen partial pressure. ► Broad PL emission was observed when the ZnO changed from O-rich to Zn-rich. ► Origin of broad PL emission thought to be an increase of oxygen vacancies. ► Chemical stoichiometry will help us to understand formation of intrinsic defects in ZnO.