Modulation of the microstructure, optical properties and electrical properties of zinc-doped nickel oxide films via direct current sputtering power

Abstract

Zinc-doped NiO (NiO:Zn) films were direct-current-magnetron sputtered on the glass substrates. The modulation of the properties of the films via sputtering powers (Pspu) was especially studied. The conducting transition from p to n type was also proposed in mechanism. The NiO:Zn films are all preferentially 〈111〉 oriented. The films with high Pspu almost have small lattice distortion due to the improved crystallization caused by the thermal effect and the Zn element doping. The films begin to exhibit the n-type conduction at 90 W Pspu. The conducting transition from p to n type is mainly attributed to the occupation of Ni vacancies by Zn2+ and the interstitial Zn, and the improved n-type conduction in Pspu range of 140 W through 160 W to the increase in content of the interstitial Zn atoms. The absorption edge of the NiO:Zn films remaining at about 3.7 eV is slightly affected by the increase in Pspu, showing that the doping of the Zn element in the NiO is not mainly in the form of the Ni vacancies occupying ions.