Defects in zinc oxide

Abstract

ZnO is a wide band gap semiconductor having excellent properties for fabricating a variety of devices, including ultra-violet optoelectronic, solid-state lighting, sensor, spintronic, and etc. The realization of fabricating ZnO based devices is hindered by the asymmetric p-type doping difficulty, which is related to the poor understanding of the defects, defect compensation, and defect control in ZnO materials. Defects in semiconductors play crucial role in determining the material electrical, optical and magnetic properties. Aiming to gain the knowledge of defect control, defect study is performed in ZnO related structures, as well as their influence on the electrical, optical and magnetic properties. To obtain a comprehensive picture, the multi-spectroscopic approach including positron annihilation spectroscopy (PAS), deep level transient spectroscopy (DLTS), photoluminescence (PL), X-ray photoelectron spectroscopy, secondary ion mass spectroscopy (SIMS) and Raman spectroscopy, is adopted. The present presentation will illustrate some of our recent results, which include: (i) the role of Zn-vacancy on determining the rectifying property of Au/undoped-ZnO contact; (ii) the influence of defects on the p-type conductivity of As-doped ZnO; and (iii) the defects in ZnO grown by pulsed laser deposition (PLD), and the origins of the green defect emission and the near-band-edge emission.