Film thickness effect in c-axis oxygen vacancy-passivated ZnO prepared via atomic layer deposition by using H2O2

Abstract

The presence of oxygen vacancies in zinc oxide is a long-standing problem preventing the fabrication of p-type ZnO materials; however, the use of H2O2 as the oxygen source for preparing ZnO films via atomic layer deposition can significantly suppress their formation. Thus, this paper presents the investigation of the film thickness effect on the properties of oxygen vacancy-passivated ZnO prepared using H2O2. Increasing the ZnO film thickness increased the crystallinity along the c-axis preferred growth orientation, the grain size, and the surface roughness but also reduced the c-axis tensile strain, oxygen vacancies, optical bandgap, and film transmittance. The oxygen vacancy decrease was due to the reduced grain boundaries and improved crystallinity resulting from the film thickness increase, consequently weakening the resistivity through a large decrease in carrier concentration and a small increase in carrier mobility.