APPLIED PHYSICS REVIEWS—FOCUSED REVIEW Review of zincblende ZnO: Stability of metastable ZnO phases

Common II-VI compound semiconducting materials are stable thermodynamically with zincblende phase, while the II-O materials such as zinc oxide ZnO and beryllium oxide BeO are stable with wurtzite phase, and cadmium oxide CdO and magnesium oxide MgO are stable in rocksalt phase. This phase disharmony in the same material family laid a challenge for the basic physics and in practical applications in optoelectronic devices, where ternary and quaternary compounds are employed. Thermodynamically the zincblende ZnO is a metastable phase which is free from the giant internal electric fields in the 001 directions and has an easy cleavage facet in the 110 directions for laser cavity fabrication that combined with evidence for the higher optical gain. The zincblende materials also have lower ionicity that leads to the lower carrier scattering and higher doping efficiencies. Even with these outstanding features in the zincblende materials, the growth of zincblende ZnO and its fundamental properties are still limited. In this paper, recent progress in growth and fundamental properties of zincblende ZnO material has been reviewed. © 2007 American Institute of Physics. DOI: 10.1063/1.2787957