First-Principles Study of Structural, Electronic and Optical Properties of wz-Zinc Oxide

Zinc oxide (ZnO) is a wide band gap II-VI semiconductor widely used in various applications. Zinc oxide crystallizes in different phases depending on different growth conditions and types of substrates used. Among them the wurtzite phase is the thermodynamically stable phase of ZnO in ambient conditions. The first principles study based on density functional theory is performed to explore the structural, electronic and optical properties of wurtzite phase of ZnO. The structural parameter values obtained within generalized gradient approximation are in good agreement with experimental values. The electronic structure shows that the O 2p state primarily contributes for upper most valence band. The ZnO is a good optoelectronic material since it has highly dispersive Zn 4s state of conduction band minimum which generates high value of mobility. The band structure is in good agreement to the previous reports which show that the Zn 3d-derived bands are narrowest near the gamma point as a result of the suppressed hybridization. It is also observed that for smaller frequencies the real part of dielectric exhibits maxima close to the absorption edge followed by a plateau like frequency region and for values more than 12.5 eV it becomes negative.