Structural Defects in GaN and ZnO

Abstract

Characteristics of the various kinds of structural defects in GaN and ZnO films and advances in techniques to reduce a dislocation density are presented. Heteroepitaxial GaN and ZnO films have various kinds of structural defects including misfit dislocations, threading dislocations, stacking faults, nanopipes, and inversion domain boundary, which inevitably affect the properties of the films and devices. Transmission electron microscopy of these defects is described in addition to discussions on basic characteristics of the defects. Many different technical approaches to reduce a dislocation density have been reported. Detailed techniques including epitaxial lateral over growth and employment of buffers that lead to the growth of high quality films with a low dislocation density are discussed.