Evaluation of nanoindentation and nanoscratch characteristics of GaN/InGaN epilayers

The potential use of thin films in many engineering applications has prompted the mechanical characterization of small volumes, such as thin films or micro-sized phases to receive considerable attention. In this study, nanoindentation-induced mechanical deformation behavior of the GaN/InGaN Multiple quantum well structure (MQW) grown on (0001) sapphire was investigated using Berkovich and cube corner indenters. A single discontinuity ('pop-in') in the load-indentation depth curve was observed for the films, the physical mechanism being the interaction of the deformed regions produced by the indenter. The nanoscratch technique, a versatile approach to evaluate the nanotribological properties of thin films was employed to study the elastic and plastic behavior of the sample. The Atomic force microscopy (AFM) was helpful to reveal the deformation morphologies and scratch profiles. Analysis of the residual indentation impression revealed pile-up and sink-in behavior related to the plasticity of the samples.