Measurement and evaluation of micro-sized strain fields in GaN epitaxial structure

The elastic strain field in a GaN/sapphire structure was measured via electron backscatter diffraction (EBSD). Image quality and small misorientation of EBSD Kikuchi patterns as strain sensitive parameters were applied to evaluate the distortion and the rotation of crystal lattices in GaN-buffer-sapphire structure, as well as to display micro-sized elastic strain field. The influence region of the elastic strain in GaN/sapphire structure is about 200700 nm. The diffraction intensities of Kikuchi patterns were extracted and the strained/unstrained regions in GaN epitaxial structure were recognized by using the fast Fourier transform (FFT).