Recent progress made in the optical analysis of dislocation-related physical properties in GaN-based epilayers were surveyed with a brief review. The influence of dislocations on both near-band edge emission and yellow luminescence was examined either in a statistical way as a function of dislocation density or focused on individual dislocation lines with a high spatial resolution. Threading dislocations may introduce non-radiative recombination centers and enhance yellow luminescence, but their effects were affected by the structural and chemical environment. The minority carrier diffusion length may be dependent on either dislocation density or impurity doping as confirmed by the result of photovoltaic spectra. The in situ optical monitoring of the strain evolution process was employed during GaN heteroepitaxy using an AlN interlayer. A typical transition of strain from compression to tension was observed and its correlation with the reduction and inclination of threading dislocation lines was revealed.

Optical Analysis of Dislocation-Related Physical Processes in GaN-Based Epilayers. D.S.Jiang, D.G.Zhao, H.Yang: Physica Status Solidi B, 2007, 244[8], 2878-91