Anisotropic diffusion and drift of photogenerated carriers near coreless dislocations in InGaN quantum well

We report on a photoluminescence (PL) study on pinholes and their effects o n the carrier recombination process in an InGaN/GaN single quantum well sam ple. By directly imaging the luminescence from the sample, we observed an a nisotropic distribution of photogenerated carriers due to diffusion and dri ft of the carriers near pinholes. The anisotropy, together with micro-PL sp ectra at different locations near a pinhole, shows evidence of narrowing of the band gap of the quantum well layer near pinholes. The existence of the band gap gradient is confirmed by reflective and photoluminescence images of the sample under global illumination. Possible causes of the band gap gr adient include indium concentration inhomogeneity and partial strain relaxa tion near pinholes. (C) 2001 American Institute of Physics.