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 on the carrier recombination process in an InGaN/GaN single quantum well sample. By directly imaging the luminescence from the sample, we observed an anisotropic distribution of photogenerated carriers due to diffusion and drift of the carriers near pinholes. The anisotropy, together with micro-PL spectra 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 gradient include indium concentration inhomogeneity and partial strain relaxation near pinholes.