Near-field photoluminescence mapping and atomic force microscopy of the same scanning area were used to clarify the relationship between luminescence dynamics and threading dislocations in violet and blue light-emitting InGaN single-quantum-well structures on epitaxially laterally overgrown GaN templates at room temperature. A clear correlation was found between the distribution of dark areas in photoluminescence mapping data and threading dislocations of screw and mixed types in the violet sample. On the other hand, no such correlation was found in the blue sample. The results indicated that the carriers/excitons were captured easily in non-radiative recombination centers originating from threading dislocations in the violet sample, because the lateral diffusion length of carriers/excitons was large due to small potential fluctuations induced by compositional fluctuations of In as compared to those in the blue samples. However, capture by such non-radiative recombination centers was effectively hindered in the blue samples because of localization to potential minima.

Direct Correlation Between Non-Radiative Recombination Centers and Threading Dislocations in InGaN Quantum Wells by Near-Field Photoluminescence Spectroscopy. A.Kaneta, M.Funato, Y.Narukawa, T.Mukai, Y.Kawakami: Physica Status Solidi C, 2006, 3[6], 1897-901