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 area in PL mapping data and threading dislocations with screw and mixed types in violet samples. On the other hand, such correlation has not been found in the blue sample. These results indicated that the carriers/excitons were captured easily in non-radiative recombination centres (NRCs) originating from the threading dislocations in the violet sample, because the lateral diffusion length of carriers/excitons was large due to a small potential fluctuation induced by compositional fluctuation of In comparing to those in the blue sample. However, the capture to such NRCs was hindered effectively in the blue one because of the 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