NEAR-FIELD SCANNING OPTICAL SPECTROSCOPY OF AN INGAN QUANTUM-WELL

Near-field scanning optical microscopy is used to image photoluminesce nce (PL) in an InGaN/GaN quantum well (QW) with spatial resolution of approximately 100 nm for temperatures between 50 and 295 K. Strong (si milar to 50%) fluctuations in the quantum well photoluminescence as we ll as a tenfold enhancement of deep level-related emission at lower en ergies occur at large (similar to 500 nm diam:) pits in the heterostru cture. Regions of smaller (similar to 15%) fluctuations in the QW PL a re not correlated with the presence of pits. The spectrum of the QW FL shows no significant variations on the length scales probed in this e xperiment. We thus fin no spectroscopic signature of the recombination of strongly localized carriers at temperatures above 150 K. (C) 1998 American Institute of Physics.