Spatially resolved band-edge emission from partially coalesced GaN pyramids prepared by epitaxial lateral overgrowth

Partially coalesced GaN pyramidal structures are formed by metal-organic ch emical vapor deposition using the epitaxial lateral overgrowth method. Spat ially resolved optical characterization of these structures has been carrie d out using cathodoluminescence (CL) microscopy and spectroscopy. The coale sced region exhibits much stronger and more uniform luminescence than other regions of the sample. In addition, the emission from the coalesced region is blue-shifted, while that from the sidewalls is red-shifted, relative to broad area grown samples. The peak shift mechanism is discussed based on t he CL temperature and power dependence and analysis of the confocal Raman s cattering. (C) 2000 American Institute of Physics. [S0003-6951(00)03521-X].