High-resolution near-field spectroscopy investigation of GaN laterally overgrown structures on SiC

We investigated epitaxial lateral overgrown GaN structures with different wing tilt using a spectroscopic scanning near-field optical microscope (spectroscopic SNOM), which takes a complete optical spectrum at each point of a sample surface. From these measurements, we obtain information about strain at different points of the surface, and comparing emission intensity between regions of lateral growth and vertical growth, we directly see the efficiency of defect density reduction. For the high wing-tilt sample, an increased defect density at the window-wing interface could be identified. (C) 2003 American Institute of Physics.