Temperature dependence of cathodoluminescence spectra and stress analysis of a GaN layer grown on a mesa structured Si substrate

The temperature dependence of cathodoluminescence (CL) spectra is measured on n-GaN grown on a Si (111) substrate patterned by deep etching in the temperature range 6-280 K. The temperature dependence of the peak energy of A free exciton (FXA) and its 1LO and 2LO phonon replicas are obtained. The stress distribution from corner to center in the patterned mesa area at low temperature 10 K is estimated roughly by FXA energy using a line scanning measurement of the CL spectra. The maximum tensile stress at a point far from the mesa edge is about 0.6 GPa and relaxed to 0.1 GPa at the corner. The relaxation distance extends to about 40 mu m. (C) 2007 American Institute of Physics.