Degradation of AlGaN during high-temperature annealing monitored by ultraviolet Raman scattering

We have illustrated the use of ultraviolet (UV) Raman scattering to investi gate the thermal stability of AlGaN layers with high-aluminum content. The degradation pathway of Al0.72Ga0.28N was monitored for high-temperature tre atments up to 1200 degrees C. For annealing temperatures higher than 1150 d egrees C, the Al0.72Ga0.28N film decomposes: a low- and a high-aluminum com position AlxGa1-xN phase emerge. At 1100 degrees C, prior to the Al0.72Ga0. 28N decomposition, UV Raman scattering detects the buildup of a large strai n in the Al0.72Ga0.28N film The crystalline quality of Al0.72Ga0.28N is una ffected up to 1000 degrees C. (C) 1999 American Institute of Physics. [S000 3-6951(99)00704-4].