Strain relaxation of GaN nucleation layers during rapid thermal annealing

The strain relaxation of GaN nucleation layers grown on sapphire (0001) dur ing rapid thermal annealing was studied in a synchrotron x-ray scattering e xperiment. The as-grown GaN nucleation layer is compressively strained. Upo n annealing to 750 degreesC, the lattice strain first changes to tensile. T his tensile strain is released progressively as the annealing temperature i ncreases. The nucleation layer sublimates significantly at 1050 degreesC wh ere it becomes mostly strain-free hexagonal GaN. (C) 2001 American Institut e of Physics.