Strain relaxation of GaN nucleation layers during rapid thermal annealing

The strain relaxation of GaN nucleation layers grown on sapphire (0001) during rapid thermal annealing was studied in a synchrotron x-ray scattering experiment. The as-grown GaN nucleation layer is compressively strained. Upon annealing to 750 degreesC, the lattice strain first changes to tensile. This tensile strain is released progressively as the annealing temperature increases. The nucleation layer sublimates significantly at 1050 degreesC where it becomes mostly strain-free hexagonal GaN. (C) 2001 American Institute of Physics.