Synchrotron x-ray scattering study on the evolution of surface morphology of the InN/Al2O3(0001) system

Dynamic scaling behavior was studied for InN films grown on sapphire(0001) substrates using high-resolution synchrotron x-ray reflectivity and atomic force microscopy measurements. In the early stage of growth, highly strained planar InN films were grown. As the film thickness approaches an effective critical thickness, the growth gradually crosses over to the island growth. Concurrently, the relaxation of the lattice strain begins and the growth front becomes rougher. The roughness increases mostly during the intermediate crossover regime where the strain is relieved. In this regime, the dynamic scaling exponent, beta, is estimated as 1.754+/-0.071. The evolution of the surface roughness in the final-stage growth can be described by the dynamic scaling exponent of 0.236+/-0.022. (C) 2002 American Institute of Physics.