Examination of Schwoebel Barrier Influence on GaN Quantum Dot Formation

The formation of gallium nitride nanoclusters (NCs), during high-temperature annealing of thin GaN layers, grown on aluminum nitride, is modeled using Monte Carlo method. It is shown, that the reason of GaN cluster formation can be Schwoebel barriers (SB) at the step edges of a defected GaN layer. Schwoebel barriers change the probability of atom diffusional hops across surface steps. Depending on the energy parameters of the model, different sizes and shapes of GaN nanoclusters were obtained after decomposition of a GaN layer during annealing. Kinetics of nanocluster formation is presented. Nanocluster shape turns out to be very sensitive to SB value and the energy of binding bonds. Nanocluster surface density is not only a function of energy barriers, but also of the level of initial surface imperfection and defect types.