GaN films were grown on c-Al2O3 substrates with the insertion of AlxGa1-xN (x = 0.5 to 1.0)/GaN short-period strained-layer superlattices at high temperatures. It appears that the insertion of an AlxGa1-xN (x = 0.5 to 1.0)/GaN short-period strained-layer superlattices having certain thickness and pair combinations was helpful to reduce the etch-pit density in GaN film for more than one order of magnitude. Cross-sectional transmission electron microscopic observations confirm the efficiency of AlxGa1-xN (x = 0.5 to 1.0)/GaN intermediate short-period strained-layer superlattices on blocking threading dislocation propagation in GaN films. The presence of intermediate AlxGa1-xN (x = 0.5 to 1.0)/GaN short-period strained-layer superlattices in a GaN film was believed to encourage threading dislocation density reduction in the film through threading dislocation annihilation and de-multiplication processes involving interactions between 2 edge-type threading dislocations.

Behaviors of AlxGa1-xN (0.5 ≤ x ≤ 1.0)/GaN Short-Period Strained-Layer Superlattices on the Threading Dislocation Density Reduction in GaN Films. J.R.Gong, C.W.Huang, S.F.Tseng, T.Y.Lin, K.M.Lin, W.T.Liao, Y.L.Tsai, B.H.Shi, C.L.Wang: Journal of Crystal Growth, 2004, 260[1-2], 73-8