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We found different behaviors of misfit dislocations in a Ga0.83In0.17N single layer and in Ga0.83In0.17N/Ga0.93In0.07N superlattices, both on GaN substrates. In the case of the single layer, misfit dislocations were formed at the GaInN/GaN interfaces and extended through the GaInN layer to the surface. In contrast, the misfit dislocations in the superlattices are bent laterally at interfaces between the Ga0.83In0.17N and Ga0.93In0.07N layers. In addition, most of the dislocations do not reach the surface owing to the formation of dislocation loops. As a result, the dislocation density at the surface of the GaInN superlattice sample was 5×107 cm-2.

Two strain relaxation processes have been observed in AGaN layers grown on thick AlN templates. In Process I, a-type threading dislocations (TDs) with b= 1/3 from the AlN underlayer are inclined away from the [0001] axis toward the directions when they enter the AlGaN film, forming dislocation line projection perpendicular to the Burger vector. In Process II, a+c-type TDs from the AlN underlayer with Burgers vector of b= 1/3 glide on {0111} planes when they enter the AlGaN film to generate interfacial misfit dislocations lying along the directions at the AlGaN/AlN interface.