Reduction of threading dislocations in InGaN/GaN double heterostructure through the introduction of low-temperature GaN intermediate layer

The reduction mechanism of threading dislocation at the interface of InGaN/low-temperature GaN (LT-GaN) layers was investigated by atomic force microscopy, transmission electron microscopy and secondary ion mass spectroscopy measurements. Introducing the LT-GaN intermediate layer onto the InGaN active layer not only prevented indium evaporation during the growth of the p-GaN layer but also suppressed the propagation of threading dislocations from InGaN to p-GaN. The propagation of threading dislocations is reduced by the formation of two-dimensional lateral islands, and further defect generation is prevented by the formation of In_xGa_1-xN alloy due to the relaxation of lattice mismatch between active InGaN and p-GaN.