Comparison of microstructure of N-polar GaN/AlGaN/GaN heterostructures grown on different substrates

► N-polar GaN/AlGaN/GaN heterostructures were grown by molecular beam epitaxy. ► The microstructure of these heterostructures was studied using TEM. ► Considerable 1:1 ordering was observed within the AlxGa1−xN layers. ► Threading dislocations were the primary defects in structures grown on SiC. ► Interfacial misfit dislocations and surface pits were observed in samples grown on GaN.