Symmetrically abrupt GaN/AlGaN superlattices by alternative interface–interruption scheme

We report an alternative interruption scheme to effectively improve the abruptness of GaN/AlGaN superlattices by minimizing the asymmetric feature of different types of heterointerfaces. It is found by x-ray diffraction that the interface abruptness is degraded and the GaN thickness is reduced with the interruption time increasing. Detailed investigation with scanning transmission electron microscopy demonstrates that the Al diffusion and the interface etching effect at the GaN/AlGaN interface are the critical reasons leading to the interfacial asymmetry. An alternative interface–interruption scheme is then proposed to enhance the abruptness of the superlattice interfaces, and consequently, the emission efficiency can also be significantly enhanced.