Interfaces in heterostructures of AlInGaN/GaN/ Al2O3

Rutherford backscattering/channeling (RBS/C) and X-ray diffraction (XRD) are used to comprehensively characterize a heterostructure of AlInGaN/GaN/ Al2O3(0001). The AlInGaN quaternary layer was revealed to process a high crystalline quality with a minimum yield of 1.4% from RBS/C measurements. The channeling spectrum of 〈12¯13〉 exhibits higher dechanneling than that of 〈0001〉〈0001〉 at the interface of AlInGaN/GaN. XRD measurements prove a coherent growth of AlInGaN on the GaN template layer. Combining RBS/C and XRD measurements, we found that the interface of GaN/ Al2O3 is a nucleation layer, composed of a large amount of disorders and cubic GaN slabs, while the interface of AlInGaN/GaN is free of extra disordering (i.e. compare with the GaN layer). The conclusion is further evidenced by transmission electron microscopy (TEM).