Misoriented domains in (0001)-GaN/(111)-Ge grown by molecular beam epitaxy

Structural characterization has been performed on (0001)-GaN epilayers grown on (111)-Ge substrates using plasma assisted molecular beam epitaxy. By combining high-resolution x-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy, it has been shown that the GaN epilayer consists of misoriented domains. The domains are rotated about the GaN-[0001] (Ge-[111]) zone axis by 8° with respect to each other and by ±4° with respect to the Ge substrate. These domains need to be eliminated to reduce grain boundary defects and improve GaN crystal quality.