A RHEED investigation of self-assembled GaN nanowire nucleation dynamics on bare Si and on Si covered with a thin AlN buffer layer

Based on reflection high energy electron diffraction (RHEED) experiments, we show that the nucleation delay of GaN nanowire growth by plasma-assisted molecular beam epitaxy on nitrided Si(111) and on AlN/Si(111) exhibit similar behaviors in function of the substrate temperature and of the Ga flux. On bare Si(111), a finite delay, estimated to be one minute in our system and under our set of growth conditions, is necessary to form and subsequently amorphize crystalline -Si3N4 before GaN can start to form. Although the amorphization time is found to be independent of the substrate temperature, this process adds a supplemental delay within the overall delay in the growth of GaN nanowires on bare Si(111), compared to growth on AlN/Si(111) or on amorphous silicon nitride on Si(111). ((c) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)