Self-induced growth of GaN nanowires by molecular beam epitaxy: A critical review of the formation mechanisms

GaN nanowires, also called nanocolumns, have emerged over the last decade as promising nanosized building blocks for a wide variety of optoelectronic devices. In contrast to other III-V semiconductors, GaN nanowires have the ability to grow catalyst-free within the self-induced approach by plasma-assisted molecular beam epitaxy, which does not require the use of any foreign materials or patterned substrate. The self-induced growth has accordingly been considered as a valuable growth mode to form GaN nanowires on a wide number of substrates such as Si, Al2O3, diamond or SiC. The formation mechanisms have extensively been investigated and are specifically reviewed here from the very onset of the nucleation phase through the elongation phase to the coalescence process. A general approach of the self-induced growth of GaN nanowires is gained. ((c) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)