Growth mode control and micro-Raman characterization of triangular GaN nanowires in a vapor phase epitaxy process

The synthesis of single-crystalline GaN nanowires on c-Al 2O 3 substrates using a vapor phase epitaxy process was studied. The GaN nanowires synthesized at a high NH 3 gas flow rate and thus with a sufficient supply of the N source grew via the vapor–solid mechanism, while those synthesized at a low NH 3 gas flow rate grew via the vapor–liquid–solid mechanism. The internal stress between the nanowires and the substrate was investigated using micro-Raman spectroscopy. The X-ray diffraction indicated that the triangular GaN nanowires have a single-crystalline hexagonal structure.