Polarity conversion of GaN nanowires grown by plasma-assisted molecular beam epitaxy

It is demonstrated that the N-polarity of GaN nanowires (NWs) spontaneously nucleated on Si (111) by molecular beam epitaxy can be reversed by intercalation of an Al- or a Ga-oxynitride thin layer. The polarity change has been assessed by a combination of chemical etching, Kelvin probe force microscopy, cathodo- and photoluminescence spectroscopy, and transmission electron microscopy experiments. Cathodoluminescence of the Ga-polar NW section exhibits a higher intensity in the band edge region, consistent with a reduced incorporation of chemical impurities. The polarity reversal method we propose opens the path to the integration of optimized metal-polar NW devices on any kind of substrate. Published under license by AIP Publishing.