Growth and doping of semipolar GaN grown on patterned sapphire substrates

•Improved semipolar (112¯2) GaN layers on patterned sapphire substrates by SiN nano-mask layer.•Very low stacking fault density below 5×103 cm−1 was obtained.•Lower Mg incorporation into (112¯2) plane as compared to c-plane.

In order to achieve large area semipolar GaN layers with high crystal quality, we have etched trenches into n-plane and r-plane sapphire wafers exposing c-plane-like side-walls, from which GaN stripes can be grown by metalorganic vapor phase epitaxy mainly in c  -direction, forming semipolar {101¯1} or {112¯2} surfaces after coalescence. Here, we describe how to improve such layers by optimizing the side-facet orientation and by including a SiN nanomask interlayer in situ   into the growth process, eventually resulting in a basal plane stacking fault density below 5×103cm−1. Moreover, doping experiments have revealed a substantially lower Mg incorporation efficiency on the {112¯2} surface as compared to the c-plane, whereas Si does not show such differences.