Growth and doping of semipolar GaN grown on patterned sapphire substrates

Publication date: 1 November 2014
Source:Journal of Crystal Growth, Volume 405
Author(s): F. Scholz , T. Meisch , M. Caliebe , S. Schörner , K. Thonke , L. Kirste , S. Bauer , S. Lazarev , T. Baumbach
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 $\left\{10\overline{1}1\right\}$ or $\left\{11\overline{2}2\right\}$ 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 $5\times {10}^3{\mathrm{cm}}^{-1}$. Moreover, doping experiments have revealed a substantially lower Mg incorporation efficiency on the $\left\{11\overline{2}2\right\}$ surface as compared to the c-plane, whereas Si does not show such differences.