Surface topology caused by dislocations in polar, semipolar, and nonpolar InGaN/GaN heterostructures

The impact of dislocations on surface topology as well as on quantum well emission in c-plane, semipolar, and nonpolar InGaN/GaN heterostructures is being analyzed by micro-photoluminescence and white-light-interferometry. V-pits with (1011) and (1014) side facets are identified in a (1012) semipolar heterostructure. Hillocks formed by spiral growth around screw dislocations change from hexagonal to triangular to rectangular shape in polar, semipolar, and nonpolar heterostructures, respectively, reflecting the symmetry of the individual surface. The emission in semipolar quantum wells, grown homoepitaxially on bulk GaN substrates, show dark stripes aligned with misfit dislocations. For (1122) and (2021) orientation, these dark stripes are perpendicular and parallel, respectively, to surface striation.