The effectiveness of two different methods for the reduction of defect densities in hetero-epitaxially grown a-plane GaN by heavy Si doping were compared. The insertion of well-established in situ SixNy nanomasks led to locally heavy Si δ-doped GaN. By increasing the SixNy deposition time in the range from 0 to 300s the full width at half maxima of the X-ray diffraction ω-scans at in-plane GaN(1¯1•0) and GaN(00•2) Bragg reflections decreases from 0.55° to 0.24° and from 0.45° to 0.16°, respectively. When growing without any SixNy interlayer but instead with continuously heavy Si-doping, these values were further decreased to 0.13° and 0.15°, respectively. By measuring several higher order reflections and detailed evaluation of the ω-scan broadening in Williamson–Hall-plots a considerable reduction in defect densities and no hint of basal plane stacking faults were found for the heavy Si doped a-plane GaN sample. To verify this result the micro-structural properties of this sample were additionally investigated by transmission electron microscopy and cathodoluminescence.

Heavy Si Doping: the Key in Heteroepitaxial Growth of a-Plane GaN without Basal Plane Stacking Faults? M.Wieneke, M.Noltemeyer, B.Bastek, A.Rohrbeck, H.Witte, P.Veit, J.Bläsing, A.Dadgar, J.Christen, A.Krost: Physica Status Solidi B, 2011, 248[3], 578–82