Heavy Si doping: The key in heteroepitaxial growth of a‐plane GaN without basal plane stacking faults?

Abstract

Abstract In this paper, we compare the effectiveness of two different methods regarding the reduction of defect densities in heteroepitaxially grown a‐plane GaN by heavy Si doping. The insertion of well‐established in situ Si x N y nanomasks leads to locally heavy Si δ‐doped GaN. By increasing the Si x N y deposition time in the range from 0 to 300 s the full width at half maxima (FWHM) of the X‐ray diffraction ω‐scans at in‐plane GaN(1 ${\bar {1}}$ 00) and GaN(0002) Bragg reflections decreases from 0.55° to 0.24° and from 0.45° to 0.16°, respectively. When growing without any Si x N y interlayer but instead with continuously heavy Si‐doping, these values are 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 (WHPs) a considerable reduction in defect densities and no hint of basal plane stacking faults (BSFs) 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 (CL).