Luminescence related to high density of Mg-induced stacking faults in homoepitaxially grown GaN

Abstract

The effect of Mg doping on stacking fault (SF) formation in $c$-plane GaN grown by metal-organic chemical-vapor deposition has been studied for Mg concentration between 2 \ifmmode\times\else\texttimes\fi{} 10${}^{18}$ cm${}^{\ensuremath{-}3}$ and 5 \ifmmode\times\else\texttimes\fi{} 10${}^{19}$ cm${}^{\ensuremath{-}3}$. Transmission electron microscopy studies demonstrate a direct correlation between the increasing Mg content and the number of small (3--10-nm long) SFs present. The energy dispersive x-ray analysis (EDX) line profile of a SF shows that the Mg-impurity atom resides at a distance approximately 5 nm from the SF. Cathodoluminescence (CL) mapping reveals that the Mg-doped regions radiate at energies corresponding to known SF emission peaks. SF-related peaks in CL spectra show metastability, which may be attributed to transfer processes involving Mg acceptors and nearby associated SFs.