A photoluminescence study of plasma reactive ion etching-induced damage in GaN

GaN films with reactive ion etching (RIE) induced damage were analyzed using photoluminescence (PL). We observed band-edge as well as donor-acceptor peaks with associated phonon replicas, all in agreement with previous studies. While both the control and damaged samples have their band-edge peak location change with temperature following the Varshni formula, its intensity however decreases with damage while the D-A peak increases considerably. Nitrogen post-etch plasma was shown to improve the band edge peak and decrease the D-A peak. This suggests that the N-2 plasma has helped reduce the number of trapped carriers that were participating in the D-A transition and made the D degrees X transition more active, which reaffirms the N-2 post-etch plasma treatment as a good technique to heal the GaN surface, most likely by filling the nitrogen vacancies previously created by etch damage.