Optical gain spectra in semipolar {2021} oriented green InGaN LDs in comparison with (0001) LDs

摘要

Optical gain is assessed for a green laser diode (LD) grown on a semipolar {2021} GaN substrate. The estimated internal loss is 20±5 /cm, and the maximum gain becomes saturated with the injection current, suggesting the existence of gain suppression mechanisms. The quantum confined Stark effect due to the pn junction, state filling, and screening of polarization-induced electric fields can explain shifts in the gain and the emission peaks with the injection current. The tail states in {2021} LDs are much smaller than those in (0001) LDs, and are not the major cause of the gain suppression in {2021} LDs, in contrast to (0001) LDs.