The Fundamental Band-edge Optical Transitions in GaN: Exciton, Phonon, and their Coupling Effects

GaN, a polar semiconductor with wide band gap, is the fundamental material of blue LEDs and emerging solid state lighting devices. It also has tremendous applications in high-power and high-temperature microelectronics. In this seminar, I’ll present a study of the fundamental optical transitions in GaN at different temperatures. Luminescence spectral features of various excitons, including heavy- and light-hole free excitons, shallow-donor-bound excitons and acceptor-like surface-defect-bound excitons, as well as their coupling with longitudinal optical phonons have been examined in the study. Temperature effect in these optical transitions of GaN has been particularly addressed. Some unidentified spectral structures will be also reported.