Dynamics of ground and excited states of bound excitons in gallium nitride

Time-resolved photoluminescence measurements of high-quality GaN show that the spectra of two-electron satellites (TES) in GaN include also lines coming from excited states of a donor-bound exciton (D0X) complex. The lines connected with recombination from the ground and excited states have generally similarly long lifetimes (1.1–1.4 ns, in the case of an exciton bound to oxygen donor). However, analysis of initial dynamics (between 0 and 0.5 ns) shows some transfer of energy between the lines. In fact, the ground-state-related line reaches its maximum 0.1 ns after the excited-state–related line. A rate-equation model taking into account internal transitions in the D0X complex gives a characteristic internal time constant of about 0.2 ns.