Time-resolved photoluminescence studies of free and donor-bound exciton in GaN grown by hydride vapor phase epitaxy

Time-resolved photoluminescence (PL) spectroscopy was used to study the radiative recombination of free and donor-bound excitons in unintentionally doped GaN grown by hydride vapor phase epitaxy. Low temperature (4 K), time-integrated PL spectra identified the free exciton (A), the donor-bound exciton peak similar to 6 meV below, and the acceptor-bound exciton similar to 20 meV below the free exciton peak. A radiative recombination lifetime of 295 ps for the free exciton and 530 ps for donor-bound exciton were found at 4 K. The decay of the free exciton remained single exponential to room temperature, with an increase in lifetime to 530 ps, consistent with the thermal excitation of exciton states. (C) 1999 American Institute of Physics. [S0003-6951(99)04032-2].