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

Time-resolved photoluminescence (PL) spectroscopy was used to study the rad iative recombination of free and donor-bound excitons in unintentionally do ped GaN grown by hydride vapor phase epitaxy. Low temperature (4 K), time-i ntegrated PL spectra identified the free exciton (A), the donor-bound excit on peak similar to 6 meV below, and the acceptor-bound exciton similar to 2 0 meV below the free exciton peak. A radiative recombination lifetime of 29 5 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 temp erature, with an increase in lifetime to 530 ps, consistent with the therma l excitation of exciton states. (C) 1999 American Institute of Physics. [S0 003-6951(99)04032-2].