Time-resolved photoluminescence studies of an ionized donor-bound exciton in GaN
نویسندگان
چکیده
Time-resolved photoluminescence ~PL! spectroscopy has been used to study the radiative recombination of excitons bound to ionized donors in GaN doped with both Mg and Si at concentrations of 5310/cm and 1.5310/cm, respectively. Low temperature (T;10K) time-resolved, as well as integrated PL spectra, identify an ionized donor-bound ~Si! exciton peak (DX) approximately 11.5 meV below and a neutral acceptor-bound exciton (AX) 20.5 meV below the free exciton peak. Rapid decay of the free exciton emission ~<20 ps! implies that excitons are quickly captured by acceptors and ionized donors. We find the (AX) emission lifetime is consistent with previous measurements for GaN:Mg epilayers, while the (DX) lifetime of 160 ps is longer than that of the well studied neutral donor-bound exciton (DX). The measured (DX) lifetime, in comparison with (DX) and (AX), suggests that the state is stable at low temperature. © 1999 American Institute of Physics. @S0003-6951~99!03604-9#
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