Spectral and temporal resolution of recombination from multiple excitation states in modulation-doped AlGaN/GaN multiple quantum well heterostructures

Time-resolved photoluminescence measurements of carrier lifetimes in modulation-doped s100 Åd AlxGa1−xN/ s100 Åd GaN multiple quantum well heterostructures are reported. The photoluminescence sPLd spectrum exhibits several lines associated with recombination of carriers from multiple excited electron states to the hole ground state. The PL decay times associated with ground state recombination, e0h0, are found to be much longer than the inverse repetition rate of our system s20 msd and estimated to be 9 ms. The experimental lifetimes associated with carrier recombination from excited states vary between 4 ms for the first excited state, e1h0, and 4.5 ns for the fourth excited state, e4h0. These lifetimes are in very good agreement with a self-consistent calculation of radiative recombination lifetimes which takes into account piezoelectric and spontaneous polarization. The significant differences in recombination lifetimes are the result of the large built-in electric field in the wells s0.5 MV/cmd. © 2005 American Institute of Physics. fDOI: 10.1063/1.1905785g