Tunneling of photoexcited holes through a double-barrier resonant tunneling structure observed by time-resolved photoluminescence

The tunneling dynamics of photogenerated holes in a biased GaAs/AlGaAs double-barrier resonant tunneling structure is studied using time-resolved photoluminescence. For voltages biasing the structure in the resonant tunneling regime, a single exponential time decay was observed. However, for voltages which bias the structure in the nonresonant tunneling regime, beyond the region of negative differential resistance, the exciton decays with two time constants: one similar to that observed at low voltages and one that is approximately one order of magnitude slower. We attribute the fast time constant to the decay of exciton population originating from holes photoexcited directly in the well. The slower time constant is associated with excitons that are created from holes which are photoexcited in the GaAs contact region, and which subsequently tunnel into the well.