Tunneling at room temperature in GaAs/AlGaAs asymmetric coupled double quantum wells observed via time resolved photoluminescence spectroscopy

We have demonstrated experimental evidence of non-resonant tunneling at room temperature in GaAs/AlGaAs asymmetric coupled double quantum wells (ACDQW's) using time-resolved photoluminescence (TRPL) spectroscopy at 300 K. Two ACDQW samples (A and B) with a barrier thickness of 25 Å were grown via molecular beam epitaxy. The energy separation (ΔE) between the ground state of the conduction band of the wide well and that of the narrow well are 42.7 meV and 19.5 meV, for samples A and B respectively. The TRPL measurement revealed a double decay rate in sample A whose ΔE is greater than one GaAs longitudinal optical phonon energy (36 meV), suggesting a phonon assisted tunneling mechanism. The evidence of tunneling was supported by measuring the relative intensity of the PL contributions from the narrow and wide well at 10 K.