Time Evolution of Excitonic Absorption Bleaching of Resonant Tunneling Bi-Quantum-Well Structures

We report the time evolution of excitonic absorption bleaching in resonant tunneling bi-quantum-well (TBQ) structures, in which the ground electron level in a narrow well has the same energy as the second electron level in a wide well. In resonant TBQ structure, we observed a reduction in the absorption recovery time and an increase in the tail-to-peak ratio of the absorption change. By comparing the absorption change of resonant TBQ with the e2-hh2 excitonic absorption change of conventional multiple quantum wells (MQW), we show that the increase in the tail-to-peak ratio of a resonant TBQ can be attributed to the thermally remaining holes in the first excited subband of heavy holes.