InGaAs/GaAsP asymmetric quantum wells for enhancing carrier escape through resonant tunneling

In the multiple quantum wells system, deep well supplies wide absorption range. But at the same time, the large band offset would increase the thermionic escape time constant of carriers exponentially. We utilized resonant tunneling effect to assist the carrier collection in InGaAs/GaAsP strain-balanced multiple quantum wells (MQWs). Through the optimization of confinement energy levels and barrier thicknesses, the collection time of photo-generated carriers is calculated to be reduced significantly from several ns to a few hundred ps compared with conventional multiple quantum wells. The asymmetric MQWs for tunneling-assisted carrier escape were fabricated successfully and the carrier collection time was investigated using time-resolved photoluminescence. The advantage of the tunneling design has been confirmed.