Compensation mechanism of carriers within weakly coupled quantum wells

Applied Physics Letters, Volume 118, Issue 12, March 2021. The study of coupling effect (CE) within low-dimensional quantum structures is essential not only for the comprehensive understanding of quantum transport but also for improving the performances of photoelectric devices. Recently, electronically weakly coupled quantum well (QW) structures pave the way for low threshold lasing, but the related coupling mechanism has not been clarified yet. Here, we report the direct experimental evidence of compensation mechanism in the carrier migration process within weakly coupled double QWs (DQWs). It is proved that the leakage rate of charges could be modulated within the two InGaSb QWs of the DQW structure owing to CE. Compared to the single QW configuration, the dissipation of carriers from the QWs within the DQW structure is alleviated under an external field. Further, radiative recombination efficiency for the DQW structure could be enhanced to obtain a lower threshold power. Thus, it may be deduced that the carrier compensation effect between QWs profoundly impacts the multiple-QW laser performance.