Enhanced hetero-dimensional electron-spin injection in a resonantly tunnel-coupled InGaAs quantum dot-well nanosystem

Abstract

Enhanced hetero-dimensional electron-spin injection in a resonantly tunnel-coupled InGaAs quantum dot (QD)-well (QW) nanosystem has been demonstrated. Photo-excited spin-polarized electrons in the 2-dimensional (2D) QW can be injected into 0D QDs via tunneling, detected by circularly polarized photoluminescence from the QDs, where the tunnel-coupling potential is modified by applying electric fields. We find the existence of a specific bias enabling a highly efficient spin injection. Resonant coupling between the QW and QD excited states can be formed through a 2D wetting layer at this specific bias, resulting in higher rates of electron injection without a significant loss of spin.