Temperature-dependent spin injection dynamics in InGaAs/GaAs quantum well-dot tunnel-coupled nanostructures

摘要

Time-resolved optical spin orientation spectroscopy was employed to investigate the temperature-dependent electron spin injection in In0.1Ga0.9As quantum well (QW) and In0.5Ga0.5As quantum dots (QDs) tunnel-coupled nanostructures with 4, 6, and 8 nm-thick GaAs barriers. The fast picosecond-ranged spin injection from QW to QD excited states (ES) was observed to speed up with temperature, as induced by pronounced longitudinal-optical (LO)-phonon-involved multiple scattering process, which contributes to a thermally stable and almost fully spin-conserving injection within 5-180 K. The LO-phonon coupling was also found to cause accelerated electron spin relaxation of QD ES at elevated temperature, mainly via hyperfine interaction with random nuclear field. (C) 2016 AIP Publishing LLC.