Competition Between Tunneling and Exciton Formation of Photoexcited Carriers in Asymmetric Double Quantum Wells

Abstract : Time-resolved photoluminescence (TRPL) spectroscopy has been utilized by various groups to determine resonant and nonresonant tunneling times of electrons as well as of holes in asymmetric double quantum well (ADWQ) structures. The main disadvantage of the TRPL method arises from the fact that it is impossible to measure electron and hole tunneling times simultaneously or to determine hole tunneling times directly in the absence of an electric field. These drawbacks are inherent to the linear TRPL technique since the photoluminescence (PL) decay time of the narrow quantum well (QWn) depends only on the tunneling time of the carrier type which tunnels faster.