Sequential hole tunneling in n-type AlAs/GaAs resonant-tunneling structures from time-resolved photoluminescence

Time-resolved photoluminescence measurements on two n-type double-barrier AlAs/GaAs resonant tunneling structure devices under operation reveal that sequential tunneling of minority carriers governs the time dependence of the photoluminescence. Both the quantum well and the ${\mathit{n}}^{+}$-type GaAs emission reflect the hole transport from the accumulation layer into the quantum well and the escape through the second barrier, which is described in a three-level model. In the ${\mathit{L}}_{\mathit{B}}$=4 nm barrier sample, transport rates are unchanged from T=80 K to room temperature, which supports the tunneling character of the hole transport. Furthermore, the single barrier tunneling rate monotonously increases with applied electric field, and is much larger in a narrow-barrier device (${\mathit{L}}_{\mathit{B}}$=3 nm).