Effect of the X point on the escape of electrons from the quantum well of a double-barrier heterostructure.

Abstract

We describe a photoluminescence study of a series of GaAs/AlAs/GaAs/AlAs/GaAs double-barrier heterostructures. We report the observation in double-barrier heterostructures of photoluminescence from the recombination of electrons at {ital X}-point levels localized in the AlAs barriers, with heavy holes localized in the GaAs quantum well. As the quantum-well width is decreased, the increasing confinement energy of the {Gamma}-point electron level in the quantum well results in increasing interaction with the {ital X}-point levels in the barriers. As the well width is decreased, the integrated {Gamma}-point photoluminescence intensity decreases, and then increases just before the {Gamma}-{ital X} crossover; further decrease in the well width results in monotonic decrease of intensity. This behavior is consistent with eight-band tight-binding calculations of the {Gamma}-point electron quasi-bound-state lifetime.