Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures

Intrinsic, heterointerface excitonic states in GaAs(n)/Al0.3Ga0.7As(p) double heterostructures

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We have used extensive photoluminescence (PL), PL time-decay measurements, and detailed quantum mechanical modeling to both interpret and quantify the electronic and optical properties of free excitons localized near heterointerfaces. Through detailed spectroscopic measure of the recombination kinetics of the recently observed H-band emission, we find this emission arises from the radiative decay of such weakly bound (≃0.5 meV) excitonic species confined to the hole-attractive quantum potentials formed at the p-n heterointerfaces. Detailed measurements in virtually "interface-free" double GaAs(n)/Al0.3Ga0.7As(p) heterostructures shows the effects of GaAs layer thickness upon the H-band kinetics - thus confirming quasi-2D excitons become effectively "shared" by both heterointerfaces for sufficiently thin GaAs layers (<0.5 μm). Moreover, we find detailed dynamics of these 2D excitons to be influenced by nonradiative interfacial recombination present in nonideal structures. Lastly, we use a novel, all-optical technique to measure the transport properties of these quasi-2D excitons, and find exceedingly long-range (>400 μm) low temperature diffusion.