Harrison, Samuel and Young, Matthew and Hodgson, Peter David and Young, Robert James and Hayne, Manus and Danos, Eleftherios and Schliwa, A. and Strittmatter, Andre and Lenz, Andrea and Eisele, Holger and Pohl, Udo and Bimberg, Dieter (2016) Heterodimensional charge-carrier confinement in stacked submonolayer InAs in GaAs. Physical review B, 93: 085302. ISSN 1098-0121
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Abstract
Charge-carrier confinement in nanoscale In-rich agglomerations within a lateral InGaAs quantum well (QW) formed from stacked submonolayers (SMLs) of InAs in GaAs is studied. Low-temperature photoluminescence (PL) and magneto-PL clearly demonstrate strong vertical and weak lateral confinement, yielding two-dimensional (2D) excitons. In contrast, high-temperature (400 K) magneto-PL reveals excited states that fit a Fock-Darwin spectrum, characteristic of a zero-dimensional (0D) system in a magnetic field. This paradox is resolved by concluding that the system is heterodimensional: the light electrons extend over several In-rich agglomerations and see only the lateral InGaAs QW, i.e., are 2D, while the heavier holes are confined within the In-rich agglomerations, i.e., are 0D. This description is supported by single-particle effective-mass and eight-band k⋅p calculations. We suggest that the heterodimensional nature of nanoscale SML inclusions is fundamental to the ability of respective optoelectronic devices to operate efficiently and at high speed.