Study of Charge Distributions and Electrical Properties in GaAs/AlGaAs Single Quantum Well/Nanowire Heterostructures

摘要

By embedding quantum wells (QWs) in semiconductor nanowires (NWs), the confined electronic states perpendicular to the NW axis as well as free movements along the NW axis can be simultaneously achieved. Among them, AlGaAs NWs are ideal candidates for radial two-dimensional GaAs QWs because of their nearly perfect lattice matching, negligible piezoelectric, and strain effects. A series of studies based on AlGaAs NWs with embedded QWs have revealed novel electronic states and outstanding properties. On the other hand, their electrical properties and underlying mechanism at the nanometer scale have less been reported. Herein, the electrical properties of GaAs QW/AlGaAs NW interfaces are quantitatively characterized via off-axis electron holography. Our results reveal that considerable electrons are confined in the GaAs QW, leaving massive holes distributing at the GaAs/AlGaAs hetero-interfaces. In addition, in combination with the first-principles calculations, the redistribution of charges causing band bending at GaAs/AlGaAs interfaces is calculated, which complies well with our experiment. The quantum confinement effect in this heterostructure due to the introduction of GaAs QW is also revealed, which causes the change of related band gap, leading to blue-shift in photoluminescence (PL) spectra. This work provides insight into the nanometer-scale electrical properties of III-V semiconductor NWs comprising QW, which may shed light on optimizing similar hybrid structures as optoelectronic devices in the future.