Observation of dielectrically confined excitons in ultrathin GaN nanowires up to room temperature

Abstract

The realization of semiconductor structures with stable excitons at room temperature is crucial for the development of excitonics and polaritonics. Quantum confinement has commonly been employed for enhancing excitonic effects in semiconductor heterostructures. Dielectric confinement, which is potentially much stronger, has proven to be more difficult to achieve because of the rapid nonradiative surface/interface recombination in hybrid dielectric-semiconductor structures. Here, we demonstrate intense excitonic emission from bare GaN nanowires with diameters down to 6 nm. The large dielectric mismatch between the nanowires and vacuum greatly enhances the Coulomb interaction, with the thinnest nanowires showing the strongest dielectric confinement and the highest radiative efficiency at room temperature. In situ monitoring of the fabrication of these structures allows one to accurately control the degree of dielectric enhancement. These ultrathin nanowires may constitute the basis for the fabrication of advanced low-dimensional structures with an unprecedented degree of confinement.

arXiv commentThis document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Nano Letters, after peer review

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• A route for the top-down fabrication of ordered ultrathin GaN nanowires
• External control of GaN band bending using phosphonate self-assembled monolayers
• Crystal-phase quantum dots in GaN quantum wires
• Density control of GaN nanowires at the wafer scale using self-assembled SiN${}_x$ patches on sputtered TiN(111)
• Influence of strain relaxation in axial (In,Ga)N/GaN nanowire heterostructures on their electronic properties