Visualising highly localised luminescence in GaN/AlN heterostructures in nanowires

Abstract

The optical properties of a stack of GaN/AlN quantum discs (QDiscs) in a GaN nanowire have been studied by spatially resolved cathodoluminescence (CL) at the nanoscale (nanoCL) using a Scanning Transmission Electron Microscope (STEM) operating in spectrum imaging mode. For the electron beam excitation in the QDisc region, the luminescence signal is highly localized with spatial extension as low as 5 nm due to the high band gap difference between GaN and AlN. This allows for the discrimination between the emission of neighbouring QDiscs and for evidencing the presence of lateral inclusions, about 3 nm thick and 20 nm long rods (quantum rods, QRods), grown unintentionally on the nanowire sidewalls. These structures, also observed by STEM dark-field imaging, are proven to be optically active in nanoCL, emitting at similar, but usually shorter, wavelengths with respect to most QDiscs.

25 Pages, 18 Figures, manuscript format

References in corpus (5)

• Optical excitations in electron microscopy
• Nanometer Scale Spectral Imaging of Quantum Emitters in Nanowires and Its Correlation to Their Atomically Resolved Structure
• High resolution cathodoluminescence hyperspectral imaging of surface features in InGaN/GaN multiple quantum well structures
• Quantum transport in GaN/AlN double-barrier heterostructure nanowires
• Carrier Confinement in GaN/AlGaN Nanowire Heterostructures for 0 < x <= 1

Cited by in corpus (5)

• Tunneling-current-induced local excitonic luminescence in p-doped WSe${}_2$ monolayers
• Nanometre scale monitoring of the quantum confined stark effect and emission efficiency droop in multiple GaN/AlN quantum disks in nanowires
• Assessment of AlGaN/AlN superlattices on GaN nanowires as active region of electron-pumped ultraviolet sources
• Localization and defects in axial (In,Ga)N/GaN nanowire heterostructures investigated by spatially-resolved luminescence spectroscopy
• Design and implementation of a device based on an off-axis parabolic mirror to perform luminescence experiments in a scanning tunneling microscope