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Visualising highly localised luminescence in GaN/AlN heterostructures in nanowires

By Luiz Fernando Zagonel, L Rigutti, M Tchernycheva, G Jacopin, R Songmuang and M Kociak


International audienceThe 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

Topics: Spectrum Image, Cathodoluminescence, Nanowires, Galium Nitride, GaN, GaN AlN, TEM, STEM, CL, Scanning transmission Electron Microscopy, 73.40.Kp III-V semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions 68.37.Lp Transmission electron microscopy (TEM) 78.67.Lt Quantum wires 78.60.Hk Cathodoluminescence, ionoluminescence 61.46.-w Structure of nanoscale materials 71.20.Nr Semiconductor compounds, [PHYS]Physics [physics]
Publisher: 'IOP Publishing'
Year: 2012
DOI identifier: 10.1088/0957-4484/23/45/455205
OAI identifier: oai:HAL:hal-01114176v1
Provided by: HAL-CEA

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