title: Nanometer scale spectral imaging of quantum emitters in nanowires and its correlation to their atomically resolved structure.
abstract: We report the spectral imaging in the UV to visible range with nanometer scale resolution of closely packed GaN/AlN quantum disks in individual nanowires using an improved custom-made cathodoluminescence system. We demonstrate the possibility to measure full spectral features of individual quantum emitters as small as 1 nm and separated from each other by only a few nanometers and the ability to correlate their optical properties to their size, measured with atomic resolution. The direct correlation between the quantum disk size and emission wavelength provides evidence of the quantum confined Stark effect leading to an emission below the bulk GaN band gap for disks thicker than 2.6 nm. With the help of simulations, we show that the internal electric field in the studied quantum disks is smaller than what is expected in the quantum well case. We show evidence of a clear dispersion of the emission wavelengths of different quantum disks of identical size but different positions along the wire. This dispersion is systematically correlated to a change of the diameter of the AlN shell coating the wire and is thus attributed to the related strain variations along the wire. The present work opens the way both to fundamental studies of quantum confinement in closely packed quantum emitters and to characterizations of optoelectronic devices presenting carrier localization on the nanometer scale.
authors.affiliation: Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud XI, Orsay, France.
authors.forename: Luiz Fernando
authors.initials: LF
authors.lastname: Zagonel
authors.forename: Stefano
authors.initials: S
authors.lastname: Mazzucco
authors.forename: Marcel
authors.initials: M
authors.lastname: Tencé
authors.forename: Katia
authors.initials: K
authors.lastname: March
authors.forename: Romain
authors.initials: R
authors.lastname: Bernard
authors.forename: Benoît
authors.initials: B
authors.lastname: Laslier
authors.forename: Gwénolé
authors.initials: G
authors.lastname: Jacopin
authors.forename: Maria
authors.initials: M
authors.lastname: Tchernycheva
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Rigutti
authors.forename: Francois H
authors.initials: FH
authors.lastname: Julien
authors.forename: Rudeesun
authors.initials: R
authors.lastname: Songmuang
authors.forename: Mathieu
authors.initials: M
authors.lastname: Kociak
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008029:Lighting / Q000295:instrumentation*; D036103:Nanotechnology / Q000295:instrumentation*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D045663:Quantum Dots; D012542:Scattering, Radiation; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*