title: Extremely high aspect ratio GaAs and GaAs/AlGaAs nanowaveguides fabricated using chlorine ICP etching with N2-promoted passivation.
abstract: Semiconductor nanowaveguides are the key structure for light-guiding nanophotonics applications. Efficient guiding and confinement of single-mode light in these waveguides require high aspect ratio geometries. In these conditions, sidewall verticality becomes crucial. We fabricated such structures using a top-down process combining electron beam lithography and inductively coupled plasma (ICP) etching of hard masks and GaAs/AlGaAs semiconductors with Al concentrations varying from 0 to 100%. The GaAs/AlGaAs plasma etching was a single-step process using a Cl(2)/BCl(3)/Ar gas mixture with various fractions of N(2). Scanning electron microscope (SEM) observations showed that the presence of nitrogen generated the deposition of a passivation layer, which had a significant effect on sidewall slope. Near-ideal vertical sidewalls were obtained over a very narrow range of N(2), allowing the production of extremely high aspect ratios (>32) for 80 nm wide nanowaveguides.
authors.affiliation: Centre de Recherche en Nanofabrication et en Nanocaractérisation (CRN2), Université de Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Maïté
authors.initials: M
authors.lastname: Volatier
authors.forename: David
authors.initials: D
authors.lastname: Duchesne
authors.forename: Roberto
authors.initials: R
authors.lastname: Morandotti
authors.forename: Richard
authors.initials: R
authors.lastname: Arès
authors.forename: Vincent
authors.initials: V
authors.lastname: Aimez