Surface passivated InAs/InP core/shell nanowires

• Published in: Semiconductor science and technology Vol. 25; no. 2; pp. 024011 - 024011 (7)
• Main Authors: van Tilburg, J W W, Algra, R E, Immink, W G G, Verheijen, M, Bakkers, E P A M, Kouwenhoven, L P
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.02.2010; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Exact sciences and technology; Physics; Quantum wires; Accumulation layers; Roughness; Impurity ionization; Low field; Indium arsenides; Indium phosphide; Surface scattering; Electron mobility; Nanowires; Electron density; Surface layers; Electron-impurity interactions; Passivation
• ISSN: 0268-1242; 1361-6641
• DOI: 10.1088/0268-1242/25/2/024011

We report the growth and characterization of InAs nanowires capped with a 0.5-1 nm epitaxial InP shell. The low-temperature field-effect mobility is increased by a factor 2-5 compared to bare InAs nanowires. We extract the highest low-temperature peak electron mobilities obtained for nanowires to this date, exceeding 20 000 cm2 V s-1. The electron density in the nanowires, determined at zero gate voltage, is reduced by an order of magnitude compared to uncapped InAs nanowires. For smaller diameter nanowires we find an increase in electron density, which can be related to the presence of an accumulation layer at the InAs/InP interface. However, compared to the surface accumulation layer in uncapped InAs, this electron density is much reduced. We suggest that the increase in the observed field-effect mobility can be attributed to an increase of conduction through the inner part of the nanowire and a reduction of the contribution of electrons from the low-mobility accumulation layer. Furthermore the shell around the InAs reduces the surface roughness scattering and ionized impurity scattering in the nanowire.