Modulation Doping of GaAs/AlGaAs Core–Shell Nanowires With Effective Defect Passivation and High Electron Mobility
Open Access
- 20 January 2015
- journal article
- letter
- Published by American Chemical Society (ACS) in Nano Letters
- Vol. 15 (2), 1336-1342
- https://doi.org/10.1021/nl504566t
Abstract
Reliable doping is required to realize many devices based on semiconductor nanowires. Group III–V nanowires show great promise as elements of high-speed optoelectronic devices, but for such applications it is important that the electron mobility is not compromised by the inclusion of dopants. Here we show that GaAs nanowires can be n-type doped with negligible loss of electron mobility. Molecular beam epitaxy was used to fabricate modulation-doped GaAs nanowires with Al0.33Ga0.67As shells that contained a layer of Si dopants. We identify the presence of the doped layer from a high-angle annular dark field scanning electron microscopy cross-section image. The doping density, carrier mobility, and charge carrier lifetimes of these n-type nanowires and nominally undoped reference samples were determined using the noncontact method of optical pump terahertz probe spectroscopy. An n-type extrinsic carrier concentration of 1.10 ± 0.06 × 1016 cm–3 was extracted, demonstrating the effectiveness of modulation doping in GaAs nanowires. The room-temperature electron mobility was also found to be high at 2200 ± 300 cm2 V–1 s–1 and importantly minimal degradation was observed compared with undoped reference nanowires at similar electron densities. In addition, modulation doping significantly enhanced the room-temperature photoconductivity and photoluminescence lifetimes to 3.9 ± 0.3 and 2.4 ± 0.1 ns respectively, revealing that modulation doping can passivate interfacial trap states.Keywords
Funding Information
- Engineering and Physical Sciences Research Council (EP/H016368/1)
- Schweizerische Nationalfonds zur Förderung der Wissenschaftlichen Forschung (137648, 156081, 156081)
- Royal Commission for the Exhibition of 1851
This publication has 51 references indexed in Scilit:
- Growth of n-Doped and p-Doped GaAs Nanowires by Au-Assisted Metalorganic Chemical Vapor Deposition: Effect of Dopants Flux RatesAdvanced Materials Research, 2013
- Ultralow Surface Recombination Velocity in InP Nanowires Probed by Terahertz SpectroscopyNano Letters, 2012
- Doping of semiconductor nanowiresJournal of Materials Research, 2011
- III–V semiconductor nanowires for optoelectronic device applicationsProgress in Quantum Electronics, 2011
- GaAs Core−Shell Nanowires for Photovoltaic ApplicationsNano Letters, 2009
- Single nanowire photovoltaicsChemical Society Reviews, 2009
- Transient Terahertz Conductivity of GaAs NanowiresNano Letters, 2007
- Surface plasmon–polariton length scales: a route to sub-wavelength opticsJournal of Optics A: Pure and Applied Optics, 2006
- Transient photoconductivity in GaAs as measured by time-resolved terahertz spectroscopyPhysical Review B, 2000
- Empirical low-field mobility model for III–V compounds applicable in device simulation codesJournal of Applied Physics, 2000