CUED Publications database

Modulation doping of GaAs/AlGaAs core-shell nanowires with effective defect passivation and high electron mobility.

Boland, JL and Conesa-Boj, S and Parkinson, P and Tütüncüoglu, G and Matteini, F and Rüffer, D and Casadei, A and Amaduzzi, F and Jabeen, F and Davies, CL and Joyce, HJ and Herz, LM and Fontcuberta i Morral, A and Johnston, MB (2015) Modulation doping of GaAs/AlGaAs core-shell nanowires with effective defect passivation and high electron mobility. Nano Lett, 15. pp. 1336-1342.

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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 × 10(16) 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 cm(2) 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.

Item Type: Article
Uncontrolled Keywords: GaAs mobility modulation doping photoconductivity photoluminescence surface plasmon terahertz spectroscopy Aluminum Arsenicals Electrons Gallium Microscopy, Electron, Scanning Transmission Nanowires
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 17 Jul 2017 18:59
Last Modified: 21 Jun 2018 02:34