title: Increased Photoconductivity Lifetime in GaAs Nanowires by Controlled n-Type and p-Type Doping.
abstract: Controlled doping of GaAs nanowires is crucial for the development of nanowire-based electronic and optoelectronic devices. Here, we present a noncontact method based on time-resolved terahertz photoconductivity for assessing n- and p-type doping efficiency in nanowires. Using this technique, we measure extrinsic electron and hole concentrations in excess of 10(18) cm(-3) for GaAs nanowires with n-type and p-type doped shells. Furthermore, we show that controlled doping can significantly increase the photoconductivity lifetime of GaAs nanowires by over an order of magnitude: from 0.13 ns in undoped nanowires to 3.8 and 2.5 ns in n-doped and p-doped nanowires, respectively. Thus, controlled doping can be used to reduce the effects of parasitic surface recombination in optoelectronic nanowire devices, which is promising for nanowire devices, such as solar cells and nanowire lasers.
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford, OX1 3PU, United Kingdom.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Boland
authors.forename: Alberto
authors.initials: A
authors.lastname: Casadei
authors.forename: Gözde
authors.initials: G
authors.lastname: Tütüncüoglu
authors.forename: Federico
authors.initials: F
authors.lastname: Matteini
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford, OX1 3PU, United Kingdom.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Davies
authors.forename: Fauzia
authors.initials: F
authors.lastname: Jabeen
authors.affiliation: Department of Engineering, University of Cambridge , 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom.
authors.forename: Hannah J
authors.initials: HJ
authors.lastname: Joyce
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford, OX1 3PU, United Kingdom.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Herz
authors.forename: Anna
authors.initials: A
authors.lastname: Fontcuberta I Morral
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford , Parks Road, Oxford, OX1 3PU, United Kingdom.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Johnston
keywords: GaAs; carrier lifetime; mobility; n-type doping; nanowires; p-type doping; photoconductivity; surface recombination; surface states; terahertz spectroscopy