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The influence of surfaces on the transient terahertz conductivity and electron mobility of GaAs nanowires

Joyce, Hannah Jane; Baig, Sarwat A; Parkinson, Patrick; Davies, Christopher L.; Boland, Jessica L.; Tan, Hoe; Jagadish, Chennupati; Herz, Laura; Johnston, Michael B

Description

Bare unpassivated GaAs nanowires feature relatively high electron mobilities (400-2100 cm2 V-1 s-1) and ultrashort charge carrier lifetimes (1-5 ps) at room temperature. These two properties are highly desirable for high speed optoelectronic devices, including photoreceivers, modulators and switches operating at microwave and terahertz frequencies. When engineering these GaAs nanowire-based devices, it is important to have a quantitative understanding of how the charge carrier mobility and...[Show more]

dc.contributor.authorJoyce, Hannah Jane
dc.contributor.authorBaig, Sarwat A
dc.contributor.authorParkinson, Patrick
dc.contributor.authorDavies, Christopher L.
dc.contributor.authorBoland, Jessica L.
dc.contributor.authorTan, Hoe
dc.contributor.authorJagadish, Chennupati
dc.contributor.authorHerz, Laura
dc.contributor.authorJohnston, Michael B
dc.date.accessioned2020-12-20T20:58:07Z
dc.date.available2020-12-20T20:58:07Z
dc.identifier.issn0022-3727
dc.identifier.urihttp://hdl.handle.net/1885/218489
dc.description.abstractBare unpassivated GaAs nanowires feature relatively high electron mobilities (400-2100 cm2 V-1 s-1) and ultrashort charge carrier lifetimes (1-5 ps) at room temperature. These two properties are highly desirable for high speed optoelectronic devices, including photoreceivers, modulators and switches operating at microwave and terahertz frequencies. When engineering these GaAs nanowire-based devices, it is important to have a quantitative understanding of how the charge carrier mobility and lifetime can be tuned. Here we use optical-pump-terahertz-probe spectroscopy to quantify how mobility and lifetime depend on the nanowire surfaces and on carrier density in unpassivated GaAs nanowires. We also present two alternative frameworks for the analysis of nanowire photoconductivity: one based on plasmon resonance and the other based on Maxwell-Garnett effective medium theory with the nanowires modelled as prolate ellipsoids. We find the electron mobility decreases significantly with decreasing nanowire diameter, as charge carriers experience increased scattering at nanowire surfaces. Reducing the diameter from 50 nm to 30 nm degrades the electron mobility by up to 47%. Photoconductivity dynamics were dominated by trapping at saturable states existing at the nanowire surface, and the trapping rate was highest for the nanowires of narrowest diameter. The maximum surface recombination velocity, which occurs in the limit of all traps being empty, was calculated as 1.3 × 106 cm s-1. We note that when selecting the optimum nanowire diameter for an ultrafast device, there is a trade-off between achieving a short lifetime and a high carrier mobility. To achieve high speed GaAs nanowire devices featuring the highest charge carrier mobilities and shortest lifetimes, we recommend operating the devices at low charge carrier densities
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherInstitute of Physics Publishing
dc.sourceJournal of Physics D: Applied Physics
dc.titleThe influence of surfaces on the transient terahertz conductivity and electron mobility of GaAs nanowires
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume50
dc.date.issued2017
local.identifier.absfor090604 - Microelectronics and Integrated Circuits
local.identifier.ariespublicationa383154xPUB6485
local.type.statusPublished Version
local.contributor.affiliationJoyce, Hannah Jane, University of Cambridge, UK
local.contributor.affiliationBaig, Sarwat A, University of Cambridge
local.contributor.affiliationParkinson, Patrick, University of Manchester
local.contributor.affiliationDavies, Christopher L., University of Oxford
local.contributor.affiliationBoland, Jessica L., University of Oxford
local.contributor.affiliationTan, Hoe, College of Science, ANU
local.contributor.affiliationJagadish, Chennupati, College of Science, ANU
local.contributor.affiliationHerz, Laura, University of Oxford
local.contributor.affiliationJohnston, Michael B, University of Oxford
local.bibliographicCitation.issue22
local.identifier.doi10.1088/1361-6463/aa6a8f
dc.date.updated2020-11-23T11:17:37Z
local.identifier.scopusID2-s2.0-85019466475
CollectionsANU Research Publications

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