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The Johnston Group is a research group within the sub-department of Condensed Matter Physics, which is part of the sub-faculty of Physics at the University of Oxford. Our current research may be divided into three themes (i) Semiconductor nanowires (ii) Terahertz photonic technologies and (iii) Vapour deposited Perovskite materials for photovoltaic applications.

For enquires about the group please contact:
Prof Michael B. Johnston (group leader), M.Johnston@physics.ox.ac.uk
Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, United Kingdom.

Latest Publications


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Single Nanowire Photoconductive Terahertz Detectors
Peng et al. Nano Lett., 15:206-210 (Jan 2015)
[ pdf ][ DOI:10.1021/nl5033843 ]
We have developed a phase sensitive detector of coherent THz radiation based on a single nanowire. The device uses one GaAs/AlGaAs core-shell nanowire as is active component.

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Modulation Doping of GaAs/AlGaAs Core–Shell Nanowires With Effective Defect Passivation and High Electron Mobility
Boland et al. Nano Lett., 15:1336-1342 (Jan 2015)
[ pdf ][ DOI:10.1021/nl504566t ]
We demonstrate effective modulation doping in GaAs nanowires. n-doping results in very long photoconductivity and PL lifetimes of 3.9ns and 2.4ns, in these nanowires.

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Ultrafast Transient Terahertz Conductivity of Monolayer MoS2 and WSe2 Grown by Chemical Vapor Deposition
Docherty et al. ACS Nano, 8:11147-11153 (Nov 2014)
[ pdf ][ DOI:10.1021/nn5034746 ]
We show that the photoconductivity and photoluminescence response time of just 350 fs from CVD-grown monolayer MoS2, and 1 ps from trilayer MoS2 and monolayer WSe2. Our results indicate the potential of these materials as high-speed optoelectronic materials.

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Solution deposition-conversion for planar heterojunction mixed halide perovskite solar cells
Docampo et al. Adv. Energy Mater., 4:1400355 (Oct 2014)
[ pdf ][ DOI:10.1002/aenm.201400355 ]
We present planar, fully solution-processed heterojunction mixed halide solar cells based on the solution deposition-conversion technique.

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Electron Mobilities Approaching Bulk Limits in “Surface-Free” GaAs Nanowires
Joyce et al. Nano Lett., 14:5989-5994 (Sep 2014)
[ pdf ][ DOI:10.1021/nl503043p ]
We demonstrate that engineering the GaAs nanowire surface by overcoating with optimized AlGaAs shells is an effective means of obtaining exceptionally high carrier mobilities and lifetimes.

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Charge carrier recombination channels in the low-temperature phase of organic-inorganic lead halide perovskite thin films
Wehrenfennig et al. APL Mater., 2:081513 (Aug 2014)
[ pdf ][ DOI:10.1063/1.4891595 ]
we present a temperature-dependent study of optical absorption and photoluminescence (PL) emission of vapor-deposited organic-inorganic Perovskite semiconductors exploring the nature of recombination channels in the room- and the low-temperature phase of the material.
Group members April 2012

News

Funded Studentship avaiable in the group for Oct 2015 start
[May 2015] We currently have a vacancy for a fully funded PhD studentship on "Polymer Photonic Structures for Control of Terahertz Light" with the EPSRC Centre for Doctoral Training in Plastic Electronics. [more...]
Postdoctoral Position in Nanowire Spectroscopy
[May 2015] We are currently advertising for a postdoctoral researcher to work on optical spectroscopy of semiconductor nanowires [more...]
Hannah appointed as University Lecturer at Cambridge
[Sept 2013] Dr Hannah Joyce has been appointed as a University Lecturer in the Department of Engineering at the University of Cambridge. Hannah will be leaving us mid-September. [more...]
Callum awarded 2013 EPSRC Doctoral Prize
[May 2013] Callum Docherty has been awarded an EPSRC Doctorial Prize for his work on terahertz spectroscopy of 2D systems. Callum will start postdoctoral work funded by the award early in 2014. [more...]
Noah wins prize for his MPhys Project
[July 2013] Congratulations to Noah Waterfield-Price for winning a Physics Prize for his MPhys project. [more...]