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Carter-Searjeant S, Fairclough SM, Haigh SJ, Zou Y, Curry RJ, Taylor PN, Huang C, Fleck R, Machado P, Kirkland AI, Green MA. Nanoscale LiZnN - Luminescent Half-Heusler Quantum Dots. ACS Appl Opt Mater 2023; 1:1169-1173. [PMID: 37384133 PMCID: PMC10294247 DOI: 10.1021/acsaom.3c00065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 06/02/2023] [Accepted: 06/02/2023] [Indexed: 06/30/2023]
Abstract
Colloidal semiconductor quantum dots are a well-established technology, with numerous materials available either commercially or through the vast body of literature. The prevalent materials are cadmium-based and are unlikely to find general acceptance in most applications. While the III-V family of materials is a likely substitute, issues remain about its long-term suitability, and other earth-abundant materials are being explored. In this report, we highlight a nanoscale half-Heusler semiconductor, LiZnN, composed of readily available elements as a potential alternative system to luminescent II-VI and III-V nanoparticle quantum dots.
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Affiliation(s)
| | - S. M. Fairclough
- Department
of Physics, King’s College London, Strand, London WC2R 2LS, U.K.
| | - S. J. Haigh
- Department
of Materials, University of Manchester, Oxford Road, Manchester M19 9PL, U.K.
| | - Y. Zou
- Department
of Materials, University of Manchester, Oxford Road, Manchester M19 9PL, U.K.
| | - R. J. Curry
- Department
of Electrical and Electronic Engineering, Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
| | - P. N. Taylor
- Sharp
Life Science (EU) Ltd., The Hayakawa
Building, Edmund Halley Road, Oxford
Science Park, Oxford OX4 4GB, U.K.
| | - C. Huang
- Electron
Physical Sciences Imaging Centre, Diamond
Light Source, Harwell Science Innovation
Campus, Fermi Ave, Didcot OX110DE, U.K.
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
| | - R. Fleck
- Centre
for
Ultrastructural Imaging, King’s College
London, New Hunts House, Guys Campus, London SE1 1UL, U.K.
| | - P. Machado
- Centre
for
Ultrastructural Imaging, King’s College
London, New Hunts House, Guys Campus, London SE1 1UL, U.K.
| | - A. I. Kirkland
- Electron
Physical Sciences Imaging Centre, Diamond
Light Source, Harwell Science Innovation
Campus, Fermi Ave, Didcot OX110DE, U.K.
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
| | - M. A. Green
- Department
of Physics, King’s College London, Strand, London WC2R 2LS, U.K.
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Loeto K, Kusch G, Coulon PM, Fairclough SM, Boulbar EL, Girgel I, Shields PA, Oliver RA. Point Defects in InGaN/GaN Core–Shell Nanorods: Role of the Regrowth Interface. Nano Ex 2021. [DOI: 10.1088/2632-959x/abe990] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
Core-shell nanorod based light-emitting diodes (LEDs) with their exposed non-polar surfaces have the potential to overcome the limitations of planar LEDs by circumventing the quantum confined stark effect. In this experiment, InGaN/GaN core-shell nanorods were fabricated by a combination of top-down etching and bottom-up regrowth using metal-organic vapour phase epitaxy. When viewing the nanorods along their long axis, monochromatic cathodoluminescence maps taken at the GaN near-band-edge emission energy (3.39 eV) reveal a ring-like region of lower emission intensity. The diameter of this ring is found to be 530 (±20)nm corresponding to the ∼510 nm diameter nickel etch masks used to produce the initial GaN nanopillars. Thus, the dark ring corresponds to the regrowth interface. To understand the origin of the ring, scanning transmission electron microscopy (STEM) and cathodoluminescence (CL) hyperspectral mapping at 10K were performed. STEM imaging reveals the absence of extended defects in the nanorods and indeed near the regrowth interface. Monochromatic CL maps recorded at 10K show that the ring remains dark for monochromatic maps taken at the GaN near-band-edge emission energy (3.47 eV) but is bright when considering the donor-acceptor pair emission energy (3.27 eV). This peculiar anticorrelation indicates that the dark ring originates from an agglomeration of point defects associated with donor-acceptor pair emission. The point defects are incorporated and buried at the GaN regrowth interface from the chemical and/or physical damage induced by etching and lower the radiative recombination rate; limiting the radiative efficiency close to the regrowth interface.
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Jones S, Fairclough SM, Gordon-Brown M, Zheng W, Kolpin A, Pang B, Kuo WCH, Smith JM, Tsang SCE. Dual doping effects (site blockage and electronic promotion) imposed by adatoms on Pd nanocrystals for catalytic hydrogen production. Chem Commun (Camb) 2015; 51:46-9. [DOI: 10.1039/c4cc06195k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Distinctive doping effects are presented, which modify electronic and geometric properties of Pd nanocrystals for HCOOH decomposition affecting activity and selectivity.
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Affiliation(s)
- S. Jones
- Department of Chemistry
- University of Oxford
- UK
| | - S. M. Fairclough
- Department of Chemistry
- University of Oxford
- UK
- Department of Materials
- University of Oxford
| | | | - W. Zheng
- Department of Chemistry
- University of Oxford
- UK
| | - A. Kolpin
- Department of Chemistry
- University of Oxford
- UK
| | - B. Pang
- Metallurgy and Materials
- University of Birmingham
- UK
| | - W. C. H. Kuo
- Johnson Matthey
- Blount’s Court
- Sonning Common
- Reading
- UK
| | - J. M. Smith
- Department of Materials
- University of Oxford
- UK
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Cadirci M, Stubbs SK, Fairclough SM, Tyrrell EJ, Watt AAR, Smith JM, Binks DJ. Ultrafast exciton dynamics in Type II ZnTe-ZnSe colloidal quantum dots. Phys Chem Chem Phys 2013; 14:13638-45. [PMID: 22964845 DOI: 10.1039/c2cp41978e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Ultrafast transient absorption spectroscopy is used to investigate the exciton dynamics of Type II ZnTe-ZnSe core-shell colloidal quantum dots. Surface-trapping is shown to occur within a few picosecond for hot electrons and with a few 10s of picoseconds for electrons cooled to the band-edge, and is the dominant process in the decay of the band-edge bleach for well-stirred samples pumped at moderate powers. The surface-trapped electrons produce a broad photo-induced absorption that spectrally overlaps with the band-edge, distorting and partially cancelling out the bleach feature. At high pump powers and for unstirred samples, these surface-trapped electrons can survive sufficiently long within the pumped volume to accumulate under repeated excitation of the sample, resulting in the formation of an additional exciton decay channel.
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Affiliation(s)
- M Cadirci
- School of Physics and Astronomy & Photon Science Institute, University of Manchester, Manchester, UK
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