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The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon

Khara, GS; Murphy, ST; Daraszewicz, SL; Duffy, DM; (2016) The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon. Journal of Physics: Condensed Matter , 28 (39) , Article 395201. 10.1088/0953-8984/28/39/395201. Green open access

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Abstract

The swift heavy ion (SHI) irradiation of materials is often modelled using the two-temperature model. While the model has been successful in describing SHI damage in metals, it fails to account for the presence of a bandgap in semiconductors and insulators. Here we explore the potential to overcome this limitation by explicitly incorporating the influence of the bandgap in the parameterisation of the electronic specific heat for Si. The specific heat as a function of electronic temperature is calculated using finite temperature density functional theory with three different exchange correlation functionals, each with a characteristic bandgap. These electronic temperature dependent specific heats are employed with two-temperature molecular dynamics to model ion track creation in Si. The results obtained using a specific heat derived from density functional theory showed dramatically reduced defect creation compared to models that used the free electron gas specific heat. As a consequence, the track radii are smaller and in much better agreement with experimental observations. We also observe a correlation between the width of the band gap and the track radius, arising due to the variation in the temperature dependence of the electronic specific heat.

Type: Article
Title: The influence of the electronic specific heat on swift heavy ion irradiation simulations of silicon
Open access status: An open access version is available from UCL Discovery
DOI: 10.1088/0953-8984/28/39/395201
Publisher version: http://dx.doi.org/10.1088/0953-8984/28/39/395201
Additional information: © Copyright 2016 IOP Publishing
Keywords: Science & Technology, Physical Sciences, Physics, Condensed Matter, Physics, swift heavy ions, radiation damage, silicon, molecular dynamics, density functional theory, electronic effects, thermal spike description, wave basis-set, inorganic insulators, radiation-damage, track formation, band-gap, dynamics, germanium, solids
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: https://discovery.ucl.ac.uk/id/eprint/1522380
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