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DFT study of undoped and As-doped Si nanowires approaching the bulk limit

Kumarasinghe, C; Bowler, DR; (2019) DFT study of undoped and As-doped Si nanowires approaching the bulk limit. Journal of Physics: Condensed Matter , 32 (3) , Article 035304. 10.1088/1361-648X/ab4b3c. Green open access

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Kumarasinghe+et+al_2019_J._Phys.__Condens._Matter_10.1088_1361-648X_ab4b3c.pdf - Accepted Version

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Abstract

The electronic properties of pure and As-doped Si nanowires (NWs) with radii up to 9.53 nm are studied using large scale density functional theory (DFT) calculations. We show that, for the undoped NWs, the DFT bandgap reduces with increasing diameter and converges to its bulk value, a trend in agreement with experimental data. Moreover, we show that the atoms closest to the surface of the nanowire (NW) contribute less to the states near the band edges, when compared with atoms close to the centre; this is shown to be due to differences in Si-Si atomic distances, as well as surface passivation effects. When considering As-doped Si NWs we show that dopant placement within the NW plays an important role in deciding electronic properties. We show that a low velocity band is introduced by As doping, in the gap, but close to the conduction band edge. The curvature of this low velocity band depends on the dopant location, with the curvature reducing when the dopant is placed closer to the center. We also show that asymmetry of dopant location with the NW leads to splitting of the valence band edge.

Type: Article
Title: DFT study of undoped and As-doped Si nanowires approaching the bulk limit
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1088/1361-648X/ab4b3c
Publisher version: https://doi.org/10.1088/1361-648X/ab4b3c
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Doping, Large-scale DFT, Nanowires
UCL classification: UCL
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 > Dept of Physics and Astronomy
URI: https://discovery-pp.ucl.ac.uk/id/eprint/10083614
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