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A DFT investigation of Al-based atomically precise epitaxy

Smith, Richard; (2021) A DFT investigation of Al-based atomically precise epitaxy. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

This thesis is about the growth and placement of dopants in silicon semiconductor devices and specifically acceptor dopants as device dimensions enter the nanoscale. Single-atom donor dopant devices have already been demonstrated in the laboratory. Using density functional theory (DFT) and the aluminium atom we now show how acceptor sites might be fabricated and characterize their electronic behaviour. The thesis opens with a review of the physical basis of statistical doping and the operation of the silicon CMOS transistor which is the most widespread microfabricated device by a wide margin. We show how downscaling requires ever-increasing accuracy in dopant placement and illustrate using some current process techniques. Next, we describe some prototype single-dopant devices and the chapter concludes with a description of a phosphorus nuclear spin qubit and its application. Chapter 2 outlines the theoretical basis of the DFT nanostructure models found in later chapters and chapter 3 presents some elementary calculations intended to validate the local DFT environment. Chapters 4, 5 and 6 are based on published papers produced during this work and listed on page 11. In chapter 4 we introduce patterned atomic layer epitaxy (PALE), an experimental fabrication technique for Si nanostructures. Chapters 5 and 6 describe how PALE could be applied to locate Al dopant atoms in an Si substrate. The final chapter offers some calculations indicating the electronic behaviour of this dopant when embedded in Si nanostructures of various kinds.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: A DFT investigation of Al-based atomically precise epitaxy
Event: UCL (University College London)
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request.
Keywords: nanostructure, precision doping, DFT
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
URI: https://discovery.ucl.ac.uk/id/eprint/10129132
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