Regensburg 2019 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 2: Microstructure of Thin Films / Crystal Structure
KFM 2.1: Vortrag
Montag, 1. April 2019, 09:30–09:50, PHY 5.0.20
Structural modification of thin Bi(1 1 1) films by passivation and native oxide model — •Christian König1, Stephen Fahy1,2, and James C. Greer3 — 1Tyndall National Institute, University College Cork, Lee Maltings, Cork T12 R5CP, Ireland — 2Department of Physics, University College Cork, College Road, Cork T12 K8AF, Ireland — 3Nottingham Ningbo New Material Institute and Department of Electrical and Electronic Engineering, University of Nottingham Ningbo China, 199 Taikang East Road, Ningbo, 315100, China
Bismuth is a promising material for electronic devices on the nanometer scale. Although the bulk material is semimetallic, a band gap can be expected in a thin film or nanowire due to quantum confinement. We investigated the structure of thin Bi(1 1 1) films with a thickness of approximately 1 nm with density functional theory. In order to remove metallic surface states, a passivation of the devices is necessary. Our calculations show considerable interaction of the surface with passivants like hydrogen and hydroxyl. The orientation of the thin films is changed completely whereas thick films are only affected at the surface. As the electronic properties of the material depend on the crystal structure, this effect is detrimental for device performance. Furthermore, we present model structures for the native oxide which form a protective capping layer and interact only weakly with the film so that the crystal orientation remains unchanged.