Electronic properties of molybdenum disulphide calculated from first principles

Hayati, Farzad (2017). Electronic properties of molybdenum disulphide calculated from first principles. University of Birmingham. Ph.D.

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Abstract

The electrical properties of bulk and single-layer molybdenum disulphide and the electrical and magnetic properties of molybdenum disulphide nanoribbons have been investigated using density functional theory within the first principles’ calculation framework. Changes in energy band structure observed during the transition from bulk to single-layer MoS\(_2\) are linked to atomic orbitals through the use of maximally-localised Wannier functions. Extensive structural optimisation studies have been used to explore the effects of stress and strain on the electronic properties of both bulk and single-layer MoS\(_2\). It has been found that the electronic structure and in particular, the energy band gap of MoS\(_2\) nanoribbons are sensitive to the relaxation of the lattice; and consequently, measurements of the electronic properties will depend strongly on both the preparation of the sample and the substrate on which it is deposited. The spin polarised energy band structure and the charge density were used to determine the magnetic states of zigzag nanoribbons. It has been found that both ferromagnetic and anti-ferromagnetic states are equally probable in both passivated and non-passivated zigzag nanoribbons and the calculated result depends on the initial spin configuration prior to optimisation. A new hydrogen passivation structure on the edges of MoS\(_2\) nanoribbons was suggested, which shows zigzag nanoribbons can also become semiconducting. Finally, the electrical and magnetic properties of a novel chiral MoS\(_2\) nanoribbon were modelled, which showed that the chiral MoS\(_2\) nanoribbons can exhibit both semiconducting and ferromagnetic behaviour simultaneously; this has never been previously reported.

Type of Work:	Thesis (Doctorates > Ph.D.)
Award Type:	Doctorates > Ph.D.
Supervisor(s):	Supervisor(s) Email ORCID Jackson, Timothy James UNSPECIFIED UNSPECIFIED
Licence:
College/Faculty:	Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department:	School of Engineering, Department of Electronic, Electrical and Systems Engineering
Funders:	None/not applicable
Subjects:	Q Science > QC Physics Q Science > QD Chemistry T Technology > TK Electrical engineering. Electronics Nuclear engineering
URI:	http://etheses.bham.ac.uk/id/eprint/7489

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