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Title: Transport in silicon nanowires
Author: Evans, G. J.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2002
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This thesis models the electrical breakup of geometrically uniform heavily doped silicon nanowires under the action of the random dopant potential. A self-consistent Thomas-Fermi model is used to show the natural formation of islands and structured characteristics of the system are presented. The island's electrical exhibits Coulomb blockade which is a single electronic effect by which the transport of electrons is strongly affected by the discrete nature of the current and where electron-electron repulsion can prevent current flowing. The system is modelled by calculation of the full capacitance matrix, an approximation to the tunnel resistance matrix and a single electron transport simulator, from which the I-V characteristics of a particular nanowire can be simulated. An electrical characteristic of the wire is the threshold voltage and is the point at which it first starts to conduct. However, extraneous charge in the environment (so-called offset charge) can change the device's characteristics and hence the threshold voltage. The numerical evaluation of the threshold voltage distribution for the nanowires is performed for a few examples before developing an analytical approximation to the distribution under offset charge disorder. The approximation is a geometrical interpretation of the phase space describing the device and the limits of applicability are discussed and in particular a two-island system is investigated. Negative differential conductance is shown to be present even in a two-island system and is explained in geometrical terms.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available