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Title:Quantum transport in graphene nanotransistors
Author(s):Girdhar, Anuj
Director of Research:Leburton, Jean-Pierre
Doctoral Committee Chair(s):Mason, Nadya
Doctoral Committee Member(s):Schulten, Klaus J.; Bashir, Rashid
Department / Program:Physics
Discipline:Physics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):graphene
quantum
transport
nanoribbon
Deoxyribonucleic Acid (DNA)
sequencing
transistor
nanopore
sensing
genome
monolayer
gate
Abstract:Over the past decade, interest in using graphene in condensed-matter physics and materials science applications has exploded, owing to its unique electrical properties. Narrow strips of graphene, called graphene nanoribbons, also display exotic behavior. A nanoribbon’s edge geometry determines its electronic transport properties, and the rich behavior of conductance of nanoribbons in response to external potentials makes them ideal for use within transistors. In this thesis, we work towards creating an accurate model of graphene nanoribbon transistors, and we asses two possible applications which exploit their amazing potential. We begin by outlining the basic theoretical and computational framework for the model developed in this work. We then demonstrate the capability of graphene nanoribbon transistors, with nanopores, to electronically detect, characterize, and manipulate translocating DNA strands. Specifically, we explore the tunability of such devices, by examining the role of lattice geometry, such as a quantum point contact constriction, on their performance. We perform a demonstration of the ability to detect the passage of double and single-stranded DNA, through molecular dynamics simulations. The transistors presented are capable of sensing the helical shape of double-stranded DNA molecules, the unraveling of a DNA helix into a planar-zipper form, and the passage of individual nucleotides of a single strand of DNA through the nanopore. We outline a preliminary analysis on the proper design of a multilayer transistor stack to control both the electronic properties of the conducting membrane, as well as the motion of the DNA. Lastly, we present another type of nanoribbon device, an all-carbon spintronic transistor for use in cascaded logic circuits. A thorough analysis of the transport properties of zigzag nanoribbon transistors in magnetic fields, in addition to the design and construction of logic gate circuits containing these spintronic transistors, is presented.
Issue Date:2015-04-24
Type:Thesis
URI:http://hdl.handle.net/2142/78634
Rights Information:Copyright 2015 Anuj Girdhar
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015


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