Modeling and Simulation of Electron Transport through Nanoscale Heterojunctions
type: CreativeWork
description: The thesis discusses some transport aspects of nanoscale heterojunctions, the archetypal devices which constitute a considerable part of the rapidly growing nanotechnology and nanoscience today. It discusses two distinct types of nanoscale heterojunctions, namely weakly correlated and strongly correlated heterojunctions. The weakly correlated heterojunction employs normal metal for its leads, where the particles behave like typical 3D electron gas and the standard density functional theory allows rigorous ab initio analysis for such systems. On the other hand, the strongly correlated heterojunction employs superconductors for its leads, therefore appropriate models need to be used to describe the essential physics from which the transport properties are derived. The weakly correlated heterojunction consists of two normal metals and a carbon nanotube (CNT) in between, a ubiquitous system in nanoscale experimental devices. Despite of all its novel and great promises, a full exploitation of the device has so far been hindered by various problems, and one of them is the interface problems with the metal probes which typically produce considerable resistance. Schottky barriers formed at CNT-metal contacts have been well known to be crucial for the performance of CNT based field effect transistors (FETs). Through an extensive first principles calculations we show that an optical nanowelding process can drastically reduce the Schottky barriers at CNT-metal interfaces, resulting in significantly improved conductivity. Results presented may have great implications in future design CNT-based nanoelectronics. The strongly correlated heterojunction consists of two superconducting leads and a quantum dot in between. A phenomenon of so-called differential conductance anomaly} is predicted to occur in such devices at high bias when the transport is theoretically linear. The phenomenon is caused by the potential symmetry which affects the pinning mechanisms of the localized level b…
abstract: The thesis discusses some transport aspects of nanoscale heterojunctions, the archetypal devices which constitute a considerable part of the rapidly growing nanotechnology and nanoscience today. It discusses two distinct types of nanoscale heterojunctions, namely weakly correlated and strongly correlated heterojunctions. The weakly correlated heterojunction employs normal metal for its leads, where the particles behave like typical 3D electron gas and the standard density functional theory allows rigorous ab initio analysis for such systems. On the other hand, the strongly correlated heterojunction employs superconductors for its leads, therefore appropriate models need to be used to describe the essential physics from which the transport properties are derived. The weakly correlated heterojunction consists of two normal metals and a carbon nanotube (CNT) in between, a ubiquitous system in nanoscale experimental devices. Despite of all its novel and great promises, a full exploitation of the device has so far been hindered by various problems, and one of them is the interface problems with the metal probes which typically produce considerable resistance. Schottky barriers formed at CNT-metal contacts have been well known to be crucial for the performance of CNT based field effect transistors (FETs). Through an extensive first principles calculations we show that an optical nanowelding process can drastically reduce the Schottky barriers at CNT-metal interfaces, resulting in significantly improved conductivity. Results presented may have great implications in future design CNT-based nanoelectronics. The strongly correlated heterojunction consists of two superconducting leads and a quantum dot in between. A phenomenon of so-called differential conductance anomaly} is predicted to occur in such devices at high bias when the transport is theoretically linear. The phenomenon is caused by the potential symmetry which affects the pinning mechanisms of the localized level b…
author: ARGO NURBAWONO
keywords: superconductivity, quantum transport, point contact, CNT, Schottky barrier, Green's functions
date published: 2011-05-24
date modified: 2026-07-24T03:32:04Z
provider: National University of Singapore
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: National University of Singapore