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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Transport properties of graphene nanodevices - nanoribbons, quantum dots and double quantum dots

Chiu, Kuei-Lin January 2012 (has links)
No description available.
2

Non-equilibrium current fluctuations in graphene

Wiener, Alexander David 20 December 2012 (has links)
We analyze experimental evidence of transport through evanescent waves in graphene, reconciling existing experimental data with theory. We propose novel experimental geometries that provide even more compelling evidence of evanescent waves. We investigate the shot noise generated by evanescent modes in graphene for several experimental setups. For two impurity-free graphene strips kept at the Dirac point by gate potentials, separated by a long highly doped region, we find that the Fano factor takes the universal value F=1/4. For a large superlattice consisting of many strips gated to the Dirac point, interspersed among doped regions, we find F=1/(8ln2). These results differ from the value F=1/3 predicted for a disordered metal, providing an unambiguous experimental signature of evanescent mode transport in graphene. For a graphene nano-ribbon transistor geometry, we explain that the experimentally observed anomalous voltage scale of the shot noise can arise from doping by the contacts to the electrical circuit. These observations provide strong evidence of evanescent mode transport in graphene.
3

Transport in graphene tunnel junctions

Malec, Christopher Evan 20 June 2011 (has links)
It has been predicted that gold, aluminum, and copper do not fundamentally change the graphene band structure when they are in close proximity to graphene, but merely increase the doping. My data confirms this prediction, as well as explores other consequences of the metal/graphene interface. First, I present a technique to fabricate thin oxide barriers between graphene and aluminum and copper to create tunnel junctions and directly probe graphene in close proximity to a metal. I map the differential conductance of the junctions versus tunnel probe and back gate voltage, and observe mesoscopic fluctuations in the conductance that are directly related to the graphene density of states. I develop a simple theory of tunneling into graphene to extract experimental numbers, such as the doping level of the graphene, and take into account the electrostatic gating of graphene by the tunneling probe. Next, results of measurements in magnetic fields will also be discussed, including evidence for incompressible states in the Quantum Hall regime wherein an electron is forced to tunnel between a localized state and an extended state that is connected to the lead. The physics of this system is similar to that encountered in Single Electron Transistors, and some work in this area will be reviewed. Finally, another possible method of understanding the interface between a metal and graphene through transport is presented. By depositing disconnected gold islands on graphene, I am able to measure resonances in the bias dependent differential resistance, that I connect to interactions between the graphene and gold islands.

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