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Title: Electron transport in two-dimensional molybdenum disulphide
Author: Sackville Hamilton, Alice Charlotte
ISNI:       0000 0004 7659 778X
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2018
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This thesis will describe the experimental details used to make two-dimensional field-effect transistors using monolayer and bilayer transition metal dichalcogenides, including the fabrication of new sample holders required to cross between multiple experimental set-ups. Electron transport in these devices is measured at room temperature and at low temperature in a dilution refrigerator with a base temperature below 10 mK. Atomic force microscope lithography is explored as a technique for locally functionalising the surface of the device to create nano-features, with particular interest paid to the formation of quantum dots. Transport curves before and after lithography demonstrate the change in transport characteristics. A comprehensive study of device behaviour at room temperature is carried out. The effects of pumping and heating on the device are measured and discussed. Improvements in the transport occur from the removal of charge traps and the improved contact between the Ti/Au contact and the crystal. Low temperature (< 10 mK) measurements of bilayer MoS2 devices show evidence of Coulomb blockade and the presence of small, unstable, naturally formed quantum dots. We suspect that interface states due to naturally occurring atomic defects in MoS2 which result in Fermi level pinning at room temperature are being probed here. The evolution of these states with magnetic field is measured, for devices positioned parallel and perpendicular to the magnetic field.
Supervisor: Buitelaar, M. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available