Functional nanoelectronic devices: single-electron transport, memristivity, and thermoelectricity in nanoscale flms using self-assembly and graphene

Change log
Astier, Hippolyte Pierre Andre Georges 

This dissertation reports on several experimental projects studying electronic transport in thin-flm electronic devices. Self-assembly methods and graphene were used to realise devices contacting films of self-assembled PbS quantum dots. The devices have exhibited single-electron tunnelling with a high yield. The electrical properties of the junctions are studied individually and collectively using statistical tools to extract correlations between device geometries and electrical data. The dissertation includes discussion of the theory of relevant electronic transport including numerical simulations. Several initiated projects deriving from this work are introduced. A second device reported in this thesis is a memristive switch. Contacting thin films of Al2O3 with graphene delivered junctions which exhibit memristive behaviour with an ultrahigh on-off conductance ratio. The conduction state of the junctions is correlated with morphological changes in the devices, whereby conductive flament formation in the junction is found to lead to electrically-controllable and reversible gas encapsulation in bubbles in the structure. The device is measured electrically and topographically, and the correlation between the two aspects is studied. A discussion of memristive conduction is included with numerical simulations. A third section reports on a project studying thermoelectricity in self-assembled molecular junctions, as they show potential for improved thermoelectric efficiency for energy harvesting; this is discussed in the dissertation. Strategies to benchmark the studies are presented with relevant devices fabricated and measured. These include the development of a measurement protocol to study thermoelectricity in devices, studies of electrical coupling between various molecular structures and graphene electrodes, molecular-structure dependence of electrical and thermal conductance of junctions. Preliminary results and on-going work are discussed.

Ford, Christopher John Bristow
molecular elctronics, graphene, devices, nanoelectronics, thin films, self-assembly, quantum dot, thermoelectricity, single-electron tunnelling, single-electron tunneling, self-assembled monolayer, memristor, memristivity, nanoactuation, semiconductor physics, condensed matter physics, thermoelectric, energy harvesting, Coulomb blockade, Coulomb staircase, nanocrystal
Doctor of Philosophy (PhD)
Awarding Institution
University of Cambridge
I want to thank the Semiconductor Physics Group of the Cavendish Laboratory, the Semiconductor Physics Group of the Institute of Physics, the Cambridge NanoDTC, and Fitzwilliam College, Cambridge for their support. I want also to thank the collaborators acknowledged in the thesis for contributions in materials and services.