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Title: The optical characterisation of graphene
Author: Xiao, Ye
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2013
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The discovery of graphene in 2004 [1] has prompted research into its potential in developing future electronic and photonic devices owing to its exceptional electronic and mechanical properties. Efforts to develop a scalable method of synthesis are ongoing and require a better understanding of the growth mechanisms of the various synthesis routes, as well as an examination of the properties of films produced by such methods. In this Thesis Raman spectroscopy is used to investigate graphene samples grown both by the reduction of graphite via graphene oxide as well as chemical vapour deposition on copper. In the case of the former, in-situ Raman spectroscopy was used to investigate the temporal evolution of graphene oxide exposed to different thermal treatments and under different reducing atmospheres. The study focused on the chemical processes which occur when graphene oxide is reduced by examination of the ID/G ratio which can be used to determine defect density by the Tuinstra-Koenig relationship [2]. The growth mechanism of graphene samples grown by chemical vapour deposition was also investigated. Here, the study focused on growth morphology by using simultaneous AFM-Raman mapping to characterise the strain and layer number profile, by analysis of the G and 2D peaks, of graphene samples grown on copper and relate them to the topography of the underlying substrate. The integration of graphene with plasmonic devices offers the potential for novel optoelectronic devices, which requires a better understanding of the optical response of graphene. Here, FTIR spectroscopy was used to probe the change in the resonance profile of a gold plasmonic nanoresonator array when encapsulated with a graphene overlayer. By comparison of the experimentally measured shift with simulated results using finite element modelling the photoconductivity of graphene was determined. The study also investigated the feasibility of graphene integrated plasmonic devices for chemical sensing applications.
Supervisor: Cohen, Lesley F.; Maier, Stefan A. Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available