Surface Modification and Electronic Structure Characterisation of Carbon-based and Iron-based Materials

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Student thesis: Doctoral ThesisDoctor of Philosophy

Original languageEnglish
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Award date2017
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Abstract

This thesis provides an important basis for understanding the surface
modulation mechanism and electronic structure variation on semiconducting
surfaces and metallic thin films. The use of real-time photoelectron
spectroscopy (REES) makes it possible to monitor the solid surfaces during in
situ processing. The surfaces that have been investigated were (100) facet
boron-doped diamond surfaces and iron thin films. The surface processing
treatments include annealing, thin film coating and exposure to oxygen and
hydrogen microwave plasma sources.

The oxygen-terminated (100) facet diamond was annealed up to 1000℃ while
monitoring with REES. The oxygen desorption process on the surface can be
divided into four distinct stages according the oxygen concentration on the
diamond (100) surface during the heating cycle. The ratio of ketone/ether
groups has been investigated. Moreover, the true band bending on
O-terminated (100) has been investigated with real-time characterization, which
has a maximum difference of +1.0 eV comparing with the room temperature
XPS spectra data.

Fluorouracil (5-FU), as a drug widely used in leukaemia and bowel cancer
treatment, which is demonstrated to degrade on silver coated catheter surfaces,
producing hydrofluoric acid and therefor leading to adverse effects on
patients. In order to compare diamond as coating material, the adsorption of
5-FU on the oxygen and hydrogen terminated diamond (100) surfaces has been
studied with x-ray photoelectron spectroscopy (XPS), showing extremely
different behaviours.

Utilising the shape memory alloy (SMA) substrate, the continuously mediated
strain was transferred from the substrate to Fe films through a thermally
controlled shape memory effect. The pure strain modulated electronic structure
in the Fe thin films was studied using in situ XPS and first-principle calculations.
The result demonstrates that the compressive strain increases the overlap of
outer orbits and enhances the shielding effect to core electrons, resulting in
significant tunability on the binding energy of core electrons and related
magnetic anisotropy.