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Title: The electrical properties of disordered copper oxide films
Author: Boucher, R. A.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2003
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Films of copper oxide were deposited on glass substrates by the reactive ion beam sputtering method. The amount of oxygen contained within was changed so that both metallic and insulating type films were obtained. Several basic measurements were attempted: comparison measurement by electron probe micro-analysis, CuO concentration measurements by electron spin resonance, optical measurements, magnetoresistance measurements and electrical measurements. The results showed that the metallic system could be well described by quantum corrections to the Boltzmann conductivity. There appeared to be both an electron-electron interaction correction and an electron-electron scattering mediated weak localisation, although in the latter the sign was negative due to spin-orbit scattering. The magnitude of the weak-localisation was shown to decrease as the metal insulator transition was approached. On the insulating side of the metal insulator transition the hopping type behaviour describes the conductivity, with both Mott hopping and hopping in a coulomb gap being seen. However, their relationship describes an unusual band structure around the fermi energy, where it is parabolic at higher energies and shows a flat bottom at lower energies. Composition was shown to be mixed, with both Cu, Cu2O and CuO being seen for Cu2O or below, nominal compositions. The films were also shown to contain un-reacted oxygen within. The metal insulator transition was found to occur at an oxygen concentration of 30.1±2 Atomic %, which is in broad agreement with that calculated from the minimum metallic conductivity.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available