Monitoring in-situ processing of solid surfaces with real-time x-ray photoelectron spectroscopy

  • Gruffudd Trefor Williams

Student thesis: Doctoral ThesisDoctor of Philosophy


This thesis details the use of x-ray photoelectron spectroscopy to monitor in-situ surface processing of solid surfaces in real-time. The processing methods investigated were annealing, deposition of thin organic films and exposure to oxygen and hydrogen produced by in-situ microwave plasmas. Three solid surfaces were investigated; metals, diamond and zinc oxide.
Clean copper and gold were annealed up to 1000 K while monitoring with real-time XPS. A temperature-dependent shift of the Cu 2p3/2 and Au 4f7/2 core-level to lower binding energy was measured, -1.29 ± 0.04 meV / 10 K and -2.36 ± 0.01 meV / 10 K respectively. The shift was identified as being due to a thermal expansion of the lattice. The removal of argon ion induced damage to the copper surface was monitored in real-time and a critical temperature of 680 ± 20 K for the removal of the damage was measured. The formation of an interface between aluminium and copper phthalocyanine was monitored in real-time.
Hydrogen and oxygen terminated (111) natural diamond surfaces were prepared in-situ and surface reconstruction by annealing up to 1200 K was monitored in real-time. Large reversible shifts to core-level binding energies were attributed to a surface photovoltage that was persistent at high temperature on the hydrogen and oxygen terminated surfaces. A model of the surface photovoltage is given where the bulk resistance of the diamond is identified as sustaining the photovoltage at elevated temperature.
The zinc oxide (0001) surface was found to have a temperature-dependent core-level binding energy shift that was fully reversible up to 900 K and symmetric with cooling. The shift was attributed to a diffusion of oxygen vacancies from the bulk into the sub-surface.
The zinc oxide (0001) surface was found to exhibit different temperature dependence to the (0001) surface that was fully reversible up to 700K but not symmetric with cooling. The shift was attributed to an additional disruption to stabilizing charge transfer between the polar surfaces. The formation of interfaces between the (0001) surface with copper phthalocyanine and C60 were monitored in real-time.
Date of Award03 Oct 2011
Original languageEnglish
Awarding Institution
  • Aberystwyth University
SupervisorAndrew Evans (Supervisor) & Nigel Robert Poolton (Supervisor)


  • solid surfaces
  • photoelectron spectroscopy

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