Abstract:
This thesis reports on the development of a new method for studying the growth of
thin films and the dynamics of surface processes. Real-time photoelectron spectroscopy
enabled by advances in electron detection technology has been applied to the study of
metal overlayers on a p-type CVD (001) diamond single crystal and tin (II)
phthalocyanine (SnPc) overlayers on Si (111), GaAs (001) and polycrystalline Au
substrates. The performance of the Aberystwyth real-time electron spectroscopy
(REES) system is also reviewed.
Temperature-dependent real-time photoelectron studies of an oxygen-terminated
boron-doped CVD (001) single crystal diamond is performed with a fully reversible
temperature dependent Fermi level shift of ~ 1 eV observed on the oxygen-terminated
1 x 1 surface up to a temperature of 700 °C. This shift is found to correlate with oxygen
coverage where the maximum reversible shift reduces in magnitude with decreasing
oxygen coverage.
The growth of aluminium contacts on the (001) diamond surface is investigated with
the formation of a Schottky contact for which current-voltage measurements yield a
barrier height of 1.05 eV and an ideality factor of 1.4. Real-time measurements monitor
the formation of the contact revealing the transition from layered to clustered growth
of the aluminium film during in vacuo deposition. During annealing of the contact to
860 °C real-time measurements reveal a direct correlation between the transition from
Schottky to Ohmic behaviour and the formation of interfacial carbide at 482 °C.
Deposition of iron on the (001) diamond surface is found to form an uniform layer
with iron carbide species present at the interface. Subsequent annealing of the diamond
to 850 °C results in the formation of a graphite layer with iron acting as a catalyst for
the graphitisation process. AFM and NEXAFS of the resulting graphite layer reveal an
ordered surface. A mechanism is proposed for the graphitisation.
Finally, the growth of SnPc is investigated on Si (111), GaAs (001) and polycrystalline
Au. Growth is found to proceed in two stages and re-organisation of the molecules is
detected by real-time measurements and found to continue after deposition for a period
of up to 30 minutes. Studies also suggest that substrate temperature affects the angle of
stacking and the rate of molecular re-organisation. A theoretical molecular model for
this re-organisation was successfully developed.
