Metal oxide thin films have a wide range of applications, for example in so-called
“plastic electronics” as semiconductors and contacts. However, their synthesis traditionally
involves a high temperature step which is not compatible with plastic substrates, and the
morphology can be difficult to tailor to different applications.
Recently a new method to form oxide films from molecular precursors using only
processes close to room temperature has been developed. The procedure relied on
irradiating metal phthalocyanines (MPcs) using vacuum ultra-violet (VUV) radiation produced
by an excimer lamp (λ =172 nm). In this thesis, we extend the procedure to the fabrication of
functional oxides and aim to elucidate the mechanisms of degradation at the nanoscale.
The first chapter explores the degradation mechanisms of MPcs. The influence
atmosphere is assessed by varying the O concentration and overall pressure in the irradiation
process. The existence of O radicals and excited species are found to play a major role in the
kinetics of the reaction. An optimized atmosphere for the degradation of the films is
obtained.
The second chapter explores whether the technique is applicable to new
morphologies. Films with flat topography like zinc porphyrin highlight the importance of
grain boundaries and the diffusion of reactive species between grains as one of the main
reasons to promote film degradation, while nanowires show shape retention. Blends of Zn1-
XCoXPc show similar degradation mechanisms to pure films. The CoPc concentration in the
blend influences the reaction rate.
The final chapter is a study of the elemental composition of irradiated films with
energy-dispersive X-ray spectroscopy and secondary ion mass spectrometry. It shows
formation of a thin layer of metal oxide as a result of exposure to VUV light on the
phthalocyanine thin films.