In-situ Characterisation during Fabrication of Nanostructured Functional Thin Films
via Chemical Vapour Deposition
Thomas Fischer, Sanjay Mathur*
Division of Inorganic and Materials Chemistry, Institute of Inorganic Chemistry, University
of Cologne, Greinstr. 6, 50939 Germany
E-mail:
The full potential of Chemical Vapour Deposition (CVD) techniques can be maxed when
using tailored molecular precursors with a predefined arrangement of atoms on the molecular
level, thus facilitating solid phase formation at relatively low temperatures. Moreover by
changing the ligand sphere in precursor molecules alternate decomposition pathways can be
followed resulting in non-stoichiometric or even meta-stable phases for coatings and/or fabri-
cation of nanostructured materials. Only a precise control over the reaction conditions (i.e.
temperature, pressure, flow, etc.) as well as an analysis of the ongoing reaction in the gas
phase as well as at the solid/gas interface gives access to a complete understanding of the
whole deposition processes vital to a full process control. In addition, by providing metal or
metal oxide catalyst centres on the substrate, anisotropic growth can be induced,
thus resulting in one-dimensional metal oxide nanowires, which demand stringent reaction
control for homogeneous nucleation and growth.
A novel CVD reactor system was developed which allows not only to monitor the gas phase
composition via online mass spectrometry but also follow the electrical properties of the
growing thin films on micro hotplates with integrated electrodes, thus providing an ideal
testbed for a controlled deposition of metal oxide thin-films. The application of the resulting
functional coatings in gas sensing as well as photoelectrochemical water splitting applications
are demonstrated.
The following presentation will highlight the aspects of controlling precursor chemistry, reac-
tor design as well as process conditions for the synthesis and integration of nanostructured
films of various metal oxides and showcase how in-situ diagnostics using i.e. mass spectro-
metric analysis and in-operando electrical characterization can support the process develop-
ment in gas phase deposition reactions.
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