Low pressure CVD of transparent Cu-Al-O and Cu-Ti-O thin films

Abstract

Semiconducting materials with optical transparency are gaining increasing attention for the preparation of next-generation optical devices. In this work, Chemical Vapour Deposition of nanophasic Cu-Ti-O and Cu-Al-O thin films is performed on glassy substrates by using copper(II) acetylacetonate hydrate [Cu(acac) 2 -H 2 O], titanium tetraisopropoxide [Ti(O 1 Pr) 4 ] and aluminium dimethylisopropoxide [(CH 3 ) 2 Al(O 1 C 3 H 7 )] as Cu, Ti and Al precursors respectively, in the temperature range 215-370°. The syntheses are carried out in a N 2 +O 2 or N 2 +H 2 O atmosphere. The obtained coatings are characterised in detail in their composition, microstructure, optical and electrical properties. The discussion is focused on the most relevant results concerning their composition, with particular attention to Cu oxidation state as a function of experimental conditions, optical transparency and semiconductor behaviour.