Influence of ion bombardment and annealing on the structural and optical properties of TiOx thin films deposited in inductively coupled TTIP/O2 plasma

Abstract

TiO2 films were deposited in a low-pressure inductively coupled rf plasma in O2/titanium tetraisopropoxide (TTIP). First, depositions were realized at floating potential using nitrogen as bubbling gas. The structural and optical properties of the films were studied, before and after annealing at 450 °C under air. As expected, as-deposited films are amorphous, with a columnar structure. A post-annealing under flowing air allows obtaining partially crystallized films in anatase phase. Secondly, films were deposited using nitrogen and oxygen as bubbling gas. In both cases, TiO 2-like films exhibit very similar structure and optical properties. Finally, the effect of biasing the substrate was investigated. An improvement of film properties has been found for a bias voltage of -15 V at T<100 °C: deposited TiO2 film is dense (3.7) with a high refractive index (n = 2.32 at 634 nm) and partially crystallized in rutile phase. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.