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, TiO2‐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.
International audienceA first generation of dielectric rib waveguides has been designed and shaped to support a monomode confinement by using organosilicon materials elaborated by plasma enhanced chemical vapor deposition (PECVD). Optical losses have been measured around 5.5dB.cm-1 and 11.5dB.cm-1 for TE00 and TM00 modes, respectively. Then, synthesis of titanium dioxide thin films by PECVD has been investigated to improve optical and propagation properties. The first results on these films exhibit a refractive index around 1.99 at a 633 nm wavelength with a 380 nm optical gap. When an rf bias is applied to the substrate, the refractive index reaches 2.36, from -5V, without significant optical gap variation
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