Atomic Layer Deposited TiO2 thin films for environmental gas sensing

Functional nanostructured metal oxide thin films produced by Atomic Layer Deposition (ALD) are promising for environmental gas sensing. NO₂ sensing is particularly interesting as short term exposure has been shown to cause respiratory problems including asthma attacks. The film thickness control and conformal coating offered by ALD enable tailoring of film thickness to the Debye length for enhancing depletion region effects and high surface to volume ratios for enhanced sensitivity. Exploration of annealing conditions to control surface morphology, crystallinity and oxygen vacancy density will enable highly optimized sensing films for fast and reliable sensors. Here we have characterized our ALD TiO₂ process and for the first time, demonstrated the sensing ability of ALD TiO₂ films with thicknesses on the order of the Debye length toward NO₂ in the low ppm range.