Role of Oxide Defects in ALD grown TiO2 Coatings on Performance as Photoanode Protection Layer
Research output: Other conference contribution › Paper, poster or abstract › Scientific
|Publication status||Published - 4 Dec 2017|
|Event||Joint Annual Meeting of Finnish Synchrotron Radiation User Organisation (FSRUO) and Finnish Structural Biology Network (FinnBox) - University of Turku, Turku, Finland|
Duration: 4 Dec 2017 → 5 Dec 2017
|Seminar||Joint Annual Meeting of Finnish Synchrotron Radiation User Organisation (FSRUO) and Finnish Structural Biology Network (FinnBox)|
|Period||4/12/17 → 5/12/17|
In this work , structural, optical and photoelectrochemical properties of the ALD grown TiO2 films were studied in as-deposited condition and after annealing in air at 500 °C. TiO2 films were grown on n-type phosphorus-doped silicon and fused quartz by ALD at 200 °C using tetrakis(dimethylamido)titanium (TDMAT) and deionized water as precursors. The properties of TiO2 were investigated by X-ray photoelectron spectroscopy (XPS), ellipsometry and UV/Vis/NIR spectrophotometry. In addition, results from X-ray diffraction (XRD), Raman spectroscopy and photoelectrochemical (PEC) cell are discussed.
Based on the results, as-deposited TiO2 is amorphous and absorbs visible light as ''black'' TiO2. After annealing in air at 500 °C TiO2 crystallizes as rutile and becomes ''white'' TiO2 that absorbs light only in the UV region. As-deposited TiO2 contains significant amount of Ti3+/2+ oxygen vacancies that are oxidized as Ti4+ upon annealing in air. In addition, nitrogen is found only in as-deposited titanium dioxide. As-deposited TiO2 is not chemically stable under PEC conditions. In contrast, the annealed TiO2 is chemically stable and showed 0.20 % ABPE efficiency for water splitting reaction.