Atomikerroskasvatusmenetelmällä kasvatetun titaanidioksidikalvon ominaisuudet valosähkökemiallisessa veden hajottamisessa
Tutkimustuotos: Diplomityö tai pro gradu -työ ›
|Tila||Julkaistu - 4 lokakuuta 2017|
|OKM-julkaisutyyppi||G2 Pro gradu, diplomityö, ylempi amk-opinnäytetyö|
Titanium dioxide ﬁlms examined in this study were grown on n-type phosphorus-doped silicon (n-Si(100)(P)) and fused quartz used as substrates by atomic layer deposition at 200 °C using tetrakis(dimethylamido)titanium (TDMAT) and deionized water as precursors. The annealing of some of the samples at 500 °C in air was made in a tube furnace. The concentrations of the elements and chemical states of the atomic layer deposited titanium dioxide ﬁlms were studied by X-ray photoelectron spectroscopy (XPS). The ﬁlm thickness and refractive index were determined by ellipsometer and the absorption properties of the titanium dioxide ﬁlm were measured by UV/Vis/NIR spectrophotometer. In addition, crystallographic results from X-ray diﬀraction (XRD) and Raman spectroscopy were also utilized, as well as the results of the photoelectrochemical cell and solar simulator on titanium dioxide photoanode performance.
Based on the results, at 200 °C atomic layer deposited titanium dioxide is amorphous and absorbs visible light as ”black” TiO2. At the oxidative annealing at 500 °C titanium dioxide crystallizes into rutile and becomes ”white” TiO2 that absorbs less visible light. Both titanium dioxide ﬁlms contain the lower Ti3+/2+ oxidation states of titanium that may indicate oxygen vacancies. Nitrogen is found only in as-deposited titanium dioxide. The annealed titanium dioxide is stable in electrolyte, achieving 0.20 % ABPE for water splitting reaction.