Defect engineering of atomic layer deposited TiO2 for photocatalytic applications
Research output: Other conference contribution › Paper, poster or abstract › Scientific
|Publication status||Published - 7 Mar 2019|
|Publication type||Not Eligible|
|Event||Physics Days 2019 - Helsingin yliopisto, Helsinki, Finland|
Duration: 5 Mar 2019 → 7 Mar 2019
|Conference||Physics Days 2019|
|Period||5/03/19 → 7/03/19|
In our recent studies, we have reported means to thermally modify the defect structure of ALD grown am.-TiO2 thin film under oxidative  and reductive  conditions. TiO2 films were grown on silicon and fused quartz substrates by ALD at 200 °C using tetrakis(dimethylamido)titanium (TDMAT) and deionized water as precursors. Based on the results, the as-deposited am.-TiO2 is chemically unstable and visually black exhibiting both enhanced absorbance in the visible range and exceptionally high conductivity due to the trapped charge carriers (Ti3+). Heat treatment in air at 200°C induces oxidation of Ti3+, decrease in absorbance and conductivity but has only a minor effect on the stability. However, a reasonable stability is obtained after oxidation at 300 °C, simultaneously with the crystallization of TiO2 into rutile. Furthermore, oxidation at 500 °C results in stable rutile TiO2 that produces the highest photocurrent for water oxidation. In contrast, reductive heat treatment in ultra-high vacuum (UHV) at 500 °C retains the amorphous phase for TiO2 but enhances the stability due to the formation of O– species via electron transfer from O to Ti.
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