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On reactant delivery into a new fixed-bed atomic layer deposition reactor for particulate matter
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Kemian tekniikan korkeakoulu |
Master's thesis
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CHEM3047
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en
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80+20
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Low-volatility reactants are often utilized in atomic layer deposition (ALD) processes. These reactants are delivered from the reactant feed vessel by evaporating or subliming the liquid or solid reactant respectively. This thesis aimed at understanding the delivery of liquid and solid reactants from a reactant feed vessel to a new fixed-bed powder ALD reactor at Aalto University. The literature review discusses the concept and effect of different process parameters on the delivery of reactants. The parameters include carrier gas flow rate, reactant feed vessel temperature, system pressure, and reactant delivery time.
The experimental part of the thesis was focused on the performance of the reactant feed vessel. This thesis work presents the initial results of the ALDI-1 reactor. Water and zinc acetylacetonate hydrate were delivered on a γ-alumina sphere bed. The amount of reactant delivered (g/h) increases with increasing reactant feed vessel temperature, the delivery time of the reactants, and the flow rate of the carrier gas. A clear trend of decreasing source vessel efficiency with increasing flow rate of carrier gas was observed. Moderate carrier gas flow rate (>200 sccm) and low reactant temperature favor the high source vessel efficiency. The Zn(acac)2 hydrate-ALD reaction on γ-alumina increased the temperature along the particulate bed. Qualitative gas analysis of oxidative treatment after Zn(acac)2 hydrate-ALD on alumina produced water and carbon dioxide spikes in a mass spectrometer. Complete combustion of acetylacetonate ligands was confirmed at 500 °C. Constant MS signal spikes for carbon dioxide and water after Zn(acac)2 hydrate-ALD at argon flow rates of 100, 200, and 400 sccm indicate the saturation of the alumina bed.