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Selective Interface Reaction Studies during Atomic Layer Deposition Process Based on Surface Properties of Metal Oxide Substrate and Chemical Properties of Precursors
Title
Selective Interface Reaction Studies during Atomic Layer Deposition Process Based on Surface Properties of Metal Oxide Substrate and Chemical Properties of Precursors
Creator
Luo, Chunxin
Date
2024
Description
Site-selective atomic layer deposition (SS-ALD) on metal oxide nanoparticles will require subtle surface chemical control through site...
Show moreSite-selective atomic layer deposition (SS-ALD) on metal oxide nanoparticles will require subtle surface chemical control through site-specific surface functionalization (e.g. selective hydration) or highly discriminating reactivity. Two main factors, including the properties of substrate and proton-affinity of the precursors, which would affect the selectivity of ALD process will be discussed and the mechanism will be revealed in this thesis.The adsorption step on substrate surface of the metal precursors will affect the first half reaction of ALD process. Our hypothesis here is that surface hydroxyl group on different oriented metal oxide surface have different desorption temperature points. In this case, we can control the adsorption step by simply adjusting substrate temperature to targeting temperature point where it allows us to achieve selectively removal of the targeting hydroxyl groups while leaving the hydroxyl remain on desired site. Selectively dihydroxylation on In2O3 (111) and (211) single crystal surface is studied, and further SS-ALD is achieved on high-oriented In2O3 (111) thin-film by simply thermal treatment, which indicated that discriminant dihydroxylation can be a promising pathway to SS-ALD. Thermal dehydration of facet-specific anatase TiO2 truncated-octahedron, disks, and rods samples is investigated by Fourier-transform infrared spectroscopy (FTIR). Potential facet-specific reaction window was revealed. However, the various oxidation state on transition metal created more complicated surface atomic arrangement, which make the study of thermal dihydroxylation on nanoparticles even more complicated. Thus, we turn our focus back on the In2O3 material. Well-constructed and facet specific In2O3 nanoparticle cube, octahedron and trapezohedron with only one of (100), (111), and (211) surface exposed, respectively, were synthesized and investigated by DRIFT. Further ALD treated In2O3 nanoparticles were studied. Moreover, epitaxial growth of In2O3 on YSZ (100) and (111) substrates were obtained by thermal ALD method. Post-annealing treatments applied on these epitaxial growth In2O3 samples. The relationship between the grow orientation of single crystal surface and electrical performance are investigated and discussed. Finally, some preliminary studies of the relationship between the ligand-dependent precursor and ALD performance were conducted by using the in-situ FTIR method. Surface reaction mechanisms during the ALD process with porous AAOAl film as substrate were studied. Selectivity exhibited from DMAI precursor was investigated and discussed. ALD performance and related surface reaction of Ga precursor such as Ga2(NMe2)6, Ga(amd)(NMe2)2, and Ga(amd)3 were studied by in-situ FTIR as well. Overall, thermal evolution of surface hydroxyl group on faceted TiO2, In2O3 nanoparticles were probed by temperature variable FTIR. Selective proton-dependent chemical reaction can be achieved on different oriented metal oxide surface. Orientation dependent electrical properties was studied on high-oriented In2O3 (111) and In2O3 (100) surface. An alternative way of in-situ FTIR measurement to study the surface reaction during ALD process was designed and investigated. Despite the remaining work, the concept and methodology of site-selective atomic layer deposition (SS-ALD) and associated probing techniques have the potential to captivate researchers in the fields of surface chemistry, semiconductors, and electrical devices.
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