Construction of Inverse Metal-Zeolite Interfaces via Area-Selective Atomic Layer Deposition.
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ABSTRACT:
SUBMITTER: Zhai P
PROVIDER: S-EPMC8569675 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The atomic layer deposition of gallium and indium oxide was investigated on mesoporous silica powder and compared to the related aluminum oxide process. The respective oxide (GaOx, InOx) was deposited using sequential dosing of trimethylgallium or trimethylindium and water at 150 °C. In-situ thermogravimetry provided direct insight into the growth rates and deposition behavior. The highly amorphous and well-dispersed nature of the oxides was shown by XRD and STEM EDX-mappings. N2 sorption analysis revealed that both ALD processes resulted in high specific surface areas while maintaining the pore structure. The stoichiometry of GaOx and InOx was suggested by thermogravimetry and confirmed by XPS. FTIR and solid-state NMR were conducted to investigate the ligand deposition behavior and thermogravimetric data helped estimate the layer thicknesses. Finally, this study provides a deeper understanding of ALD on powder substrates and enables the precise synthesis of high surface area metal oxides for catalytic applications.
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Project description:Two-dimensional transition metal dichalcogenides, such as MoS2, are intensely studied for applications in electronics. However, the difficulty of depositing large-area films of sufficient quality under application-relevant conditions remains a major challenge. Herein, we demonstrate deposition of polycrystalline, wafer-scale MoS2, TiS2, and WS2 films of controlled thickness at record-low temperatures down to 100 °C using plasma-enhanced atomic layer deposition. We show that preventing excess sulfur incorporation from H2S-based plasma is the key to deposition of crystalline films, which can be achieved by adding H2 to the plasma feed gas. Film composition, crystallinity, growth, morphology, and electrical properties of MoS x films prepared within a broad range of deposition conditions have been systematically characterized. Film characteristics are correlated with results of field-effect transistors based on MoS2 films deposited at 100 °C. The capability to deposit MoS2 on poly(ethylene terephthalate) substrates showcases the potential of our process for flexible devices. Furthermore, the composition control achieved by tailoring plasma chemistry is relevant for all low-temperature plasma-enhanced deposition processes of metal chalcogenides.
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Project description:Area-selective atomic layer deposition using small-molecule inhibitors (SMIs) involves vapor-phase dosing of inhibitor molecules, resulting in an industry-compatible approach. However, the identification of suitable SMIs that yield a high selectivity remains a challenging task. Recently, aniline (C6H5NH2) was shown to be an effective SMI during the area-selective deposition (ASD) of TiN, giving 6 nm of selective growth on SiO2 in the presence of Ru and Co non-growth areas. In this work, using density functional theory (DFT) and random sequential adsorption (RSA) simulations, we investigated how aniline can effectively block precursor adsorption on specific areas. Our DFT calculations confirmed that aniline selectively adsorbs on Ru and Co non-growth areas, whereas its adsorption on the SiO2 growth area is limited to physisorption. DFT reveals two stable adsorption configurations of aniline on the metal surfaces. Further calculations on the aniline-functionalized surfaces show that the aniline inhibitor significantly reduces the interaction of Ti precursor, tetrakis(dimethylamino)titanium, with the non-growth area. In addition, RSA simulations showed that the co-presence of two stable adsorption configurations allows for a high surface inhibitor coverage on both Co and Ru surfaces. As the surface saturates, there is a transition from the thermodynamically most favorable adsorption configuration to the sterically most favorable adsorption configuration, which results in a sufficiently dense inhibition layer, such that an incoming precursor molecule cannot fit in between the adsorbed precursor molecules. We also found that, as a result of the catalytic activity of the metallic non-growth area, further reactions of inhibitor molecules, such as hydrogenolysis, can play a role in precursor blocking.
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