Atomic Layer Deposition of Inorganic-Organic Hybrid Material Thin Films
Year: 2020
Type: dissertation
Abstract: Inorganic–organic hybrids represent a class of materials consisting of inorganic and organic components mixed at the molecular level. This offers not only the possibility to combine material properties of the constituents, but also to discover completely new characteristics. Because of this, hybrid materials have become an important part of materials research. Atomic layer deposition (ALD) is a gas phase thin film deposition method with the ability to deposit conformal films with good control over film thickness and composition. Furthermore, ALD offers large-area uniformity and perfect step-coverage. Molecular layer deposition (MLD), used for depositing organic polymers, is a method derived directly from ALD. The combination of ALD and MLD offers a convenient way of depositing inorganic–organic hybrid material thin films for applications, such as electronics and optics, where ultimate precision is needed. In this thesis, ALD/MLD was used to deposit hybrid nanolaminates, metal–organic frameworks, and zinc glutarate. Nanolaminates of Ta2O5 and polyimide were deposited using tantalum ethoxide, water, pyromellitic dianhydride, and diaminohexane as the precursors. The leakage currents could be greatly reduced compared to the bare Ta2O5 and polyimide by layering of the materials. It was also shown that the mechanical properties could be improved by introduction of the organic layers. MOF-5 and IRMOF-8 thin films were deposited using zinc acetate, 1,4-benzenedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid as the precursors. The deposition process included ALD/MLD combined with a two-step post-deposition crystallization in moist air and in an autoclave with dimethylformamide. Despite the need for a liquid-phase crystallization, the conformality and continuity of the films could be preserved. ALD/MLD of zinc glutarate thin films was shown for the first time ever using zinc acetate and glutaric acid as the precursors. The films were crystalline as-deposited with a structure matching to zinc glutarate. Catalytic activity of the films was demonstrated by polymerizing propylene oxide and CO2 in the presence of zinc glutarate coated glass wool and steel mesh.
Source: Työväentutkimus Vuosikirja
Author: Leo D. Salmi
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3048659795