Molecular Layer Deposition of Zeolitic Imidazolate Framework-8 Films
Jorid Smets, Alexander John Cruz, Víctor Rubio‐Giménez, Max L. Tietze, Dmitry E. Kravchenko, Giel Arnauts, Aleksander Matavž, Nathalie Wauteraerts, Min Tu, Kristof Marcoen, Inhar Imaz, Daniel Maspoch, M. Korytov, Philippe M. Vereecken, Steven De Feyter, Tom Hauffman, Rob Ameloot
Abstract
Vapor-phase film deposition of metal–organic frameworks (MOFs) would facilitate the integration of these materials into electronic devices. We studied the vapor-phase layer-by-layer deposition of zeolitic imidazolate framework 8 (ZIF-8) by consecutive, self-saturating reactions of diethyl zinc, water, and 2-methylimidazole on a substrate. Two approaches were compared: (1) Direct ZIF-8 “molecular layer deposition” (MLD), which enables a nanometer-resolution thickness control and employs only self-saturating reactions, resulting in smooth films that are crystalline as-deposited, and (2) two-step ZIF-8 MLD, in which crystallization occurs during a postdeposition treatment with additional linker vapor. The latter approach resulted in a reduced deposition time and an improved MOF quality, i.e., increased crystallinity and probe molecule uptake, although the smoothness and thickness control were partially lost. Both approaches were developed in a modified atomic layer deposition reactor to ensure cleanroom compatibility.