Thin films of stable metal-organic frameworks (MOFs) such as UiO-66 have enormous application potential, for instance in microelectronics. However, all-gas-phase deposition techniques are currently not available for such MOFs. We here report on thin-film deposition of the thermally and chemically stable UiO-66 in an all-gas-phase process by the aid of atomic layer deposition (ALD). Sequential reactions of ZrCl₄ and 1,4-benzenedicarboxylic acid produce amorphous organic–inorganic hybrid films that are subsequently crystallized to the UiO-66 structure by treatment in acetic acid vapour. We also introduce a new approach to control the stoichiometry between metal clusters and organic linkers by modulation of the ALD growth with additional acetic acid pulses. An all-gas-phase synthesis technique for UiO-66 could enable implementations in microelectronics that are not compatible with solvothermal synthesis. Since this technique is ALD-based, it could also give enhanced thickness control and the possibility to coat irregular substrates with high aspect ratios.

Thin films of MoO₃ have been obtained by the atomic layer deposition (ALD) technique using molybdenum hexacarbonyl (Mo(CO)₆), ozone, and water as precursors. A window for ALD growth was found in the temperature range 152 to 172 °C. Self-limiting growth was verified at a deposition temperature of 163 °C. The upper temperature range is determined by the thermal stability of the Mo(CO)₆ precursor. The growth dynamics was further investigated by quartz crystal microbalance to determine the effect of ozone and water on the deposition process. Growth using only water as oxygen source is hardly detectable. The growth rate increases to 0.75 Å per cycle when ozone is introduced. X-ray diffraction analysis indicates that the films are amorphous as deposited, but crystallise into the α- and β-MoO₃ phases during annealing in air at 500 °C and to phase-pure, highly oriented α-MoO₃ at 600 °C. Analysis by X-ray photoelectron spectroscopy shows that both as-deposited and annealed films contain Mo(VI). Atomic force microscopy proves a very low surface roughness for as-deposited films, which becomes rather rough for annealed films. This investigation has clearly proven the capability of carbonyls as useful precursors for ALD growth of oxides.

Thin films of organic–inorganic hybrid materials have been grown by the atomic layer deposition (ALD) technique, using trimethylaluminium (TMA) and aromatic carboxylic acids such as 1,2-benzene dicarboxylic acid, 1,3-benzene dicarboxylic acid, 1,4-benzene dicarboxylic acid, 1,3,5-benzene tricarboxylic acid, 1,2,4,5-benzene tetracarboxylic acid as precursors. Growth rates as function of temperature show that all systems, with the exception of the benzoic acid–TMA system, possess ALD-windows and provides growth rates in the range of 0.25–1.34 nm/cycle. X-ray diffraction studies of the as-deposited films reveal their amorphous character, which is also supported by very low surface roughness as measured by atomic force microscopy. As-deposited films were investigated by Fourier Transform Infrared Spectroscopy proving that the deposited films are of a hybrid character.