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.
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.
Energy and power densities of all-solid-state lithium ion batteries can be improved by moving from planar battery structures to three-dimensional structures. Atomic layer deposition (ALD) is a very suitable technique for fabrication of such three-dimensional battery structures. The solid-state electrolyte material lithium lanthanum titanate (LLT) that we have previously made by ALD is unstable in direct contact with many anode materials, and therefore, Li 2 OÀAl 2 O 3 is proposed as a barrier material between the anode and the LLT electrolyte. The deposition of Li 2 OÀAl 2 O 3 thin films by ALD has been accomplished by combining ALD processes for lithium oxide/hydroxide and aluminum oxide. The surface layer composition of the obtained films is Li 2.2 Al 1.0 O z as analyzed by X-ray photoelectron spectroscopy (XPS) while the composition of the bulk film as dissolved in 10% HNO 3 is Li 1.6 Al 1.0 O z as analyzed by inductively coupled plasma mass spectroscopy (ICP-MS). The growth mechanisms of Li 2 OÀAl 2 O 3 films were studied by quartz crystal microbalance (QCM). The QCM data indicates that some absorbed water is left inside the films and that the absorbed water reacts with the metal precursor during subsequent pulses. The amount of absorbed water is reduced when the purge time after the water pulse is increased. Even if there is a contribution of absorbed water to the film growth, the growth saturates to about 2.8 Å/cycle and the film thickness increases linearly with increasing number of deposition cycles.
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