Atomic layer deposition (ALD) has successfully provided thin films of organic-inorganic hybrid materials based on saturated linear carboxylic acids and trimethylaluminium (TMA). Films were grown for seven carboxylic acids: oxalic, malonic, succinic, glutaric, pimelic, suberic and sebacic acid, i.e. ranging from 2 to 10 carbon atoms in the molecular structure. These processes show exceptionally high growth rates; up to 4.3 nm/cycle for the pimelic acid-TMA system. Quartz crystal microbalance measurements of the growth dynamics indicate that all systems are of a self limiting ALD-type. Nevertheless, temperature dependent growth was observed in several systems. The width of the ALD windows shows correlations with the length of the carbon chains. Fourier transform infrared spectroscopy clearly proved that the deposited films are of a hybrid character, where the carboxylic acids primarily form bidentate complexes, though bridging complexes may also form. All films are X-ray amorphous as deposited. The films were further analyzed by atomic force microscopy for surface roughness and topography, UV-Vis spectroscopy and ellipsometry for optical properties, and the goniometer method for measuring sessile drops for surface wetting properties. Apart from the oxalic and malonic acid-TMA systems, the films are stable in contact with water. The films are generally smooth, transparent and have a refractive index close to 1.5. The complete coverage and accurate growth control offered by the ALD technique is here proven to provide surface-functionalized hybrid materials resembling metal-organic frameworks (MOF), probably as rather dense structures, yet with substantial potential for applications.

Thin films of metal–organic frameworks (MOFs) are promising for a wide range of applications including membranes for separations and sensor materials in microelectronics.

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Ln 2 O 3 thin films with optically active f-electrons (Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb) have been grown on Si(100) and soda lime glass substrates by atomic layer deposition (ALD) using Ln(thd) 3 (Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione) and ozone as precursors. The temperature range for depositions was 200 -400 °C. Growth rates were measured by spectroscopic ellipsometry and a region with constant growth rate (ALD window) was found for Ln = Ho and Tm. All the compounds are grown as amorphous films at low temperatures, whereas crystalline films (cubic C-Ln 2 O 3 ) are obtained above a certain temperature ranging from 300 to 250 °C for 10 Nd 2 O 3 to Yb 2 O 3 , respectively. AFM studies show that the films were smooth (rms < 1 nm) except for depositions at the highest temperatures. Refractive index was measured by spectroscopic ellipsometry and was found to depend on the deposition temperature. Optical absorption measurements show that the absorption from the f-f transitions depends strongly on the crystallinity of the material. The clear correlation between the degree of crystallinity, optical absorptions and refractive index, is discussed.

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