Atomic/Molecular Layer Deposition of s-Block Metal Carboxylate Coordination Network Thin Films

We present novel atomic/molecular layer deposition (ALD/MLD) processes for the fabrication of crystalline inorganic-organic coordination network thin films with different s-block elements. Terephthalic acid is employed as the organic precursor. Such thin films could enable for example, next-generation battery, sensor and gas-storage technologies. The deposition processes fulfill the basic principles of ALD/MLD-type growth including the sequential self-saturated gas-surface reactions and atomic/molecular-level control for the film thickness, and yield crystalline thin films in a wide deposition temperature range. Structural characterization of the films is performed by grazing incidence X-ray diffraction (GIXRD) and Fourier-transform infrared (FTIR) spectroscopy. The data do not unambiguously prove but also do not rule out the crystal structures previously reported for the corresponding bulk samples. We moreover demonstrate the growth of crystalline thin films of a new terephthalate material with La as the metal component. Upon humidity treatments the Li, Na, K, Ba, and La terephthalate films remain unaffected while the Mg, Ca, and Sr terephthalate films reversibly absorb water molecules forming well-defined crystalline water-derivative phases.