[Paper] Deposition of Ultra-Thin Polythiourea Films by Molecular Layer Deposition




Deposition of Ultra-Thin Polythiourea Films by Molecular Layer Deposition, Paul W. Loscutoff, Han-Bo-Ram Lee, and Stacey F. Bent, Chemistry of Materials,2010


http://dx.doi.org/10.1021/cm1016239


Abstract


Molecular layer deposition (MLD) is a film growth technique which utilizes self-saturating surface chemistry to deposit organic films layer-by-layer. In this study we report a new MLD coupling chemistry to grow oxygen-free films with polythiourea groups. 1,4-Phenylene diisothiocyanate and ethylenediamine are reacted to form thiourea moieties. The films exhibit a constant growth rate and showsaturation behavior in dosing each of the precursor molecules. The chemical composition of the films is probed by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory, which confirm that the expected polythiourea films are formed by the MLD process. Transmission electron micrographs demonstrate conformal coating of SiO2 nano- particles. Thermal stability studies reveal that the thiourea films are stable to 200 C, and indicate that desorption likely occurs at the SiO2/organic interface.