Liquid film deposition of chalcogenide thin films

Abstract

Thin films of MoSx were prepared by liquid film deposition of MoS42- solutions in 1,2-diaminoethane (en) and 1,2-diaminopropane (pn) and subsequent thermolysis at temperatures up to 800°C under N2. As the coatings show a high carbon content of up to 30 at.% that influences the morphology and the physical properties, the precursor thermolysis and the solution properties were analysed in detail and correlated to the coating properties. A reduction of the intermediately formed MoS3 by organic residues at approx. 300°C was made out as the main cause of the carbon contamination during the thermolysis of the precursor salts (enH2)MoS4 and (pnH2)MoS4, leading to an immobilisation of the organic carbon. In the corresponding solutions cations of the form [RNH2...H...NH2R]+ could be detected, that result in an incorporation of additional diamine with 3-4 molecules per MoS42- ion in the wet films. This cross-linked structure on the one hand reduces the tendency of the precursor salts to crystallise and thus makes it easier to obtain amorphous precursor films, but on the other hand increases the content of organic residues before thermolysis.