Spin deposition of MoSx thin films

Thin films of MoS2 and amorphous MoS3 have been prepared on various glass a nd stainless steel substrates by thermolysis of spin cast solutions of (NH4 )(2)MOS4 in an organic diamine (ethylenediamine and 1,2-diaminopropane), Af ter deposition the resulting single-source precursor film [(H3NCnH2nNH3)MoS 4] was dried at 250 degrees C in air and subsequently heat treated at tempe ratures between 300 and 800 degrees C under inert nitrogen (N-2) atmosphere yielding films of MoSx (2 less than or equal to x less than or equal to 3) with carbon impurities. The resulting films with thicknesses up to 160 nm (800 degrees C) and 250 nm (300 degrees C) are highly homogeneous with a me tallic lustre and appear brown in transmission. While the films are amorpho us to X-ray diffraction up to temperatures of 400 degrees C, the crystallin ity increases for higher temperatures due to the formation of MoS2 microcry stallites. Furthermore, the composition and the microstructure strongly dep end on the used diamine solvent. Both X-ray and electron diffraction reveal a partially preferred orientation of the crystallites with their basal pla nes parallel to the substrate ( perpendicular to c, type II). After heat tr eatment at 800 degrees C under N-2 the MoS2 layer stacks consist of three t o four layers with a length of 5-8 nm. The optical characterisation of the thin films shows a strong absorption in the visible part of the spectrum ch aracteristic of MoS2 with an absorption coefficient alpha(550) of 2 x 10(5) cm-l. Tribological measurements up to 5000 cycles against steel reveal the highest wear-life with a friction coefficient mu < 0.1 for coatings heat t reated at 500 degrees C. The highest capacity for reversible electrochemica l Li intercalation of 30 mC/cm(2) was found in amorphous MoSx coatings (400 degrees C heat treatment). A weak electrochromic effect with a change in t ransmission of Delta T approximate to 0.08 around 800 nm was observed after Li intercalation. (C) 1999 Elsevier Science S.A. All rights reserved.