Atmospheric pressure CVD of molybdenum diselenide films on glass

Atmospheric pressure (AP)CVD of molybdenum diselenide films on glass substrates was achieved by reaction of diethyl selenide or di-tert-butylselenide with MoCl(5) at 500-650 degrees C. X-ray diffraction (XRD) showed that the MoSe(2) films were crystalline with a mixed 2Hb/3R polytype stacking and typical cell constants of a = 3.28, c = 6.48 angstrom (c-axis is x 2 for the 2Hb form and x 3 for the 3R form). Energy dispersive X-ray analysis (EDAX) gave a Mo/Se ratio close to 1:2 for films formed at 600-650 degrees C, those formed at lower temperatures contained some chlorine. The films were brown in appearance, were adhesive, passed the Scotch tape, test but could be scratched with a steel scalpel. Scanning electron microscopy (SEM) showed that the films were composed of needlelike agglomerates which became longer and thinner with increasing deposition temperature. The films showed high absorbance in the visible spectrum but were more transparent in the near-infrared.