Applied Surface Science, Vol.474, 227-231, 2019
Trigonal (1T) and hexagonal (2H) mixed phases MoS2 thin films
Molybdenum di-sulfide thin films of thickness < 1500 angstrom, were prepared by the dip-coating technique at different baking temperatures within the range 400 degrees C-450 degrees C using methanolic solution of ammonium molybdate and ammonium thiocyanate and hence studied their different properties using X-ray diffraction (XRD), UV-vis spectroscopy, Photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and Current-Voltage (I-V) relationship measurements. XRD result shows that the MoS2 films are mixed metallic octahedral prismatic 1T-and trigonal prismatic bulk crystal 2H-phases. The I-V relationships show higher electrical conductivity for the films prepared at 400 degrees C and 450 degrees C than the films prepared at 425 degrees C. XPS measurement also shows the formation of mixed phases of MoS2 thin films as revealed by XRD. We have estimated the valence band maximum (VBM) and work functions from higher and lower energy range of UPS (He-I) spectra of MoS2 thin films prepared at 425 degrees C and 450 degrees C. The VBM are similar to 4.4 eV & similar to 4.2 eV and their work functions are similar to 3.5 eV & similar to 3.3 eV respectively that are correlated with conductivity and formation of mixed phases of MoS2 thin films. (C) 2018 Elsevier B. V. All rights reserved.