High crystalline MoS2 films are prepared by one-step ALD without followed high-temperature annealing. MoCl5 and H2S are used as precursors, while Si and Al2O3 are used as substrates respectively. The obtained MoS2 films are characterized by Atomic Force Microscopy (AFM), Raman spectroscopy, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), indicating they possess structures in high quality. Experimental results demonstrate the film grain sizes can be tuned from similar to 20 nm to similar to 100 nm at various growth temperatures from 420 degrees C to 480 degrees C and excellent crystal performance can be guaranteed from 430 degrees C to 470 degrees C. Meanwhile, the growth temperature should not exceed 480 degrees C due to decomposition of the functional groups. Furthermore, Al2O3 can do better than Si as a substrate for the film building for more necessary hydroxyls during initial reaction on its surface. The average growth rate of the high crystallinity MoS2 film is similar to 4.3 angstrom/cycle for Al2O3 substrate and -3.8 angstrom/cycle for Si substrate. (C) 2017 Elsevier B.V. All rights reserved.