Large-scale integration of MoS 2 in electronic devices requires the development of reliable and cost-effective deposition processes, leading to uniform MoS 2 layers on a wafer scale. Here we report on the detailed study of the heterogeneous vapor–solid reaction between a pre-deposited molybdenum solid film and sulfur vapor, thus resulting in a controlled growth of MoS 2 films onto SiO 2/Si substrates with a tunable thickness and cm 2-scale uniformity. Based on Raman spectroscopy and photoluminescence, we show that the degree of crystallinity in the MoS 2 layers is dictated by the deposition temperature and thickness. In particular, the MoS 2 structural disorder observed at low temperature (< 750 C) and low thickness (two layers) evolves to a more ordered crystalline structure at high temperature (1000 C) and high thickness (four layers). From an atomic force microscopy investigation prior to and after …