We report on the effects of the substrate, starting material, and temperature on the growth of MoS2 atomic layers by thermal vapor sulfurization in a tube-furnace system. With Mo as the staring material, atomic layers of MoS2 are obtained on sapphire substrates while MoS2 nanoparticles embedded in SiO2 amorphous are obtained on native-SiO2/Si substrates under the same sulfurizing conditions. An anomalous thickness-dependent Raman shift (A1g) of the MoS2 atomic layers is observed in Mo-sulfurizations on sapphire
substrates, which can be attributed to the competition between the effect of thickness and that of surface/interface. Both effects vary with the sulfurizing temperatures for a certain initial Mo thickness. This anomalous frequency trance of A1g is missing when using MoO3, instead of Mo, as the starting material. In this case, the lateral growth of MoS2 on sapphire substrates is largely improved; meanwhile, the area density of the resultant MoS2 atomic layers is significantly increased by increasing the deposition temperature of
the starting MoO3. The thickness of MoS2 is generally controlled by the thickness of the starting material; however, the structural and morphological properties of the MoS2 crystallites, towards large area and continuous atomic layers, are strongly dependent on the temperature of the initial material deposition as well as that of the post-deposition sulfurization.