Engineering the Growth of MoS2 via Atomic Layer Deposition of Molybdenum Oxide Film Precursor

In this Letter, varying the thickness of the ALD precursor films, we systematically investigate the properties of MoS2 by means of Raman and X-ray photoelectron spectroscopies (XPS) in addition to atomic force microscopy (AFM). We show that the use of the ALD technique allows the growth of MoS2 films with thicknesses down to four layers. On the contrary, at very low precursor thicknesses (<=2 nm), the interface energetics between the ALD precursor film and SiO2 play a dramatic role affecting the evolution of the sulfurization process and leading to MoS2 nanocluster formation. Nevertheless, this limitation is overcome exploiting monocrystalline sapphire substrate as support for the precursor.