Tuning the orientation of few-layer MoS(2) films using one-zone sulfurization

Few-layer MoS(2) films are promising candidates for applications in numerous areas, such as photovoltaics, photocatalysis, nanotribology, lithium batteries, hydro-desulfurization catalysis and dry lubricants, especially due to their distinctive electronic, optical, and catalytic properties. In general, two alignments of MoS(2) layers are possible – the horizontal and the vertical one, having different physicochemical properties. Layers of both orientations are conventionally fabricated by a sulfurization of pre-deposited Mo films. So far, the Mo thickness was considered as a critical parameter influencing the final orientation of MoS(2) layers with horizontally and vertically aligned MoS(2) grown from thin (1 nm) and thick (3 nm) Mo films, respectively. Here, we present a fabrication protocol enabling the growth of horizontally or vertically aligned few-layer MoS(2) films utilizing the same Mo thickness of 3 nm. We show that the sulfur vapor is another parameter influencing the growth mechanism, where a sulfurization with higher sulfur vapor pressure leads to vertical MoS(2) layers and slow sulfur evaporation results in horizontally aligned layers for a thicker Mo starting layer.