Polytype Control of MoS Using Chemical Bath Deposition

Molybdenum disulfide (MoS) has a wide range of applications from electronics to catalysis. While the properties of single-layer and multilayer MoS films are well understood, controlling the deposited MoS polytype remains a significant challenge. In this work, we employ chemical bath deposition, an aqueous deposition technique, to deposit large area MoS thin films at room temperature. Using Raman spectroscopy and x-ray photoelectron spectroscopy, we show that the deposited MoS polytype can be changed from semiconducting 2H MoS on hydrophobic -CH and -COCF terminated self-assembled monolayers (SAMs) to semimetallic 1T MoS on hydrophilic -OH and -COOH terminated SAMs. The data suggest that the deposition of MoS polytypes is controlled by the substrate surface energy. High surface energy substrates stabilize 1T MoS films, while 2H MoS is deposited on lower surface energy substrates. This effect appears to be general enabling the deposition of different MoS polytypes on a wide range of substrates.