Introduction of an Al seed layer for facile adsorption of MoCl5 during atomic layer deposition of MoS2
Journal
Physica Status Solidi A: Applications and Materials Science
Date
2020.08.07
Abstract
A low-temperature one-step growth method for few-layer MoS2 using an atomic layer deposition scheme with MoCl5 and H2S precursors was systematically studied by introducing an ultrathin Al seed layer. First, to optimize the deposition conditions, we investigated the effects of the deposition (200？420 °C) and MoCl5 canister (100？160 °C) temperatures on the MoS2 growth behavior. On the SiO2 surface, increasing the deposition temperature reduced the growth rate while favoring more lateral growth. However, an increase in the MoCl5 sublimating temperature, which was beneficial for improving the film quality, sharply reduced the growth rate, probably owing to the pronounced self-etching effect of MoCl5. To compensate for the reduced deposition rate while maintaining the MoS2 quality, we introduced an ultrathin Al seed layer (~5 nm), which promoted the surface adsorption of MoCl5 molecules at an early growth stage according to density functional theory calculations. Thus, we successfully synthesized a polycrystalline mono-to-bilayer MoS2 film with negligible amounts of residual contaminants (particularly Cl and Al) using the proposed Al seeding approach.