Substrate modified thermal stability of mono- and few-layer MoS.

Two-dimensional semiconducting transition metal dichalcogenides have been employed as key components in various electronic devices. The thermal stability of these ultrathin materials must be carefully considered in device applications because the heating caused by current flow, light absorption, or other harsh environmental conditions is usually unavoidable. In this work, we found that the substrate plays a role in modifying the thermal stability of mono- and few-layer MoS. Triangular etching holes, which are considered to initiate from defect sites, form on MoS when the temperature exceeds a threshold. On AlO and SiO, monolayer MoS is found to be more stable in thermal annealing than few-layer MoS either in atmospheric-pressure air or under vacuum; while on mica, the absolute opposite behavior exists. However, this difference due to substrates appears to vanish when using defective, chemical-vapor-deposited MoS samples. The substrate modification of the thermal stability of MoS with various thicknesses is attributed to the competition between MoS-substrate interface interaction and MoS-MoS interlayer interaction. Our findings provide important design rules for MoS-based devices, and also potentially point to a route of controlled patterning of MoS with substrate engineering.