Substrate modified thermal stability of mono- and few-layer MoS 2 .

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 MoS2 . Triangular etching holes, which are considered to initiate from defect sites, form on MoS2 when the temperature exceeds a threshold. On Al2 O3 and SiO2 , monolayer MoS2 is found to be more stable in thermal annealing than few-layer MoS2 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 MoS2 samples. The substrate modification of the thermal stability of MoS2 with various thicknesses is attributed to the competition between MoS2 -substrate interface interaction and MoS2 -MoS2 interlayer interaction. Our findings provide important design rules for MoS2 -based devices, and also potentially point to a route of controlled patterning of MoS2 with substrate engineering.