Highly Improved Air-Stability of Monolayer TMDs Grown on Graphene Substrate

Abstract

In this work, we have identified a new role of graphene in improving the air stability of two-dimensional transition metal dichalcogenides (TMDs). Unlike the aging phenomenon that has been observed in a short period of time in TMDs flakes grown on SiO2/Si substrates (representatively, WS2/SiO2), it was observed that epitaxially grown WS2 flakes on graphene substrate (WS2/Gr) maintained a clean surface and good crystallinity as in the initial growth without any encapsulation even after a year in ambient air conditions. Our investigations describe the relationship between crystal defects and aging phenomena through experimental and analytical results. We also show for the first time the effect of "doping effect induced by charge transfer" on improving air stability. This study emphasize the effect of the target substrate on the stability of TMDs material, and it is expected to pave the way for commercialization of TMDs with stable performance for a long time.