Selective etching in graphene-MoS2 heterostructures for fabricating graphene-contacted MoS2 transistors

Semiconducting molybdenum disulfide (MoS2) has drawn a lot of attention for its exceptional electronic and optoelectronic properties. Despite the potential advantages, the large contact resistance at the metal-MoS2 interfaces has been one of the biggest obstacles for the realization of ideal MoS2 transistors. One solution to improve the metal-MoS2 interfaces is to use the graphene electrodes. Here, we provide a selective etching method for fabricating graphene-contacted MoS2 transistors. It has been proved that the graphene could be totally etched with Ar+ plasma treatment, and the multilayer MoS2 flake can also be reduced layer by layer with Ar+ plasma treatment. By etching graphene selectively in graphene-MoS2 heterostructures, one can obtain graphene-contacted MoS2 transistors successfully. The transistor reported in this paper shows an on-off ratio about 10(6) and a carrier mobility about 42 cm(2) V-1 s(-1). This selective etching method would be beneficial for some other graphene-contacted electronic devices.