Tailoring of the optoelectronic properties of few layer Molybdenum Disulfide (MoS2) Devices via Pulsed eBeam Gas Assisted Patterning

Two dimensional materials have received much attention in recent years for their outstanding properties. Semiconducting 2D MoS2 is considered a good candidate for device applications due to its superior electrical and optical properties. Optoelectronic properties of MoS2 flakes strongly depend on the geometry and number of atomic layers present in the flake. In general, these properties can not be modified once a device is fabricated. In this work we present prelimiary results on a novel nano-patterning method, pulsed e-beam gas assisted patterning (PEBGAP), that allows us to tailor the electronic or optical properties of MoS2 devices. We can modify the carrier channel geometry, its thickness or even underetch it to release a suspended membrane. Field effect devices were fabricated from mechanically exfoliated few-layer MoS2 flakes via optical and electron beam lithography followed by a metal evaporation and lift-off process to define the gate-contact structures. The devices were characterised employing Optical (Raman, μPL) and electrical light dependence transport measurements and Scanning Near Field Optical Microscopy (SNOM). Afterwards, PEBGAP was utilized to alter device geometries and structures with the aim of modifying their optoelectronic properties. By using this method, it may also be possible to bring out new physical phenomena in this material (superconductivity of suspended MoS2 wires in membranes, quantum correlation phenomena, magnetic response, etc.) or develope new routes towards nano-electro-mechanical-optical systems (NEMOS). We will show our preliminary results of the devices properties before and after their modification