Enhanced Ion/Ioff ratio of multi-layer MoS2 field-effect transistors treated by reactive ion etching process

Abstract

Semiconducting two-dimensional (2-D) transition metal dichalcogenides (TMDs) materials, such as MoS2 and WSe2, have promising advantages such as good surface roughness without dangling bonds, diverse electronic and optical properties with the desired value of bandgap. In particular, multi-layer MoS2 has great potential for advanced field-effect transistors (FETs). In this work, multi-layer MoS2 FETs were fabricated by using mechanical exfoliation method and selective patterning process with an alignment technique. Then, the fabricated devices were treated by a systematic reactive ion etching (RIE) with CF4 plasma. A dramatically improved ratio of on-current to off-current (Ion/Ioff) has been investigated in the device with MoS2 channel thinned by the RIE process. Channel doping concentration (Nd), MoS2 thickness measured by atomic force microscope (AFM) and maximum depletion width (Dmax) were also discussed in detail to verify experimental results. Our work provides important information for the development of energy efficient electronic devices with optimal channel thickness, as well as better understanding the switching operation of MoS2 FETs.