We study field effect transistor characteristics in etched single layer MoS2 nanoribbon devices of width 50 nm with ohmic contacts. We employ a SF6 dry plasma process to etch MoS2 nanoribbons using low etching (RF) power allowing very good control over the etching rate. Transconductance measurements reveal a steep sub-threshold slope of 3.5 V/dec using a global backgate. Moreover, we measure a high current density of 38 μA/μm, resulting in a high on/off ratio of the order of 105. We observe mobility reaching as high as 50 cm2/V s with increasing source-drain bias.