The Effect of a Vacuum Environment on the Electrical Properties of a MoS2 Back-Gate Field Effect Transistor

Adsorption of gas molecules on the surface of two-dimensional (2D) molybdenum disulfide (MoS2) can significantly affect its carrier transport properties. In this letter, we investigated the effect of a vacuum environment on the electrical properties of a back-gate MoS2 FET. Benefiting from the reduced scattering centers caused by the adsorbed oxygen and water molecules in a vacuum, the current Ion/Ioff ratio of back-gate MoS2 field effect transistor increased from 1.4 × 106 to 1.8 × 107. In addition, the values of field effect carrier mobility were increased by more than four times, from 1 cm2/Vs to 4.2 cm2/Vs. Furthermore, the values of subthreshold swing could be decreased by 30% compared with the sample in ambient air. We demonstrate that the vacuum process can effectively remove absorbates and improve device performances.