Annealing and transport studies of suspended molybdenum disulfide devices.

We fabricate suspended molybdenum disulfide (MoS2) field effect transistor devices and develop an effective gas annealing technique that significantly improves device quality and increases conductance by 3-4 orders of magnitude. Mobility of the suspended devices ranges from 0.01 to 46 cm(2) V(-1) s(-1) before annealing, and from 0.5 to 105 cm(2) V(-1) s(-1) after annealing. Temperature dependence measurements reveal two transport mechanisms: electron-phonon scattering at high temperatures and thermal activation over a gate-tunable barrier height at low temperatures. Our results suggest that transport in these devices is not limited by the substrates, but likely by defects, charge impurities and/or Schottky barriers at the metal-MoS2 interfaces. Finally, this suspended MoS2 device structure provides a versatile platform for other research areas, such as thermal, optical and mechanical studies.