Field Effect Transistors with Current Saturation and Voltage Gain in Ultrathin ReS2

We report the fabrication and device characteristics of exfoliated, few-layer, dual-gated ReS2 field effect transistors (FETs). The ReS2 FETs display n-type behavior with a room temperature I on/I off of 105. Many devices were studied with a maximum intrinsic mobility of 12 cm2·V–1·s–1 at room temperature and 26 cm2·V–1·s–1 at 77 K. The Cr/Au-ReS2 contact resistance determined using the transfer length method is gate-bias dependent and ranges from 175 kΩ·μm to 5 kΩ·μm, and shows an exponential dependence on back-gate voltage indicating Schottky barriers at the source and drain contacts. Dual-gated ReS2 FETs demonstrate current saturation, voltage gain, and a subthreshold swing of 148 mV/decade.