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)o(ff) of 10 (5). Many devices were studied with a maximum intrinsic mobility of 12 cm2 center dot V1 center dot s1 at room temperature and 26 cm(2) center dot V-1 center dot 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 k Omega center dot mu m to 5 k Omega center dot mu m, 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.