Fig. 5: Optimized dual transport (DT) steep slope FET transfer characteristic and analog/digital figures of merit.

a Qualitative transfer characteristics of our 2D–2D TFET and its built-in MOSFET together with the sought after characteristic of the DT FET. Ideally, the dual transport FET should turn ON following the steep TFET curve, and then reach the thermionic I_ON current provided by the WSe₂ MOSFET. b Transfer characteristics of the WSe₂ FET and WSe₂/SnSe₂ TFET with optimized threshold voltages, so to obtain V_Th,TFET > V_Th,MOSFET. The resulting DT transfer characteristics inherits the advantages of the two devices. All the curves are measured at V_D = 500 mV. c Transconductance efficiency of the DT FET and its constituting devices. While not reaching the peak transconductance value of the WSe₂/SnSe₂ heterojunction, the DT FET maintains better performance of the MOSFET for all the output current range, outperforming also the TFET at large current values. d Direct comparison of the substhreshold slope as a function of output current for the DT FET and the base components. Similarly to the transconductance efficiency, the DT FET exhibits a minimum point subthreshold slope larger than the TFET, but it outperforms the WSe₂ MOSFET over the entire range of output current and maintains steeper characteristic than the heterojunction FET for large I_D.