P-type cold-source field-effect transistors with TcX ₂ and ReX ₂ (X = S, Se) cold source electrodes: A computational study

Cold-source field-effect transistors (CS-FETs) have been developed to overcome the major challenge of power dissipation in modern integrated circuits. Cold metals suitable for n-type CS-FETs have been proposed as the ideal electrode to filter the high-energy electrons and break the thermal limit on subthreshold swing (SS). In this work, regarding the p-type CS-FETs, we propose TcX2 and ReX2 (X = S, Se) as the injection source to realize the sub-thermal switching for holes. First-principles calculations unveils the cold-metal characteristics of monolayer TcX2 and ReX2, possessing a sub-gap below the Fermi level and a decreasing DOS with energy. Quantum device simulations demonstrate that TcX2 and ReX2 can enable the cold source effects in WSe2 p-type FETs, achieving steep SS of 29-38 mV/dec and high on/off ratios of (2.3-5.6) x 10(7). Moreover, multilayer ReS2 retains the cold metal characteristic, thus ensuring similar CS-FET performances to that of the monolayer source. This work underlines the significance of cold metals for the design of p-type CS-FETs.