P-type cold-source field-effect transistors with TcX₂ and ReX₂ (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) × 10⁷. 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.