Sub-5 nm monolayer SnNX (X = Cl, Br)-based homogeneous CMOS devices

For next-generation CMOS electronics beyond silicon, the pursuit of channel materials capable of achieving symmetrical performance for n- and p-type devices, while supporting extreme device scaling, is of fundamental importance. Monolayer SnNX (X = Cl, Br) has emerged as a promising candidate, owing to its atomically thin structure and high carrier mobilities for both electrons and holes. Using first-principles calculations, the performance limits of sub-5 nm-L_g double-gated monolayer SnNX (X = Cl, Br) metal-oxide semiconductor field-effect transistors (MOSFETs) are explored. It is found that SnNX MOSFETs can meet the International Technology Roadmap for Semiconductors (ITRS) 2028 requirements for both high-performance (HP) and low-power (LP) applications, even at a reduced L_g of 3 nm. Notably, n-type SnNX MOSFETs with L_g = 5 nm exhibit ultra-high ON-state currents, even reaching 4533 μA μm^-1, which surpass those of most reported monolayer MOSFETs. In addition, the key performance metrics, i.e., ON-state current, subthreshold swing, delay time, total capacitance and power-delay product, indicate high symmetry between n- and p-type devices. These findings highlight the potential of SnNX (X = Cl, Br) monolayers as next-generation channel materials for building CMOS integrated circuits in the post-silicon era.