Quantum Transport Simulation and Logic Gate Application of n-Type Sub-10 nm Monolayer MoSi ₂ N ₄ MOSFETs ^†

Nowadays, silicon-based field-effect transistors (FETs) are approaching the physical limits, while two-dimensional (2D) materials have emerged as promising channel material candidates to overcome these limitations owing to their natural atomic thickness, smooth surface, and superior gate control ability. Here, we investigate the electronic properties of monolayer (ML) MoSi2N4 and the transport properties of ML MoSi2N4 n-type metal-oxide-semiconductor field-effect transistors (MOSFETs) using density functional theory (DFT) combined with the nonequilibrium Green’s function (NEGF) formalism. The ML MoSi2N4 has an indirect band gap of 1.74 eV and a small electron effective mass. For high-performance (HP) applications, the MoSi2N4 FETs with 5, 6, and 7 nm gate length (Lg) all meet the International Technology Roadmap for Semiconductors (ITRS) requirements. Notably, the 5 nm Lg MoSi2N4 FETs exhibit a high on-state current of 1846 μA/μm. For low-power (LP) applications, both the 6 and 7 nm Lg MoSi2N4 FETs exhibit an on/off ratio exceeding 107, while the 7 nm Lg MoSi2N4 FETs achieve a low subthreshold swing (SS) of 53 mV/dec, which is below the room-temperature Boltzmann limit. Through underlap structure, the 2 nm Lg MoSi2N4 FETs can meet the ITRS requirements for both HP and LP applications. Furthermore, compared to other 2D FETs, the MoSi2N4 FETs demonstrate competitive advantages in terms of energy-delay product (EDP). At last, we design and simulate pseudo-CMOS logic gate circuits based on ML MoSi2N4 n-type MOSFETs. Our study indicates that ML MoSi2N4 is a promising channel material for FETs in the postsilicon era.