Performance Limit of Monolayer WSe₂ Transistors; Significantly Outperform Their MoS₂ Counterpart

With the scaling limits of silicon-based MOS technology, the critical and challenging issue is to explore more and more alternative materials to improve the performance of devices. Two-dimensional (2D) semiconductor WSe₂ with a proper band gap and inherent stability under ambient conditions makes it a potential channel material for realizing new generation field-effect transistors (FETs). In light of the low on-state current of the experimental sub-10 nm 2D MoS₂ FETs, we explore the limitation of the monolayer (ML) WSe₂ device performance by using accurate ab initio quantum transport simulation. We find that the sub-10 nm 2D WSe₂ FETs apparently outperform their MoS₂ counterpart. The on-state current of the optimized p-type ML WSe₂ FETs can satisfy the criteria of the International Technology Roadmap for Semiconductors (ITRS) on both the high-performance (HP) and low-power (LP) devices until the gate length is scaled down to 2 and 3 nm, respectively. By the aid of the negative capacitance effect, even the 1 nm gate-length WSe₂ MOSFETs can satisfy both the HP and LP requirements in the ITRS 2028 completely. Remarkably, the ML WSe₂ MOSFET has the highest theoretical on-current in LP application among the examined 2D MOSFETs at the 5 nm gate length to the best of our knowledge.