2D Semiconductor FETs—Projections and Design for Sub-10 nm VLSI

Abstract

Two-dimensional (2D) crystal semiconductors, such as the well-known molybdenum disulfide (MoS2), are witnessing an explosion in research activities due to their apparent potential for various electronic and optoelectronic applications. In this paper, dissipative quantum transport simulations using nonequilibrium Green’s function formalism are performed to rigorously evaluate the scalability and performance of monolayer/multilayer 2D semiconductor-based FETs for sub-10 nm gate length very large-scale integration (VLSI) technologies. Device design considerations in terms of the choice of prospective 2D material/structure/technology to fulfill sub-10 nm International Technology Roadmap for Semiconductors (ITRS) requirements are analyzed. First, it is found that MoS2 FETs can meet high-performance (HP) requirement up to 6.6 nm gate length using bilayer MoS2 as the channel material, while low-standby-power (LSTP) requirements present significant challenges for all sub-10 nm gate lengths. Second, by studying the effects of underlap (UL) structures, scattering strength, and carrier effective mass, it is found that the high mobility and suitably low effective mass of tungsten diselenide (WSe2), aided by the UL, enable 2D FETs for both HP and LSTP applications at the smallest foreseeable (5.9 nm) gate length. Finally, possible solutions for sub-5 nm gate lengths, specifically anisotropic 2D semiconductor materials for HP and sub- $kT/q$ switch (2D tunnel FET) for LSTP, are also proposed based on the effects of critical material parameters on the device performance.