Performance Analysis of Strained Monolayer ${\rm MoS}_{2}$ MOSFET

We present a computational study on the impact of tensile/compressive uniaxial (ε_xx) and biaxial (ε_xx=ε_yy) strain on monolayer MoS₂, n-, and p-MOSFETs. The material properties like band structure, carrier effective mass, and the multiband Hamiltonian of the channel are evaluated using the density functional theory. Using these parameters, self-consistent Poisson-Schrödinger solution under the nonequilibrium Green's function formalism is carried out to simulate the MOS device characteristics. 1.75% uniaxial tensile strain is found to provide a minor (6%) ON current improvement for the n-MOSFET, whereas same amount of biaxial tensile strain is found to considerably improve the p-MOSFET ON currents by 2-3 times. Compressive strain, however, degrades both n-MOS and p-MOS devices performance. It is also observed that the improvement in p-MOSFET can be attained only when the channel material becomes indirect gap in nature. We further study the performance degradation in the quasi-ballistic long-channel regime using a projected current method.

I. Introduction

Among the various classes of alternate channel materials under research, the 2-D materials having nonzero bandgap in their sheet form like the transition metal dichalcogenides (, W; , Se, and Te) seem very promising for MOSFET applications. This is due to their better electrostatic integrity, optical transparency, mechanical flexibility, and the geometrical compatibility with the standard planar CMOS technology. Among such materials the performance of -based MOS transistor and logic have been successfully demonstrated experimentally [1], [2]. This has generated great interest in studying such nongraphene 2-D crystals for future MOSFET channel application [3]–[5].