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

TL;DR

This study computationally examines how tensile and compressive strains affect the electronic properties and performance of monolayer MoS$_{2}$ MOSFETs, revealing strain-dependent improvements and degradations in device currents.

Contribution

It provides a detailed analysis of strain effects on monolayer MoS$_{2}$ FETs using DFT and NEGF, highlighting conditions for performance enhancement and degradation.

Findings

Biaxial tensile strain significantly improves PMOS ON current.

Uniaxial tensile strain slightly enhances NMOS ON current.

Compressive strain degrades device performance.

Abstract

We present a computational study on the impact of tensile/compressive uniaxial ($\varepsilon_{xx}$) and biaxial ($\varepsilon_{xx}=\varepsilon_{yy}$) strain on monolayer MoS$_{2}$ NMOS and PMOS FETs. The material properties like band structure, carrier effective mass and the multi-band Hamiltonian of the channel, are evaluated using the Density Functional Theory (DFT). Using these parameters, self-consistent Poisson-Schr\"{o}dinger solution under the Non-Equilibrium Green's Function (NEGF) 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 NMOSFET, whereas same amount of biaxial tensile strain is found to considerably improve the PMOSFET ON currents by 2-3 times. Compressive strain however degrades both NMOS and PMOS device performance. It is also observed that the improvement in PMOSFET 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.