Role of interface trap charges in the performance of monolayer and bilayer MoS2-based field-effect transistors

Abstract

The two-dimensional MoS 2 -based field-effect transistor emerges as a promising candidate for scaling down the channel length beyond the end of silicon CMOS nanoelectronics. Although several recent experimental studies have reported the presence of interface trap charges between MoS 2 and oxide interface, their deleterious effects on MoS 2 -FET performance remain unexplored. Therefore, in this work, we investigate the digital performance of monolayer and bilayer MoS 2 -FETs in the presence of constant energy and Gaussian trap distributions. To this purpose, the trap charge description is introduced in device electrostatics using 2-D Poisson’s equation, which is self-consistently solved with non-equilibrium Green’s function (NEGF) equations for accurately capturing their effect in the semi-ballistic transport. It is found that monolayer MoS 2 -FET undergoes higher degradation in the drive current than bilayer MoS 2 -FET in both the cases of constant energy and Gaussian trap distributions. The interface trap charges possess severe limitations on the key MoS 2 -FET metrics, such as ON-current and sub-threshold slope, rather than the OFF-state current. Our studies suggest that minimizing the distributed trap at MoS 2 and oxide interface can significantly enhance the drive current, and hence, improve the speed and energy efficiency.