Modeling the Impact of Phonon Scattering with Strain Effects on the Electrical Properties of MoS2 Field-Effect Transistors

Abstract

Molybdenum disulfide (MoS2) has distinctive electronic and mechanical properties which make it a highly prospective material for use as a channel in upcoming nanoelectronic devices. An analytical modeling framework was used to investigate the I–V characteristics of field-effect transistors based on MoS2. The study begins by developing a ballistic current equation using a circuit model with two contacts. The transmission probability, which considers both the acoustic and optical mean free path, is then derived. Next, the effect of phonon scattering on the device was examined by including transmission probabilities into the ballistic current equation. According to the findings, the presence of phonon scattering caused a decrease of 43.7% in the ballistic current of the device at room temperature when L = 10 nm. The influence of phonon scattering became more prominent as the temperature increased. In addition, this study also considers the impact of strain on the device. It is reported that applying compressive strain could increase the phonon scattering current by 13.3% at L = 10 nm at room temperature, as evaluated in terms of the electrons’ effective masses. However, the phonon scattering current decreased by 13.3% under the same condition due to the existence of tensile strain. Moreover, incorporating a high-k dielectric to mitigate the impact of scattering resulted in an even greater improvement in device performance. Specifically, at L = 6 nm, the ballistic current was surpassed by 58.4%. Furthermore, the study achieved SS = 68.2 mV/dec using Al2O3 and an on–off ratio of 7.75 × 104 using HfO2. Finally, the analytical results were validated with previous works, showing comparable agreement with the existing literature.

Evolution of type-II hetero-strain cylindrical-gate-all-around nanowire FET for exploration and analysis of enriched performances

“…Due to the channel length being short (10 nm) for devices A to F developed here, ballistic transport overrules and negligible roughness scattering inducts as is clearly observed from the mobility graphs (Fig. 5 d)showing no much variation in the channel for the transport of electrons from source to drain through the strained-Si layer, while slight reduction in carrier mobility is observed in line with the perception of 29 , 30 due to the influence of negligible roughness at the strained-Si–SiGe interface. In this novel device the strain on the tri-layered system causes band bending in the channel area, initiating energy band splitting and increasing occupancy of electrons in twofold valleys of the heterostructure, which in turn congregates in enhanced electron mobility, suppressing the intervalley transition of electrons from lower valley to upper valley reducing the phonon scattering in the ultrathin channel.…”