Modeling of anisotropic two-dimensional materials monolayer HfS₂ and phosphorene metal-oxide semiconductor field effect transistors

Ballistic transport characteristics of metal-oxide semiconductor field effect transistors (MOSFETs) based on anisotropic two-dimensional materials monolayer HfS₂ and phosphorene are explored through quantum transport simulations. We focus on the effects of the channel crystal orientation and the channel length scaling on device performances. Especially, the role of degenerate conduction band (CB) valleys in monolayer HfS₂ is comprehensively analyzed. Benchmarking monolayer HfS₂ with phosphorene MOSFETs, we predict that the effect of channel orientation on device performances is much weaker in monolayer HfS₂ than in phosphorene due to the degenerate CB valleys of monolayer HfS₂. Our simulations also reveal that at 10 nm channel length scale, phosphorene MOSFETs outperform monolayer HfS₂ MOSFETs in terms of the on-state current. However, it is observed that monolayer HfS₂ MOSFETs may offer comparable, but a little bit degraded, device performances as compared with phosphorene MOSFETs at 5 nm channel length.