Computational study on electrical properties of transition metal dichalcogenide field-effect transistors with strained channel

The performance limits of monolayer transition metal dichalcogenide (TMDC) field-effect transistors (FETs) with isotropic biaxial strain were examined with the "top-of-the-barrier" ballistic MOSFET model. Using a first-principle theory, we calculated the band structures and density of states of strained monolayer MoS2 and WS2, and used the results in model calculations. Introducing strain moves the positions of the conduction band minimum and valence band maximum in k-space with resultant variation in the effective mass and population of carriers. Introducing 2% tensile strain into n-type MoS2 FETs decreases the electron effective mass and, at the same time, increases energy separation between the lower and the higher valleys in the conduction band, resulting in 26% improvement of the ON current up to 1260 A/m. Whereas compressive strain results in complicated effects, -2% strain also improves the ON current by 15%. These results suggest that introducing artificial strain is promising to improve TMDC FET performance. (C) 2014 AIP Publishing LLC.