First-principles study of carrier mobility and strain effect in MX (M=Sn, Pb; X=P, As) monolayers

Abstract

The pursuit of two-dimensional semiconductor materials that feature tunable electronic structures and high mobility is crucial for advancing nanoelectronic and optoelectronic devices. In this study, the MX monolayers (M=Sn, Pb; N=P, As) are investigated with first-principles calculations based on Boltzmann transport theory. The results show that SnP, SnAs, and PbAs all exhibit indirect band gaps, whereas PbP is the only semiconductor with a direct band gap. One important finding is that intravalley scattering has a significant impact on electron-phonon coupling. Interestingly, changes in carrier concentration do not affect the electron mobility within these MX monolayers, with SnP exhibiting the highest electron mobility among them. Subsequently, the SnP under a 6% biaxial strain is further explored and the results demonstrated a considerable increase in electron mobility to 2,511.9 cm²/Vs, which is attributable to decreased scattering. This suggests that MX monolayers, especially SnP, are promising options for 2D semiconductor materials in the future.