Out-of-plane vibrations are considered as the dominant factor limiting the intrinsic carrier mobility of suspended two-dimensional materials at low carrier concentrations. Anharmonic coupling between in-plane and flexural phonon modes is usually excluded from the consideration. Here we present a theory for electron-phonon scattering, in which the anharmonic coupling between acoustic phonons is systematically taken into account. Our theory is applied to the typical group V two-dimensional semiconductors: hexagonal phosphorus, arsenic, and antimony. We find that the role of the flexural modes is essentially suppressed by their coupling with in-plane modes. At dopings lower than ${10}^{12}{\mathrm{cm}}^{-2}$ the mobility reduction does not exceed 30%, being almost independent of the concentration. Our findings suggest that compared to in-plane phonons, flexural phonons are considerably less important in the electronic transport of two-dimensional semiconductors, even at low carrier concentrations.

• Received 29 January 2019
• Revised 24 March 2019

DOI:https://doi.org/10.1103/PhysRevB.100.075417