The electron-phonon scattering and charge transport of the two-dimensional (2D) polar h-BX(X = P, As, Sb) monolayers

In this paper, the electron-phonon scattering and phonon-limited transport properties of the two-dimensional polar h-BX(X = P, As, Sb) have been studied through first-principles calculations in combination with Boltzmann transport theory. The electron-phonon scattering in these three systems is systematically assessed. Remarkably, intravalley scattering and intervalley scattering are separately investigated, of which the contribution to total scattering is found to be relatively comparable. The carrier mobility is determined over a broad range of carrier concentrations. The results indicate that h-BX (BP, BAs, BSb) simultaneously possess ultrahigh electron mobilities (4097 cm2 V-1 s-1, 4141 cm2 V-1 s-1, 12 215 cm2 V-1 s-1) and hole mobilities (7563 cm2 V-1 s-1, 7606 cm2 V-1 s-1, 22 282 cm2 V-1 s-1) at room temperature as compared to the most known two-dimensional (2D) materials. Additionally, it is discovered that compressive strain can induce a further increase in carrier mobility. The exceptional charge transport properties exhibited by these 2D semiconductors are attributed to the small effective masses in combination with the significant suppression of scattering due to high optical longitudinal optical- and transverse optical-phonon frequencies. This is the first time that we have provided a systematic interpretation of the reason for the exceptional charge transport properties exhibited by the 2D h-BX(X = P, As, Sb) semiconductors. Our finding can provide a theoretical perspective regarding the search for 2D materials with the high carrier mobility.