Phonon-limited electronic transport of two-dimensional ultrawide bandgap material h-BeO

Abstract

Two-dimensional ultrawide bandgap materials have compelling potential advantages in nano high-power semiconductors, deep-ultraviolet optoelectronics, and so on. Recently, two-dimensional few-layer h-BeO predicted as an ultrawide bandgap material has been synthesized in the experiment. In the present work, the first-principles calculations show that monolayer h-BeO has an indirect bandgap of 7.05 eV with the HSE functional. The ultrawide bandgap results from the atomic electronegativity difference in the polar h-BeO. The electronic transport properties are also systematically investigated by using the Boltzmann transport theory. The polar LO phonons generate the macroscopic polarization field and strongly couple to electrons by the Fröhlich interaction. Limited by the electron-phonon scattering, monolayer h-BeO has a high mobility of 452 cm2 V−1 s−1 at room temperature. Further studies indicate that the biaxial tensile strain can reduce the electron effective mass and enhance the electron-phonon coupling strength. A suitable strain promotes the mobility to ∼1000 cm2 V−1 s−1 at room temperature.