2022/04/25 by Shiru Song, Shixu Liu, Song, Shiru +7
Materials Science · Physics and Astronomy · #2D Materials and Applications #Advanced Thermoelectric Materials and Devices #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Superconductivity in MgB2 and Alloys
paper · pdf · doi:10.48550/arxiv.2204.11419
openalex publication_date 2022/04/25 · openalex created_date 2022/04/28 · openalex updated_date 2026/07/28
Ideal two-dimensional (2D) semiconductors with high mobility comparable to three-dimensional (3D) Si or GaAs are still lacking, hindering the development of high-performance 2D devices. Here in this work, using first-principles calculations and considering all the electron-phonon couplings, we show that monolayer BX (X = P, As, Sb) with honeycomb lattices have intrinsic phonon-limited carrier mobility reaching record-high values of 1200-14000 cm2V-1s-1 at room temperature. Despite being polar and the band edges located at the K point with multiple valleys, these three systems unusually have small carrier scattering rates. Detailed analysis shows that, both the intravalley scattering and the intervalley scattering between two equivalent K points are weak, which can be understood from the large mismatch between the electron bands and phonon spectrum and suppressed electron-phonon coupling strength. Furthermore, we reveal the general trend of mobility increase from BP to BAs and to BSb and conclude that: smaller effective masses, larger sound velocities, higher optical phonon energies, heavy atomic masses, and out-of-plane orbitals tend to result in small match between the electron and phonon bands, small electron-phonon coupling strengths, and thus high mobility. Our work demonstrates that 2D semiconductors can achieve comparable carrier mobility to 3D GaAs, thus opening doors to 2D high-performance electronic devices.