Electron-phonon scattering and stacking sequences in hexagonal boron nitride: An <i>ab initio</i> study
Zirui He, An-An Sun, Shang‐Peng Gao
Abstract
Analogous to graphite, bulk $h$-BN is a layered material in which the hexagonal layers may exhibit different stacking sequences. Effects of the stacking sequences on the stability, electronic, and transport properties of $h$-BN are investigated thoroughly based on fully ab initio calculations. We identify three stable $h$-BN stackings $({\mathrm{AA}}^{\ensuremath{'}}$, AB, and ABC) and present the tight-binding analysis based on Wannier functions as a fresh perspective on the effect of the stacking sequences on interorbital coupling. We also perform ab initio calculations of the electron-phonon interaction and phonon-limited electron mobilities for differently stacked $h$-BN. Our analysis of electron scattering rates associated with different phonon modes reveals that (i) the room-temperature electron mobilities are limited by acoustic phonons, (ii) for stackings ${\mathrm{AA}}^{\ensuremath{'}}$ and AB, the interlayer shear optical phonons also have significant contributions, and (iii) Fr\"ohlich scattering (via longitudinal optical phonons) contributes negligibly to the room-temperature electron mobilities but may play a crucial role at higher temperatures. Semiempirical models, despite their widespread use owing to simplicity, cannot capture these effects precisely when applied to the electron mobility calculation of $h$-BN. We thus observe a significant discrepancy between our calculated ab initio mobilities and the semiempirical results, which highlights the importance of the accurate fully ab initio determination of the carrier mobilities in $h$-BN. Our findings can provide a benchmark for exploring the carrier transport properties of van der Waals layered materials.