Electron-phonon scattering and stacking sequences in hexagonal boron nitride: An ab initio study

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 (AA', 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 AA' and AB, the interlayer shear optical phonons also have significant contributions, and (iii) Frohlich 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.

Automated summary

The effects of stacking sequences on the properties of h-BN are investigated through ab initio calculations. Three stable stackings are identified, and the tight-binding analysis based on Wannier functions provides a fresh perspective on interorbital coupling in h-BN. The discrepancies between ab initio and semiempirical results highlight the importance of accurate determination of carrier mobilities in h-BN.