Boron arsenide (BAs) is considered a scientifically intriguing semiconductor material because of its extraordinary transport properties. In this work, we use state-of-the-art ab initio computational methods to study the carrier mobilities and scattering mechanisms in BAs and other boron-V compounds (BN, BP, and BSb). BAs has both high electron and hole mobilities, and the computed values agree well with experimental data. Our analysis of the carrier-phonon interactions indicates that the predominant scattering mechanism at room temperature is the piezoelectric (PE) scattering for BN and the acoustic deformation potential scattering for BP, BAs, and BSb. At elevated temperatures, the optical deformation potential scattering has an enhanced effect on the hole mobility, whereas the Fröhlich interaction affects both electrons and holes considerably. Consequently, the high mobilities in BAs can be attributed to the small carrier effective masses, low polarity, small PE constant, large dielectric constant, and high energies of optical phonons. The interband scattering is found to provide important scattering channels for holes. The intervalley scattering is trivial for electrons in BN, but it plays a crucial role for electrons in BP, BAs, and BSb, with the $f$-process much more significant than the $g$-process. We also move beyond carrier-phonon scattering to include other scattering sources. The carrier mobility with ionized impurity (ii) scattering is computed under various ii concentrations, which becomes appreciable with the ii concentration above ${10}^{17}{\mathrm{cm}}^{-3}$ at room temperature. Based on the phonon-limited and ii-limited mobilities, the reliability of Matthiessen's rule is discussed. And the carrier mobility with surface scattering in films is calculated as a function of the thickness, which exhibits significant deviation from the bulk value, especially for BP and BAs. The {100} surfaces are found preferable for charge transport, consistent with the computed electronic mean free path spectra. Finally, we have also identified that the self-energy relaxation time approximation (SERTA) fails in predicting carrier mobilities in certain materials because of the significant forward scattering. This suggests that SERTA may be unreliable for systems where scattering induced by long-range potentials predominates, including PE scattering, Fröhlich interaction, and ii scattering. Moreover, although the momentum relaxation time approximation is usually accurate, it may overestimate carrier mobilities in some systems where Fröhlich interaction plays a substantial role.

Close

PrevNext

View figure in article

• Electronic structure
• First-principles calculations
• Transport phenomena
• III-V semiconductors
• Boltzmann theory
• Density functional theory
• Wannier function methods