Point defects and dopants of boron arsenide from first-principles calculations: donor compensation and doping asymmetry

BAs has received attention due to its unusually high thermal conductivity, yet, its defect properties are relatively unknown. Particularly, point defects crucially affect its electronic, thermal, and optical properties as a semiconductor. Here, we apply hybrid density functional theory calculations to identify the formation energies and thermodynamic charge transition levels of native point defects, common impurities, and shallow dopants in BAs [1]. We find that As_B, V_B, B_As, B_i-V_B, As_B-B_As, are the dominant intrinsic defects, while C_As, C_B, H_i are common impurities. Be_B, Si_As and Ge_As are predicted to be excellent shallow acceptors with low ionization energy (< 0.03 eV) and negligible compensation by other point defects. However, donors such as Se_As, Te_As, Si_B, and Ge_B have a relatively large ionization energy (~0.15 eV) and are likely to be passivated by native defects such as B_As and V_B, as well as C_As, H_i, and H_B. The hole and electron doping asymmetry originates from the heavy effective mass of the conduction band due to its boron orbital character, as well as from boron-related intrinsic defects that compensate donors.
[1] arXiv:1809.09213