Theoretical insights into the defect performance of the wide bandgap semiconductor BaS

Wide bandgap semiconductors materials (WBGSMs) are of great interest for their applications in transparent electronics and power electronics. Recent studies have shown that BaS is a potential transparent conducting material but the knowledge of it is deficient. Herein, we systemically investigate its electronic structure and evaluate the effects of its intrinsic defects and extrinsic dopants by utilizing the hybrid density functional method. The obtained results show that BaS is an indirect bandgap semiconductor with a bandgap of 3.88 eV. Its electron-effective mass is very small (0.33 m₀). We find that the intrinsic n-type conductivity of BaS is connected with the shallow donor defect sulfur vacancy (V_S). Regarding extrinsic dopants (group IA atoms), we find that Li and Na are favorable n-type dopants, while K and Rb are p-type dopants. Among these impurities, the Li interstitial (Li_int) configuration possesses the lowest formation energy of 0.114 eV. Based on thermodynamic simulations, we find that the electron density can reach 2.39 × 10²⁰ cm^-3 in Li-doped BaS at room temperature, which is comparable to those of typical WBGSMs In₂O₃, BaSnO₃, and β-Ga₂O₃. We expect BaS could replace typical WBGSMs in some applications. Moreover, its component elements Ba and S are non-toxic, cheap, and earth-abundant, making it a very competitive candidate for WBGSMs. Based on these results, we deem BaS a promising candidate for optoelectronic applications.