A first-principles study of the electronic structure and point defects in higher manganese silicide Mn₄Si₇

Point defects play a crucial role in determining the physical properties of solid-state semiconductor materials. However, theoretical investigations dedicated to point defects in higher manganese silicides (HMSs), promising thermoelectric materials composed of earth-abundant and eco-friendly elements, are surprisingly absent in the literature. Here, using first-principles calculations we systematically investigate the intrinsic and extrinsic point defects in a HMS, Mn₄Si₇. Our results indicate that the formation energies of intrinsic defects in Mn₄Si₇ are sufficiently high to preclude their significant concentration under thermal equilibrium growth conditions, and the experimentally observed p-type conductivity of the pure HMS could be a result of self-doping. Additionally, we calculated the defect formation energies of 14 candidate dopants by fully considering the secondary phases, which are in good agreement with experimental findings. Our results provide valuable guidance for optimizing the doping strategy of HMSs for device applications.