First-principles calculation of electronic density of states and Seebeck coefficient in transition-metal-doped Si–Ge alloys.

High Z T value and large Seebeck coefficient have been reported in the nanostructured Fe-doped Si–Ge alloys. In this work, the large Seebeck coefficient in Fe-doped Si–Ge systems was qualitatively reproduced from the computed electronic density of states, where a hybrid functional, HSE06, was used for an exchange-correlation functional, as well as a special quasi-random structure (SQS) for a disordered atomic configuration. Furthermore, by replacing Fe with other transition metals, such as Mn, Co, Ni, Cu, Zn, and Au, a dopant that produces a large Seebeck coefficient in Si–Ge alloy systems was explored. It was found that the Mn-doped system produces a large Seebeck coefficient comparable with the Fe-doped system. • Hybrid functional DFT is used to calculate Seebeck coefficient of SiGe alloys. • The investigation is applied to transition metal (Mn, Co, Fe, Ni, Cu, Zn, Au) doping. • Large Seebeck coefficient in Fe-doped SiGe systems was qualitatively reproduced. • Impurity states at band-edges of Fe-doped SiGe boost the Seebeck coefficient. • Large Seebeck coefficient is also found in Mn-doped SiGe due to these impurity states. [ABSTRACT FROM AUTHOR]