Resonant level formed by tin inBi2Te3and the enhancement of room-temperature thermoelectric power

Tin is a known resonant impurity in the valence band of ${\text{Bi}}_{2}{\text{Te}}_{3}$ that was previously reported to enhance the thermoelectric power $S$ of the host material at cryogenic temperatures through resonant scattering. We show here that Sn provides an excess density of states (DOS) about 15 meV below the valence band edge and that it is the increases in DOS itself that enhances $S$ of this technologically important semiconductor even at room temperature. The experimental proof for the existence of this resonant level comes from Shubnikov-de Haas measurements combined with galvanomagnetic and thermomagnetic properties measurements.