The effect of a multivalley energy band structure on the thermoelectric figure of merit

Abstract

A comparison is drawn between the dimensionless thermoelectric figure of merit of a multivalleyed semiconductor (ZT)mv and one having a single valleyed structure (ZT)sv. In the analysis both acoustic phonon scattering and ionized impurity scattering are considered. Although it is advantageous to employ a multivalleyed semiconductor in thermoelectric applications it is concluded that the beneficial effect of a multivalleyed structure is reduced with increase in carrier concentration and the presence of intervalley scattering. At a carrier concentration which optimizes the thermoelectric figure of merit, the ratio (ZT)mv/(ZT)sv for silicon-germanium alloy is reduced by approximately 40 percent.