Thermoelectric figure of merit of Si-Ge multilayered thin films

Abstract

The electrical conductivity /spl sigma/, the Seebeck coefficient /spl alpha/, the thermal conductivity /spl kappa/ and the figure of merit ZT (Z=/spl sigma/ /spl alpha//sup 2///spl kappa/) were calculated theoretically for multilayered thin film with quantum wells (QWs) made of Si, Si/sub 70/Ge/sub 30/ and silicide thermoelectric materials. Two-dimensional transport model for single band semiconductor was applied to these materials. As results of the calculation it is found that carrier confinement by QWs mainly have effects on increasing the carrier energy and on shifting optimizing point of power factor /spl sigma/ /spl alpha//sup 2/. The calculated figure of merit for modulated doping Si/sub 70/Ge/sub 30/ QWs was the same as that of bulk material at 300 K. Modulated doping silicide QWs had larger figure of merit than that of Si/sub 70/Ge/sub 30/ QWs.