Significantly enhanced thermoelectric figure of merit through Cu, Sb co-substitutions for Te in Ga_2Te_3

摘要

Here, we used two elements Cu and Sb as the substitutes for Te in Ga_2Te_3 and observed a giant enhancement in thermoelectric figure of merit (ZT). This potential substituted Ga_2Cu_(0.05)Sb_xTe_(2.95-x) (x = 0.2) gives the maximum ZT value of 0.5 at 700 K, more than 3 times as high as that of intrinsic Ga_2Te_3. The enhancement in ZT is attributed to the significantly reduced thermal conductivity caused mainly by the presence of Cu at Ga vacancy planes, and remarkably improved electrical conductivity by the occupation of Sb at Te sites, which increases the carrier concentration and conserves the high mobility.