Anomalous increase of the thermopower and thermoelectric figure of merit in Ga-doped p-(Bi0.5Sb0.5)2Te3 single crystals

The effect of Ga doping on the temperature dependences (5 K a parts per thousand currency sign T a parts per thousand currency sign 300 K) of the Seebeck coefficient alpha, electrical conductivity sigma, thermal conductivity coefficient kappa, and thermoelectric figure of merit Z of p-(Bi0.5Sb0.5)(2)Te-3 single crystals has been investigated. It has been shown that, upon Ga doping, the hole concentration decreases, the Seebeck coefficient increases, the electrical conductivity decreases, and the thermoelectric figure of merit increases. The observed variations in the Seebeck coefficient cannot be completely explained by the decrease in the hole concentration and indicate a noticeable variation in the density of states due to the Ga doping.