Maximizing thermoelectric properties by nanoinclusion of γ-SbTe in Sb2Te3 film via solid-state phase transition from amorphous Sb-Te electrodeposits

In this work, we demonstrate an enhancement of thermoelectric properties by creating gamma-SbTe/Sb2Te3 nanocomposite film, where gamma-SbTe nanoinclusions are embedded in a nanocrystalline Sb2Te3 matrix. The two-phase nanocomposite was formed via solid-state phase transition using an amorphous Sb2Te3 electrodeposits as the starting materials. The crystallinity and crystal structure of intermediate states during the amorphous-crystalline solid-state transformation were characterized by sequentially annealing the sample. The formation of the gamma-SbTe is attributed to the different enthalpy of mixing for the bonding structures available in the Sb-Te system. Room temperature measurement of electrical and thermoelectrical properties as a function of annealing temperature revealed that the two-phase system provided the carrier energy filtering effect at the interfaces between two phases, leading to enhanced Seebeck coefficient without affecting its electrical transport properties. The band bending at the two-phase interfaces was indirectly manifested by measuring their difference in the valence band, advocating the possibility of a strong energy-dependent charge scattering to the enhanced Seebeck coefficient. (C) 2015 Published by Elsevier Ltd.