Energy filtering enhancement of thermoelectric performance of nanocrystalline Cr1-x Six composites

We report on thermoelectric properties of nanocrystalline Cr1-chi Six composite films. As-deposited amorphous films were transformed into a nanocrystalline state with the average grain size of 10-20 nm by annealing during in-situ thermopower and electrical resistivity measurements. Partially crystallized films, i.e. films consisting of crystalline grains dispersed in an amorphous matrix, are a new type of a heterogeneous material where the nanocrystalline phase plays the role of scattering centers giving rise to a large contribution to the thermopower. We show that the thermopower enhancement is related to the energy dependent scattering (energy filtering) of the charge carriers on the nanograin interfaces. (C) 2016 Elsevier B.V. All rights reserved.