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

We report on thermoelectric properties of nanocrystalline Cr1−x 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.