Thin films of cobaltates are promising as thermoelectric materials and their properties can be engineered in several ways. By engineering the average grain size in Nax
thin films, a doubling of the thermoelectric power factor was obtained (Brinks, Kuiper, etÂ al., 2014
). Furthermore, size effects of these thin films result in preservation of the electronic properties in ultrathin Nax
films (Brinks, Rijnders, etÂ al., 2014
). Although the thermal conductivity of thin films of Nax
is significantly lower than that of single crystals (Brinks, Kuiper, etÂ al., 2014
), it can be even more reducedÂ by enhanced phonon scattering. This can be obtained in superlattice structures, where the interfaces act as phonon ...