Invited Paper TF+EM+NS+SS-ThA3
Growth of Nanocomposite and Epitaxial Nitride and Oxide Thin Films by Magnetron Sputtering for Thermoelectric Applications

Thursday, October 31, 2013, 2:40 pm, Room 104 A

In this invited talk, we first review our recent work on ScN-based thin films for thermoelectrics and correlated theoretical studies. The anomalously high thermoelectric power factor of ScN can be explained in terms of the band structure, with vacancy and impurity states introducing sharp features near the Fermi level yielding a large power factor. We further present results on calcium cobalt oxide thin films grown on Al₂O₃(0001) substrate by co-sputtering from Ca and Co-targets by reactive rf-magnetron sputtering in presence of 1.5 % O₂. As-deposited films were found to be amorphous. Subsequent ex-situ annealing in O₂-atmosphere well crystallized highly c-axis-oriented Ca₃Co₄O₉ films were obtained. For higher annealing temperature of 800 °C, the films are found to be single-phase epitaxial Ca₃Co₄O₉. X-ray diffraction and pole figure XRD analyses reveal the films are having (001)-orientation. Furthermore, altering the nominal starting composition of the as-deposited films yielded Ca₃Co₄O₉-based nanocomposite films with cobalt oxide inclusions, which may act as phonon scatterers for potential reduction of thermal conductivity in a thermoelectric application.