Influence of pulsed laser deposition growth conditions on the thermoelectric properties of Ca3Co4O9 thin films

Abstract

Thin films of the misfit cobaltite Ca3Co4O9 were grown on (0001)-oriented (c cut) sapphire substrates, using pulsed-laser deposition techniques. The dependence of the thermoelectric/transport properties on the film growth conditions was investigated. The optimal conditions (for low resistivities) were found to be 600°C, 0.1–0.2mbar of oxygen pressure, and 1.7J∕cm2. These films exhibited slightly metallic behavior, consistent with in-plane resistivity curves of single crystals and c-axis magnetically aligned samples. Hall effect measurements showed the density of the holelike carriers was 6.8×1020∕cm3. The in-plane epitaxial relationship between the thin film and the sapphire substrate is investigated.