In situ growth of c -axis-oriented Ca3 Co4 O9 thin films on Si (100)

High-quality c -axis-oriented Ca3 Co4 O9 thin films have been grown directly on Si (100) wafers by pulsed-laser deposition without prechemical treatment of the substrate surface. Cross-sectional transmission electron microscopy shows good crystallinity of the Ca3 Co4 O9 films. The Seebeck coefficient and resistivity of the Ca3 Co4 O9 thin films on Si (100) substrate are 126 μVK and 4.3 mΩ cm, respectively, at room temperature, comparable to the single-crystal samples. This advance demonstrates the possibility of integrating the cobaltate-based high thermoelectric materials with the current state-of-the-art silicon technology for thermoelectricity-on-a- chip applications.