Thermoelectric Properties of B_12+xC_3-x Thin Films Prepared by Pulsed Ion-Beam Evaporation

Abstract

Thin films of boron carbide (B 12+x C 3-x ) were prepared on glass substrates by a pulsed ion-beam evaporation method. A pulsed proton beam with an energy of 1 MV (peak) and a current of 60 kA was focused on sintered B 12+x C 3-x targets. Ablation plasma was formed from the irradiated targets and thin films were prepared on Pyrex and SiO 2 glass substrates at room temperature. From results of X-ray diffraction, the thin films consisted of a B 12+x C 3-x phase. Using a known relationship between the composition and the lattice parameters, the composition of B 12+x C 3-x thin films was estimated to be x = 0.3 and 1.0, which were close to the nominal composition of the targets. These results indicate that B 12+x C 3-x with different carbon contents has been successfully prepared by IBE without substrate heating or sample annealing. Thermoelectric properties of the thin films were measured. A B 12+x C 3-x thin film with estimated composition of x =0.9 exhibited the highest power factor at room temperature among the B 12+x C 3-x samples reported.