Study of Yb-Doped CoSb3 Thermoelectric Thin Films Prepared by Laser

Abstract

Thin films of Yb filled CoSb3 were prepared on fused silica substrates using pulsed laser deposition method. The stoichiometric Yb0.19Co4Sb12 target was prepared by hot pressing method. The deposition conditions were changed with the goal to reach layers of smooth morphology. The target-to substrate distance was kept equal to 4 cm. The ambient argon pressure moved from 0.5 Pa to 13 Pa, laser repetition rate from 3 Hz to 10 Hz, and substrate temperature from 250 °C to 400 °C. We tested laser fluencies from 0.8 J·cm-2 to 5 J·cm-2. Films roughness was determined by mechanical profilometer and by atomic force microscopy. The lowest roughness of about 5 nm – 10 nm was reached for low laser fluencies but mechanical quality of films was poor and growth rate low (about 0.1 A/pulse). From WDX analysis follows that there is an excess of Yb and Sb compared to Yb0.19Co4Sb12 target.