Formation of Phase Composition and Structure in CoSb3-Antimonide-Based Nanoscale Films-Functional Elements of Thermoelectric Devices

The processes of formation of structure and phase composition in CoSb3(30 nm)/SiO2(100 nm)/Si(001) nanodimensional film system during annealings in nitrogen atmosphere are investigated by methods of X-ray diffraction, atomic-force microscopy, Rutherford backscattering, and resistance measurements. As revealed, the CoSb3 film is amorphous after deposition. Annealing at 570 K is accompanied with formation of three-phase state consisting of CoSb2 with monoclinic lattice, CoSb3 with skutterudite-type cubic lattice, and free Sb. A single-phase state of CoSb3 skutterudite in the film is observed after annealing at 770 K. Annealings within the temperature range of 770 970 K are accompanied with growth of both grains from 20 to 250 nm and pores from 20 to 200 nm. CoSb3, film after annealings within the temperature range of 270-770 K has the highest electric conductivity of 0.67 (mOm.cm)(-1) that promotes increase of thermoelectric efficiency ZT.