Preparation and thermoelectric characterization of boron-doped Si nanocrystals/silicon oxide multilayers

Abstract Boron-doped silicon nanocrystals (Si-NCs)/amorphous silicon oxide (a-SiO y ) multilayers were prepared by plasma-enhanced chemical vapor deposition and post-annealing of boron-doped Si-rich amorphous silicon oxide (a-SiO x ) and a-SiO y multilayers. The diameter of Si-NCs was changed by varying the thickness of the a-SiO x layer ( t a-SiO x ) from 3 to 50 nm. The electrical conductivity ( σ ) was increased in the t a-SiO x range of 3 to 13 nm and saturated around 5.7 kS·m −1 . This tendency corresponds to crystal volume fraction in the Si-NCs multilayers. Seebeck coefficient ( S ) was almost constant at 230 μ V·K −1 and showed no dependence on t a-SiO x . Thermal conductivity ( κ ) was in the range of 1.4–1.5 W·m −1 ·K −1 and almost independent of t a-SiO x , which is much lower than that of bulk Si. A maximum power factor of 0.33 mW·m −1 ·K −2 was obtained at t a-SiO x = 13 nm.