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-SiOx ) from 3 to 50 nm. The electrical conductivity (σ) was increased in the t a-SiOx 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 μV·K−1 and showed no dependence on t a-SiOx . Thermal conductivity (κ) was in the range of 1.4–1.5 W·m−1·K−1 and almost independent of t a-SiOx , 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-SiOx = 13 nm.