Thermoelectric properties of SiC thick films deposited by thermal plasma physical vapor deposition

SiC thick films of about 300 µm could be prepared with a deposition rate above 300 nm/s by thermal plasma physical vapor deposition (TPPVD) using ultrafine SiC powder as a starting material. The thermoelectric properties were investigated as a function of composition and doping content. The nondoped films showed n-type conduction. Although the Seebeck coefficient reached as high as -480 µV/K, the power factor was only around 1.6 × 10-4 Wm-1 K-2 at 973 K due to the relatively high electrical resistivity. In order to reduce the electrical resistivity and to deposit layers with n-type and p-type conduction, N2, B and B4C were selected as the dopants. Nitrogen-doped samples exhibit n-type characterization, B and B4C-doped samples exhibit p-type characterization, and the electrical resistivity decreased from 10-2–10-3 to 10-4–10-5 Ωm after doping. The maximum power factor of the nitrogen-doped SiC and the thick films deposited with B4C powder reached 1.0 × 10-3 and 6.4 × 10-4 Wm-1 K-2 at 973 K, respectively.