Optimization of the thermoelectric power factors in 50-nm n- and p-type silicon nanowires by varying the doping concentration

Abstract

The electric and the thermoelectric properties of 50-nm n- and p-type silicon nanowires (SiNWs) obtained by doping with boron di-fluoride and phosphorus, respectively, were investigated by varying the doping concentration from 1.0 × 10²⁰ to 2.5 × 10²¹ cm ^-3. The SiNWs were manufactured using conventional semiconductor processing techniques. The values of the optimized maximum power factor values were 1.59 and 2.43 mW·m ^-1K^-2 for the n- and the p-type SiNWs at a doping concentration of 4.0 × 10²⁰ cm^-3. For doping concentrations higher than over 4.0 × 10²⁰ cm^-3, the electrical resistivity was larger and the Seebeck coefficient was sharply lower due to imperfections in the crystal structure. For lower doping concentrations below 4.0 × 10²⁰ cm^-3, the increased resistivity had a dominant impact on the power factor.