Composite films of highly ordered Si nanowires embedded in SiGe_0.3 for thermoelectric applications

We fabricated a high-density array of silicon nanowires (SiNWs) with a diameter of 10 nm embedded in silicon germanium (SiGe_0.3) to give a composite thin film for thermoelectric device applications. The SiNW array was first fabricated by biolate mask and neutral beam etching techniques. The SiNW array was then embedded in SiGe_0.3 by thermal chemical vapor deposition. The cross-plane thermal conductivity of the SiNW-SiGe_0.3 composite film with a thickness of 100 nm was 3.5 ± 0.3 W/mK in the temperature range of 300-350 K. Moreover, the temperature dependences of the in-plane electrical conductivity and in-plane Seebeck coefficient of the SiNW-SiGe_0.3 composite were evaluated. The fabricated SiNW-SiGe_0.3 composite film displayed a maximum power factor of 1 × 10³ W/m K² (a Seebeck coefficient of 4.8 × 10³ μV/K and an electrical conductivity of 4.4 × 10³ S/m) at 873 K. The present high-density SiNW array structure represents a new route to realize practical thermoelectric devices using mature Si processes without any rare metals.