Semiconductor Nanowires for Thermoelectric Applications

Abstract

Silicon/silicon-germanium (Si/SiGe) based nanowires (NWs) hold potential for low-cost and efficient thermoelectric device (TED). For the first time, in this work the design, fabrication, and characterization of a complete Si/SiGe NW-based TED are reported. Using finite element analysis, the impact of key material parameters in the performance was elucidated for practical applications, followed by a design guideline for a complete SiNW-based TED. Using complementary-metal-oxide-semiconductor process which is prevalent in the semiconductor industry, we successfully integrated Si/SiGe NWs into a complete TED. With various process optimizations, our SiNW-based TED achieved a power output density (17kW/m3) comparable to a bismuth/antimony-based TED (18.1kW/m3). The formation of good ohmic contacts to the NW is a key to device performance. For SiGe NWs, attempts at silicidation gave rise to voids. The growth mechanism of nickel-germanosilicide was investigated; it was then discovered that void formation can be effectively suppressed with compressive stress applied at the boundary.