Si1-xGex Nanowire Arrays for Thermoelectric Power Generation

Thermoelectricity offers an excellent clean energy generation opportunity and has attracted renewed attention in the last few decades. The low conversion efficiency and high costs currently limit its practical application. Much effort is still needed to enhance its efficiency and reduce its cost. Nanostructures have been proven to greatly enhance the thermoelectric figure of merit (ZT) because of increased phonon scattering at the interfaces. It has been demonstrated that single Si nanowires (NWs) exhibit a 60 times higher ZT than Si bulk. Meanwhile, SiGe alloys can also reduce the thermal conductivity via alloy scattering without deteriorating the other performance parameters such as Seebeck coefficient, S and electrical conductivity, σ. SiGe NWs thus promise to offer even better thermoelectric performance than Si. In this work, recent research results on the fabrication and thermoelectric characterisation of SiGe nanowire arrays (NWAs) are given. The NWAs are arrays of millions of parallel upstanding NWs attached to Si bulk.