Si/SiGe thermoelectric generator

• Main Author: Xu, Bin
• Other Authors: Fobelets, Kristel
• Published: Imperial College London 2015
• Subjects: 621.3
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.749088

This PhD thesis researches thermoelectric generator (TEG) which transfers wasted heat into electricity by thermoelectric materials. As a parameter used to characterize thermoelectric materials, figure-of-merit (ZT) models of Si bulk, Si/Si_(1-x) Ge_x bulk and Si bulk/nanowires (NWs) are built via building their models of Seebeck coefficient, electrical conductivity and thermal conductivity in this thesis. ZT of Si bulk is increased by 18% by applying a 3μm thick Si_0.8 Ge_0.2 bulk layer, and it is increased by 1000% by applying 35μm long Si NWs. TEG’s output power model which takes account of the effects of thermoelectric material, as well as all parasitic effects that affect TEG’s output power. TEG’s output power model demonstrates the output power depends on thermoelectric material’s characteristics and the contact interface quality between thermoelectric material and metal probe. Thermoelectric material’s characteristics are improved by Si NWs, Si_(1-x) Ge_x bulk, Si_(1-x) Ge_x NWs and spin-on-doping (SOD). SOD also improves the contact interface quality between thermoelectric material and metal probe, which also can be improved by sputter coating a layer of metal on thermoelectric material’s surface. Finally, TEG’s output power is increased by an order of 3 by these techniques.