Performance evaluation of Ge/SiGe-based thermoelectric generator

The performance of the Ge/SiGe-based Thermoelectric Generator (TEG), is significantly affected by the design and configuration of its Ge/SiGe superlattice structure. Superlattice structures in general play a significant role in the performance of the TEG - module. Experimental observations to design and fabricate an optimized Ge/SiGe based thermoelectric generator are conducted. The Ge element represents the 2D quantum well while Si_1-xGe_x alloy forms the barriers required to reduce the lattice thermal conductivity of the material. The alternate combination of the Ge quantum wells and Si_1-xGe_x barrier forms the superlattice structure. Experiments were conducted for both open and close circuit connections of the Ge/SiGe TEG-module. An estimated Seebeck coefficient of 471.9 μV/K was obtained for the open circuit connection while for the close circuit connections, an estimated power density of 0.111 μW/cm² and thermal efficiency factor of 0.0035 μWcm⁻² K⁻² was obtained at a temperature difference of 5.6 K. The results obtained were compared with previous published works. Based on this comparison, it was recommended that the contact resistance should be reduced significantly for improved performance. Also, the TEG module should be extended to multiple legs in order to yield better performances.