Superior power generation capacity of GeSn over Si demonstrated in cavity-free thermoelectric device architecture

The performance of a thermoelectric (TE) generator consisting of GeSn wire is experimentally found to be higher than that of a TE generator fabricated by Si wire. The TE generators are developed in a cavity-free architecture, where the wires are directly placed on the substrate without forming a cavity space underneath. In the cavity-free structure, the heat current flows perpendicularly to the substrate and the TE generator is driven by a steep temperature gradient established around the heater inlet. With an identical patterning design, the TE performance of both generators is characterized by varying lengths. The maximum Seebeck coefficient of the generator consisting of GeSn is −277 μV K⁻¹ and that for the Si is −97 μV K⁻¹. The GeSn-TE generator achieves a higher power factor of 31 μW· K⁻²· cm⁻¹ than that of the Si-TE generator of 12 μW· K⁻²· cm⁻¹. The maximum areal power density of the GeSn-TE generator is intrinsically higher than that of the Si-TE generator by approximately 2.5 to 6 times considering the wire thickness difference. The obtained results support the superiority of the GeSn-TE generator over the Si-TE generator.