Field-effect modulation of thermoelectric properties in multigated silicon nanowires

Electric-field-induced charge carriers typically exhibit greater mobility over carriers contributed by chemical dopants and offer a powerful mechanism for thermoelectric power factor enhancement. We fabricate multigated silicon nanowires (Si NWs) and demonstrate significant modulation of electrical conductivity and the Seebeck coefficient with gate bias. Because of the higher mobility of field-effect charge carriers, we demonstrate that power factor for the gated Si NWs is similar to the highest values reported for n-type Si nanostructures despite charge transport only occurring at the NW surface. Field-effect doping is a promising strategy for optimizing power factor and may result in significant power factor enhancement in smaller diameter Si NWs where high average carrier densities can be obtained with induced surface charge.