Geometrically Enhanced Thermoelectric Effects in Graphene Nanoconstrictions

Graphene’s thermal and electronic properties have been studied extensively over the last decade, however the influence of geometry on the thermoelectric properties has not been investigated to date. Here we will present for the first time spatially resolved measurements of Peltier, Joule and Seebeck effects on various graphene nanoconstriction geometries with a resolution down to tens of nms. Using Scanning Thermal Microscopy, we observe a strong enhancement of the local Peltier and Seebeck effect around the constriction. We attribute these observations to a combination of the geometric properties of the constriction and edge doping induced during fabrication. These findings offer a new understanding of the influence of geometry on the thermoelectric effects in graphene, opening a pathway for readily enhancing its thermoelectric properties but also those of other materials. This could possibly lead to the design of more efficient heating/cooling and thermoelectric energy conversion devices in the future.