Field-Effect Thermoelectric Hotspot in Monolayer Graphene Transistor

Graphene is a promising candidate for the thermal management of downscaled microelectronic devices owing to its exceptional electrical and thermal properties. Nevertheless, a comprehensive understanding of the intricate electrical and thermal interconversions at a nanoscale, particularly in field-effect transistors with prevalent gate operations, remains elusive. In this study, nanothermometric imaging is used to examine a current-carrying monolayer graphene channel sandwiched between hexagonal boron nitride dielectrics. It is revealed for the first time that beyond the expected Joule heating, the thermoelectric Peltier effect actively plays a significant role in generating hotspots beneath the gated region. With gate-controlled charge redistribution and a shift in the Dirac point position, an unprecedented systematic evolution of thermoelectric hotspots, underscoring their remarkable tenability is demonstrated. This study reveals the field-effect Peltier contribution in a single graphene-material channel of transistors, offering valuable insights into field-effect thermoelectrics and future on-chip energy management. Field-effect thermoelectrics in monolayer graphene transistor is reported. Spatially localized hotspot is observed at Dirac point and arises from both Joule and Peltier heating, characterized by scanning thermal microscopy and analyzed through simulation. The position of the observed Dirac hotspot can shift in the gated region, highly controllable by the gate bias. image