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.