Heat Flow Overshooting in Suspended Graphene

ABSTRACT

In this work we found that when the hydrodynamic heat conduction in suspended graphene is in the under-damped free oscillation regime the disturbance of heat flux at the boundaries of graphene and the joint action of the initial heat flux and its time change rate can cause the heat flow overshooting which refers to the excess heat flux established in the heat conduction medium when two heat flow wave-fronts meet. The overshooting can make the maximum amplitude of the heat flux more than twice that of the initial heat flux, which poses a great danger to the next high-frequency and high-efficiency electronic devices based on graphene, such as the graphene field-effect transistors. Interestingly, results show that when the scale ratio of graphene with rectangular shape in the heat flow direction to its vertical direction is greater than a certain value, the overshooting caused by the disturbance of the heat flux at the boundaries no longer occurs. For the overshooting induced by the uneven distribution of the initial heat flux and its time change rate, it is shown that if the length in the region with the higher heat flux and time change rate in the direction of heat flow is less than a critical value the overshooting phenomenon can be avoided. These findings provide a new way for thermal management of electronic devices based on graphene.

KEY WORDS:

• Hydrodynamics phonon transport
• Guyer-Krumhansl model
• overshooting phenomenon

Disclosure statement

No potential conflict of interest was reported by the author(s).