Coupled electron-phonon transport and heat transfer pathways in graphene nanostructures

A hybrid Boltzmann transport equation model coupled with a two-temperature model is developed to simulate the heat dissipation in single layer graphene (SLG) suspended or supported on SiO2 and with/without Cu contacts. This hybrid model includes the phonon transport in SLG, electron-phonon interaction (EPI) in SLG, and phonon/electron transmission at the interface between SLG and its surroundings. The EPI strength between electrons and various phonon modes is obtained at different temperatures using first-principle calculations. Simulations are performed for SLG with different graphene lengths, contact configurations and heating powers. For the SLG suspended on SiO2, adding Cu contact at ends can remarkably improve the heat dissipation and lower the maximum temperature in SLG, especially at small lengths of SLG. The SLG/Cu interface can still be the major heat dissipation pathway when its contact area is similar with that of SLG/SiO2 interface, which can be attributed to the higher thermal conductivity of Cu. For the SLG fully supported on SiO2, adding Cu contact can effectively lower the temperature in SLG of small length, but the dominating heat dissipation pathway will be shifted from SLG/Cu interface to SLG/SiO2 interface as the SLG length increases.

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