High interfacial thermal conductance across heterogeneous GaN/graphene interface

Gallium nitride (GaN)-based high-electron-mobility transistors (HEMTs) have attracted significant research attention because of their high-power and high-frequency electronics applications such as 5G wireless networks and light-emitting diodes. Meanwhile, the output power density of these HEMTs is particularly high, and strong Joule self-heating hot spots formed at the near-junction seriously restricts device performance and reliability. Hence, heat removal is in urgent demand for GaN-based HEMTs. Multilayer graphene, featuring high thermal conductivity and being easily prepared, is of interest for integration with GaN to improve the device thermal management. In this work, we have investigated the interfacial thermal conductance (ITC) across GaN/graphene interface using nonequilibrium molecular dynamics simulations. The results show that a 0.6% point-defect concentration results in 2.4-fold enhancement in ITC. Moreover, the ITC value can be increased up to 520.7 MWm(-2) K-1 by applying similar to 1GPa cross-plane pressure, which is close to the measurement result for epitaxially grown GaN/ZnO interface. Detailed analyses of vibrational spectra and spectral phonon transmission are performed to help understand the significant enhancement of ITC. Furthermore, the ITC could be also regulated by the external temperature and h-BN intercalation. Our findings presented here provide important guidelines for solving the thermal management issue in GaN-based electronic devices.