Ultrahigh interfacial thermal conductance for cooling gallium oxide electronics using cubic boron arsenide

Abstract

Gallium oxide (Ga${}_2$O${}_3$) has attracted significant interest for its unique potential especially in power electronics. However, its low and anisotropic thermal conductivity poses a major challenge for heat dissipation. Here, we explore an effective cooling strategy centering on the heterogeneous integration of ${\hat{I}}^2$-Ga${}_2$O${}_3$ devices with cubic boron arsenide (cBAs), an emerging material with an ultrahigh thermal conductivity $\hat{I}º$ of ~1300 Wm${}^{-1}$K${}^{-1}$. Machine-learned potentials for representative ${\hat{I}}^2$-Ga${}_2$O${}_3$/cBAs interfaces are trained, enabling accurate and efficient calculation of the interfacial thermal conductance $G$ via nonequilibrium molecular dynamics. At 300 K, remarkable $G$ values of 749$\pm$33 MWm${}^{-2}$K${}^{-1}$ and 824$\pm$35 MWm${}^{-2}$K${}^{-1}$ are predicted for Ga-As and O-B bonding across the interface, respectively, which are primarily attributed to the well-matched phonon density of states considering the similar Debye temperatures of ${\hat{I}}^2$-Ga${}_2$O${}_3$ and cBAs. Moreover, finite-element simulations directly show a notable device temperature reduction when comparing cBAs with other substrates. The simultaneously ultrahigh $\hat{I}º$ and $G$ highlight cBAs as an ideal substrate for Ga${}_2$O${}_3$ electronics.