Molecular dynamics study of thermal transport across Ga2O3-diamond interfaces

Integration of beta-Ga2O3 with high thermal conductivity materials such as diamond has been considered due to beta-Ga2O3's low and anisotropic thermal conductivity, reaching only 27 W m(-1) K-1. However, the effect of crystallographic orientation on thermal interface resistance has not been studied extensively, which is relevant for potential device architectures. In this work, we use molecular dynamics simulations to investigate the crystal orientation-dependent thermal boundary resistance (TBR) across van der Waals bonded diamond-beta-Ga2O3 and ionicly bonded amorphous Al2O3-beta-Ga2O3 interfaces. Al2O3 is often used as interlayer to grow diamond onto Ga2O3. We find that TBR values across the van der Waals interface may vary by up to 70% depending on the orientation of the beta-Ga2O3, while the Al2O3-beta-Ga2O3 TBR values remain around 0.9 & PLUSMN; 0.3 m(2) KGW(-1). We, thus, conclude on the optimal direction of beta-Ga2O3 to use for reducing the TBR in these heterostructures.