Thermal boundary conductance of monolayer beyond-graphene two-dimensional materials on SiO₂and GaN

Two-dimensional (2D) materials have emerged as a platform for a broad array of future nanoelectronic devices. Here we use first-principles calculations and phonon interface transport modeling to calculate the temperature-dependent thermal boundary conductance (TBC) in single layers of beyond-graphene 2D materials silicene, hBN, boron arsenide (BAs), and blue and black phosphorene (BP) on amorphous SiO₂and crystalline GaN substrates. Our results show that for 2D/3D systems, the room temperature TBC can span a wide range from  7 to 70 MW m^-2K^-1 with the lowest being for BP and highest for hBN. We also show that 2D/3D TBC has a strong temperature dependence that can be alleviated by encapsulating the 2D/3D stack. Upon encapsulation with AlO, the TBC of several beyond-graphene 2D materials can match or exceed reported values for graphene and numerous transition-metal dichalcogendies which are in the range of 15-40 MW m^-2K^-1. We also compute the room temperature TBC as a function of van der Waals spring coupling (K) where the TBC falls in the range of 50-150 MW m^-2K^-1 at coupling strengths ofK = 2-4 N m^-1 for silicene, BAs, and blue phosphorene. We further identify group III-V materials with ultra-soft flexural branches as being promising 2D materials for thermal isolation and energy scavenging applications when matched with crystalline substrates.