Ultra-High Interfacial Thermal Conductance via Double hBN Encapsulation for Efficient Thermal Management of 2D Electronics.

Heat dissipation is a major limitation of high-performance electronics. This is especially important in emerging nanoelectronic devices consisting of ultra-thin layers, heterostructures, and interfaces, where enhancement in thermal transport is highly desired. Here, ultra-high interfacial thermal conductance in encapsulated van der Waals (vdW) heterostructures with single-layer transition metal dichalcogenides MX 2 (MoS 2 , WSe 2 , WS 2 ) sandwiched between two hexagonal boron nitride (hBN) layers is reported. Through Raman spectroscopic measurements of suspended and substrate-supported hBN/MX 2 /hBN heterostructures with varying laser power and temperature, the out-of-plane interfacial thermal conductance in the vertical stack is calibrated. The measured interfacial thermal conductance between MX 2 and hBN reaches 74 ± 25 MW m -2 K -1 , which is at least ten times higher than the interfacial thermal conductance of MX 2 in non-encapsulation structures. Molecular dynamics (MD) calculations verify and explain the experimental results, suggesting a full encapsulation by hBN layers is accounting for the high interfacial conductance. This ultra-high interfacial thermal conductance is attributed to the double heat transfer pathways and the clean and tight vdW interface between two crystalline 2D materials. The findings in this study reveal new thermal transport mechanisms in hBN/MX 2 /hBN structures and shed light on building novel hBN-encapsulated nanoelectronic devices with enhanced thermal management.