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Tailoring the thermal transport properties of monolayer hexagonal boron nitride by grain size engineering

2019; IOP Publishing; Volume: 7; Issue: 1 Linguagem: Inglês

10.1088/2053-1583/ab5ae0

2053-1583

Hao Ying, Arden L. Moore, Jie Cui, Yaoyao Liu, Deshuai Li, Shuo Han, Yuan Yao, Zhiwei Wang, Lei Wang, Shanshan Chen,

Advanced Thermoelectric Materials and Devices

The grain size effect on the thermal transport properties of hexagonal boron nitride (h-BN) thin films was experimentally investigated using the opto-thermal Raman technique. High-quality monolayer h-BN with mean grain sizes ranging from ~7 µm to ~19 nm were successfully synthesized on Pt foil by chemical vapor deposition (CVD). The thermal conductivity (κ) of the single-crystalline h-BN was measured to be ~545 Wm−1 K−1 at 315K, well above the bulk value, and more than a factor of four higher than the value of poly-crystalline h-BN with mean grain size of ~19 nm. The very low thermal boundary conductance (deduced to be ~9.6 GW m−2 K−1) accounts for the significant reduction of κ for h-BN with small grain size. Molecular dynamics (MD) simulations reveal that due to the disordered vibrations of atoms along/near GB, the phonon scattering in poly-crystalline h-BN is greatly enhanced compared to large-grained or single-crystalline samples. These results provide a deep understanding of the thermal transport in two-dimensional systems as well as the possible technological applications.