A COMPUTATIONAL STUDY OF THERMAL CONDUCTIVITY OF FREESTANDING H-BN STRUCTURES

Abstract

The fact that hexagonal boron nitride (h-BN) has remarkable thermal transport property, mechanical property and chemical stability provides endless possibilities in nanoscale thermal device designing. In this study, we investigated the thermal conductivity of different h-BN structures. We first gave a brief literature review of former experimental and simulation results, the development of MD simulations, and thermal transport theory based on Fourier's law and Green-Kubo formalism. We then applied equilibrium molecular dynamic (EMD) approach. Tersoff potential and LJ potential are applied as the in-plane/interlayer force field, respectively. Results showed that the in-plane thermal conductivity of bulk h-BN is around 170W/mK, while the interlayer thermal conductivity is reduced to 5W/mK due to interlayer phonon scattering. Thermal conductivity of pristine monolayer is around 300W/mK on average. Different phonon vibration modes could be speculated from the heat flux auto-correlation function (HCACF). We also applied non-equilibrium molecular dynamics (NEMD) methods and compared the result with the result given by Green-Kubo formalism. Both methods could give reasonable values of thermal conductivity, yet for NEMD methods the local stability should be taken into consideration.