Nanoscale size effect and phonon properties of silicon material through simple spectral energy density analysis based on molecular dynamics

Abstract

Due to the importance of spectral analysis for the development of highly efficient semiconductor silicon devices and the complexity of current research techniques, the realization of an effective and simple method for phonon spectral analysis is imperative. Based on the molecular dynamics (MD) simulations and the phonon spectral energy density (SED) analysis (Thomas et al 2010 Phys. Rev. B 81 081411), a straightforward method is adopted to obtain the phonon dispersion for silicon films. The MD method is used to investigate the heat conduction of the three-dimensional (3D) thin silicon film with Stillinger–Weber (SW) potential. The thermal conductivity of the silicon is obtained from the non-equilibrium molecular dynamics (NEMD) simulation by using Muller–Plathe (M–P) method (Müller-Plathe 1997 J. Chem. Phys. 106 6082). For further analysis of thermal transport properties based on the phonon concept, the SED analysis technique is utilized by adopting the previously obtained atomic velocities as input. Moreover, the nanoscale size effect on the spectral analysis is considered. Domains with different sizes are studied to achieve a sufficient resolution of the dispersion relation from the phonon SED. The comparison with the results of existing approach demonstrates that the utilized method can accurately and directly obtain the phonon SED profiles along the frequency axis.