Molecular Dynamics Simulation Of Thermal Conductivity Of Silicon Crystal And Silicon Nanowires

Thin films with thickness in microscale and nanoscale are important subassemblies in the application areas such as integrated-circuit transinstors, quantum-well lasers and microelectromechanical systems. Since the performance and reliability of the devices are strongly dependent on the heat conduction in thin films, exploring thin film thermal conductivity is of great significance for the design of these devices.This paper elucidates the process of the material micromation, the theory of thermoelectricity cooling, and the recent research of micro-scale thermal transport; discusses the basic theory, detailed steps of molecular dynamics simulation, the classification and application conditions.The temperature-dependent thermal conductivity of silicon crystal is calculated using equilibrium molecular-dynamics simulation based on Gree-Kubo's formula in the temperature range 400～1400k. Quantum corrections are introduced in the simulation process to modify the simulation temperature and the thermal conductivity. Thermal expansion, isotope composition and vacancy effects on the lattices thermal conductivity of silicon crystal have been investigated . Temperature-dependented lattice constant is used in the simulation for calculating the thermal conductivity in order to discuss thermal expansion effects. The results of calculation show that the temperature dependence of thermal conductivity can be fitted with a function k∝T^-n, n = 1.1693,and all the result under that calculated by fixed lattice constant. The results also show that the thermal conductivity of silicon with isotope composition ( ²⁹Si ) is smaller than that of pure silicon. The increasing concentration of ²⁹Si results in the degradation of thermal conductivity. And with increasing temperature, the impurity effects on the thermal conductivity are observed to diminish; In addition, the thermal conductivity of silicon crystal with vacancy defects are lower than the pure silicon case date. And vacancy defecteffects on the thermal conductivity are stronger than isotoped-silicon.Nonequilibrium Molecular Dynamics simulation method is used in this paper to calculate the thermal conductivity of Si nanowires .The simulated thermal conductivities of nanowires with squar...