Molecule Dynamic Study On The Thermal Conductivity Of Aluminum Nitride

Recently researchers pay more attention on the thermal conductivity problems within puny space and time. Studying on nanoscale thermal transport conduces to increasing thermoelectric efficiency using nanostructures, also to the design and thermal optimization of MEMS, IC, etc. Since the performance and reliability of the devices are strongly dependent on the heat conduction in thin film thermal conductivity and management and thermal-electrical coupling optimization design of devices. When the film thickness is reduced within 1～100nm, however, it is extremely difficult to measure thin film thermal conductivity. In this case, molecular dynamics technique is a valuable and promising tool for the study of the heat conduction in solids. The present work is mainly focus on the thermal conductivity of bulk materials and thin films by using molecular dynamics.In nanoscale, experiments and computation works of thermal conductivity about aluminum nitride thin films are very lack. The investigating method of consolidating step by step is adopted to insure the dependability of the results. Firstly, heat conduction of aluminum nitride with forms bulk is simulated by means of equilibrium MD(EMD) with periodic boundary condition. In this simulation, we use Stillinger-Weber potential and Green-Kubo formula to calculate the thermal conductivity of bulk material. Secondly, Heat conduction perpendicular to nanoscale aluminum nitride thin film is simulated by non-equilibrium molecular dynamics (NEMD) with fixed boundary condition. All the results are in good agreement with the experiment data. Finally, based on the above simulation, we calculated the effect of points defect on the thermal conductivity.In present work, we use equilibrium and non-equilibrium molecular dynamics respectively to study the thin film thermal conductivity values as a function of thin film thickness and system temperature. The results showed that, in the microscale, the thin film thermal conductivity values are much lower than their bulk counterparts'. If average temperature and heat flux are given, the conductivity increases linearly as the film thickness increases from 4.978nm to 14.934 nm. If film thickness and heat flux are given, the thermal conductivity values match well with the experimental values when the temperature is higher than Debye temperature. It also shows that the thermal conductivity values are remarkably reduced due to phonon scattering which is caused by defects.