Molecular Dynamics Simulations and Kapitza Conductance Prediction of Si/Au Systems Using the New Full 2NN MEAM Si/Au Cross-Potential
Résumé
Superlattices made by superposing dielectric and metal nanolayers are of great interest as their small size restricts the thermal energy carrier mean free path, decreasing the thermal conductivity and thereby increasing the thermoelectric figure of merit. It is, therefore, essential to predict their thermal conductivity. Potentials for Au and Si are discussed, and the potential of second nearest-neighbor modified embedded atom method (2NN MEAM) is chosen as being the best for simulating heat transfer in Si/Au systems. Full 2NN MEAM Si/Au cross-potential parameterization is developed, and the results are compared with ab initio calculations to test its ability to reproduce local density approximation (LDA) calculations. Volume-constant (NVT) molecular dynamics simulations are performed to deposit Au atoms on an Si substrate by physical vapor deposition, and the results of the intermixing zone are in good agreement with the Cahn and Hilliard theory. Nonequilibrium molecular dynamics simulations are performed for an average temperature of 300 K to determine the Kapitza conductance of Si/Au systems, and the obtained value of 158 MW/m 2 K is in good agreement with the results of Komarov for Au deposited on isotopically pure Si- 28 and natural Si, with values ranging between 133 and 182 MW/m2 K.