Interfacial Thermal Resistance in Nanoscale Heat Transfer

We investigate nanoscale thermal transport across a solid-fluid interface using molecular dynamics simulations. Cooler fluid argon (Ar) is placed between two heated iron (Fe) walls, thereby imposing a temperature gradient within the system. Fluid-fluid and solid-fluid interactions are modeled with Lennard-Jones potential parameters, while Embedded Atom Method (EAM) is used to describe the interactions between solid molecules. The Fe-Ar interaction causes ordering of fluid molecules into quasi-crystalline layers near the walls. This causes temperature discontinuity between these solid-like Ar molecules and the adjacent fluid. The time evolution of the interfacial (Kapitza) thermal resistance (Rk) and Kapitza length (Lk) are observed. The averaged Kapitza resistance (Rk,av) varies with the initial temperature difference between the wall and the fluid (ΔTw) as Rk,av∝ΔTw−0.82.

Effect Of Pressure On Boron Diffusion In Silicon

We are studying the effect of pressure on boron diffusion in silicon in order to better understand the nature of the point defects responsible for diffusion. Si homoepitaxial layers deltadoped with boron were grown using molecular beam epitaxy. Diffusion anneals were performed in a high temperature diamond anvil cell using fluid argon as a pressure medium. Diffusivities were deduced from B concentration-depth profiles measured with using secondary ion mass spectrometry. Preliminary results indicate that pressure enhances B diffusion in Si at 850 °C, characterized by an average activation volume of -0.125±0.02 times the atomic volume, and thus appear consistent with an interstitial-based diffusion mechanism. Results are compared with previous hydrostatic-pressure studies, with results in biaxially strained films, and with atomistic calculations of activation volumes for self diffusion.