Al-Si/AlN nanomultilayered systems with reduced melting point: Experiments and simulations

T Wejrzanowski and J Lipecka and J Janczak-Rusch and M Lewandowska, APPLIED SURFACE SCIENCE, 493, 261-270 (2019).

DOI: 10.1016/j.apsusc.2019.07.045

The melting behavior of Al-Si nanolayers with two different thicknesses (4 and 6 nm) confined by thin AlN layers (thickness: 3 nm) was investigated experimentally and simulated using molecular dynamics. The experimental study showed a noticeable decrease in the melting temperature of both systems, resulting in the presence of Si-enriched Al-Si protrusions on the free nanomultilayer surface, forming at temperatures of T >= 673 K for 4 nm and T >= 723 K for 6 nm Al-Si nanolayers, respectively. To study the mechanism of melting, as well as to explain the experimental observations, molecular dynamics simulations were performed. These revealed that silicon plays a great role in the melting process (melting always starts at the Al/Si interface and is strictly controlled by the diffusion of silicon atoms). Based on calculated non-equilibrium concentration of Si in melted Al-Si nanolayers, the phase diagram for confined Al-Si nanolayers was derived. Also, a mechanism of liquid outflow was proposed to explain the localized character of the melting observed experimentally.

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