Understanding of phase transformation in Pd/a-Si bilayered system

• Interface thermodynamics was innovatively applied for phase transition in thin films.
• Phase transformation in Pd/Si thin film system was interpretated semi-quantitatively.
• The calculation results are in good agreement with the experimental observation.

An interfacial thermodynamic model is applied for understanding the phase transformation occurring in Pd/a-Si (amorphous Si) bilayered system. The results of calculations indicate that, upon annealing, Si atoms diffuse into Pd grain boundary (GB) and crystallize at temperature above 460 °C, and Pd2Si phase forms at both Pd GB and Pd/a-Si interface. c-Si (crystalline Si) grains nucleated at Pd GB grow laterally. Pd2Si grains nucleated at both Pd GB and Pd/a-Si interface grow laterally and vertically.