Kinetic study of a-Si crystallization induced by an intermetallic compound

The problem under study is concerned with amorphous silicon (a-Si) crystallization which is induced by an intermetallic compound, with this compound chosen to be Al2Cu, formed by a solid-state reaction between nanolayers of aluminum and copper in a Cu/Al/a-Si multilayer system. In the case of crystallization initiated by the intermetallic compound Al2Cu, the crystallization temperature of amorphous silicon was found to be approximate to 300 degrees & Scy; (upon heating at a rate of 5-10 degrees C/min), which was significantly higher than in the case of pure Al (approximate to 170 degrees & Scy;), but lower as compared to using pure Cu (approximate to 485 degrees & Scy;). The higher crystallization temperatures in comparison with aluminium-induced crystallization are assumed to be caused by a decrease in the number of free electrons due to the presence of copper and formation of the Al2Cu phase. By kinetic modeling, it was revealed that the mechanism of a-Si crystallization induced by the intermetallic compound Al2Cu was similar to the mechanism of Alinduced crystallization of a-Si in multilayer (Al/a-Si)nfilms, i.e the process of a-Si crystallization occurred in two subsequent stages: Cn-X -> Fn. Kinetic parameters of silicon crystallization for each reaction step were obtained. The enthalpy of a-Si crystallization initiated by Al2Cu was estimated to be Delta H = 12.3 +/- 0.5 kJ/mol.