Crystallization of Sputter-Deposited Amorphous (FeSi2)1-xAlx Thin Films

Crystallization of sputter-deposited amorphous (FeSi2)(1-x)Al-x on SiO2/Si substrate was studied for different fractions (x) of Al content varying from 0.033 to 0.081. The activation energy of crystallization for beta-phase iron-disilicide (beta-FeSi2) was extracted by using the Kissingers method. It was found to be 2.93-4.01 eV for (beta-FeSi2)(1-x)Al-x thin film, increasing with x. The fraction of Al that can be incorporated into beta-FeSi2 without any phase transformation is similar to 0.066. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed the formation of alpha-phase iron-disilicide (alpha-FeSi2) together with beta-FeSi2 at temperatures as low as 600 degrees C for x >= 0.075. Micro-Raman spectroscopy and electron energy-loss spectroscopy (EELS) showed the presence of crystalline Si precipitates in beta-FeSi2 for x >= 0.075.