An Interface-Sensitive Conversion Electron Mössbauer Spectroscopic Study of the Ion Beam Induced Reactions at Fe-Si Interface.

Abstract

ABSTRACTThe ion beam induced reactions at Fe-Si interface are studied for the first time using a novel interface-sensitive Mössbauer probe.The samples used in these studies are prepared by depositing a thin layer (<450A°) of enriched Fe57 isotope (95.45% by composition) on a freshly cleaned silicon (111) substrate followed by a deposition of a 150Ao film of natural iron (Fe 57 only 2.2%).These samples are subjected to Xetion bombardment at an incident ion energy of 100 keV and a dose of 6 × 1015 ions/cm2 The technique of Conversion Electron Mössbauer Spectroscopy (CEMS) is used to characterize the formation and growth of different phases as a function of annealing treatment. The spectra are leastsquare fitted using the MOSFIT programme.The MHssbauer lines for as-deposited and ion bombarded samples show a considerable broadening, which is a clear signature of a large concentration of defects formed at the interface due to ion beam induced collision cascades. As the samples are annealed the resonance lines are sharpened indicating recovery of stoichiometrically well-defined phases from an initial defective state. The present study indicates formation of FeSi and Fe3 Si phases after the annealing treatment-RBS measurements are used to confirm the mixing.These results are analyzed in terms of the non-equilibrium features of the directed energy processing of interface.