Mossbauer study of the magnetic character and ordering process of the cubic gamma-fesi/sub 2/ phase obtained by fe implantation into a si(100) matrix

Abstract

The magnetic character and the ordering process of y-FeSi₂ precipitates formed by Fe implantation into Si(100) followed by ion-beam epitaxial crystallization (IBIEC) have been studied using the Mössbauer technique. Measurements performed at 4 K have shown no evidence of magnetic interaction indicating that the y-FeSi₂ phase is not of magnetic character. Conversely, conversion-electron Mössbauer experiments performed after the IBIEC procedure show basically the presence of a doublet, despite the cubic structure of the y-FeSi₂ precipitates. However, after 1 h of annealing at 600 °C, a singlet, which before was barely recognizable, became more pronounced. The singlet-to-doublet proportion increases with increasing Fe concentration (2 at.%≤Cp≤8.5 at.%), indicating that after annealing a better ordering in the y-FeSi₂ precipitates is achieved. This ordering is obtained by an adequate combination of Fe-implanted concentration and thermal annealing. These studies have been complemented by Rutherford backscattering and/or channeling and transmission electron microscopy experiments.