MOSSBAUER STUDY OF THE MAGNETIC CHARACTER AND ORDERING PROCESS OF THECUBIC GAMMA-FESI2 PHASE OBTAINED BY FE IMPLANTATION INTO A SI(100) MATRIX

The magnetic character and the ordering process of gamma-FeSi2 precipi tates formed by Fe implantation into Si(100) followed by ion-beam epit axial crystallization (IBIEC) have been studied using the Mossbauer te chnique. Measurements performed at 4 K have shown no evidence of magne tic interaction indicating that the gamma-FeSi2 phase is not of magnet ic character. Conversely, conversion-electron Mossbauer experiments pe rformed after the IBIEC procedure show basically the presence of a dou blet, despite the cubic structure of the gamma-FeSi2 precipitates. How ever, after 1 h of annealing at 600 degrees C, a singlet, which before was barely recognizable, became more pronounced. The singlet-to-doubl et proportion increases with increasing Fe concentration (2 at. %less than or equal to C-p less than or equal to 8.5 at. %), indicating that after annealing a better ordering in the gamma-FeSi2 precipitates is achieved. This ordering is obtained by an adequate combination of Fe-i mplanted concentration and thermal annealing. These studies have been complemented by Rutherford backscattering and/or channeling and transm ission electron microscopy experiments.