Luminescence from beta-fesi2 precipitates in Si. I: Morphology and epitaxial relationship

The goal of this paper is to investigate the morphology and the structure
of ion-beam synthesized beta-FeSi2 precipitates and the defects in the Si
matrix by using transmission electron microscopy (TEM) and, in a few
cases, conversion electron Mo¨ssbauer spectroscopy or Rutherford
backscattering spectrometry. We shall point out how the different process
parameters affect the resulting structure and the optimum process window
for light emitting application of beta-FeSi2. In particular, we will also
show that within the optimum process window at least two different types of
precipitates are obtained in separate regions: small ball-shaped
precipitates in the surface region and large disc-shaped precipitates
deeper in the sample. The latter are shown to display a very good interface
to the Si matrix, as obtained by TEM analysis and dedicated molecular
dynamics simulation. In the second part of this paper (Martinelli et al.,
Phys. Rev. B 66, 085320 2002), the nature and the origin of the 1.54
microns photoluminescence signal obtained from our best samples will be
analyzed in detail.