  A method of scanning mid-IR-laser microscopy has recently been proposed for
the investigation of large-scale electrically and recombination-active defects
in semiconductors and non-destructive inspection of semiconductor materials and
structures in the industries of microelectronics and photovoltaics. The basis
for this development was laid with a wide cycle of investigations on low-angle
mid-IR-light scattering in semiconductors. The essence of the technical idea
was to apply the dark-field method for spatial filtering of the scattered light
in the scanning mid-IR-laser microscope together with the local photoexcitation
of excess carriers within a small domain in a studied sample, thus forming an
artificial source of scattering of the probe IR light for the recombination
contrast imaging of defects.
  The current paper presents three contrasting examples of application of the
above technique for defect visualization in silicon-based materials designed
for photovoltaics and photonics which demonstrate that this technique might be
an efficient tool for both defect investigation and industrial testing of
semiconducting materials.
