  When the sulfur element is hyperdoped into crystalline silicon to a
supersaturated density of 1020 cm-3, it can enhance the sub-bandgap light
absorption of silicon from 0 to 70%, with the antireflection of surface dome
structures. On the other hand, the local Si: S configuration that can
contribute to the strong sub-bandgap absorption is still unknown. In order to
find more characteristics of this local Si:S configuration, we thermally
annealed the textured sulfur hyperdoped silicon, and analyzed the changes of
its optical and electrical properties. We find that the imaginary part of the
complex dielectric constant of this Si:S configuration is almost constant in
the wavelength range from 1250 nm to 2500 nm ...
