Raman spectra and optical properties of the chalcogen-hyperdoped silicon: a first-principles study

The Raman peaks observed in the ultrafast-laser induced chalcogen-hyperdoped Si are assigned to different configurations of defects formed in crystal Si. The disappearance of the Raman peaks of the chalcogen-hyperdoped Si after thermal annealing is attributed to the formation of polymers, which cannot display any Raman peaks except the strong peak of crystal Si. The imaginary parts of the dielectric functions indicate that sub-bandgap absorptions are also reduced when the chalcogen atoms combine to form a polymer. The reductions of the sub-bandgap absorptions are different for S- and Se-hyperdoped Si, which can give a good explanation for their different variations of infrared absorptance at the same annealing conditions.