Spectral range of crystalline silicon absorption could be extended to near- and even mid-infrared region by its hyperdoping via ion-implantation technology, requiring the following thermal annealing for removing ion-induced defects, recrystallizing the crystalline structure and activating the doping impurity. In this article, the crystalline structure, chemical and electrical characteristics of sulfur-hyperdoped silicon layers with broadly variable impurity concentration (1018-1021 cm−3) and annealed by a nanosecond laser were investigated for the first time by Raman, energy-dispersion x-ray and infrared spectroscopy, as well as by van der Paw and Hall measurements, respectively. The most preferable sulfur concentration for silicon hyperdoping from the point of view of impurity optical and electrical activation was found to be 1020 cm−3.