Optical and electrical properties of textured sulfur-hyperdoped silicon: a thermal annealing study

When elemental sulfur was used to hyperdope crystalline silicon to a supersaturated density of ~10²⁰ cm⁻³, it was found to enhance the sub-bandgap light absorptance of the silicon substrate from 0 up to 70 % when combined with the antireflection properties of the surface dome structures that were formed by surface texturing. These textured sulfur-hyperdoped silicon samples were then thermally annealed at various temperatures, and the effects of the annealing on each sample’s optical and electrical properties were investigated. In the silicon sub-bandgap wavelength range, the absorptance of the textured hyperdoped silicon was attenuated more slowly than that of a non-textured sample, and the modulation of its reflectance and transmittance properties was attributed to the density damping of the optically absorbing state. In addition, the optically absorbing state can release more electrons than the optically non-absorbing state, and the former state also has a stronger ability to scatter electrons than the latter.