Defect engineering for improved thermal stability of sulfur hyperdoped silicon

Sulfur hyperdoped silicon (Si:S) is a promising material for sub-bandgap photovoltaics or infrared photodetectors. However, previous publications show that a temperature step is necessary to improve device performance. This temperature step leads to a decrease in sub-bandgap absorptance, which is a major challenge. We show a post-treatment that increases the thermal stability of Si:S in terms of sub-bandgap absorptance, sheet carrier density and mobility. In addition, we investigate a post-treatment for optical reactivation of Si:S regarding sheet carrier density and mobility and thus gain atomistic insights into the reactivation step.