Intermediate band conduction in femtosecond-laser hyperdoped silicon

We use femtosecond-laser hyperdoping to introduce non-equilibrium concentrations of sulfur into silicon and study the nature of the resulting intermediate band. With increasing dopant concentration, the sub-bandgap absorption increases. To better understand the dopant energetics, we perform temperature-dependent Hall and resistivity measurements. We analyze the carrier concentration and the energetics of the intermediate band using a two-band model. The temperature-dependence of the carrier concentration and resistivity suggests that the dopant concentration is below the insulator-to-metal transition and that the samples have a localized intermediate band at 70 meV below the conduction band edge. (C) 2014 AIP Publishing LLC.