Picosecond carrier recombination dynamics in chalcogen-hyperdoped silicon
Abstract
Intermediate-band materials have the potential to be highly efficient solar cells and can be fabricated by incorporating ultrahigh concentrations of deep-level dopants. Direct measurements of the ultrafast carrier recombination processes under supersaturated dopant concentrations have not been previously conducted. Here, we use optical-pump/terahertz-probe measurements to study carrier recombination dynamics of chalcogen-hyperdoped silicon with sub-picosecond resolution. The recombination dynamics is described by two exponential decay time scales: a fast decay time scale ranges between 1 and 200 ps followed by a slow decay on the order of 1 ns. In contrast to the prior theoretical predictions, we find that the carrier lifetime decreases with increasing dopant concentration up to and above the insulator-to-metal transition. Evaluating the material's figure of merit reveals an optimum doping concentration for maximizing performance.
- Publication:
-
Applied Physics Letters
- Pub Date:
- August 2014
- DOI:
- 10.1063/1.4892357
- Bibcode:
- 2014ApPhL.105e3905S