Emergence of very broad infrared absorption band by hyperdoping of silicon with chalcogens

We report the near through mid-infrared (MIR) optical absorption spectra, over the range 0.05–1.3 eV, of monocrystalline silicon layers hyperdoped with chalcogen atoms synthesized by ion implantation followed by pulsed laser melting. A broad mid-infrared optical absorption band emerges, peaking near 0.5 eV for sulfur and selenium and 0.3 eV for tellurium hyperdoped samples. Its strength and width increase with impurity concentration. Its strength decreases markedly with subsequent thermal annealing. The emergence of a broad MIR absorption band is consistent with the formation of an impurity band from isolated deep donor levels as the concentration of chalcogen atoms in metastable local configurations increases.This research was supported in part by the U.S. Army ARDEC under Contract No. W15QKN-07-P-0092, and a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science. The Australian Research Council is also acknowledged for partial financial support