Mid-infrared spectroscopy of the Er-related donor state in Si/Si:Er3+ nanolayers

We present experimental evidence on the donor level related to optical properties of the Er3+ ion in crystalline silicon. Using two-color spectroscopy with a free-electron laser we provide a direct link between the identified level in the bandgap and the optical properties of EP,. The investigation is performed in sublimation MBE-grown Si/Si:Er multinanolayer structure, which allows us to take advantage of the preferential formation of a single Er-related center. Quenching of the Er-related 1.5 mu m photoluminescence, due to ionization of the donor state with energy E-D approximate to 225 meV, is demonstrated. A microscopic model of the PL quenching mechanism as Auger type energy transfer between excited Er3+ ions and free carriers optically ionized from the Er-related donor states is put forward

Terahertz electromagnetic transitions observed within the 4I15/2 ground multiplet of Er3+ ions in Si

An optically induced terahertz transition within the crystal-field-split ground state of Er3+ ion in Si has been conclusively established. A Si/Si:Er multinanolayer structure, where a single type of Er-related centers dominates, has been used. The study was conducted by pump-probe technique with a free-electron laser. Using the transient grating experimental configuration, we identify an absorption band at λ≈43.5 μm and measure the related effective lifetime as τ≈50 ps