PROPERTIES OF ER-RELATED EMISSION IN IN-SITU DOPED SI EPILAYERS GROWNBY MOLECULAR-BEAM EPITAXY

Optical properties of in situ Er-doped Si epilayers grown by molecular beam epitaxy at low temperatures (<450 degrees C), using oxygen and f luorine as codopants, are studied using photoluminescence (PL) and ele ctroluminescence (EL) spectroscopies. Sharp and intense Er-related PL is observed at low temperatures from the as-grown Si epilayers with Er concentrations up to 5 x 10(19) cm(-3). The structure of the dominant optically active Er centers is shown to be dependent of the codopants used and can essentially be modified by postgrowth thermal annealing. The chemical nature of the codopants as well as postgrowth treatments have only a minor effect on the thermal quenching of Er-related emiss ions. Thermal quenching of the Er-related PL and EL is shown to occur with a similar activation energy suggesting the same quenching mechani sm may be involved for both processes. The observed higher EL efficien cy at elevated temperatures is tentatively attributed to the higher co ncentration of excited Er ions under impact ionization conditions (EL) . (C) 1998 American Vacuum Society.