ZnSe-based short period superlattice quantum well with Te-doping: atomic layer epitaxial growth and optical properties

ZnSe-based short period superlattice quantum well (SPSQW) with Te- doping have been fabricated by mean of atomic layer epitaxy. Luminescence from these SPSQW structures was strongly modified by spatially selective introduction of Te isoelectronic centers. Typical photoluminescence spectrum from well-'doped' SPSQW is a broad and very efficient emission band with large stokes shift due to radiative recombination of self-trapped excitons high-efficiently localized at the ZnSe-ZnTe interface. In some properly designed structures, recombination from free-quantum-well excitons can been observed due to the enhancement of quantum confinement. For barrier-doped SPSQW, free-quantum-well and self-trapped excitons can co-exist in a wide range of temperature due to the fact that they are separated from each other spatially. Room-temperature-luminescence was dominated by narrow recombination of quantum-well-excitons. The decay rate for the free excitons at the n equals 1 resonance from barrier-doped SPSQW has a long lifetime tail of more than 10 nsec. All the phenomena were discussed in term of doping position and doping density, using the model of exciton extrinsic self-trapping.