Developing Rare-Earth Doped Semiconductor Light Sources
Final rept. 1 Aug 94-31 Mar 97
ARIZONA UNIV TUCSON OPTICAL SCIENCES CENTER
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The possibility of enhancing the luminescence efficiency of Er ions embedded in a semiconductor was investigated by growing about forty erbium-doped InGaAsGaAs and GaAsAlGaAs multiple quantum well samples pies by molecular beam epitaxy. The idea was to enhance the semiconductor-to-erbium transfer when the quantum well and erbium-ion transition engergies are equal. Photoluminescence of Er ions and Er induced defects was studied at liquid helium and higher temperatures. A strong diffusion of erbium and interdiffusion of Ga and Al ions was observed, leading at high erbium concentrations to the degradation of the QWs and macroscopic average leveling of Er and A1 concentrations over the whole grown structure. From high-resolution photoluminescence spectra the existence of three types of Er centers was deduced which differ by positions of fine structure lines, photo luminescence lifetimes, and temperature dependence. These centers cause three types of carrier traps with binding energies of 20, 50, and 400 meV. Evidence is given that carriers captured into these traps control the Auger excitation of Er ions assisted by multiphonon emission. Er luminescence associated with the 400 meV trap is still detectable at room temperature. This grant was terminated abruptly after 71 of the funding was received, purportedly for financial rather than scientific reason.
- Electrical and Electronic Equipment
- Solid State Physics