Origin of a nonradiative center in AlGaAs grown by molecularhyphen;beam epitaxy was investigated by secondary ion mass spectroscopy and deephyphen;level transient spectroscopy, from the change of photoluminescence intensity with anneal treatment, and from its comparison with GaAs. Aluminumhyphen;oxygen complex is a most probable defect which acts as a nonradiative center in AlGaAs, and the oxygen would evaporate as Al2O from the surface, which would be a reason why the photoluminescence intensity increases under higher substrate temperature and lower V/III flux ratio. The electronhyphen;trap level at 0.76 eV from the conduction band would be the recombination center, and the photoluminescence intensity is inversely proportional to the trap concentration.
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