Near-infrared Near-field Imaging Spectroscopy of Semiconductor Quantum Structures for Optical Communication Devices

The nonuniform distribution of N in GaInNAs alloys was investigated by near-field photoluminescence imaging spectroscopy of localized states driven by giant band-gap reduction due to N incorporation. We observed both strongly localized excitons confined in N clusters and rather delocalized excitons, which indicate the onset of alloy formation.