Compound 4 also showed a strong emission band attributed to the Yb(III), suggesting an antenna effect of the ligand. An energy transfer diagram is proposed to explain these luminescent properties.

Articles you may be interested inEmission properties of a -plane GaN grown by metal-organic chemical-vapor deposition J. Appl. Phys. 98, 093519 (2005); 10.1063/1.2128496 Photoluminescence of Mg-doped GaN grown by metalorganic chemical vapor deposition Stability investigation of cubic GaN films grown by metalorganic chemical vapor deposition on GaAs (001)Scanning electron microscopy, micro-Raman, and photoluminescence ͑PL͒ measurements are reported for Mg-doped GaN films grown on ͑0001͒ sapphire substrates by low-pressure metalorganic chemical vapor phase deposition. The surface morphology, structural, and optical properties of GaN samples with Mg concentrations ranging from 10 19 to 10 21 cm Ϫ3 have been studied. In the scanning micrographs large triangular pyramids are observed, probably due to stacking fault formation and three-dimensional growth. The density and size of these structures increase with the amount of magnesium incorporated in the samples. In the photoluminescence spectra, intense lines were found at 3.36 and 3.31 eV on the triangular regions, where the presence of cubic inclusions was confirmed by micro-Raman measurements. The excitation dependence and temperature behavior of these lines enable us to identify their excitonic nature. From our study we conclude that the interface region between these defects and the surrounding wurtzite GaN could be responsible for PL lines.

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Raman scattering and photoluminescence (PL) spectroscopy with sub-bandgap excitation has been applied to explore tracing of common impurities (in particular of oxygen) in AlN. Bulk AlN crystals grown by the high temperature sublimation method were studied. PL bands have been observed at around 375 nm and at 560–660 nm and have been attributed to oxygen and to nitrogen vacancy/aluminium excess defects, respectively. The 375 nm UV PL band was found to shift with oxygen concentration. Micro-Raman spectra of the bulk AlN samples were measured in different polarisations. Besides normal Raman modes of AlN the presence of additional vibrational modes was detected. The modes were discussed and tentatively attributed to oxygen and silicon local vibrational modes (LVMs) in AlN.