54 research outputs found

    Green, red and infrared Er-related emission in implanted GaN:Er and GaN:Er,O samples

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    Er-related luminescence near 1.54 mm ~;805 meV! is observed under below band gap excitation at 4.2 K in GaN:Er and GaN:Er,O implanted samples. The spectrum of the recovered damage samples is a multiline structure. So far, these lines are the sharpest ones reported for GaN. Well-resolved green and red luminescences are observed in implanted samples. The dependence of luminescence on the excitation energy as well as the influence of different nominal fluence and annealing conditions is discussed. Combining the results obtained from photoluminescence and Rutherford backscattering spectrometry, different lattice sites for the optical active Er-related centers are identified

    Lattice Dynamics of II-VI materials using adiabatic bond charge model

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    We extend the adiabatic bond charge model, originally developed for group IV semiconductors and III-V compounds, to study phonons in more ionic II-VI compounds with a zincblende structure. Phonon spectra, density of states and specific heats are calculated for six II-VI compounds and compared with both experimental data and the results of other models. We show that the 6-parameter bond charge model gives a good description of the lattice dynamics of these materials. We also discuss trends in the parameters with respect to the ionicity and metallicity of these compounds.Comment: 16 pages of RevTex with 3 figures submitted as a uuencode compressed tar fil

    Construction of Number Fields of Odd Degree with Class Numbers Divisible by Three, Five or by Seven

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    Reell-quadratische Zahlkörper mit großer Grundeinheit

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