Near band-edge optical properties of cubic GaN with and without carbon doping
We report the results of studying the optical properties of cubic GaN thin films with photoluminescence and photoluminescence excitation spectroscopies. The films are deposited by plasma-assisted molecular beam epitaxy on GaAs (001) substrates, with and without intentional doping with carbon atoms (p-type doping). The evolution of the optical spectra of the C-doped samples is consistent with a picture in which carbon enters into N-vacancies at low concentrations, producing a marked improvement in the crystalline properties of the material. At higher concentrations it begins to form complexes, possibly due to interstitial occupation. The temperature dependence on the absorption edge of the doped material is also measured and is analyzed with standard theoretical models.
Electronic Energy Levels in Group-III Nitrides
This chapter reviews the published information concerning the electronic energy levels created within the valence-band to conduction-band energy gap of crystalline boron nitride, aluminum nitride, gallium nitride, and indium nitride by the presence of lattice defects and impurities. Knowledge and understanding of the band-gap levels that can occur in these group-III semiconductors are essential for producing effective p-type and n-type doping as well as for optimization of their properties, including electrical conductivity, carrier mobilities, and optical luminescence, for their many electronic and optoelectronic applications. Theoretical and experimental data for the zincblende and wurtzite structures are considered in detail, and certainties and uncertainties concerning the energy levels and their likely impurity or defect identities are assessed.
Pseudo-Chediak-Higashi anomaly in acute myeloid leukaemia. An electron microscopical study.
2 cases of acute myeloid leukaemia with inclusion bodies are presented. The inclusions were found mainly in the blast cells but could also be encountered in lymphocytes and plasma cells. Cytochemical and ultrastructural studies showed a great resemblance of these inclusions to the ones found in Chediak-Higashi anomaly, i.e., high acid phosphatase activity, varying in size of inclusions from clusters of small granules to hugh inclusion, sometimes found in vacuoles, featuring fusion of lysosomes.