Using blue-emitting GaN/6H-SiC chips as primary light sources, we have fabricated green, yellow, red and white emitting LEDs. The generation of mixed colors, as turquoise and magenta is also demonstrated. The underlying physical principle is that of luminescence down- conversion (Stokes shift), as typical for organic luminescent dye molecules. A white emitting LED, using an inorganic converter, Y3Al5O12:Ce(3+)(4 integral of 1 ), has also been realized
A new manganese-related isotropic electron-spin-resonance signal at g=2.77 has been observed in GaAs. It is shown to arise from the neutral Mn acceptor, MnE0. The analysis gives an answer to the longstanding question of whether the structure of MnE0 corresponds to 3dE4 or do 3dE5+hole. The data clearly favor the latter case, thus revealing that Mn is an exception within the 3d acceptor family in GaAs. (IAF
AsGa antisite defects formed during plastic deformation of GaAs are identified by electron paramagnetic resonance (EPR) measurements. From photo-EPR results it can be concluded that the two levels of this double donor are located near Ec −0.75 eV and Ev +0.5 eV. These values are coincident with the Fermi level pinning energies at Schottky barriers. The upper level can be related to the ’’main electron trap’’ EL2 in GaAs. Photoluminescence experiments before and after thermal annealing suggest that AsGa defects reduce the near band edge luminescence efficiency. A dislocation climb model is presented which is able to explain AsGa formation during dislocation movement. The production of AsGa antisites during dislocation motion under injection conditions in light emitting devices may thus be connected with degradation of the light output.
Nuclear magnetic resonance spectra of Cue3 and AlZ7, Gaaa and In115 have been recorded in ternary IB-III-VI, semiconductors, which crystallize in the tetragonal chalcopyrite structure. Nuclear electric quadrupole coupling constants have been determined and are discussed in connection with the structural parameters of these compounds, which were determined by X-ray diffraction.Es wurden die Kernresonanzspektren von Cus3 und AP7, Ga60 und In115 in den ternaren IB-III-VI,-Halbleitern, die in der tetragonalen Chalkopyrit-Struktur kristallisieren, bestimmt. Die elektrischen Kern-Quadrupol-Kopplungskonstanten wurden bestimmt und werden in Verbindung mit den Strukturparametern dieser Verbindungen diskutiert, die durch Rontgenbeugung bestimmt wurden.
Trace impurities of vanadium in Lely-grown silicon carbide single crystals have been detected by their strong, polytype-specific photoluminescence in the 1.3-1.5 mym near-infrared spectral rang, as well as by infrared absorption. A high 0/A high-, and possibly also as a deep donor. The role of vanadium as minority-carrier lifetime killer in SiC-based optoelectronic devices is suggested from these data
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