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Structural and optical properties of GaN-based nanocrystalline thin films |
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| Authors: | C.E.A. Grigorescu L. Tortet L. Argeme S. Granville F. Budde G.V.M. Williams A. Tonetto C. Logofatu |
| Affiliation: | a National Institute R&D Optoelectronics-INOE 2000, P.O. Box MG-5, Bucuresti-Magurele, Judet Ilfov, 77125, Romania b MADIREL, Universite de Provence, Centre Saint Jerome, Marseille, MacDiarmid Institute for Advanced Materials and Nanotechnology, France c Victoria University, PO Box 600, Wellington, New Zealand d Industrial Research Ltd., PO Box 31310, Lower Hutt, New Zealand e SCM, Universite de Provence, Centre Saint Charles, Marseille, France f National Institute R&D Materials Physics, P.O. Box MG-7, Bucuresti-Magurele, Judet Ilfov, 77125, Romania |
| Abstract: | We study the effect of annealing on structure, morphology and optical properties of nanocrystalline films of GaN, GaN:O and GaN:Mn prepared by ion assisted deposition on silicon, quartz and glassy carbon substrates. Blisters and holes having diameters proportional with the thickness of the film were observed in GaN:O deposited on silicon and glassy carbon. The Mn excess in GaN:Mn turns through annealing into MnxNy islands. The degree of short- and intermediate-range order in the films was investigated by micro-Raman spectroscopy, extending to about 3 nm for gallium oxynitride films annealed to 973 K and to more than 10 nm in GaN samples. A diminished oxygen content following the annealing procedures on GaN:O samples is noticed from the reduced intensity of the oxygen mode at 1000 cm− 1 in the Raman spectra. This observation is supported with X-ray photoemission spectroscopy measurements. The presence of oxygen at concentrations above 15at.% in the films leads to an abrupt nanocrystalline-amorphous transition. |
| Keywords: | Ion assisted deposition Gallium nitride Annealing Scanning electron microscopy X-ray diffraction X-ray photoemission spectroscopy Raman spectroscopy Short range order |
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