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TitleCompositional and structural studies of amorphous GaN grown by ion-assisted deposition
Publication TypeConference Paper
Year of Publication2002
AuthorsLanke, U.D., Koo A., Ruck B.J., Lee H.K., Markwitz A., Kennedy V.J., Ariza M.J., Jones D.J., Rozière J., Bittar A., and Trodahl H.J.
Conference NameMaterials Research Society Symposium - Proceedings
Date Published2002
KeywordsAmorphous films, Annealing, Approximation theory, Bonding, Composition, Extended x ray absorption fine structure, Film growth, Gallium nitride, Ion assisted deposition, Nuclear reaction analysis, Raman spectroscopy, Rutherford backscattering spectroscopy, Thermal effects, Transmission electron microscopy, Transparency, X ray diffraction analysis
AbstractAmorphous GaN films have been deposited onto various substrates by ion-assisted deposition. The films were deposited at room temperature using nitrogen ion energies in the range 40-900 eV. Rutherford backscattering spectroscopy and nuclear reaction analysis show that the Ga:N atomic ratio is approximately one for films grown with ion energy near 500 eV; these films have the highest transparency. Films grown with ion energies below 300 eV are Ga rich, and show reduced transparency across the visible. Raman spectroscopy, x-ray diffraction, and transmission electron microscopy confirm the amorphous nature of the films. Annealing studies on a-GaN establish that the films begin to crystallise at a temperature of about 700°C. To investigate the local bonding environment of the Ga or N atoms, we have measured the extended x-ray absorption fine structure (EXAFS) of the transparent GaN films. The EXAFS results indicate that the films are dominated by heteropolar tetrahedral bonding, with a low density of homopolar bonds.

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