Zinc-blende AlGaN epilayers were grown by plasma-assisted MBE on thick (001) SiC deposited by CVD on Si substrates. Alloy compositions were controlled in situ by reflection high energy diffraction (RHEED) oscillations, and confirmed by Rutherford backscattering (RBS) post growth analysis. The zinc-blende nature of our samples was assessed by RHEED analysis. From reflectivity measurements at room temperature, we deduce the variation of the lowest direct absorption edge of zinc-blende AlGaN as a function of the Al content x, E0(x) = 3.25 (1 - x) + 6.05x - 1.4x (1 - x), E0 in eV. The dispersion of the refractive index n of cubic AlN was also extracted from our reflectivity and RBS data, and fitted by a Sellmeier-type relation, n^2 = 3.05 + 1.38 lambda^2/(lambda^2 - 180^2), lambda being the wavelength in nm.
Optical characterization of MBE grown zinc-blende AlGaN
MULA, GUIDO
2001-01-01
Abstract
Zinc-blende AlGaN epilayers were grown by plasma-assisted MBE on thick (001) SiC deposited by CVD on Si substrates. Alloy compositions were controlled in situ by reflection high energy diffraction (RHEED) oscillations, and confirmed by Rutherford backscattering (RBS) post growth analysis. The zinc-blende nature of our samples was assessed by RHEED analysis. From reflectivity measurements at room temperature, we deduce the variation of the lowest direct absorption edge of zinc-blende AlGaN as a function of the Al content x, E0(x) = 3.25 (1 - x) + 6.05x - 1.4x (1 - x), E0 in eV. The dispersion of the refractive index n of cubic AlN was also extracted from our reflectivity and RBS data, and fitted by a Sellmeier-type relation, n^2 = 3.05 + 1.38 lambda^2/(lambda^2 - 180^2), lambda being the wavelength in nm.
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