Refractive indices of MBE-grown AlxGa(1−<i>x</i>)As ternary alloys in the transparent wavelength region
Konstantinos Papatryfonos, T. Angelova, A. Brimont, Barry Reid, Stefan Guldin, Peter R. Smith, Mingchu Tang, Keshuang Li, A.J. Seeds, Huiyun Liu, David R. Selviah
Abstract
A series of AlxGa(1−x)As ternary alloys were grown by molecular beam epitaxy (MBE) at the technologically relevant composition range, x &lt; 0.45, and characterized using spectroscopic ellipsometry to provide accurate refractive index values in the wavelength region below the bandgap. Particular attention is given to O-band and C-band telecommunication wavelengths around 1.3 µm and 1.55 µm, as well as at 825 nm. MBE gave a very high accuracy for grown layer thicknesses, and the alloys’ precise compositions and bandgap values were confirmed using high-resolution x-ray diffraction and photoluminescence, to improve the refractive index model fitting accuracy. This work is the first systematic study for MBE-grown AlxGa(1−x)As across a wide spectral range. In addition, we employed a very rigorous measurement-fitting procedure, which we present in detail.