AIP Advances (Feb 2021)

Refractive indices of MBE-grown AlxGa(1−x)As ternary alloys in the transparent wavelength region

  • Konstantinos Papatryfonos,
  • Todora Angelova,
  • Antoine Brimont,
  • Barry Reid,
  • Stefan Guldin,
  • Peter Raymond Smith,
  • Mingchu Tang,
  • Keshuang Li,
  • Alwyn J. Seeds,
  • Huiyun Liu,
  • David R. Selviah

DOI
https://doi.org/10.1063/5.0039631
Journal volume & issue
Vol. 11, no. 2
pp. 025327 – 025327-10

Abstract

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A series of AlxGa(1−x)As ternary alloys were grown by molecular beam epitaxy (MBE) at the technologically relevant composition range, x < 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.