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

Abstract

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.

Tuning nonlinear second-harmonic generation in AlGaAs nanoantennas via chalcogenide phase change material

“…In this design, the semiconductor Al-GaAs has been recently investigated by several groups since it possesses high transparency in a broad spectral window up to the far infrared and giant second-order nonlinear susceptibility 45,46 . For the dispersion of AlGaAs, here we adopt the wavelength-dependent complex-value refractive index which is consistent with the experimental measurement 47 , as plotted in Fig. 2(a).…”

“…The refractive indices of GST for its amorphous phase (blue line) and crystalline phase (red line), respectively. The optical constants are extracted from the experimental measurement using spectroscopic ellipsometry 47,49 .…”

Complex Waveguide Supermode Analysis of Coherently-Coupled Microcavity Laser Arrays

“…For modeling the VCSEL arrays as 2D waveguides, we start by determining the refractive index values for our model. At a wavelength of 850 nanometers undoped GaAs has a complex index n ≈ 3.5708 + 0.02426i [19]. However, our structure is a GaAs/AlGaAs cavity defined by a pair of doped DBR mirrors which would imply a lower real index value (as AlGaAs has a lower index than GaAs) and higher imaginary component (as higher carrier concentrations would increase free-carrier absorption).…”

“…Past work using a simplified cylindrical step-index optical fiber waveguide model for a single cavity has assumed a real index value of 3.5 and would use a cladding imaginary index value of 0.05 to model all of the losses in the cladding layers [20] (this value incorporates all losses, both material and photonic crystal effects). We assume that the same real index value of 3.5 from [20] but will use an imaginary index value estimated from [19]. We correspondingly scale down the complex index of GaAs for an assumed bulk complex index value of n ≈ 3.5 + 0.02378i (assuming that additional losses due to doping are negligible and that the effect of the AlGaAs layers decreases the imaginary index in proportion to the real index).…”

Co-Package Technology Platform for Low-Power and Low-Cost Data Centers

“…CST simulations were combined with semi-analytical modelling, which helped determine the lowest Al composition in the barriers that resulted in sufficient III-V to Si coupling. To be able to model the mode profiles with higher precision, we obtained very precise measurements of Al x Ga (1−x) As refractive indices at 1.3 µm by growing dedicated samples with various compositions (x) and measuring them with spectroscopic ellipsometry [39]. InGaAs QWells and InAs QDs have also been grown and measured separately, and the Al x Ga (1−x) As ternaries have been studied on both lattice-matched GaAs substrates and over QWells (strained layers).…”