Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAs

We present our results for simultaneous measurement of the refractive indices of gallium arsenide (GaAs) and aluminum gallium arsenide (Al_{x}Ga_{1-x}As) in the spectral region from 2.0µmto7.1µm (5000cm^{−1}to1400cm^{−1}). We obtain these values from a monocrystalline superlattice Bragg mirror of ex...

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Main Authors: Lukas W. Perner, Gar-Wing Truong, David Follman, Maximilian Prinz, Georg Winkler, Stephan Puchegger, Garrett D. Cole, Oliver H. Heckl
Format: Article
Language:English
Published: American Physical Society 2023-07-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.5.033048
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author Lukas W. Perner
Gar-Wing Truong
David Follman
Maximilian Prinz
Georg Winkler
Stephan Puchegger
Garrett D. Cole
Oliver H. Heckl
author_facet Lukas W. Perner
Gar-Wing Truong
David Follman
Maximilian Prinz
Georg Winkler
Stephan Puchegger
Garrett D. Cole
Oliver H. Heckl
author_sort Lukas W. Perner
collection DOAJ
description We present our results for simultaneous measurement of the refractive indices of gallium arsenide (GaAs) and aluminum gallium arsenide (Al_{x}Ga_{1-x}As) in the spectral region from 2.0µmto7.1µm (5000cm^{−1}to1400cm^{−1}). We obtain these values from a monocrystalline superlattice Bragg mirror of excellent purity (background doping ≤1×10^{−14}/cm^{3}), grown via molecular beam epitaxy. To recover the refractive indices over such a broad wavelength range, we fit a dispersion model for each material. In a novel combination of well-established methods, we measure both a photometrically accurate transmittance spectrum of the Bragg mirror via Fourier-transform infrared spectrometry and the individual physical layer thicknesses of the structure via scanning electron microscopy. To infer the uncertainty of the refractive index values, we estimate relevant measurement uncertainties and propagate them via a Monte Carlo method. This highly-adaptable approach conclusively yields propagated relative uncertainties on the order of 10^{−4} over the measured spectral range for both GaAs and Al_{0.929}Ga_{0.071}As. The fitted model can also approximate the refractive index for MBE-grown Al_{x}Ga_{1-x}As for 0≤x≤1. Both these updated values and the measurement approach will be essential in the design, fabrication, and characterization of next-generation active and passive optical devices in a spectral region that is of high interest in many fields, e.g., laser design and cavity-enhanced spectroscopy in the mid-infrared.
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spelling doaj.art-a2c0ed5877ff4862aca2bc17197a2e5e2024-04-12T17:32:41ZengAmerican Physical SocietyPhysical Review Research2643-15642023-07-015303304810.1103/PhysRevResearch.5.033048Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAsLukas W. PernerGar-Wing TruongDavid FollmanMaximilian PrinzGeorg WinklerStephan PucheggerGarrett D. ColeOliver H. HecklWe present our results for simultaneous measurement of the refractive indices of gallium arsenide (GaAs) and aluminum gallium arsenide (Al_{x}Ga_{1-x}As) in the spectral region from 2.0µmto7.1µm (5000cm^{−1}to1400cm^{−1}). We obtain these values from a monocrystalline superlattice Bragg mirror of excellent purity (background doping ≤1×10^{−14}/cm^{3}), grown via molecular beam epitaxy. To recover the refractive indices over such a broad wavelength range, we fit a dispersion model for each material. In a novel combination of well-established methods, we measure both a photometrically accurate transmittance spectrum of the Bragg mirror via Fourier-transform infrared spectrometry and the individual physical layer thicknesses of the structure via scanning electron microscopy. To infer the uncertainty of the refractive index values, we estimate relevant measurement uncertainties and propagate them via a Monte Carlo method. This highly-adaptable approach conclusively yields propagated relative uncertainties on the order of 10^{−4} over the measured spectral range for both GaAs and Al_{0.929}Ga_{0.071}As. The fitted model can also approximate the refractive index for MBE-grown Al_{x}Ga_{1-x}As for 0≤x≤1. Both these updated values and the measurement approach will be essential in the design, fabrication, and characterization of next-generation active and passive optical devices in a spectral region that is of high interest in many fields, e.g., laser design and cavity-enhanced spectroscopy in the mid-infrared.http://doi.org/10.1103/PhysRevResearch.5.033048
spellingShingle Lukas W. Perner
Gar-Wing Truong
David Follman
Maximilian Prinz
Georg Winkler
Stephan Puchegger
Garrett D. Cole
Oliver H. Heckl
Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAs
Physical Review Research
title Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAs
title_full Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAs
title_fullStr Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAs
title_full_unstemmed Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAs
title_short Simultaneous measurement of mid-infrared refractive indices in thin-film heterostructures: Methodology and results for GaAs/AlGaAs
title_sort simultaneous measurement of mid infrared refractive indices in thin film heterostructures methodology and results for gaas algaas
url http://doi.org/10.1103/PhysRevResearch.5.033048
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