Electron effective mass in Al0.72Ga0.28N alloys determined by mid-infrared optical Hall effect

Schöche, S.; Kühne, Philipp; Hofmann, Tino; Schubert, M.; Nilsson, Daniel; Kakanakova‐Georgieva, Anelia; Janzén, Erik; Darakchieva, Vanya

doi:10.1063/1.4833195

Cited by 37 publications

(29 citation statements)

References 33 publications

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“…In order to derive the free charge carrier density and mobility parameters from the plasma frequency and broadening parameters one needs the effective mass parameters. Unless magnetic fields are exploited and the optical Hall effect can be measured [93,[95][96][97][98][99][100][101], long-wavelength ellipsometry requires these parameters from auxiliary investigations.…”

Section: -11mentioning

confidence: 99%

Anisotropy, phonon modes, and free charge carrier parameters in monoclinicβ-gallium oxide single crystals

et al. 2016

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We derive a dielectric function tensor model approach to render the optical response of monoclinic and triclinic symmetry materials with multiple uncoupled infrared and far-infrared active modes. We apply our model approach to monoclinic β-Ga 2 O 3 single-crystal samples. Surfaces cut under different angles from a bulk crystal, (010) and (201), are investigated by generalized spectroscopic ellipsometry within infrared and far-infrared spectral regions. We determine the frequency dependence of 4 independent β-Ga 2 O 3 Cartesian dielectric function tensor elements by matching large sets of experimental data using a point-by-point data inversion approach. From matching our monoclinic model to the obtained 4 dielectric function tensor components, we determine all infrared and far-infrared active transverse optic phonon modes with A u and B u symmetry, and their eigenvectors within the monoclinic lattice. We find excellent agreement between our model results and results of density functional theory calculations. We derive and discuss the frequencies of longitudinal optical phonons in β-Ga 2 O 3 . We derive and report density and anisotropic mobility parameters of the free charge carriers within the tin-doped crystals. We discuss the occurrence of longitudinal phonon plasmon coupled modes in β-Ga 2 O 3 and provide their frequencies and eigenvectors. We also discuss and present monoclinic dielectric constants for static electric fields and frequencies above the reststrahlen range, and we provide a generalization of the Lyddane-Sachs-Teller relation for monoclinic lattices with infrared and far-infrared active modes. We find that the generalized Lyddane-Sachs-Teller relation is fulfilled excellently for β-Ga 2 O 3 .

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Section: -11mentioning

confidence: 99%

Anisotropy, phonon modes, and free charge carrier parameters in monoclinicβ-gallium oxide single crystals

et al. 2016

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“…[30][31][32][33] Since the magnitude of the OHE depends on the magnetic field strength, higher magnetic fields facilitate the detection of the OHE. Furthermore, the sensitivity to the OHE is greatly enhanced by phonon mode coupling, 34,35 surface guided waves 27 and Fabry-Pérot interferences. 31,36 Since these effects appear from the THz to the mid-infrared (MIR) spectral range, depending on the structure and material of the sample, it is necessary to extend the spectral range covered by OHE instrumentation.…”

Section: Introductionmentioning

confidence: 99%

Invited Article: An integrated mid-infrared, far-infrared, and terahertz optical Hall effect instrument

Kühne

Herzinger

Schubert

et al. 2014

Review of Scientific Instruments

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We report on the development of the first integrated mid-infrared, far-infrared and terahertz optical Hall effect instrument, covering an ultra wide spectral range from 3 cm −1 to 7000 cm −1 (0.1-210 THz or 0.4-870 meV). The instrument comprises four sub-systems, where the magneto-cryostat-transfer sub-system enables the usage of the magneto-cryostat sub-system with the mid-infrared ellipsometer sub-system, and the far-infrared/terahertz ellipsometer sub-system. Both ellipsometer sub-systems can be used as variable angleof-incidence spectroscopic ellipsometers in reflection or transmission mode, and are equipped with multiple light sources and detectors. The ellipsometer sub-systems are operated in polarizer-sample-rotating-analyzer configuration granting access to the upper left 3 × 3 block of the normalized 4 × 4 Mueller matrix. The closed cycle magneto-cryostat sub-system provides sample temperatures between room temperature and 1.4 K and magnetic fields up to 8 T, enabling the detection of transverse and longitudinal magnetic field-induced birefringence. We discuss theoretical background and practical realization of the integrated mid-infrared, far-infrared and terahertz optical Hall effect instrument, as well as acquisition of optical Hall effect data and the corresponding model analysis procedures. Exemplarily, epitaxial graphene grown on 6H -SiC, a tellurium doped bulk GaAs sample and an AlGaN/GaN high electron mobility transistor structure are investigated. The selected experimental datasets display the full spectral, magnetic field and temperature range of the instrument and demonstrate data analysis strategies. Effects from free charge carriers in two dimensional confinement and in a volume material, as well as quantum mechanical effects (inter-Landau-level transitions) are observed and discussed exemplarily.

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“…The OHE allows for detection of three free charge carrier parameters, charge density, charge mobility and effective mass [54][55][56][57][58]. The magnitude of the OHE birefringence can be further tuned by adding a cavity with varying thickness on the backside of a (transparent) sample [42,59,60].…”

Section: Terahertz Optical Hall Effect (Thz-ohe)mentioning

confidence: 99%

Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications

Kühne

Armakavicius

Stanishev

et al. 2018

IEEE Trans. THz Sci. Technol.

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Abstract-We present a terahertz (THz) frequency-domain spectroscopic (FDS) ellipsometer design which suppresses formation of standing waves by use of stealth technology approaches. The strategy to suppress standing waves consists of three elements geometry, coating and modulation. The instrument is based on the rotating analyzer ellipsometer principle and can incorporate various sample compartments, such as a superconducting magnet, in-situ gas cells or resonant sample cavities, for example. A backward wave oscillator and three detectors are employed, which permit operation in the spectral range of 0.1-1 THz (3.3-33 cm −1 or 0.4-4 meV). The THz frequency-domain ellipsometer allows for standard and generalized ellipsometry at variable angles of incidence in both reflection and transmission configurations. The methods used to suppress standing waves and strategies for an accurate frequency calibration are presented. Experimental results from dielectric constant determination in anisotropic materials, and free charge carrier determination in optical Hall effect, resonant-cavity enhanced optical Hall effect and in-situ optical Hall effect experiments are discussed. Examples include silicon and sapphire optical constants, free charge carrier properties of two dimensional electron gas in group-III nitride high electron mobility transistor structure, and ambient effects on free electron mobility and density in epitaxial graphene.

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Electron effective mass in Al0.72Ga0.28N alloys determined by mid-infrared optical Hall effect

Cited by 37 publications

References 33 publications

Anisotropy, phonon modes, and free charge carrier parameters in monoclinicβ-gallium oxide single crystals

Anisotropy, phonon modes, and free charge carrier parameters in monoclinicβ-gallium oxide single crystals

Invited Article: An integrated mid-infrared, far-infrared, and terahertz optical Hall effect instrument

Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications

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