The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Mathias Schubert - One of the best experts on this subject based on the ideXlab platform.
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critical point model dielectric function analysis of wo3 thin films deposited by atomic layer deposition techniques
Journal of Applied Physics, 2018Co-Authors: Ufuk Kilic, Alyssa Mock, Rafal Korlacki, Derek Sekora, Shah R Valloppilly, Elena Echeverria, Natale J Ianno, Eva Schubert, Mathias SchubertAbstract:WO3 thin films were grown by atomic layer deposition and spectroscopic Ellipsometry data gathered in the photon energy range of 0.72–8.5 eV, and from multiple samples were utilized to determine the frequency dependent complex-valued isotropic dielectric function for WO3. We employ a critical-point model dielectric function analysis and determine a parameterized set of oscillators and compare the observed critical-point contributions with the vertical transition energy distribution found within the band structure of WO3 calculated by the density functional theory. The surface roughness was investigated using atomic force microscopy, and compared with the effective roughness as seen by the spectroscopic Ellipsometry.
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anisotropy and phonon modes from analysis of the dielectric function tensor and the inverse dielectric function tensor of monoclinic yttrium orthosilicate
Physical Review B, 2018Co-Authors: Alyssa Mock, Rafal Korlacki, Sean Knight, Mathias SchubertAbstract:We determine the frequency dependence of the four independent Cartesian tensor elements of the dielectric function for monoclinic symmetry Y2SiO5 using generalized spectroscopic Ellipsometry from 4 ...
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anisotropy phonon modes and lattice anharmonicity from dielectric function tensor analysis of monoclinic cadmium tungstate
Physical Review B, 2017Co-Authors: Alyssa Mock, Rafal Korlacki, Sean Knight, Mathias SchubertAbstract:We determine the frequency dependence of four independent Cartesian tensor elements of the dielectric function for CdWO4 using generalized spectroscopic Ellipsometry within mid-infrared and far-inf ...
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visible to vacuum ultraviolet dielectric functions of epitaxial graphene on 3c and 4h sic polytypes determined by spectroscopic Ellipsometry
Applied Physics Letters, 2012Co-Authors: A Boosalis, Tino Hofmann, Vanya Darakchieva, Rositsa Yakimova, Mathias SchubertAbstract:Spectroscopic Ellipsometry measurements in the visible to vacuum-ultraviolet spectra (3.5-9.5 eV) are performed to determine the dielectric function of epitaxial graphene on SiC polytypes, includin ...
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infrared Ellipsometry on semiconductor layer structures phonons plasmons and polaritons
2010Co-Authors: Mathias SchubertAbstract:Introduction.- Ellipsometry.- Infrared Model Dielectric Functions.- Polaritons in Semiconductor Layer Structures.- Anisotropic Substrates.- Zinsblende-Structure Materials (III-V).- Wurtzite-Structure Materials (Group-III Nitrides, ZnO).- Magneto-optic Ellipsometry.
Hans Arwin - One of the best experts on this subject based on the ideXlab platform.
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chirality induced polarization effects in the cuticle of scarab beetles 100 years after michelson
Philosophical Magazine, 2012Co-Authors: Hans Arwin, Roger Magnusson, Jan Landin, Kenneth JärrendahlAbstract:One hundred years ago Michelson discovered circular polarization in reflection from beetles. Today a novel Mueller-matrix Ellipsometry setup allows unprecedented detailed characterization of the be ...
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characterization of plasmonic effects in thin films and metamaterials using spectroscopic Ellipsometry
Progress in Surface Science, 2011Co-Authors: T. W. H. Oates, Herbert Wormeester, Hans ArwinAbstract:In this article, spectroscopic Ellipsometry studies of plasmon resonances at metal–dielectric interfaces of thin films are reviewed. We show how Ellipsometry provides valuable non-invasive amplitude and phase information from which one can determine the effective dielectric functions, and how these relate to the material nanostructure and define exactly the plasmonic characteristics of the system. There are three related plasmons that are observable using spectroscopic Ellipsometry; volume plasmon resonances, surface plasmon polaritons and particle plasmon resonances. We demonstrate that the established method of exploiting surface plasmon polaritons for chemical and biological sensing may be enhanced using the ellipsometric phase information and provide a comprehensive theoretical basis for the technique. We show how the particle and volume plasmon resonances in the ellipsometric spectra of nanoparticle films are directly related to size, surface coverage and constituent dielectric functions of the nanoparticles. The regularly observed splitting of the particle plasmon resonance is theoretically described using modified effective medium theories within the framework of Ellipsometry. We demonstrate the wealth of information available from real-time in situ spectroscopic Ellipsometry measurements of metal film deposition, including the evolution of the plasmon resonances and percolation events. Finally, we discuss how generalized and Mueller matrix Ellipsometry hold great potential for characterizing plasmonic metamaterials and sub-wavelength hole arrays.
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spectroscopic Ellipsometry study on the dielectric function of bulk ti2aln ti2alc nb2alc ti0 5 nb0 5 2alc and ti3gec2 max phases
Journal of Applied Physics, 2011Co-Authors: A Mendozagalvan, Marcin Rybka, Hans Arwin, Kenneth Järrendahl, Martin Magnuson, Lars Hultman, Michel W. BarsoumAbstract:The averaged complex dielectric function =2+ /3 of polycrystalline Ti2AlN, Ti2AlC,Nb2AlC, Ti0.5,Nb0.52AlC, and Ti3GeC2 was determined by spectroscopic Ellipsometry coveringthe mid infrared to the u ...
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Total internal reflection Ellipsometry: principles and applications
Applied optics, 2004Co-Authors: Hans Arwin, Michal Poksinski, Knut JohansenAbstract:A concept for a measurement technique based on Ellipsometry in conditions of total internal reflection is presented. When combined with surface plasmon resonance (SPR) effects, this technique becomes powerful for monitoring and analyzing adsorption and desorption on thin semitransparent metal films as well as for analyzing the semitransparent films themselves. We call this technique total internal reflection Ellipsometry (TIRE). The theory of Ellipsometry under total internal reflection combined with SPR is discussed for some simple cases. For more advanced cases and to prove the concept, simulations are performed with the Fresnel formalism. The use of TIRE is exemplified by applications in protein adsorption, corrosion monitoring, and adsorption from opaque liquids on metal surfaces. Simulations and experiments show greatly enhanced thin-film sensitivity compared with ordinary Ellipsometry.
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Protein monolayers monitored by internal reflection Ellipsometry
Thin Solid Films, 2004Co-Authors: Michal Poksinski, Hans ArwinAbstract:Total internal reflection Ellipsometry (TIRE) in spectroscopic mode in the wavelength range 400–1200 nm is employed in situ at a solid/liquid interface for investigation of protein adsorption on th ...
G E Jellison - One of the best experts on this subject based on the ideXlab platform.
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measurement of optical functions of highly oriented pyrolytic graphite in the visible
Physical Review B, 2007Co-Authors: G E Jellison, John D Hunn, Ho Nyung LeeAbstract:The spectroscopic dielectric functions of highly oriented pyrolytic graphite (HOPG) are determined at 9 different wavelengths from 405 to 750 nm (3.06 to 1.65 eV). This determination is made on the basis of two Ellipsometry measurements: 1) Standard Ellipsometry measurements are performed on HOPG with the c-axis perpendicular to the sample surface, and 2) Two-modulator generalized Ellipsometry microscope (2-MGEM) measurements are performed on HOPG cut and polished such that the c-axis is parallel to the sample surface. Both the ordinary and extraordinary complex dielectric functions show non-zero absorption throughout the observed spectral range, while the ordinary dielectric function shows Drude-like behavior at longer wavelengths. From this, it can be concluded that graphite is metallic for visible light polarized parallel to the graphene planes, but acts more as a semiconductor or semimetal for visible light polarized perpendicular to the graphene planes. The 2-MGEM technique can also be used to generate images of the diattenuation, retardation, and direction of the principal axis.
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two modulator generalized Ellipsometry theory
Applied Optics, 1997Co-Authors: G E Jellison, F A ModineAbstract:A new ellipsometer is described that uses two photoelastic modulator–polarizer pairs, where the photoelastic modulators are operating at differing resonant frequencies. The time-dependent intensity of the light beam is extremely complicated but can be analyzed so that all elements of the sample Mueller matrix are obtained. For a given configuration, nine of the Mueller matrix elements can be measured at any one time; the other seven elements are accessible when the azimuthal angles of the photoelastic modulators are changed. The single-configuration measurement is often sufficient to characterize a number of real situations completely, such as film growth in a vacuum environment, anisotropic samples, and simple depolarization.
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optical functions of chemical vapor deposited thin film silicon determined by spectroscopic Ellipsometry
Applied Physics Letters, 1993Co-Authors: G E Jellison, Matthew F Chisholm, S M GorbatkinAbstract:The optical functions of several forms of thin‐film silicon (amorphous Si, fine‐grain polycrystalline Si, and large‐grain polycrystalline Si) grown on oxidized Si have been determined using 2‐channel spectroscopic polarization modulation Ellipsometry from 240 to 840 nm (∼1.5–5.2 eV). It is shown that the standard technique for simulating the optical functions of polycrystalline silicon (an effective medium consisting of crystalline Si, amorphous Si, and voids) does not fit the Ellipsometry data.
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sample depolarization effects from thin films of zns on gaas as measured by spectroscopic Ellipsometry
Applied Physics Letters, 1992Co-Authors: G E Jellison, J W MccamyAbstract:Thin films of ZnS grown on GaAs by laser ablation are examined using spectroscopic two‐channel polarization modulation Ellipsometry (2‐C PME). It is found that variations in the film thickness over the illumination spot result in the quasidepolarization of the incident light, which can be measured directly using 2‐C PME. Quantitative fits of the Ellipsometry data using a distribution‐of‐thicknesses model agree with independent reflectivity measurements of the thickness gradient, and allow for the accurate determination of the optical functions of the ZnS film.
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optical functions of silicon determined by two channel polarization modulation Ellipsometry
Optical Materials, 1992Co-Authors: G E JellisonAbstract:Abstract The optical properties of ( 100 ), ( 111 ), and ( 110 ) silicon have been determined from 234 to 840 nm ( 5.30 to 1.48 eV ) at room temperature using two-channel polarization modulation Ellipsometry. The results are tabulated in terms of the refractive index n and extinction coefficient k, including the propagated errors, and are compared with previously published spectroscopic Ellipsometry data.
R W Collins - One of the best experts on this subject based on the ideXlab platform.
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evolution of microstructure and phase in amorphous protocrystalline and microcrystalline silicon studied by real time spectroscopic Ellipsometry
Solar Energy Materials and Solar Cells, 2003Co-Authors: R W Collins, A S Ferlauto, G M Ferreira, Chi Chen, Joohyun Koh, R J Koval, Yeeheng Lee, Joshua M Pearce, C R WronskiAbstract:Abstract Real time spectroscopic Ellipsometry has been applied to develop deposition phase diagrams that can guide the fabrication of hydrogenated silicon (Si:H) thin films at low temperatures (
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in process ellipsometric monitoring of diamond film growth by microwave plasma enhanced chemical vapor deposition
Applied Physics Letters, 1992Co-Authors: Yasuaki Hayashi, W Drawl, R W Collins, R MessierAbstract:In‐process monitoring of diamond film growth was performed with near‐infrared Ellipsometry (1550 nm). The trajectories in the ellipsometric parameters (ψ,Δ) differ according to the method of substrate pretreatment and the CO/H2 gas ratio used in the microwave plasma‐enhanced chemical vapor deposition process. The nucleation density determined from Ellipsometry shows qualitative agreement with that from scanning electron microscopy performed after deposition. The rate at which nuclei develop is also monitored, and the observed induction time is shorter for conditions leading to a higher nucleation density.
Tetsuo Iwata - One of the best experts on this subject based on the ideXlab platform.
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dual comb spectroscopic Ellipsometry
Nature Communications, 2017Co-Authors: Takeo Minamikawa, Yida Hsieh, Kyuki Shibuya, Eiji Hase, Yoshiki Kaneoka, Sho Okubo, Hajime Inaba, Yasuhiro Mizutani, Hirotsugu Yamamoto, Tetsuo IwataAbstract:Spectroscopic Ellipsometry is a means of investigating optical and dielectric material responses. Conventional spectroscopic Ellipsometry is subject to trade-offs between spectral accuracy, resolution, and measurement time. Polarization modulation has afforded poor performance because of its sensitivity to mechanical vibrational noise, thermal instability, and polarization-wavelength dependency. We combine spectroscopic Ellipsometry with dual-comb spectroscopy, namely, dual-comb spectroscopic Ellipsometry. Dual-comb spectroscopic Ellipsometry (DCSE). DCSE directly and simultaneously obtains the ellipsometric parameters of the amplitude ratio and phase difference between s-polarized and p-polarized light signals with ultra-high spectral resolution and no polarization modulation, beyond the conventional limit. Ellipsometric evaluation without polarization modulation also enhances the stability and robustness of the system. In this study, we construct a polarization-modulation-free DCSE system with a spectral resolution of up to 1.2 × 10−5 nm throughout the spectral range of 1514–1595 nm and achieved an accuracy of 38.4 nm and a precision of 3.3 nm in the measurement of thin-film samples.
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Dual-optical-comb spectroscopic Ellipsometry
Nature communications, 2017Co-Authors: Takeo Minamikawa, Yida Hsieh, Kyuki Shibuya, Eiji Hase, Yoshiki Kaneoka, Sho Okubo, Hajime Inaba, Yasuhiro Mizutani, Hirotsugu Yamamoto, Tetsuo IwataAbstract:Spectroscopic Ellipsometry is a means to investigate optical and dielectric material responses. Conventional spectroscopic Ellipsometry has trade-offs between spectral accuracy, resolution, and measurement time. Polarization modulation has afforded poor performance due to its sensitivity to mechanical vibrational noise, thermal instability, and polarization wavelength dependency. We equip a spectroscopic ellipsometer with dual-optical-comb spectroscopy, viz. dual-optical-comb spectroscopic Ellipsometry (DCSE). The DCSE directly and simultaneously obtains amplitude and phase information with ultra-high spectral precision that is beyond the conventional limit. This precision is due to the automatic time-sweeping acquisition of the interferogram using Fourier transform spectroscopy and optical combs with well-defined frequency. Ellipsometric evaluation without polarization modulation also enhances the stability and robustness of the system. In this study, we evaluate the DCSE of birefringent materials and thin films, which showed improved spectral accuracy and a resolution of up to 1.2x10-5 nm across a 5-10 THz spectral bandwidth without any mechanical movement.