Ellipsometry in Interface Science

Motschmann, H.; Teppner, Renate

doi:10.1016/s1383-7303(01)80014-4

Cited by 38 publications

(45 citation statements)

References 21 publications

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“…The subphase was considered as clean when changes in surface pressure did not exceed ± 0.2 mN/m over approximately two minutes with the petri dish, or when compressed over the entire compression range (64 -567 cm 2 ) with the LT. 1where Ψ is the amplitude change and  the phase shift. In the thin film limit at the air/water interface (i.e., film thickness << laser wavelength),  is much more sensitive to changes in the amount adsorbed at the interface than Ψ [25]. Therefore, the time-dependent changes in phase shift () were measured, with (t) = (t) -(t0), where (t0) is the phase shift at the beginning of a given experiment, namely, the phase shift of the bare air/water interface (0) for BS adsorption at the air/water interface, or that of the pure DPPC monolayer (DPPC) for BS interaction with this film at the air/water interface.…”

Section: Langmuir Trough (Lt) Measurementsmentioning

confidence: 99%

Molecular insights into the behaviour of bile salts at interfaces: a key to their role in lipid digestion

Pabois

Lorenz

Harvey

et al. 2019

Journal of Colloid and Interface Science

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Section: Langmuir Trough (Lt) Measurementsmentioning

confidence: 99%

Molecular insights into the behaviour of bile salts at interfaces: a key to their role in lipid digestion

Pabois

Lorenz

Harvey

et al. 2019

Journal of Colloid and Interface Science

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“…The polarizer setting of 5° is based on our expectation of small differences in the height, e.g., thickness at the nm scale. In the present work only Δ-maps were recorded because of their high sensitivity towards thickness variations, even at ultrathin film conditions [6]. The complications and theoretical problems of estimating extremely small dispersions of Ψ for ultrathin films is known and well-described [5,21].…”

Section: Resultsmentioning

confidence: 99%

“…However, for ultrathin films there is almost no change in Ψ, which decreases the number of independent variables down to Δ only and makes the simultaneous and unambiguous determination of d and n impossible [6]. …”

Section: Introductionmentioning

confidence: 99%

An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers

Rottke¹,

Schulz²,

Richau³

et al. 2016

Beilstein J. Nanotechnol.

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SummaryThe applicability of nulling-based ellipsometric mapping as a complementary method next to Brewster angle microscopy (BAM) and imaging ellipsometry (IE) is presented for the characterization of ultrathin films at the air–water interface. First, the methodology is demonstrated for a vertically nonmoving Langmuir layer of star-shaped, 4-arm poly(ω-pentadecalactone) (PPDL-D4). Using nulling-based ellipsometric mapping, PPDL-D4-based inhomogeneously structured morphologies with a vertical dimension in the lower nm range could be mapped. In addition to the identification of these structures, the differentiation between a monolayer and bare water was possible. Second, the potential and limitations of this method were verified by applying it to more versatile Langmuir layers of telechelic poly[(rac-lactide)-co-glycolide]-diol (PLGA). All ellipsometric maps were converted into thickness maps by introduction of the refractive index that was derived from independent ellipsometric experiments, and the result was additionally evaluated in terms of the root mean square roughness, R q. Thereby, a three-dimensional view into the layers was enabled and morphological inhomogeneity could be quantified.

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“…Given equation 1.9, the polarization state of a wave can then be described by its [13] A method that utilizes these polarization states is Ellipsometry. Ellipsometry is a technique that uses polarized light to characterize optical systems.…”

Section: Polarization and Ellipsometrymentioning

confidence: 99%

“…Ellipsometry is a technique that uses polarized light to characterize optical systems. Ellipsometry measures the polarization state of light reflected or transmitted by an optical system and relates them to the fundamental equation of ellipsometry [13,15]:…”

Section: Polarization and Ellipsometrymentioning

confidence: 99%

Effect of strain on aluminum nitride/gallium nitride Distributed Bragg Reflectors

Miller¹

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III-N Distributed Bragg Reflectors (DBRs) are important components to nitride based optoelectronic devices. Nitride based DBRs are critical to the operation and performance of both Vertical Cavity Surface Emitting Lasers (VCSELs) and Light Emitting Diodes (LEDs). Aluminum Nitride (AlN)/Gallium Nitride DBRs are of particular interest because their high refractive index contrast allows the fabrication of DBRs with high reflectivity using a relatively low number of periods. The growth of high quality AlN/GaN DBRs has been held back because of tensile strain resulting from the 2.4% lattice mismatch between AlN and GaN. This tensile strain has led to cracking in DBRs and has significantly decreased their overall reflectivity. Reducing this strain and subsequent cracking is critical to improving AlN/GaN DBR reflectivity and the overall efficiency of nitride based optoelectronic devices. This work will focus on the characterization, simulation, and development of AlN/GaN DBRs. Individual AlN and GaN thin films will be characterized to determine their properties and promise for development DBR structures. AlN/GaN DBR structures will then be characterized and simulated to determine their overall performance. Finally, the effect of strain on both the apparent refractive index of individual layers and the overall performance of AlN/GaN DBRs will be investigated. iii ACKNOWLEDGMENTS I would like to first thank my parents, Joseph and Phyllis Miller, whose hard work and support made my collegiate career possible. I would like to thank my advisor and committee chair, Dr. Dimitris Korakakis, for his encouragement, guidance, and funding throughout my entire graduate and much of my undergraduate career. I would like to thank my committee members, Dr. Lawrence A. Hornak and Dr. Xian-An Cao, for all the time and support they have contributed to this work. I would like to thank Dr. Kolin Brown for his help in learning and maintaining lab equipment. Finally, I would like to thank Lee Rodak, Ronak Rahimi, Srikanth Raghavan, John Harman, Joshua Nightingale, Rich Farrell, Adam Kabulski, Vincent Pagán, and my other coworkers for their support of this work as well as other projects I have worked on during my undergraduate and graduate studies.

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Ellipsometry in Interface Science

Cited by 38 publications

References 21 publications

Molecular insights into the behaviour of bile salts at interfaces: a key to their role in lipid digestion

Molecular insights into the behaviour of bile salts at interfaces: a key to their role in lipid digestion

An ellipsometric approach towards the description of inhomogeneous polymer-based Langmuir layers

Effect of strain on aluminum nitride/gallium nitride Distributed Bragg Reflectors

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