Imaging ellipsometry of graphene

Wurstbauer, Ulrich; Röling, Christian; Wurstbauer, Ursula; Wegscheider, Werner; Vaupel, M.; Thiesen, Peter; Weiss, Dieter

doi:10.1063/1.3524226

Cited by 104 publications

(86 citation statements)

References 26 publications

(41 reference statements)

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“…Consequently, an imaging rather than a single-point method is preferred. Along these lines, imaging ellipsometry has recently been used to characterize graphene on flat surfaces 12 and to monitor the removal of large area biomolecules during plasma etching. 13 The sensitivity of these single-point or imaging methods can be a few nanometers; however, the measurements are typically hindered by vibrations and drift in the sample.…”

Section: Introductionmentioning

confidence: 99%

Optically monitoring and controlling nanoscale topography during semiconductor etching

et al. 2012

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We present epi-diffraction phase microscopy (epi-DPM) as a non-destructive optical method for monitoring semiconductor fabrication processes in real time and with nanometer level sensitivity. The method uses a compact Mach-Zehnder interferometer to recover quantitative amplitude and phase maps of the field reflected by the sample. The low temporal noise of 0.6 nm per pixel at 8.93 frames per second enabled us to collect a three-dimensional movie showing the dynamics of wet etching and thereby accurately quantify non-uniformities in the etch rate both across the sample and over time. By displaying a gray-scale digital image on the sample with a computer projector, we performed photochemical etching to define arrays of microlenses while simultaneously monitoring their etch profiles with epi-DPM.

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Section: Introductionmentioning

confidence: 99%

Optically monitoring and controlling nanoscale topography during semiconductor etching

et al. 2012

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“…Imaging ellipsometry (IE) offers a high lateral resolution while maintaining the precise control over the angel of incidence. IE has been proven to allow access to the dielectric function of 2D materials such as graphene [125] , graphene oxide [126] and mono-and multilayer MoS2 [47] . Particularly for monolayer flakes with a thickness of less than 1 nm it can be assumed that interaction with a light-field perpendicular to the 2D sheet can be neglected.…”

Section: (A) Real Part Of the In-plane Component Of The Dielectric Tementioning

confidence: 99%

Light–matter interaction in transition metal dichalcogenides and their heterostructures

Wurstbauer¹,

Miller²,

Parzinger³

et al. 2017

J. Phys. D: Appl. Phys.

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104

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Abstract:The investigation of two-dimensional van der Waals materials is a vibrant, fast moving and still growing interdisciplinary area of research. Two-dimensional van der Waals materials are truly two-dimensional crystals with strong covalent in-plane bonds and weak van der Waals interaction between the layers with a variety of different electronic, optical and mechanical properties. A very prominent class of twodimensional materials are transition metal dichalcogenides and amongst them particularly the semiconducting subclass. Their properties include bandgaps in the near-infrared to the visible range, decent charge carrier mobility together with high (photo-)catalytic and mechanical stability and exotic many body phenomena. These characteristics make the materials highly attractive for both fundamental research as well as innovative device applications. Furthermore, the materials exhibit a strong light matter interaction providing a high sun light absorbance of up to 15% in the monolayer limit, strong scattering cross section in Raman experiments and access to excitonic phenomena in van der Waals heterostructures. This review focuses on the light matter interaction in MoS2, WS2, MoSe2, and WSe2 that is dictated by the materials complex dielectric functions and on the multiplicity of studying the first order phonon modes by Raman spectroscopy to gain access to several material properties such as doping, strain, defects and temperature. Two-dimensional materials provide an interesting platform to stack them into van der Waals heterostructures without the limitation of lattice mismatch resulting in novel devices for application but also to study exotic many body interaction phenomena such as interlayer excitons. Future perspectives of semiconducting transition metal dichalcogenides and their heterostructures for applications in optoelectronic devices will be examined and routes to study emergent fundamental problems and manybody quantum phenomena under excitations with photons will be discussed.

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“…24 Imaging ellipsometry was used to determine thickness of small flakes of exfoliated graphene. [25][26][27] We have recently reported the visible-ultravacuum dielectric functions of EG grown on different polytypes of SiC, where we developed a parameterized dielectric function model for graphene. 21 frequencies combined with optical Hall effect measurements revealed and quantified conductive channels in EG on 6H-SiC.…”

mentioning

confidence: 99%

Large-area microfocal spectroscopic ellipsometry mapping of thickness and electronic properties of epitaxial graphene on Si- and C-face of 3C-SiC(111)

Darakchieva

Boosalis

Zakharov

et al. 2013

Applied Physics Letters

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Microfocal spectroscopic ellipsometry mapping of the electronic properties and thickness of epitaxial graphene grown by high-temperature sublimation on 3C-SiC (111) substrates is reported. Growth of one monolayer graphene is demonstrated on both Si- and C-polarity of the 3C-SiC substrates and it is shown that large area homogeneous single monolayer graphene can be achieved on the Si-face substrates. Correlations between the number of graphene monolayers on one hand and the main transition associated with an exciton enhanced van Hove singularity at ∼4.5 eV and the free-charge carrier scattering time, on the other are established. It is shown that the interface structure on the Si- and C-polarity of the 3C-SiC(111) differs and has a determining role for the thickness and electronic properties homogeneity of the epitaxial graphene

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Imaging ellipsometry of graphene

Cited by 104 publications

References 26 publications

Optically monitoring and controlling nanoscale topography during semiconductor etching

Optically monitoring and controlling nanoscale topography during semiconductor etching

Light–matter interaction in transition metal dichalcogenides and their heterostructures

Large-area microfocal spectroscopic ellipsometry mapping of thickness and electronic properties of epitaxial graphene on Si- and C-face of 3C-SiC(111)

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