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Article
Probing Optical Transitions in Porous Silicon by Reflectance Spectroscopy in the Near Infrared, Visible and UV
Reflectance spectroscopy has been used to obtain the dielectric function of the solid phase of porous silicon. The method is based on a fit of a parameterized dielectric function model to measured spectra. A c...
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Article
Electrical Control of the Reflectance of Porous Silicon Layers
In this paper we demonstrate the filling of porous silicon (PS) layers with liquid crystals (LC's) in order to control the reflectance electrically. The preparation of PS and the choice of the right group of L...
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Chapter and Conference Paper
Numerical Simulation of IR-Spectroscopic Experiments
In this work we demonstrate the application of numerical simulation for the investigation of the light distribution in an optical system, such as an FT-IR microscope. Because of the complexity of simulating th...
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Article
Optical Sensors based on Porous Silicon Multilayers: a Prototype
Porous silicon multilayers are easily produced by a variation of the current density during the electrochemical etching process. The obtained porosity profile in depth is equivalent to a refractive index profi...
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Article
Improved Interference Filter Structures Made of Porous Silicon
Recently passive optical devices like filter structures or waveguides based on porous silicon have attracted high interest due to their easy and cheap fabrication. We have formed interference filters using por...
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Article
Depth Gradients in Porous Silicon: How to Measure Them and How to Avoid Them
For the formation of single layers and layer systems the depth homogeneity of porous silicon (PS) plays a key role. We have measured qualitatively and quantitatively structural gradients in p-PS layers with in...
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Article
The Kramers-Kronig-Relation of effective dielectric functions
The Bergman formula is a general approach to describe the quasi-static effective dielectric function of two-phase composites. It can be used successfully to explain measured data. The existence of a Kramers-Kr...
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Article
A parameterization of the effective dielectric function of a two-phase composite medium
The effective dielectric function of a heterogeneous medium can be calculated according to the Bergman-representation. It is a general approach to calculate the effective material properties of a two-phase com...
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Article
FTIR-Microspectroscopic detection of ultra-thin organic films on chalcogenide fibers
In this paper the discovery is presented that FTIR microspectroscopy is also suitable for the micro-analysis of very thin organic layers in the range of 3.6 to 36 nm on chalcogenide fibers. Theoretical confirm...
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Chapter
The influence of microelectronic processing steps on the properties of porous Si-layers
In the view of possible applications of porous Si layers in optoelectronic devices it is necessary to study the influence of microelectronic processing steps on the properties of porous Si films. Therefore, ch...
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Article
Infrared reflection studies of ceramics: characterization of SiC layers on graphite substrates
Technical CVD-grown silicon carbide (β-SiC) layers on graphite substrates have been studied by infrared spectroscopy. Specular reflectance spectra were measured at oblique incidence, and for the same experimen...
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Article
Characterization of Porous Silicon Layers by Reflectance Spectroscopy
The characterization of porous silicon layers by optical reflectance spectroscopy in the infrared, visible and UV is presented. A fit of simulated to measured spectra is used to interprete the experimental res...
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Article
Effective dielectric functions of alkali halide composites and their spectral representation
In the electrostatic approximation inhomogeneous samples with characteristic scale of inhomogeneities much smaller than the wavelength of light can be characterized by an effective dielectric function εeff. This ...
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Article
Effective dielectric functions of samples obtained by evaporation of alkali halides
This paper investigates the dielectric properties of inhomogeneous samples consisting of small alkali halide particles (NaCl, KBr) on gold-coated substrates. Our reflection measurements in the far infrared can...
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Article
A tunable UV-light source for laser spectroscopy using second harmonic generation in β-BaB2O4
A β-BaB2O4 (BBO) crystal is used to generate UV-light tunable in the range 230–303 nm by frequency doubling of an excimer-laser-pumped dye laser. This interval can be covered by a series of continuous scans of 0....
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Article
Alternative adiabatic elimination schemes for fast variables: A case study
Adiabatic elimination of fast variables from a stochastic process requires the determination of an effective asymptotic evolution operator for the slow variables and of a projection operator that extracts the ...
