Сглаживающий эффект Si-слоев в многослойных зеркалах Be/Al для спектрального диапазона 17-31 nm

The results of studying the smoothing effect of thin Si films used as buffer layers in Be/Al multilayer mirrors optimized for operation at wavelengths longer than 17.1 nm are presented. The multilayer mirrors of the near-normal (grazing angle 88º) and sliding incidence (grazing angle 33.5º) are investigated. It is shown that the effect is observed for multilayer Be/Si/Al mirrors with periods of at least 29 nm. For normal incidence mirrors optimized for a wavelength of 17.14 nm, a record peak reflection coefficient of 62.5% was obtained with spectral selectivity λ/Δλ=59. The time stability of these mirrors was investigated.

Download Full-text

Влияние термического отжига на свойства многослойных зеркал Mo/Be

Журнал технической физики ◽

10.21883/jtf.2019.11.48345.136-19 ◽

2019 ◽

Vol 89 (11) ◽

pp. 1783

Author(s):

Р.М. Смертин ◽

С.А. Гарахин ◽

C.Ю. Зуев ◽

А.Н. Нечай ◽

Н.В. Полковников ◽

...

Keyword(s):

Reflection Coefficient ◽

Thermal Annealing ◽

Annealing Time ◽

Annealing Temperature ◽

Thermal Action ◽

Normal Incidence ◽

Multilayer Mirrors ◽

X Ray ◽

Annealing Conditions ◽

Reflection Maximum

AbstractThe influence of thermal action on X-ray optics performance and structure of films and transition regions in multilayer Mo/Be mirrors optimized for a reflection maximum in the interval 11.2–11.4 nm at normal incidence has been considered. The annealing temperature reached 300°C and the annealing time was 1 and 4 h. It has been shown that after thermal annealing in vacuum for 1 h at 300°C, the reflection coefficient rises; however, when the annealing time grows to 4 h, it drops. Grains in molybdenum films become finer, and the profiles of transition regions change from exponential to linear. The period of multilayer mirrors has remained the same under all annealing conditions.

Download Full-text

Aligned-Crystalline Si Films on Non-Single-Crystalline Substrates

MRS Proceedings ◽

10.1557/proc-1150-rr03-05 ◽

2008 ◽

Vol 1150 ◽

Author(s):

Alp Findikoglu ◽

Terry G. Holesinger ◽

Alyson Niemeyer ◽

Vladimir Matias ◽

Ozan Ugurlu

Keyword(s):

Grain Boundaries ◽

Doping Concentration ◽

Ion Beam ◽

Buffer Layers ◽

Epitaxial Silicon ◽

Single Crystalline ◽

Out Of Plane ◽

Flexible Metal ◽

Si Films ◽

Metal Tape

AbstractWe summarize recent progress in growth and characterization of aligned-crystalline silicon (ACSi) films on polycrystalline metal and amorphous glass substrates. The ACSi deposition process uses, as a key technique, ion-beam-assisted deposition (IBAD) texturing on a non-single-crystalline substrate to achieve a biaxially-oriented (i.e., with preferred out-of-plane and in-plane crystallographic orientations) IBAD seed layer, upon which homo- and hetero-epitaxial buffer layers and hetero-epitaxial silicon (i.e., ACSi) films with good electronic properties can be grown. We have demonstrated the versatility of our approach by preparing ACSi films on customized architectures, including fully insulating and transparent IBAD layer and buffer layers based on oxides on glass and flexible metal tape, and conducting and reflective IBAD layer and buffer layers based on nitrides on flexible metal tape. Optimized 0.4-μm-thick ACSi films demonstrate out-of-plane and in-plane mosaic spreads of 0.8° and 1.3°, respectively, and a room-temperature Hall mobility of ∼90 cm2/V.s (∼50% of what is achievable with epitaxial single-crystalline Si films, and ∼1000 times that of amorphous Si films) for a p-type doping concentration of ∼4×1016 cm−3. By using various experimental techniques, we have confirmed the underlying crystalline order and the superior electrical characteristics of low-angle (<5°) grain boundaries in ACSi films. Forming gas anneal experiments indicate that Si films with low-angle grain boundaries do not need to be passivated to demonstrate improved majority carrier transport properties. Measurements on metal-insulator-semiconductor structures using ACSi films yield near-electronic-grade surface properties and low surface defect densities in the ACSi films. A prototype n+/p/p+–type diode fabricated using a 4.2-μm-thick ACSi film shows minority carrier lifetime of ∼3 μs, an estimated diffusion length of ∼30 μm in the p-Si layer with a doping concentration of 5×1016 cm−3, and external quantum efficiency of ∼80% at 450 nm with the addition of an MgO film anti-reflector.

Download Full-text

Normal-Incidence Multilayer Mirrors for the 120–450 Å Wavelength Region

Journal of X-Ray Science and Technology ◽

10.3233/xst-1990-2401 ◽

1990 ◽

Vol 2 (4) ◽

pp. 241-248

Author(s):

S. V. Gaponov ◽

S. A. Gusev ◽

V. V. Dubrov ◽

A. I. Kuzmichev ◽

B. M. Luskin ◽

...

Keyword(s):

Wavelength Region ◽

Normal Incidence ◽

Multilayer Mirrors

Download Full-text

Impact of fluid saturation on the reflection coefficient of a poroelastic layer

Geophysics ◽

10.1190/1.3553002 ◽

2011 ◽

Vol 76 (2) ◽

pp. N1-N12 ◽

Cited By ~ 36

Author(s):

Beatriz Quintal ◽

Stefan M. Schmalholz ◽

Yuri Y. Podladchikov

Keyword(s):

Fluid Flow ◽

Reflection Coefficient ◽

Analytical Solution ◽

Quality Factor ◽

Velocity Dispersion ◽

Normal Incidence ◽

Sand Layer ◽

Partially Saturated ◽

Fluid Saturation ◽

Wave Induced

The impact of changes in saturation on the frequency-dependent reflection coefficient of a partially saturated layer was studied. Seismic attenuation and velocity dispersion in partially saturated (i.e., patchy saturated) poroelastic media were accounted for by using the analytical solution of the 1D White’s model for wave-induced fluid flow. White’s solution was applied in combination with an analytical solution for the normal-incidence reflection coefficient of an attenuating layer embedded in an elastic or attenuating background medium to investigate the effects of attenuation, velocity dispersion, and tuning on the reflection coefficient. Approximations for the frequency-dependent quality factor, its minimum value, and the frequency at which the minimum value of the quality factor occurs were derived. The approximations are valid for any two alternating sets of petrophysical parameters. An approximation for the normal-incidence reflection coefficient of an attenuating thin (compared to the wavelength) layer was also derived. This approximation gives insight into the influence of contrasts in acoustic impedance and/or attenuation on the reflectivity of a thin layer. Laboratory data for reflections from a water-saturated sand layer and from a dry sand layer were further fit with petrophysical parameters for unconsolidated sand partially saturated with water and air. The results showed that wave-induced fluid flow can explain low-frequency reflection anomalies, which are related to fluid saturation and can be observed in seismic field data. The results further indicate that reflection coefficients of partially saturated layers (e.g., hydrocarbon reservoirs) can vary significantly with frequency, especially at low seismic frequencies where partial saturation may often cause high attenuation.

Download Full-text

Normal Incidence Multilayer Mirrors For Extreme Ultraviolet Astronomy

10.1117/12.966166 ◽

1984 ◽

Cited By ~ 1

Author(s):

Robert A. Stern ◽

Bernhard M. Haisch ◽

George Joki ◽

Richard C. Catura

Keyword(s):

Extreme Ultraviolet ◽

Normal Incidence ◽

Multilayer Mirrors ◽

Ultraviolet Astronomy

Download Full-text

145% near-normal incidence reflectance of Cr Sc x-ray multilayer mirrors for the water window

Optics Letters ◽

10.1364/ol.28.002494 ◽

2003 ◽

Vol 28 (24) ◽

pp. 2494 ◽

Cited By ~ 38

Author(s):

Fredrik Eriksson ◽

Göran A. Johansson ◽

Hans M. Hertz ◽

Eric M. Gullikson ◽

Ulrich Kreissig ◽

...

Keyword(s):

Normal Incidence ◽

Multilayer Mirrors ◽

X Ray ◽

Water Window

Download Full-text

Waveform‐based AVO inversion and AVO prediction‐error

Geophysics ◽

10.1190/1.1444077 ◽

1996 ◽

Vol 61 (6) ◽

pp. 1575-1588 ◽

Cited By ~ 41

Author(s):

James L. Simmons ◽

Milo M. Backus

Keyword(s):

Reflection Coefficient ◽

Thin Layer ◽

Shear Wave ◽

Prediction Error ◽

Wave Reflection ◽

A Priori ◽

Normal Incidence ◽

Strong Increase ◽

Time Range ◽

Zoeppritz Equations

A practical approach to linear prestack seismic inversion in the context of a locally 1-D earth is employed to use amplitude variation with offset (AVO) information for the direct detection in hydrocarbons. The inversion is based on the three‐term linearized approximation to the Zoeppritz equations. The normal‐incidence compressional‐wave reflection coefficient [Formula: see text] models the background reflectivity in the absence of hydrocarbons and incorporates the mudrock curve and Gardner’s equation. Prediction‐error parameters, [Formula: see text] and [Formula: see text], represent perturbations in the normal‐incidence shear‐wave reflection coefficient and the density contribution to the normal incidence reflectivity, respectively, from that predicted by the mudrock curve and Gardner’s equation. This prediction‐error approach can detect hydrocarbons in the absence of an overall increase in AVO, and in the absence of bright spots, as expected in theory. Linear inversion is applied to a portion of a young, Tertiary, shallow‐marine data set that contains known hydrocarbon accumulations. Prestack data are in the form of angle stack, or constant offset‐to‐depth ratio, gathers. Prestack synthetic seismograms are obtained by primaries‐only ray tracing using the linearized approximation to the Zoeppritz equations to model the reflection amplitudes. Where the a priori assumptions hold, the data are reproduced with a single parameter [Formula: see text]. Hydrocarbons are detected as low impedance relative to the surrounding shales and the downdip brine‐filled reservoir on [Formula: see text], also as positive perturbations (opposite polarity relative to [Formula: see text]) on [Formula: see text] and [Formula: see text]. The maximum perturbation in [Formula: see text] from the normal‐incidence shear‐wave reflection coefficient predicted by the a priori assumptions is 0.08. Hydrocarbon detection is achieved, although the overall seismic response of a gas‐filled thin layer shows a decrease in amplitude with offset (angle). The angle‐stack data (70 prestack ensembles, 0.504–1.936 s time range) are reproduced with a data residual that is 7 dB down. Reflectivity‐based prestack seismograms properly model a gas/water contact as a strong increase in AVO and a gas‐filled thin layer as a decrease in AVO.

Download Full-text

Model of Е-polarized wave propagation in a multilayer dielectric structure

Technical mechanics ◽

10.15407/itm2021.03.111 ◽

2021 ◽

Vol 2021 (3) ◽

pp. 111-118

Author(s):

P.I. Zabolotnyi ◽

Keyword(s):

Dielectric Constant ◽

Electromagnetic Wave ◽

Reflection Coefficient ◽

Incidence Angle ◽

Relative Dielectric Constant ◽

Normal Incidence ◽

Dielectric Constants ◽

Dielectric Structure ◽

Range Of Variation ◽

Multilayer Dielectric

This paper addresses the determination of the dielectric constant of multilayer dielectric structures by radiowave interferometry. In the general case, in interferometry measurements to one measured value of the reflection coefficient there may correspond an infinity of dielectric constants. This ambiguity may be resolved by first determining the effect of different parameters of the probing electromagnetic wave on the reflection coefficient. In particular, it is important to have a preliminary estimate of the effect of the incidence angle and the polarization on the range of variation of the reflection coefficient with the variation of one of the structure parameters. This paper considers the case where a plane E-polarized electromagnetic wave, i.e. a wave whose magnetic field is perpendicular to the incidence plane, is incident on a multilayer dielectric structure. The aim of this work is to develop a model of the propagation of an E-polarized electromagnetic wave through a multilayer dielectric structure at an arbitrary incidence angle and to determine the range of variation of the reflection coefficient with the variation of the dielectric constants of the layers. The paper presents a model of the propagation of an E-polarized electromagnetic wave in a two-layer dielectric structure. A metal base, which is an ideal conductor, underlies the structure. The electromagnetic wave is incident from the air at an arbitrary incidence angle. Based on the model, a method is proposed for measuring the relative dielectric constant and the dielectric loss tangent. It is shown that at a normal incidence the reflection coefficient magnitude is the same both for H- and E-polarization. Because of this, determining the relative dielectric constant and the loss tangent from the measured reflection coefficient magnitude calls for measurements not only at a normal incidence, but also at an oblique incidence, at which the reflection coefficient magnitudes will be different for H- and E-polarization.

Download Full-text