We have developed the design and experimentally studied aperiodic and stack broadband Mo/Si mirrors for the purposes of the KORTES project, optimised for uniform reflection in the 17 - 21 nm ...wavelength range. It is shown that stack structures with an insignificant loss in the reflection coefficient are much more preferable from the point of view of manufacturing and certification, which, in turn, makes it possible to correct the deposition process and to reach the calculated parameters of a multilayer mirror in a small number of iterations.
In a condensed matter system, phonons and plasmons are well-known quasiparticles that represent unusual dispersion behavior of energy and momentum at nanoscales. In a nanoscale Mo/Si multilayer ...structure, phonon modes in Raman scattering indicated the coexistence of crystalline Si (c-Si) nanoclusters within an amorphous silicon (a-Si) matrix. The TO mode was red-shifted with a decrease in the nanocluster size of Si in nanolayer films. This was associated with the momentum of phonons and it is fundamentally correlated to phonon confinement. The correlation length of the Si network was significantly smaller in a-Si and the TO mode broadened asymmetrically and red-shifted due to localized phonon density of state. Consequently, with a decrease in the thickness of the Si layer, blue shifts of plasmon energy for Mo 3d, Mo 4p, and Si 2p spectra were observed in X-ray photoelectron spectroscopy. Plasmon energy of the c-Si nanocluster was related to the forbidden gap, which increased with a decrease in cluster size. The concept of quantum confinement of phonon and electron states was used to determine the size of the c-Si nanoclusters in the a-Si matrix.
The structural inhomogeneities of silicon films embedded within W/Si multilayer mirrors were studied by X‐ray reflection, grazing‐incidence small‐angle X‐ray scattering (GISAXS) and X‐ray ...photoelectron spectroscopy (XPS). In the diffuse scattering spectra, evidence of laterally and vertically ordered in‐layer inhomogeneities was consistently observed. In particular, specific substructures resonant in nature (named here `ridges') were detected. The properties of the ridges were similar to the roughness determined by quasi‐Bragg peaks of scattering, which required a high interlayer correlation of particles. The XPS showed the nanocrystalline nature of the Si particles in the amorphous matrix. The geometric characteristics and in‐layer and inter‐layer correlations of the nanoparticles were determined. In GISAXS imaging, the unusual splitting of the waists between the Bragg sheets into filament structures was observed, whose physical nature cannot yet be explained.
The nature of the observed bulk inhomogeneities in the silicon layers in W/Si multilayers is established. In the diffuse scattering spectra, specific substructures, which are clearly resonant in nature, are observed. The physical nature of some of them is not established.
The paper considers the emission spectra and dependences of the emission intensity of a number of carbon lines in absolute units for laser plasma generated by laser pulse on CO
2
, CHF
3
, and CF
4
...gas jets on the gas pressure at the nozzle inlet. A pulsed Nd:YAG laser,
λ
= 1064 nm,
τ
= 5.2 ns,
E
imp
= 0.8 J was used. Gas-jet targets were formed by a supersonic conical nozzle, the pressure at the nozzle inlet varied in the range of 5–25 bar. The emission spectra of the investigated gases were compared and the reasons for the different dependences of the radiation intensity on the gas pressure at the nozzle inlet were analyzed.
Beryllium-based multilayer X-ray optics Polkovnikov, V N; Salashchenko, N N; Svechnikov, M V ...
Physics Uspekhi,
01/2020, Letnik:
63, Številka:
1
Journal Article
Recenzirano
The article provides a review of the current state of affairs in the field of physics and technology of multilayer beryllium-containing mirrors intended for projection lithography and solar corona ...studies in the extreme ultraviolet (EUV) region. The methods of synthesizing and studying beryllium-containing multilayer mirrors are described. The results of recent studies on the internal structure and EUV reflection coefficients are given for Mo/Be, Mo/Si, Be/Al, and Be/Mg multilayer mirrors. The effect of Si and Be interlayers on the reflectivity is explained. Avenues for further research on beryllium-containing mirrors are discussed.
•The use of opposed supersonic nozzles allows the formation of a shock wave.•A new type of shock-based targets for laser-plasma sources has been developed.•Soft X-ray emission radiation of the shock ...wave excited by pulse laser was obtained.•Shock waves allows to produce laser spark at a significant distance from the nozzle.
The results from studying extreme ultraviolet emission spectra of targets based on shock waves upon excitation by pulsed laser radiation are discussed in this work. A shock wave is formed during a head-on collision of supersonic gas jets formed by supersonic conical nozzles. For excitation, we used a Nd:YAG laser with λ = 1064 nm, τ = 5 ns and Eimp = 0.8 J. The investigated spectral range is 90–200 A. The emission spectra of Ar, Kr, N2 and CO2 are explored. The obtained emission spectra are decoded and the emitting ions determined. As a result, we are able to draw a conclusion regarding the applicability of these targets as sources of extreme ultraviolet radiation.
The paper discusses the results of studying the emission spectra and absolute radiation intensities of laser plasma generated by laser pulse on a xenon gas-jet target. A Nd:YAG laser, λ = 1064 nm, τ ...= 5.2 ns,
E
pulse
= 0.8 J was used. The spectral range 3–20 nm was studied. Gas-jet targets were formed by a supersonic conical nozzle. Emission spectra of laser plasma were obtained and interpreted. Absolute radiation intensities were determined in a number of spectral bands under various conditions of gas-jet target excitation.
The influence of Mo interlayers on the microstructure of films and boundaries, and the reflective characteristics of Ru/Be multilayer mirrors (MLM) were studied by X-ray reflectometry and ...diffractometry, and secondary ion mass spectrometry (SIMS). An increase in the reflection coefficients of MLM at a wavelength of 11.4 nm to record values of R = 72.2% and FWHM to Δλ
= 0.38 nm is shown. The effect of interlayers on the structural and reflective characteristics of MLM is explained by the barrier properties of the Mo layers, which prevent the mutual mixing of the Ru and Be layers, which leads to the formation of beryllides and a decrease in the X-ray optical contrast at the boundaries.
The main problems and the approach used by the authors for roughness metrology of super-smooth surfaces designed for diffraction-quality X-ray mirrors are discussed. The limitations of white light ...interferometry and the adequacy of the method of atomic force microscopy for surface roughness measurements in a wide range of spatial frequencies are shown and the results of the studies of the effect of etching by argon and xenon ions on the surface roughness of fused quartz and optical ceramics, Zerodur, ULE and Sitall, are given. Substrates of fused quartz and ULE with the roughness, satisfying the requirements of diffraction-quality optics intended for working in the spectral range below 10 nm, are made.
Results of investigation of emission spectra of Kr and Xe under pulsed laser excitation are presented. Spectral range between 3 and 20 nm was studied using a Nd:YAG laser (λ = 1064 nm, τ = 5 ns,
Е
...pulse
= 0.8 J). A capillary tube with
d
= 500 µm, along with supersonic conical nozzles with
d
cr
= 145 µm, 2α = 12°,
L
= 5 mm and
d
cr
= 540 µm, 2α = 11°,
L
= 5 mm were used for gas-jet formation. Emission spectra were obtained for various gas targets, interpreted, and ions emitting in the spectral range under consideration were identified. Intensities of lines obtained with targets formed by different systems are compared.
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