Optical Coatings

The goal of this unit was to consolidate the project for the construction of the high resolution spectrometer of the E-ELT (HIRES). The task included the development of scientific cases and tools to predict the instrumental performances. From the technical point of view it included several R&D activities in collaboration with highly specialized Italian companies; it culminated with the detailed design of a highly modular instrument based on well established technologies. From the management point of view it lead to the consolidation of a large international consortium that spans over 12 countries and includes most of the European and ESO-related institutes interested in high resolution spectroscopy.

15. NUMBER OF PAGES 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 5c. PROGRAM ELEMENT NUMBER 5b. GRANT NUMBER 5a. CONTRACT NUMBER Form Approved OMB NO. 0704-0188 3. DATES COVERED (From -To) RPPR Final Report as of 03-Jan-2020 Training Opportunities: Ahad Talukder (MSEC PhD student, Geerts, 9/18-1/19): Ahad, a 2nd year MSEC PhD student did a collaborative research class with me in the Fall 2018 semester. He did IVT measurements and dlts measurements on oxygen low samples. The IVT show freeze out at low temperature and the dlts did not show any peaks. IVT measurements on films and dlts measurements on high oxygen films are scheduled. James Nick Talbert (MSc, Geerts,): Nick worked with the PI on electrical characterization of NiFeOheterojunctions and charge transport in NiFeO thin films. His thesis project has been the most challenging project in the PI's lab as initially the data of the device wafers were very scattered. Only after modifications were made to the deposition process, he was able to see a pattern. He finished and defended thesis in Nov. 2019. Part of his work was presented the Fall-2018 TSAP meeting in Houston and the MRS conference in Phoenix and published in an MRS conference paper. Nick is currently working on his resume and applying for jobs in industry in the Austin-San Antonio corridor. Sam Cantrell (MSc, Scolfaro, 9/18-11/19): Sam worked with the Co-Pi on Density Functional Theory calculations using the VASP code of doped NiO system and included doping with Cu, Ag, and C. For the C doped case he investigated the effect of C on an Oxygen site and C on a Ni site. In addition, he investigated the effect of Ni vacancies in NiFeO, oxygen and Ni interstitial in NiO, neutral oxygen vacancies in NiO and positively charged oxygen vacancies in NiO. Part of his work was presented at the TSAPS-2018 Fall meeting in Houston, the April APS-2019 meeting in Houston and the Wise-2019 meeting at Texas State University. He finished his thesis and defended in Nov. 2019. In addition to his thesis work, he supported the MRS paper of grad. student Nick Talbert with calculations that show that oxygen vacancies in NiO are localized which earned him a co-authorship. Sam cocoached Lauren Trombley, the 2019 URAP intern working in Dr. Scolfaro's lab. He is currently employed at the University doing DFT calculations for Dr. Zakhidov while applying for PhD programs for Fall 2019. Binod D.C. (MSc, Geerts, 9/18-8/19): Binod worked with the PI on XPS, Xray, and magnetic characterization of NiFeO thin films. In addition he verified the new Vibrating Sample Magnetometer tool that we won on an NSF-MRI grant. He submitted and defended his thesis in Aug. 2019. Part of his thesis work was presented at the TSAPS Spring-2018 meeting, the TSAPS Spring-2019 meeting, and the International Conference on Magnetism in San Francisco in July 2018. Part of his thesis is published in IEEE Trans. on Magn. in Fall 2018. Part of his thesis work involving the verification of the VSM led to a new method to determine the sample position in a VSM. This invention is currently being disclosed to the University. Binod co-coached Sarah-Beth Ragan, the 2019 HSAP intern with the PI. In the Fall 2019 semester he joined the group of Dr. Yoichi Miyahara as an MSEC-Phd student from Fall 2019. Shankar Acharya (MSc, Geerts, 9/18-8/19): Worked with the PI on the Magneto-Optical characterization of NiFeO thin films. Together with undergraduate student Brian Collier, he built a dual beam MOKE setup that was used to measure the Faraday hysteresis curves of NiFeO thin films. He submitted and defended his thesis in May 2019. Part of his thesis was presented at 4 different conferences and published in Review of Scientific Instruments in December 2019. He is currently employed with NXP Semiconductor in Austin Texas. Rigoberto Mayorga-Luna (undergrad, Geerts, 09/18-05/19): Has done an independent study with the PI in the Fall 2018 semester and extended the linear four-point probe Labview program to include a routine to double check the contacts from 2pp measurements. His program allows to identify up to two troubled contacts. He presented this work at the Wise conference in Spring 2019. He graduated in May 2019 and taught labs for us during the fall-2019 semester. He applied to graduate school and will enroll in January if his financial situation permits it. He is currently also applying for DOD internship for the summer of 2020. Clint Boldt (undergrad, Geerts, 9/18-9/19): Clint worked in the fall-2018 with graduate student Ahad Talukder on the DLTS/IVT setup. He attended the TSAPS Fall-2018 meeting to present a poster on hid work and took graduate EMT with me in the spring 2019 semester for honor's undergraduate credit. He did well in that class. He graduated in May 2019 and is currently applying to graduate school including, UTSA, Rice, University of Colorado at Boulder, and University of Denver. He is very interested in BioPhysics. Salamon Gallegos (undergrad, Geerts 6/18-12/18): refurbished the laserbeamwriter setup for an independent research class. Activities included: fixed hinges on doors on the unit, transferred the stepmotor card and software to a 64 bits windows computer and found the correct drivers, re-connected the power lines, reconnected the light sources of the background light and the alignment beam, determined the problem with the camera and installed the fixed camera on the new computer. He graduated in Dec.

An overview of the optical coherence tomography (OCT) technique is given. Time domain, spectral and sweep source modalities are briefly described, and important physical parameters of the OCT instrument are discussed. Examples of the application of OCT to diagnosis of various art objects such as oil paintings on canvas (imaging of glaze and varnish layers), porcelain, faience, and parchment are presented. Applications to surface profilometry of painting on canvas are also discussed.

Preliminary results of the application of optical coherence tomography (OCT), in particular in its spectral mode (SOCT), to tracking of deformations in paintings on canvas caused by periodical humidity changes are presented. The setup is able to monitor the position of a chosen point at the surface of a painting with micrometre precision, simultaneously in three dimensions, every 100 seconds. This allows recording of deformations associated with crack formation. For the particular painting model examined, it was shown that the surface moves in-plane towards the corner, and bulges outwards (Z-direction) in response to a rise in humidity. Subsequent to the first humidification/drying cycle, translation in the Z-direction is decreased, whilst in-plane translations increase somewhat. It was also shown that the response of the painting on canvas begins immediately on changing the relative humidity in the surroundings.

Extreme ultraviolet (EUV) masks have a very stringent cleanliness requirement that present new challenges to nanolithography industry. The cleaning of EUV mask surface is required at every exposure level due to the absence of a pellicle layer. In this study, the adhesion and removal of particles on EUV masks is investigated by calculating the interaction force and measuring the adhesion force using atomic force microscopy (AFM). Zeta potential measurements showed that the calculated interaction force was attractive on Si capping layer and Cr absorbed layer for both silica and alumina particle at all pH ranges investigated. However, the measured adhesion force of Si capping layer was similar to that of bare Si at neutral and alkaline pHs. The calculated interaction force of SiO2 buffer layer was most repulsive and the lowest adhesion force was measured. This indicates that the SiO2 buffer layer has a better cleaning efficiency at neutral and alkaline pH. The calculation of interactio...

An infrared heat reflecting multilayer thin film filter comprising alternate layers of ZrO2 and SiO2 has been modeled and prepared on a BK7 glass substrate using RF-magnetron sputtering. Initially, the individual films of the used materials have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) for structural and surface quality prior to the deposition of multilayer structure. Spectral analysis showed that the filter has an average transmission of greater than 90% in 450 to 700 nm range and less than 2% in 700-1100 nm band fulfilling the design requirements. The XRD study of multilayer structure showed few peaks of ZrO2 along with a solitary peak for SiO2 indicating some crystallinity for ZrO2 layers in the structure. Hardness analysis showed that the initial phase of the indentation is predominantly ductile with gradual transition in behaviour from ductile to brittle with increased penetration. Interface analysis of multilayered structure was carried out by Rutherford back scattering using Tandem 5 MeV ion accelerator, showed that interfaces formed in the multilayer structure are sharp and no substantial evidence of interlayer diffusion or mixing at the interfaces.

This article presents the results of the restoration treatments of a copy of Carlo Dolci’s (1616-1686) Madonna del Dito on a tinned iron plate. Based on the experience and expertise of the Department of Conservation of Paintings and Polychrome Sculpture, and Metal Conservation Studio of the Department of Conservation and Restoration of Architecture and Sculpture at the Faculty of Fine Arts at Nicolaus Copernicus University in Toruń (Poland), materials and methods have been combined to enable a comprehensive restoration of the painting. The treatments in question relate to the conservation and restoration of metal support as well as to the reconstruction of the painted surface. The criteria, materials and methodology used in this unusual case are discussed in detail.

Nano-structural evolution of layer morphology and interfacial roughness in Cr/Sc metal multilayers grown with ion assistance during magnetron sputter deposition has been investigated by high resolution transmission electron microscopy and hard X-ray reflectivity. Calculations based on a binary collision model predict an ion-assisted growth window for optimized Cr/Sc multilayer interface sharpness, within the ion energy range of 21 eV to 37 eV and an ion flux of 10 ions per deposited atom. Multilayers with nominal modulation periods in the range of 1.6 nm to 10.2 nm, grown with these conditions, exhibit a well-defined layer structure with an improved flattening and abruptness of the interfaces. It is shown that multilayers with a modulation period smaller than 3.4 nm have clear benefit from the reduced intermixing obtained by utilizing a twostage ion energy modulation for each individual layer. The amorphization of Sc and Cr layers, below certain thicknesses, is found to be independent of the low energy ion-assistance. It is also shown that the Cr/Sc multilayers, containing periods less than 2 nm are 'self healing' i.e. they re-gain abrupt interfaces and flat layers after morphological disturbances during ion assisted growth. In comparison, multilayers grown without ion-assistance exhibited severe roughness and layer distortions.

HfO{sub 2}/SiO{sub 2} Brewster`s angle polarizers are being developed at LLNL for the National Ignition Facility. Damage threshold studies using a 3-ns pulse length 1064-nm laser have revealed a number of different damage morphologies such as nodular ejection pits, plasma scalds, flat bottom pits, and overcoat delaminations. Of these laser damage morphologies, delaminations have the most negative impact on the multilayer stability. By selecting the proper SiO{sub 2} overcoat thickness, the delamination morphology is eliminated without significantly modifying the spectra characteristics of the coating and the functional damage threshold is increased by 2-4x. A model of the thermal mechanical response of the overcoats is presented for various SiO{sub 2} overcoat thicknesses. The overcoat thickness influences the electric-field profile resulting in different thermal gradients between the outer SiO{sub 2} and HfO{sub 2} layers. This modeling effort attempts to understand the relation be...

Dielectric materials subjected to energetic electron fluxes can emit light in several forms. We have observed three distinct types of emissions: (i) short-duration (<1 ms), high-intensity electrostatic discharge (ESD) or "arc" events; (ii) intermediate-duration, high-intensity events which begin with a bright arc followed by an exponential decay of intensity (~10 to 100 s decay constant), termed "flares"; and (iii) long-duration, low-intensity emission, or cathodoluminescence, that continues as long as the electron flux is on. These events were studied for bulk samples of bisphenol/amine epoxy, using an electron gun with varying current densities (0.3 to 5 nA/cm 2 ) and energies (12 to 40 keV) in a high vacuum chamber. Light emitted from the samples was measured with a high-sensitivity visible to near-infrared video camera. Results of the spatial and temporal extent for each type of event are presented as well as a discussion of how absolute spectral radiance and rates for each type of event are dependent on incident electron current density, energy, and power density and on material type, temperature, and thickness. Applications of this research to spacecraft charging and light emissions are discussed.

Modeling the Energy Dependent Cathodoluminescent Intensity of a Carbon Composite Material JUSTIN CHRISTENSEN, KELBY PETER-SON, JUSTIN DEKANY, JR DENNISON 1 , Utah State University, MATERIAL PHYSICS GROUP TEAM -The energy dependent spectral radiance from a carbon composite material under energetic (0.5-30 keV) electron bombardment was measured using visible-NIR cameras. Observed trends could not be accurately modeled using either a thin-film (penetrating electron) model which decreases with increasing electron energies or a bulk (non-penetrating electron) model which increases with increasing energies. However a linear combination of the two models, modeling thick and thin regions of luminescent polyimide above carbon particles was found to fit observed results much better. Electron microscope images of the sample were analyzed to independently determine the ratio of thick/thin sample areas which was found to reasonably match the ratio predicted by the cathodoluminescent model. A potentially more accurate model is also discussed, which uses distributions of dielectric thicknesses and incident electron energies.

Electron Yield of a Carbon-composite Nanodielectric MATTHEW ROBERTSON, JR DENNISON 1 , JUSTIN CHRISTENSEN, Utah State University -Electron irradiation experiments were conducted to investigate the electron transport, charging, discharging, and emission properties epoxy/carbon-fiber composite material. We discuss how these results are influenced by the nanoscale structure of the conducting carbon fibers embedded in the dielectric epoxy matrix. Electron yield measurements were made in an ultrahigh vacuum electron emission test chamber, with electron beam energies ranging from 15 eV to 5000 eV. Related structural and charging priorities have also been measured by scanning electron microscopy, energy dispersive x-ray analysis, cathodoluminescence, electron-induced arcing, and conductivity. The emission properties of the composite material are considered, in regard to models which combined the two component base material emission properties.

The objective of this research is to study the effect of sputter pressure on thin zinc oxide film deposited by RF magnetron sputtering technique on Si and glass substrates using ZnO disk with 99.99% purity. In order to avoid the effect of the thickness of the layers on the physical properties, we worked on samples of comparable thickness, from 0.8 to 1.1 μm. The deposition is done with heating the substrate at very low temperature, which is currently the most favorable conditions for integration into a MEMS process. X-ray diffraction spectra showed that ZnO thin films are hexagonal wurtzite and exhibited a c-axis orientation of below 0.32° full width at half maximum of X-ray rocking curves. The preferential orientation is along the (002) direction reported for all ZnO samples deposited by sputtering RF magnetron. The general observation indicates that the parameters of the microstructure such as grain size, intrinsic stresses, dislocation density and the full width at half maxima (F...

The electrical and optical properties of mesoporous gold are compared to those of thin porous gold films and a simulated thin film made by randomly distributing voids in gold, until the voids fill 76% of film volume. All layers are electrically conducting but in some cases the critical percolation thresholds are close to zero, so conduction is possible at very high void content. Significant qualitative differences are apparent between the properties of mesoporous gold, and very thin sputtered gold containing voids, in plasmonic responses at optical frequencies and in dc resistance, both as a function of fill factor. The mesoporous films have an effective plasma frequency determined by void fill factor and structure, but do not support surface plasmons. In contrast thin porous gold layers display optical features associated with localized and de-localized surface plasmons. Sputtered porous gold is 2-dimensional and its percolation threshold requires a "Swisscheese" rather than particle cluster model. Thicker mesoporous layers have critical parameters consistent with very high connectivity, or equivalently large hyper-dimensionality. Our meso-gold samples display various hyper-dimensionalities from 3 to above 10.

HfO{sub 2}/SiO{sub 2} Brewster`s angle polarizers are being developed at LLNL for the National Ignition Facility. Damage threshold studies using a 3-ns pulse length 1064-nm laser have revealed a number of different damage morphologies such as nodular ejection pits, plasma scalds, flat bottom pits, and overcoat delaminations. Of these laser damage morphologies, delaminations have the most negative impact on the multilayer stability. By selecting the proper SiO{sub 2} overcoat thickness, the delamination morphology is eliminated without significantly modifying the spectra characteristics of the coating and the functional damage threshold is increased by 2-4x. A model of the thermal mechanical response of the overcoats is presented for various SiO{sub 2} overcoat thicknesses. The overcoat thickness influences the electric-field profile resulting in different thermal gradients between the outer SiO{sub 2} and HfO{sub 2} layers. This modeling effort attempts to understand the relation be...

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Amorphous mixed titania-tantala coatings are key components of Bragg reflectors in the gravitational wave detectors (GWDs). Attaining the lowest possible values of optical absorption and mechanical losses in the coatings is of paramount importance for GWDs, and this requires a complex optimization of the coating deposition and post-deposition annealing. We present here a systematic investigation of the optical properties and internal friction of amorphous mixed titania-tantala coatings grown by ion beam sputtering. We consider coatings with six different cation mixing ratios -defined as Ti/(Ti+Ta) -and we study them both in the asdeposited and annealed state. All coatings have been subject to the same annealing of 500 • C for 10 hours in air, which is the post-deposition treatment adopted so far for Bragg reflectors in GWDs applications. By exploiting spectroscopic ellipsometry data and modelling, along with ancillary techniques, we retrieved the dielectric function of the coatings in a wide spectral range. When varying the mixing ratio and performing the annealing we find monotonic -in some cases, almost lineartrends for most of the aforementioned properties. Remakably, the post-annealing Urbach energy displays a definite minimum for a mixing ratio around 20%, very close to the composition of the coatings showing the lowest optical absorption for GWDs applications. We suggest that the observed minimum in the Urbach energy depends not only on the mixing ratio, but also on the annealing parameters. On the other hand, the minimum coating loss angle was found to be weakly dependent on the considered measurement frequency and to lie within a rather broad range of Ti content (cation ratios of 21% and 44%), suggesting that the search for an absolute minimum following post-deposition annealing should be rather sought in the study of the best annealing parameters for each specific cation ratio considered. This work constitutes a reference for the optical properties of the amorphous mixed titania-tantala coatings, and highlights the relevance of the Urbach energy in the optimization process of materials for high-performing Bragg reflectors.

We have investigated by spectroscopic ellipsometry (SE) the optical properties (190 - 1700 nm) of uniform, amorphous thin films of Ta2O5 and Nb2O5 as a function of the annealing temperature and after so-called &quot;doping&quot; with Ti atoms which leads to mixed Ti:Nb and Ti:Ta oxides. Ta2O5 and Ti:Ta2O5 are currently used as high index components in Bragg reflectors of interference Gravitational Wave Detectors (GWD). Parallel to the optical investigation we measured the mechanical energy dissipation of the same coatings, through the so-called &quot;loss angle&quot;, a parameter which is widely used to quantify the energy loss in materials. By applying the well-known Cody-Lorentz model in the analysis of SE data we have been able to derive accurate information on the fundamental absorption edge through important parameters related to the electronic density of states, such as the optical gap and the energy width of the exponential Urbach tail (the Urbach energy EU). We have found th...

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Composite materials of zinc oxide (ZnO) and graphene oxide (GO) have caused emergence of potential application in the field of optoelectronics. Phosphate based glasses (P2O5) can improve the conductivity and increase the graphene oxide (GO) concentration and homogeneity distribution in the films. This paper presents a comparative study of two types of composite thin films: ZnO/P2O5/GO and ZnO/GO deposited through a sol-gel process on glass substrates. Optical analysis derived from spectroscopic ellipsometry was involved calculating the reflectance spectral curves for different thicknesses of the thin film layers constituting the ZnO/P2O5/GO and ZnO/GO.

We have investigated by spectroscopic ellipsometry (SE) the optical properties (190 - 1700 nm) of uniform, amorphous thin films of Ta2O5 and Nb2O5 as a function of the annealing temperature and after so-called &quot;doping&quot; with Ti atoms which leads to mixed Ti:Nb and Ti:Ta oxides. Ta2O5 and Ti:Ta2O5 are currently used as high index components in Bragg reflectors of interference Gravitational Wave Detectors (GWD). Parallel to the optical investigation we measured the mechanical energy dissipation of the same coatings, through the so-called &quot;loss angle&quot;, a parameter which is widely used to quantify the energy loss in materials. By applying the well-known Cody-Lorentz model in the analysis of SE data we have been able to derive accurate information on the fundamental absorption edge through important parameters related to the electronic density of states, such as the optical gap and the energy width of the exponential Urbach tail (the Urbach energy EU). We have found th...

The understanding of how the structure rules the several properties that distinguish amorphous solids from crystals is important for a technological progress, regarding several applications. The random network structure that characterises amorphous solids and causes the loose of a long-range order forces the research to a continuous efforts in order to explain all the properties that differ from crystals, through the creation of models without using the Bloch theorem, which is based on the periodicity of the lattice. This aspect of amorphous structure is responsible of interesting feature. In this work the optical properties, related to the electronic density of states, and mechanical properties, regarding the internal friction, are compared by their relationship with the topological defects of structure in a short-medium-range order. In particular, by studying the optical and mechanical properties of oxides suitable for gravitational-wave detectors, a correlation between the Urbach...

We have investigated by spectroscopic ellipsometry (SE, 190–1700 nm) the optical properties of uniform, amorphous thin films of Ta2O5 and Nb2O5 as deposited and after annealing, and after so-called “doping” with Ti atoms which leads to mixed oxides. Ta2O5 and Ti:Ta2O5 are currently used as high-index components in Bragg reflectors for Gravitational Wave Detectors. Parallel to the optical investigation, we measured the mechanical energy dissipation of the same coatings, through the so-called “loss angle” ϕ = Q−1, which quantifies the energy loss in materials. By applying the well-known Cody-Lorentz model in the analysis of SE data we have been able to derive accurate information on the fundamental absorption edge through important parameters related to the electronic density of states, such as the optical gap (Eg) and the energy width of the exponential Urbach tail (the Urbach energy EU). We have found that EU is neatly reduced by suitable annealing as is also perceptible from direct...

Refinement and thin film synthesis methods were used by members of six different institutions to design antireflection coatings for germanium substrates. The solutions are based on the use of zinc sulfide and germanium layers only. Several systems were found with an average reflectance that is less than 1% in the 7.7 to 12.3 μm spectral region.

A new high-order adaptive optics system is now being commissioned at the Lick Observatory Shane 3-meter telescope in California. This system uses a high return efficiency sodium beacon and a combination of low and high-order deformable mirrors to achieve diffraction-limited imaging over a wide spectrum of infrared science wavelengths covering 0.8 to 2.2 microns. We present the design performance goals and the first on-sky test results. We discuss several innovations that make this system a pathfinder for next generation AO systems. These include a unique woofer-tweeter control that provides full dynamic range correction from tip/tilt to 16 cycles, variable pupil sampling wavefront sensor, new enhanced silver coatings developed at UC Observatories that improve science and LGS throughput, and tight mechanical rigidity that enables a multi-hour diffractionlimited exposure in LGS mode for faint object spectroscopy science.

The International Energy Agency was formed in November 1974 to establish cooperation among a number of industrialized countries in the vital area of energy policy. It is an autonomous body within the framework of the Organization for Economic Cooperation and Development (OECD). Twenty-one countries are presently members, with the Commission of the European Communities (CEC) also participating in the work of the lEA under a special arrangement. Collaboration among member countries in the research and development of alternative energy resources in order to reduce excessive dependence on oil is an important element of the lEA program. A number• of new and improved technologies which have the potential for making significant contributions to global energy needs were identified for collaborative efforts. The lEA Committee on Energy Research and Development (CRD), supported by a small Secretariat staff, is the focus of lEA R&D activities. Four Working Parties (in Conservation, Fossil Fuels, Renewable Energy, and Fusion) are charged with identifying new areas for cooperation and advising the CRD on policy matters in their respective technology areas. Solar Heating and Cooling was one of the technologies selected for joint R&D activities. During 1976-77, specific projects were identified in key areas of this field and a formal Implementing Agreement qrawn up. The Agreement covers the obligations and rights of the Participants and outlines the scope of each project or "task" in annexes to the document. There are now eighteen signatories to the Agreement:

The quantum efficiency of superconducting light detectors with film thicknesses 100 nm is mainly limited by the reflection losses at the superconducting film surface, which are usually higher than 50%. In this work we show that it is possible to reduce the reflection of Ti/Au and Ir/Au films to under 1% at telecommunication wavelengths, by means of properly designed antireflection coatings. The effect of optical cavity structures is also considered in the case of highly transmitting Ti and Ir films with thickness lower than 50 and 70 nm respectively in order to enhance absorption.

The EUV source output power and the collector optics lifetime have been identified as critical key issues for EUV lithography. In order to meet these requirements a heated collector concept was realized for the first time. An ellipsoidal collector substrate with an outer diameter of 320 mm was coated with a laterally graded high-temperature multilayer. The interface-engineered Mo/Si multilayer coating was optimized in terms of high peak reflectivity at 13.5 nm and a working temperature of 400 °C. Barrier layers were introduced on both interfaces to block thermally induced interdiffusion processes of molybdenum and silicon to provide long-term optical stability of the multilayer at elevated temperatures. A normal-incidence reflectance of more than 40 % at 13.55 nm was measured after heating. After initial annealing at 400 °C for one hour, no degradation of the optical properties of these multilayer coatings occurred during both long-term heating tests for up to 100 hours and multiple annealing cycles. The successful realization of this hightemperature sub-aperture collector mirror represents a major step towards the implementation of the heated collector concept and illustrates the great potential of high-temperature EUV multilayer coatings.

The spectral properties of LaN/B and LaN∕B 4 C multilayer mirrors have been investigated in the 6.5 to 6.9 nm wavelength range, based on measured B and B 4 C optical constants. We show that the wavelength of optimal reflectance for boron-based optics is between 6.63 and 6.65 nm, depending on the boron chemical state. The wavelength of the maximum reflectance of the LaN∕B 4 C multilayer system is confirmed experimentally. Calculations of the wavelength-integrated reflectance for perfect ten-multilayer-mirror stacks show that a B-based optical column can be optimized for a wavelength larger than 6.65 nm.

HfO 2 /SiO 2 Brewster's angle polarizers are being developed at Lawrence Livermore National Laboratory for the National Ignition Facility. Damage threshold studies using a 3-ns pulse length 1064-nm laser have revealed a number of different damage morphologies such as nodular ejection pits, plasma scalds, flat bottom pits, and overcoat delaminations. Of these laser damage morphologies, delaminations have the most negative impact on the multilayer stability. By selecting the proper SiO 2 overcoat thickness, the delamination morphology is eliminated without significantly modifying the spectral characteristics of the coating and the functional damage threshold is increased by 2-4×. A model of the thermal mechanical response of the overcoats is presented for various SiO 2 overcoat thicknesses. The overcoat thickness influences the electricfield profile resulting in different thermal gradients between the outer SiO 2 and HfO 2 layers. This modeling effort attempts to understand the relationship between the thermal stress distribution in the overcoat and the occurrence of delamination.

A lower resistivity and better spectra selectivity is a measurement of the quality and potential use of silver Ag and aluminium Al metals for the application as metallization contacts for solar cells. Aluminium (Al) and silver (Ag) thin films deposited by thermal evaporation at room temperature were dense with small grain sizes, and maintained a high value of reflectance (in the spectral range from 300 to 3200 nm) with annealing at 300 °C in an argon atmosphere. Experimental results indicate that the surface roughness is increased while the film's resistivities are reduced. It was also found that the surface roughness and work function of metal films are very important to enhance the stability and efficiency of electrode thin films used for solar cells.

An infrared heat reflecting multilayer thin film filter comprising alternate layers of ZrO2 and SiO2 has been modeled and prepared on a BK7 glass substrate using RF-magnetron sputtering. Initially, the individual films of the used materials have been characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) for structural and surface quality prior to the deposition of multilayer structure. Spectral analysis showed that the filter has an average transmission of greater than 90% in 450 to 700 nm range and less than 2% in 700−1100 nm band fulfilling the design requirements. The XRD study of multilayer structure showed few peaks of ZrO2 along with a solitary peak for SiO2 indicating some crystallinity for ZrO2 layers in the structure. Hardness analysis showed that the initial phase of the indentation is predominantly ductile with gradual transition in behaviour from ductile to brittle with increased penetration. Interface analysis of multilayered structure was carried out by Rutherford back scattering using Tandem 5 MeV ion accelerator, showed that interfaces formed in the multilayer structure are sharp and no substantial evidence of interlayer diffusion or mixing at the interfaces.

In microelectronic industry, multilevel interconnection technology needs interlayer insulator materials with low dielectric constant to reduce the signal propagation delay induced by the parasitic capacitance at the interconnections. Various materials with low dielectric constant (lower than that of SiO 2) have been investigated. Fluorinated silicon oxide (SiOF) is received much attention due to its low dielectric constant, thermal stability, excellent mechanical properties and to the strong electro-negativity of Si‫ــ‬F bond. In this work, SiOF like thin films have been deposited by microwave electron cyclotron resonance plasma created in a mixture of oxygenhexamethyldisiloxane (HMDSO) and CF 4. The fluorine contents in the precursor mixture were adjusted by varying the CF 4 gas flow ratio in the range 10%-70%. Optical emission spectroscopy (used for the plasma diagnostic) and Fourier transform infrared (FTIR) (used for study of the deposited films) analyses are performed for different values of the dilution ratio R {R = [HMDSO] / ([HMDSO] + [O 2 ])} in HMDSO/O 2 /CF 4 mixture. Actinometric technique was used to find trends in the concentrations of species present in the plasma. A large number of species have been detected, such as F, Si, O, C and H. These species determine the structures and/or the properties of the as-deposited film. FTIR spectra revealed the presence of several chemical bonds (such as Si-F and Si-O) depending on the gas flow ratio R. The effect of these bonds on the films refractive index behavior has been studied.

Mathematical modeling is performed in order to analyze the effects of technological errors originated from partial inhomogeneity, variations of the refractive index and the differences in geometric thickness of layers with high refractive index on spectral characteristics of narrowand wide-band filters. Using a Monte Carlo method the influence of technological errors on optical parameters of the layers and their influences on spectral characteristics of interference filters are investigated and discusses in details.

After more than a century, Michelson’s interferometer is still at the forefront of scientific investigation. While the first application was in astronomy, it is now used as a novel technique in a wide range of subjects, notably in the form of Optical Coherence Tomography used primarily for biomedical applications. This paper will introduce a new application of the interferometer for the examination of art for conservation purposes.

The temperature control of automotive brake discs during operation is a difficult process because they have shiny metallic surfaces moving rotational contact with fixed brake pads and different temperature gradients. The instrument used for measuring the temperature, in this case is the thermal camera, but requires precise calibration for the emissivity of the material being analyzed and the influence of environment. The study refers to changes depending on the temperature of thermal emissivity of the material disc brake car, both in static and in dynamic regime and determining analytical relationships to estimate this variation acceptable accuracy.

We have observed an irreversible ultrafast crystalline-to-amorphous phase transition in Ge 2 Sb 2 Te 5 chalcogenide alloy thin film using broadband single-shot imaging spectroscopy. The absorbance change that accompanied the ultrafast amorphization was measured via single-shot detection even for laser fluences above the critical value, where a permanent amorphized mark was formed. The observed rise time to reach the amorphization was found to be $130-200 fs, which was in good agreement with the half period of the A 1 phonon frequency in the octahedral GeTe 6 structure. This result strongly suggests that the ultrafast amorphization can be attributed to the rearrangement of Ge atoms from an octahedral structure to a tetrahedral structure. Finally, based on the dependence of the absorbance change on the laser fluence, the stability of the photoinduced amorphous phase is discussed. V

A new e-beam lithography grey scale method has been developed for phase shift optical elements production. It could be used only for 3D elements with lateral dimensions of constant height regions much greater than the resist height and provides an extremely precise structure height control with a very high process latitude. Resist structure height in it is controlled not by the local dose but by the exposed cell area.

An optical fibre long period grating (LPG), modified with a coating of silica core gold shell (SiO 2 :Au) nanoparticles (NPs) deposited using the layer-by-layer method, was employed for the development of a biosensor. The SiO 2 :Au NPs were electrostatically assembled onto the LPG with the aid of a poly(allylamine hydrochloride) (PAH) polycation layer. The LPG sensor operates at the phase matching turning point to provide the highest sensitivity. The SiO 2 :Au NPs were modified with biotin, which was used as a ligand for streptavidin (SV) detection. The sensing mechanism is based on the measurement of the refractive index change induced by the binding of the SV to the biotin. The effect on sensitivity of increasing the surface area by virtue of the SiO 2 :Au nanoparticles' diameter and film thickness was studied. The lowest measured concentration of SV was 2.5 nM, achieved using an LPG modified with a 3 layer (PAH/ SiO 2 :Au) thin film composed of SiO 2 NPs of 300 nm diameter with a binding constant of k 1.7 pM 1 = () − , sensitivity of 6. 9 nm/ ng/mm 2 () and limit of detection of 19 pg/mm 2 .

Background: The successful introduction of extreme ultraviolet (EUV) lithography to high volume manufacturing has increased the interest to push this technology to its ultimate limits. This will require photoresist materials, which enable a better tradeoff between resolution, linewidth roughness and sensitivity, and the adaptation of optical resolution enhancements that were originally developed for deep ultraviolet (DUV) lithography. Aim: We review published research on attenuated phase shift masks (attPSM) for EUV with special emphasis on modeling and fundamental understanding of the imaging characteristics of alternative absorber materials. The overview on previous work is intended to summarize typical observations and learning on obtained results and to serve as a reference for further research on this important topic. Review approach: The review starts with a summary of related work on attPSM for DUV lithography. It is shown that the understanding and mitigation of mask topography (or mask 3D) effects is key for the analysis and optimization of attPSM for EUV lithography. Observations from several research groups and application of dedicated modeling approaches help to understand the physical mechanisms behind observed lateral image shifts and pitch-dependent shifts of the best focus position. Results: The imaging physics of attPSM for EUV lithography differs significantly from attPSM imaging in DUV lithography. The "double diffraction" of EUV light from the absorber, the reflection characteristics of the multilayer blank, and the guidance of light through the openings in a low-refractive-index (low-n) absorber introduce important effects that need to be considered in the design and use of attPSM in EUV lithography. It is important to use the optical properties (n and k) and the thickness of the absorber as predictive design parameters of attPSM for EUV lithography (instead of phase and reflectivity). The refractive index of the absorber material is important for binary masks as well. The discussion of low-n absorbers includes both "traditional" attPSM for EUV and low reflectivity absorbers, which exploit the guidance of light inside patterned layers. Conclusions: In-depth modeling investigations of attPSM and first experiments suggest that absorbers with a refractive index around 0.9 (low-n materials) can help to push high NA EUV lithography into the low k 1 regime. Comprehensive optimization of source and mask is required to exploit the advantages of low-n absorbers. Further enhancements can help to push EUV imaging to its ultimate limit.

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