Temperature dependent optical properties of silver from spectroscopic ellipsometry and density functional theory calculations

Sundari, S. Tripura; Chandra, Sharat; Tyagi, AK

doi:10.1063/1.4813874

Cited by 34 publications

(28 citation statements)

References 36 publications

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“…For example, the noble metals Au and Ag, which have formed the basis of a great deal of plasmonics research, owing to their high electrical conductivity, are incompatible with currently ubiquitous CMOS technologies [13]. Moreover, although Au exhibits superior chemical and thermal stability compared to Ag, the optical properties of the material are subject to significant variation on exposure to temperatures in excess of approximately 300° C, thus preventing its use in high temperature applications such as heatassisted magnetic recording (HAMR) and solar thermophotovoltaics (STPV) [14,15].…”

Section: Introductionmentioning

confidence: 99%

Multiphase strontium molybdate thin films for plasmonic local heating applications

Wells¹,

Zou²,

Mihai³

et al. 2018

Opt. Mater. Express

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In the search for alternative plasmonic materials SrMoO3 has recently been identified as possessing a number of desirable optical properties. Owing to the requirement for many plasmonic devices to operate at elevated temperatures however, it is essential to characterize the degradation of these properties upon heating. Here, SrMoO3 thin films are annealed in air at temperatures ranging from 75 -500° C. Characterizations by AFM, XRD, and spectroscopic ellipsometry after each anneal identify a loss of metallic behaviour after annealing at 500° C, together with the underlying mechanism. Moreover, it is shown that by annealing the films in nitrogen following deposition, an additional crystalline phase of SrMoO4 is induced at the film surface, which suppresses oxidation at elevated temperatures. ExperimentalThe SrMoO3 PLD target material was prepared from SrMoO4 powder (99.9% purity) supplied by Alfa Aesar. The powder was placed in propan-2-ol and ball milled at 300 rpm for 20 hrs before evaporating the propan-2-ol by placing the powder in an oven overnight at 60° C. The powder was then reduced in a furnace under 100 mL min -1 gas flow of 5% H2 / 95% N2 at 1400° C for 10 hrs. The powder was then pressed into a target with a density of approximately 4 g cm -3 before sintering under the same gas flow conditions at 1500° C for 12 hours.The SrMoO3 target material was rotated throughout each pulsed laser deposition process and held 60 mm from the SrTiO3 substrate. A KrF excimer laser (240 nm) was used for the deposition of all samples with a repetition rate of 8 Hz and a 10 s relaxation period after every 20 pulses. A laser fluency of 1.2 J cm -2 was used. Vacuum conditions, approximately 1×10 -7 Torr, were used for the deposition of all samples and the substrate temperature was 650° C. The samples were cooled to room temperature after each deposition process at a rate of 10° C min -1 , either in vacuum or following annealing in 500 Torr N2 (6N purity, supplied by BOC), prior to removal from the vacuum chamber. Single side polished 5x5 mm (100) oriented STO substrates with a thickness of 0.5 mm were used.An IONTOF ToF-SIMS 5 instrument was used for SIMS depth profiling of the samples. An area of 100x100 μm 2 was analysed using a 25 keV Bi+ LMIG in high current bunch mode with a beam current of approximately 1 pA. Only negative secondary ions were collected. For depth profiling, a 1 keV Cs+ ion beam with a current of 75 nA was used, giving a sputter crater area of 300x300 μm 2 .The surfaces of the SMO films before and after annealing were characterised using X-ray photoelectron spectroscopy (XPS). The spectra were recorded on a Thermo Scientific K-Alpha+ spectrometer operating at a base pressure of 2x10 -9 mbar. This system incorporates a monochromated, microfocused Al Kα X-ray source (hν = 1486.6 eV) and a 180° double focusing hemispherical analyser with a 2D detector. The X-ray source was operated a 6 mA emission current and 12 kV anode bias. Data were collected at pass energies of 200 eV for survey, and 20 eV for core le...

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Section: Introductionmentioning

confidence: 99%

Multiphase strontium molybdate thin films for plasmonic local heating applications

Wells¹,

Zou²,

Mihai³

et al. 2018

Opt. Mater. Express

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“…However, as pointed out by Sundari et al 16 these studies only report on the imaginary part of the dielectric constant. More recently, there have been reports on the temperature dependent optical constants of 200-nm-thick silver films [16][17][18] as well as the temperature changes in the surface plasmon resonance of gold nanoparticles embedded in silica at elevated temperatures 19 . At low temperatures, optical properties of ultrathin Au films in the mid-and far-infrared regions 20 and the optical response of gold nanorods and plasmonic crystals 21 have also been studied.…”

Section: Abstract: Nanophotonics Plasmonics Metamaterials Metal Opmentioning

confidence: 99%

Temperature-dependent optical properties of gold thin films

Reddy

Guler

Kildishev

et al. 2016

Opt. Mater. Express

175

165

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ABSTRACT:Understanding the temperature dependence of the optical properties of thin metal films is critical for designing practical devices for high temperature applications in a variety of research areas, including plasmonics and near-field radiative heat transfer. Even though the optical properties of bulk metals at elevated temperatures have been studied, the temperature-dependent data for thin metal films, with thicknesses ranging from few tens to few hundreds of nanometers, is largely missing. In this work we report on the optical constants of single-and polycrystalline gold thin films at elevated temperatures in the wavelength range from 370 to 2000 nm. Our results show that while the real part of the dielectric function changes marginally with increasing temperature, the imaginary part changes drastically. For 200-nm-thick single-and polycrystalline gold films the imaginary part of the dielectric function at 500 0 C becomes nearly twice larger than that at room temperature. In contrast, in thinner films (50-nm and 30-nm) the imaginary part can show either increasing or decreasing behavior within the same temperature range and eventually at 500 0 C it becomes nearly 3-4 times larger than that at room temperature. The increase in the imaginary part at elevated temperatures significantly reduces the surface plasmon polariton propagation length and the quality factor of the localized surface plasmon resonance for a spherical particle. We provide experiment-fitted models to describe the temperature-dependent gold dielectric function as a sum of one Drude and two critical point oscillators. These causal analytical models could enable accurate multiphysics modelling of gold-based nanophotonic and plasmonic elements in both frequency and time domains. KEYWORDS: nanophotonics, plasmonics, metamaterials, metal optics, high temperatures, gold thin films, analytical models2 Nanometer-scale field localization is at the heart of metal-based nanophotonics, namely plasmonics [1][2][3][4] . In plasmonic nanostructures, strong field confinement -or so-called 'hot spots' -arise due to the excitation of subwavelength oscillations of free electrons coupled to the incident electromagnetic field at the metal-dielectric interface, known as surface plasmons 5 . Such nanoscale hot spots lead to high energy densities that inevitably increase the local temperature of the plasmonic material under study. Recently, there has been a growing interest in plasmonicsbased local heating applications such as heat-assisted magnetic recording, thermophotovoltaics, and photothermal therapy 6,7 .However, theoretical modeling of plasmonic structures in such local-heating based systems has so far been performed using room-temperature optical constants, i.e. with thermal analysis and optical material properties being decoupled. Therefore, probing the temperature dependence of the optical properties of thin metal films is critical for both gaining an insight into the physical process associated with elevated temperatures and for accurate modeling of ...

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“…Among them, the dielectric properties of Au and Ag have been studied early by optical means -mainly by traditional reflectance or transmittance measurements and scarcely by SE (see refs. [39] and [40] for Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 5/27/15 4:22 AM recent reviews of papers devoted to these two metals) -and the trends of their dielectric functions are now well known. Interband transitions are excited in the UV for Ag and up to visible wavelengths for Au.…”

Section: Optimizing the Properties Of Building Block Materials For Plmentioning

confidence: 98%

“…SE has been performed in situ for evaluating the dielectric function of metals or metallic compounds as a function of temperature, below and above their melting point [39,49,[71][72][73][74][75][76][77][78][79][80][81][82][83][84]. It has been used early to measure, in the near UV-to-near IR spectral range, the dielectric function of the liquid phase of metals with a low melting point, such as Na, Sn, Hg [71], and later that of Ga in its solid [72] and liquid [72,73] state, that of Bi in its solid [66] and liquid [73,74] state.…”

Section: Temperature-dependence Phase Transitions For Active Plasmonicsmentioning

confidence: 99%

Spectroscopic ellipsometry for active nano- and meta-materials

Toudert

2014

Nanotechnology Reviews

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Temperature dependent optical properties of silver from spectroscopic ellipsometry and density functional theory calculations

Cited by 34 publications

References 36 publications

Multiphase strontium molybdate thin films for plasmonic local heating applications

Multiphase strontium molybdate thin films for plasmonic local heating applications

Temperature-dependent optical properties of gold thin films

Spectroscopic ellipsometry for active nano- and meta-materials

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