The optical properties of Ag2Te crystals from THz to UV

Yeh, Tien Tien; Lin, Wen Hao; Tzeng, Wen Yen; Le, Phuoc Huu; Luo, Chih-Wei; Milenov, T. I.

doi:10.1016/j.jallcom.2017.07.153

Cited by 10 publications

(9 citation statements)

References 29 publications

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“…In this work, we comprehensively investigated the electronic structure and optical properties of Ag 2 Te through density functional theory (DFT). The reflectivity of Ag 2 Te coincides well with previous experimental results [15]. The real part of the dielectric function is negative when the optical energy is below 0.1 eV and in the range of 12-20 eV, in which the former comes from Drude free electrons, while the latter stems from a higher density of states (DOS) in the high-energy region.…”

Section: Introductionsupporting

confidence: 90%

“…The Ag 2 Te monoclinic phase in particular has been proven to possess an isotropic Dirac cone, which makes Ag 2 Te exhibit topological properties [14]. The large number of massless fermions supplied by Dirac cones makes Ag 2 Te a promising candidate for collective electromagnetic oscillations [15,16]. The bulk character endows Ag 2 Te with a better light-matter interaction than graphene.…”

Section: Introductionmentioning

confidence: 99%

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Robust UV Plasmonic Properties of Co-Doped Ag2Te

Gao

et al. 2022

Crystals

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Ag2Te is a novel topological insulator system and a new candidate for plasmon resonance due to the existence of a Dirac cone in the low-energy region. Although the optical response spectrum of Ag2Te has been studied by theoretical and experimental methods, the plasmon resonance and stability of Co-doped Ag2Te remain elusive. Here, we theoretically report a new unconventional UV plasmon mode and its stability in Co-doped Ag2Te. Through density functional theory (DFT), we identify a deep UV plasmon mode within 15–40 eV, which results from the enhanced inter-band transition in this range. The deep UV plasmon is important for detection and lithography, but they have previously been difficult to obtain with traditional plasmon materials such as noble metals and graphene, while most of which only support plasmons in the visible and infrared spectra. Furthermore, we should highlight that the high-energy dielectric function is almost invariant under different doping amounts, indicating that the UV plasmon of Ag2Te is robust under Co doping. Our results predict a spectrum window of a robust deep UV plasmon mode for Ag2Te-related material systems.

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Section: Introductionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Robust UV Plasmonic Properties of Co-Doped Ag2Te

Gao

et al. 2022

Crystals

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“…Therefore, bulks or relatively thick-layer specimens are used for these purposes. Some bulks are polycrystalline, prepared by direct synthesis of elements, − others are monocrystalline, obtained by the means of Bridgman and zone melting technologies. − But most of the samples are in the form of polycrystalline layers, prepared by almost all possible physical methods for deposition, as thermal deposition in vacuum, ,− arc melting, laser ablation, magnetron sputtering, − ion implantation, etc., either from preliminary synthesized bulks or from the initial elements, as the last are either coevaporated ,− or deposited by alternating layered structures. ,,, The chemical reactions for formation of the desired compounds are realized either by solid-state self-assembly of the components , or by further thermal annealing. ,, …”

Section: Preparation Of Intermetallic Ag(au) X Me Y Compoundsmentioning

confidence: 99%

“…The Ag 2 Te is a narrow band gap semiconductor with two allotropic forms, disordered high temperature α-Ag 2 Te and low temperature monoclinic β-Ag 2 Te. 110 The investigation of the optical properties of monoclinic Ag 2 Te crystals in a wide range (3.7 meV – 6.2 eV) of photon energies is presented by Yeh et al 63 The β-Ag 2 Te phase is characterized by an indirect bandgap (∼10 meV) and a direct bandgap (∼1.84 eV) and plasmon frequency at the far-infrared spectral range ∼50 meV.…”

Section: Optical Properties Of Intermetallic Compoundsmentioning

confidence: 99%

Silver and Gold Containing Compounds of p-Block Elements As Perspective Materials for UV Plasmonics

et al. 2023

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We present a review of phase formation tendencies, methods for preparation and optical properties of alloys and compounds from the binary systems of silver or gold with metals and metalloids from the p-block of the Periodic system of elements. Reference data about the homogeneity regions in the systems of interest, together with information about the crystalline structure of existing indexed compounds in them, is proposed and statistically analyzed. General background for the synthesis of intermetallic alloys and compounds, and the tendencies for their preparation for plasmonic purposes are presented. The high plasma frequency, ω p of p-block metals makes their alloys with silver and gold an interesting object of study, due to the possibility of ω p variation over a wide interval in the ultraviolet (UV) spectral region with a view to finding more efficient materials for excitation of a localized surface plasmon resonance (LSPR) necessary for various applications and techniques operating in this part of the electromagnetic spectrum. Unlike the alloys between the noble metals Cu, Ag, and Au, which form continuous series of solid solutions, different areas can be observed in the phase diagrams of the Ag(Au)−p-block systems, containing solid solutions, intermetallic compounds, and heterogeneous mixtures. The ability to vary the plasma frequency of solid solutions, like the alloys between the noble metals Cu, Ag, and Au, is the reason to pay attention to the compositions of the Ag(Au−p-block systems that fall in these regions of their phase diagrams. The analysis of the published results for complex permittivity shows that the addition of small amounts of conductive p-block elements to noble metals reduces the energy gap for interband transitions and increases their plasmonic activity in the UV spectral range. The article analyzes the relationship between electrical resistivity and LSPR excitation efficiency, which shows that the intermetallic compounds from Ag(Au)−p-block systems with a well-ordered crystalline structure and good conductivity level can be more effective materials for UV plasmonics than the boundary solid solutions. Intermetallic compounds can be easily obtained in the form of bulk samples, thin films, and nanoparticles with controlled size and geometric shape. The spectral dependences of the plasmon efficiency of the intermetallic compounds, determined from their complex permittivity functions, show that they are promising materials for excitation of LSPR in the UV spectral region.

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“…Ag 2 Te is a narrow gap semiconductor [30,31] that has various attractive properties, including near-infrared light emission [32,33], large magnetoresistance [34,35], structural phase transition [36], topological insulating behaviors [37,38], and a high thermoelectric figure of merit ZT [39][40][41]. One-dimensional structures including nanofibers, nanorods, or nanowire can modify the properties.…”

Section: Introductionmentioning

confidence: 99%

Single-crystalline Ag2Te nanorods prepared by room temperature sputtering of GeTe

Nakaya

Nakaoka

2020

SN Appl. Sci.

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We report a facile, single-crystalline Ag 2 Te nanorod formation based on electrochemical diffusion of Ag. The nanorods were grown non-epitaxially by sputtering deposition of GeTe on Ag 2 Te nanoparticles at room temperature. For the nanorod growth, the source of the Ag supply is not deposition but the diffusion of Ag from the nanoparticles. The growth of the single-crystalline Ag 2 Te nanorods required GeTe deposition onto Ag 2 Te nanoparticles, in contrast to the growth of amorphous Ag 2 Te nanorods caused by Te deposition onto Ag nanoparticles and the growth of other nanostructures caused by GeTe deposition on Ag nanoparticles. The GeTe deposition onto the Ag 2 Te nanoparticles of an amount equivalent to a 100-nm-thick film produced nanorods of a length ranging from 3 to 5 μm and a diameter ranging from 100 to 400 nm. We propose a model for the nanorod growth based on solid-state electrochemical reaction between GeTe and movable Ag ions, inducing nanoscale phase separation and precipitation of amorphous Ge. We suggest that the nanorod structure with a crystalline Ag 2 Te core and an amorphous Ge shell is useful for thermoelectric applications.

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The optical properties of Ag2Te crystals from THz to UV

Cited by 10 publications

References 29 publications

Robust UV Plasmonic Properties of Co-Doped Ag2Te

Robust UV Plasmonic Properties of Co-Doped Ag2Te

Silver and Gold Containing Compounds of p-Block Elements As Perspective Materials for UV Plasmonics

Single-crystalline Ag2Te nanorods prepared by room temperature sputtering of GeTe

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