Phononic bandgap and phonon anomalies in HfN and HfN/ScN metal/semiconductor superlattices measured with inelastic x-ray scattering

Chakraborty, Sourjyadeep; Uchiyama, Hiroshi; Garbrecht, Magnus; Bhatia, Vijay K.; Pillai, Ashalatha Indiradevi Kamalasanan; Feser, Joseph P.; Adroja, D. T.; Langridge, S.; Saha, Bivas

doi:10.1063/5.0020935

Cited by 6 publications

(7 citation statements)

References 48 publications

(52 reference statements)

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“…From the interference pattern, a period thickness of 11.3 nm is measured that matches well with the growth target and HR(S)/TEM analysis. 55 Faint MgO 002 diffraction spots from {002} planes with a d-spacing of 2.1 Å can be seen in each of the images, corresponding to a bulk MgO lattice constant of 4.20 Å.…”

Section: Resultsmentioning

confidence: 99%

Near-UV-to-Near-IR Hyperbolic Photonic Dispersion in Epitaxial (Hf,Zr)N/ScN Metal/Dielectric Superlattices

Das

Maurya

Schroeder

et al. 2022

ACS Appl. Energy Mater.

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Hyperbolic metamaterials (HMMs) with extreme dielectric anisotropy have shown great promise in nanophotonic applications such as superlensing, enhancement of spontaneous emission, negative refraction, and the diverging photonic density of states. Noble metal-based metal/dielectric multilayers (e.g., Au/SiO2 and Ag/TiO2) and metallic (Au and Ag) nanowires embedded inside a dielectric matrix have been traditionally used to demonstrate HMM properties and for implementations into devices. Noble metals are, however, unstable at high temperatures, complementary metal oxide semiconductor incompatible, and difficult to deposit in thin-film form due to their high surface energies that limit their potential applications. TiN has emerged as an alternative plasmonic material to Au in recent years, and epitaxial TiN/Al0.72Sc0.28N metal/semiconductor superlattices were developed that exhibit excellent HMM properties. As TiN exhibits ε-near-zero (ENZ) at ∼500 nm, TiN/Al0.72Sc0.28N HMM also operates from ∼500 nm to long-wavelength regions. However, for several energy-conversion-related applications as well as for fundamental studies, it is desirable to achieve HMM wavelengths from the near-UV to the near-IR region of the spectrum. In this article, we demonstrate hyperbolic photonic dispersion in (Hf,Zr)N/ScN, a class of metal/semiconducting superlattice metamaterial that covers the near-UV to the near-IR spectral range. Epitaxial HfN/ScN, ZrN/ScN, and Hf0.5Zr0.5N/ScN superlattices are deposited on (001) MgO substrates and characterized with synchrotron-radiation X-ray diffraction as well as high-resolution electron microscopy techniques. Superlattices grow with cube-on-cube epitaxy and with sharp interfaces. Optical characterization reveals both type-I and type-II hyperbolic photonic dispersions as well as low losses and high figures-of-merit. Along with its high-temperature thermal stability, demonstration of HMM properties in (Hf,Zr)N/ScN metal/dielectric superlattices makes them potential candidates for HMM devices.

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Section: Resultsmentioning

confidence: 99%

Near-UV-to-Near-IR Hyperbolic Photonic Dispersion in Epitaxial (Hf,Zr)N/ScN Metal/Dielectric Superlattices

Das

Maurya

Schroeder

et al. 2022

ACS Appl. Energy Mater.

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“…We investigate in more details the optical properties of HfN/ScN, that we assume as the reference for this class of TMX multilayers. HfN/ScN has been experimentally grown [ 71,72 ] and behaves as both type‐I and type‐II material, depending on the energy of the incoming radiation. Figure 5b shows the real and imaginary part of both parallel

{\overset{ε}{true}}_{∥}

and perpendicular

{\overset{ε}{true}}_{⊥}

components of the effective dielectric function (Equation (2)); see Figure S2, Supporting Information for the details of the constitutive dielectric functions.…”

Section: Resultsmentioning

confidence: 99%

“…We focus on the 17 superlattices that simultaneously fulfill the hyperbolicity and hardness conditions described above. A few of them, such as HfN/ScN, [71,72] ZrN/ScN, [73] TiC/TiN, [74,75] and HfC/HfN, [76] have been realized and experimentally characterized, although not studied for hyperbolic optical applications.…”

Section: Resultsmentioning

confidence: 99%

Hyperbolic Metamaterials with Extreme Mechanical Hardness

Calzolari

Catellani

Nardelli

et al. 2021

Advanced Optical Materials

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Hyperbolic metamaterials (HMMs) are highly anisotropic optical materials that behave as metals or as dielectrics depending on the direction of propagation of light. They are becoming essential for a plethora of applications, ranging from aerospace to automotive, from wireless to medical and IoT. These applications often work in harsh environments or may sustain remarkable external stresses. This calls for materials that show enhanced optical properties as well as tailorable mechanical properties. Depending on their specific use, both hard and ultrasoft materials can be required, although the combination with optical hyperbolic response is rarely addressed. Here, the possibility to combine optical hyperbolicity and tunable mechanical properties in the same (meta)material is demonstrated, focusing on the case of extreme mechanical hardness. Using high‐throughput calculations from first principles and effective medium theory, a large class of layered materials with hyperbolic optical activity in the near‐IR and visible range is explored, and a reduced number of ultrasoft and hard HMMs is identified among more than 1800 combinations of transition metal rocksalt crystals. Once validated by the experiments, this new class of metamaterials may foster previously unexplored optical/mechanical applications.

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“…We investigate in more details the optical properties of HfN/ScN, that we assume as the reference for this class of TMX multilayers. HfN/ScN has been experimentally grown [71,72] and behaves as both type-I and type-II material, depending on the energy of the incoming radiation. Figure 5b shows the real and imaginary part of both parallel ˜ and perpendicular ˜ ⊥ components of the effective dielectric function (Eq.…”

Section: Resultsmentioning

confidence: 99%

Hyperbolic metamaterials with extreme mechanical hardness

Calzolari¹,

Catellani²,

Nardelli³

et al. 2021

Preprint

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Hyperbolic metamaterials (HMMs) are highly anisotropic optical materials that behave as metals or as dielectrics depending on the direction of propagation of light. They are becoming essential for a plethora of applications, ranging from aerospace to automotive, from wireless to medical and IoT. These applications often work in harsh environments or may sustain remarkable external stresses. This calls for materials that show enhanced optical properties as well as tailorable mechanical properties. Depending on their specific use, both hard and ultrasoft materials could be required, although the combination with optical hyperbolic response is rarely addressed. Here, we demonstrate the possibility to combine optical hyperbolicity and tunable mechanical properties in the same (meta)material, focusing on the case of extreme mechanical hardness. Using high-throughput calculations from first principles and effective medium theory, we explored a large class of layered materials with hyperbolic optical activity in the near-IR and visible range, and we identified a reduced number of ultrasoft and hard HMMs among more than 1800 combinations of transition metal rocksalt crystals. Once validated by the experiments, this new class of metamaterials may foster previously unexplored optical/mechanical applications.

show abstract

Phononic bandgap and phonon anomalies in HfN and HfN/ScN metal/semiconductor superlattices measured with inelastic x-ray scattering

Abstract: This is a copy of the published version, or version of record, available on the publisher's website. This version does not track changes, errata, or withdrawals on the publisher's site.

Cited by 6 publications

References 48 publications

Near-UV-to-Near-IR Hyperbolic Photonic Dispersion in Epitaxial (Hf,Zr)N/ScN Metal/Dielectric Superlattices

Near-UV-to-Near-IR Hyperbolic Photonic Dispersion in Epitaxial (Hf,Zr)N/ScN Metal/Dielectric Superlattices

Hyperbolic Metamaterials with Extreme Mechanical Hardness

Hyperbolic metamaterials with extreme mechanical hardness

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