TiN/(Al,Sc)N metal/dielectric superlattices and multilayers as hyperbolic metamaterials in the visible spectral range

Saha, Bivas; Naik, Gururaj V.; Saber, Sammy; Akatay, Cem; Stach, Eric A.; Shalaev, Vladimir M.; Boltasseva, Alexandra; Sands, Timothy D.

doi:10.1103/physrevb.90.125420

Cited by 61 publications

(51 citation statements)

References 30 publications

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“…We recently developed the first epitaxial, single crystalline TiN/(Al,Sc)N metal/semiconductor superlattice 23,24,25 system that can be free of extended defects in a relaxed or nearly relaxed state. We analyzed the cross-plane thermal properties of these superlattices and observed an incoherent to long-wavelength coherent phonon regime transition (see Ref.…”

Section: Introductionmentioning

confidence: 99%

Cross-plane thermal conductivity of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices

et al. 2016

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Reduction of cross-plane thermal conductivity and understanding the mechanisms of heat transport in nanostructured metal/semiconductor superlattices are crucial for their potential applications in thermoelectric and thermionic energy conversion devices, thermal management systems, and thermal barrier coatings. We have developed epitaxial (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices with periodicity ranging from 1 nm to 240 nm that show significantly lower thermal conductivity compared to the parent TiN/(Al,Sc)N superlattice system. The (Ti,W)N/(Al,Sc)N superlattices grow with [001] orientation on the MgO(001) substrates with well defined coherent layers and are nominally single crystalline with low densities of extended defects. Cross-plane thermal conductivity (measured by time-domain thermoreflectance (TDTR)) decreases with an increase in the superlattice interface density in a manner that is consistent with incoherent phonon boundary scattering. Thermal conductivity values saturate at 1.7 W/m-K for short superlattice periods possibly due to a delicate balance between long wavelength coherent phonon modes and incoherent phonon scattering from heavy tungsten (W) atomic sites and superlattice interfaces. First-principles density functional theory based calculations are performed to model the vibrational spectrum of the individual component materials and transport models are used to explain the interface thermal conductance (ITC) across the (Ti,W)N/(Al,Sc)N interfaces as a function of periodicity. The long-wavelength coherent phonon modes are expected to play a dominant role in the thermal transport properties of the short-period superlattices. Our analysis of the thermal transport properties of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices addresses fundamental questions about heat transport in multi-layer materials.

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Section: Introductionmentioning

confidence: 99%

Cross-plane thermal conductivity of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices

et al. 2016

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“…Figure 2 shows the real and imaginary part of the dielectric permittivities of the TiN and Al 0.72 Sc 0.28 N films, respectively, demonstrating that TiN becomes plasmonic with negative real permittivities (e 0 ) above 500 nm spectral range. Due to its lower carrier concentration and mobilities with respect to the noble metals such as Au and Ag (the carrier concentration of sputter deposited TiN thin film is about 3.3 9 10 22 cm -3 , while traditional plasmonic materials like Au and Ag have carrier concentrations in the 5.9 9 10 22 -8 9 10 22 cm -3 ranges), the e 0 of TiN decreases rather slowly [29].…”

Section: Resultsmentioning

confidence: 99%

“…In addition to its high chemical and thermal stability, a TiN/(Al,Sc)N multilayer architecture with metal/dielectric interfaces has been proven a promising hyperbolic metamaterial in the visible spectral range and demonstrated large enhancement of its densities of photon states which could be useful in various quantum electronic and optoelectronic applications [29,30].…”

Section: Introductionmentioning

confidence: 99%

Tailoring of surface plasmon resonances in TiN/(Al0.72Sc0.28)N multilayers by dielectric layer thickness variation

et al. 2017

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Alternative designs of plasmonic metamaterials for applications in solar energyharvesting devices are necessary due to pure noble metal-based nanostructures' incompatibility with CMOS technology, limited thermal and chemical stability, and high losses in the visible spectrum. In the present study, we demonstrate the design of a material based on a multilayer architecture with systematically varying dielectric interlayer thicknesses that result in a continuous shift of surface plasmon energy. Plasmon resonance characteristics of metal/semiconductor TiN/(Al,Sc)N multilayer thin films with constant TiN and increasing (Al,Sc)N interlayer thicknesses were analyzed using aberration-corrected and monochromated scanning transmission electron microscopy-based electron energy loss spectroscopy (EELS). EEL spectrum images and line scans were systematically taken across layer interfaces and compared to spectra from the centers of the respective adjacent TiN layer. While a constant value for the TiN bulk plasmon resonance of about 2.50 eV was found, the surface plasmon resonance energy was detected to continuously decrease with increasing (Al,Sc)N interlayer thickness until 2.16 eV is reached. This effect can be understood to be the result of resonant coupling between the TiN bulk and surface plasmons across the dielectric interlayers at very low (Al,Sc)N thicknesses. That energy interval between bulk and decreasing surface plasmon resonances corresponds to wavelengths in the visible spectrum. This shows the potential of tailoring the material's plasmonic response by controlling the (Al,Sc)N interlayer thickness,

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“…This is a consequence of the repeated resonant behavior of many possible electronic transitions up to the X-ray region, therefore, the refraction index for HfN/VN was determined by Eq. (4) [11,27,28]:…”

Section: Structural Analysis Via Transmission Electron Microscopy (Tem)mentioning

confidence: 99%

Heterostructures design for Hf-Nitride/V-Nitride system

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et al. 2015

Journal of Physics and Chemistry of Solids

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TiN/(Al,Sc)N metal/dielectric superlattices and multilayers as hyperbolic metamaterials in the visible spectral range

Cited by 61 publications

References 30 publications

Cross-plane thermal conductivity of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices

Cross-plane thermal conductivity of (Ti,W)N/(Al,Sc)N metal/semiconductor superlattices

Tailoring of surface plasmon resonances in TiN/(Al0.72Sc0.28)N multilayers by dielectric layer thickness variation

Heterostructures design for Hf-Nitride/V-Nitride system

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