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Dual-rate L1 adaptive controller for cyber-physical sampled-data systems
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Ti0.5Mg0.5N has recently been predicted to be a semiconductor with a 1.3 eV band gap and promising properties for thermoelectric and plasmonic devices. As a first step towards experimental validation, epitaxial Ti0.5Mg0.5N(001) layers are deposited on MgO(001) by reactive magnetron co-sputtering from titanium and magnesium targets at 600 °C in pure N2 atmospheres. X-ray diffraction ω-2θ scans, ω-rocking curves, φ-scans, and high resolution reciprocal space maps show that Ti0.5Mg0.5N alloys form a pseudobinary rocksalt structure and are single crystals with a cube-on-cube epitaxial relationship with the substrate: (001)TiMgN║(001)MgO and [100]TiMgN║[100]MgO. A 275-nm-thick Ti0.5Mg0.5N layer is fully relaxed and exhibits a 002 ω-rocking curve width ω = 0.73°, while a 36-nm-thick layer is fully strained and has a ω = 0.49°. These results indicate a thickness-dependent strain state which suggests a critical thickness for misfit dislocation nucleation and glide which is between 36 and 275 nm. A measured negative temperature coefficient of resistivity in combination with a low optical absorption coefficient of 0.25 × 105 cm 1 for λ = 740 nm, and a vanishing density of states at the Fermi level measured by x-ray photoelectron spectroscopy support the prediction that Ti0.5Mg0.5N is a semiconductor.more » « less
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The development of active metadevices continues to present keystone challenges in fields of plasmonics and photonics. Here, we demonstrate an analogue of electromagnetically induced transparency (EIT) effect in a far-infrared metasurface device via near-field coupling of bright and quasi-dark resonances resonating at nearly the same frequency with contrasting line widths. The proposed metasurface was further optimized numerically in order to demonstrate a reconfiguration effect (frequency-shift of the spectral response). The tunability property of the device is achieved by incorporating a thin layer of Ge 2 Sb 2 Te 5 (GST), a temperature-driven phase change material (PCM). Theoretical analysis based on a coupled Lorentz oscillator model explains the physical mechanism in the proposed design and shows a good agreement with the observed results. Such active hybrid EIT metadevices could have applications in tunable slow-light effects, delay bandwidth management and ultrafast laser induced switching.more » « less
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/CDC.2017.8264602
