A5030900375- Photonic and Optical Devices
- Plasmonic and Surface Plasmon Research
- Semiconductor Quantum Structures and Devices
- Advanced Condensed Matter Physics
- Photonic Crystals and Applications
- Spectroscopy and Laser Applications
- Physics of Superconductivity and Magnetism
- Mechanical and Optical Resonators
- Photoreceptor and optogenetics research
- Magnetic and transport properties of perovskites and related materials
- Transition Metal Oxide Nanomaterials
- Terahertz technology and applications
- Strong Light-Matter Interactions
- Nanowire Synthesis and Applications
- Graphene research and applications
- Chalcogenide Semiconductor Thin Films
- Advanced Semiconductor Detectors and Materials
- Thermography and Photoacoustic Techniques
- Advanced Fiber Laser Technologies
- Semiconductor Lasers and Optical Devices
- High-pressure geophysics and materials
- Near-Field Optical Microscopy
- Iron-based superconductors research
- Optical Coatings and Gratings
- Catalysis and Oxidation Reactions
Sapienza University of Rome
2015-2024
Leibniz Institute for High Performance Microelectronics
2020-2022
Helmholtz-Zentrum Dresden-Rossendorf
2022
National Academy of Sciences of Ukraine
2022
University of Nottingham
2022
Stuttgart Observatory
2022
Friedrich-Alexander-Universität Erlangen-Nürnberg
2022
Walter de Gruyter (Germany)
2022
Naver (South Korea)
2022
Technical University of Darmstadt
2022
Midinfrared plasmonic sensing allows the direct targeting of unique vibrational fingerprints molecules. While gold has been used almost exclusively so far, recent research focused on semiconductors with potential to revolutionize devices. We fabricate antennas out heavily doped Ge films epitaxially grown Si wafers and demonstrate up 2 orders magnitude signal enhancement for molecules located in antenna hot spots compared those a bare silicon substrate. Our results set new path toward...
Raman and combined trasmission reflectivity mid infrared measurements have been carried out on monoclinic VO$_2$ at room temperature over the 0-19 GPa 0-14 pressure ranges, respectively. The dependence obtained for both lattice dynamics optical gap shows a remarkable stability of system up to P*$\sim$10 GPa. Evidence subtle modifications V ion arrangements within together with onset metallization process via band filling are observed P$>$P*. Differently from ambient pressure, where metal...
Heavily-doped semiconductor films are very promising for application in mid-infrared plasmonic devices because the real part of their dielectric function is negative and broadly tunable this wavelength range. In work we investigate heavily n-type doped germanium epilayers grown on different substrates, in-situ $10^{17}$ to $10^{19}$ cm$^{-3}$ range, by infrared spectroscopy, first principle calculations, pump-probe spectroscopy dc transport measurements determine relation between plasma edge...
Hexagonal boron nitride (hBN) is widely used as a protective layer for few-atom-thick crystals and heterostructures (HSs), it hosts quantum emitters working up to room temperature. In both instances, strain expected play an important role, either unavoidable presence in the HS fabrication or tool tune emitter electronic properties. Addressing role of exploiting its tuning potentiality require development efficient methods control reliable tools quantify it. Here we present technique based on...
The optical conductivity and the spectral weight of four topological insulators with increasing chemical compensation (Bi2Se3, Bi2-xCaxSe3, Bi2Se2Te, Bi2Te2Se) have been measured from 5 to 300 K sub-THz visible frequencies. effect is clearly observed in infrared spectra, through suppression an extrinsic Drude term appearance strong absorption peaks, that we assign electronic transitions among localized states. From far-infrared most compensated sample (Bi2Te2Se) one can estimate a density...
We demonstrate that the onset of complex spin orders in ACr2O4 spinels with magnetic and Jahn-Teller active A=Fe Cu ions lowers lattice symmetry. This is clearly indicated by emergence anisotropic dynamics-i.e., pronounced phonon splittings-even when experiments probing static distortions fail. The crystal symmetry phase reduced from tetragonal to orthorhombic for both compounds. conical ordering FeCr2O4 also manifested hardening frequencies. In contrast, multiferroic CoCr2O4 no orbital...
Germanium-on-silicon waveguides were modeled, fabricated and characterized at wavelengths ranging from 7.5 to 11 µm.Measured waveguide losses are below 5 dB/cm for both TE TM polarization reach values of ∼ 1 ≥ 10 µm the polarization.This work demonstrates experimentally first time that Ge-on-Si is a viable platform sensing in molecular fingerprint spectral region.Detailed modeling analysis presented identify various loss contributions, showing with practical techniques could be achieved...
Infrared (IR) nanospectroscopy performed in conjunction with atomic force microscopy (AFM) is a novel, label-free spectroscopic technique that meets the increasing request for nano-imaging tools chemical specificity field of life sciences. In novel resonant version AFM-IR, mid-IR wavelength-tunable quantum cascade laser illuminates sample below an AFM tip working contact mode, and repetition rate pulses matches cantilever mechanical resonance frequency. The AFM-IR signal amplitude...
Few-layer graphene possesses low-energy carriers that behave as massive Fermions, exhibiting intriguing properties in both transport and light scattering experiments. Lowering the excitation energy of resonance Raman spectroscopy down to 1.17 eV, we target these quasiparticles split bands close K point. The low weakens some processes are resonant visible, induces a clearer frequency-separation substructures 2D peak bi- trilayer samples. We follow excitation-energy dependence intensity each...
The infrared conductivity of ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ is measured in the whole phase diagram. Quasiparticles appear above N\'eel temperature ${T}_{N}$ and eventually disappear further enhancing temperature, leading to a pseudogap optical spectrum $425\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. Our calculations demonstrate that this loss coherence can be explained only if dependence lattice parameters considered. therefore effectively driven from ``metallic'' ``insulating'' side Mott...
We measure the ultrafast recombination of photoexcited quasiparticles (holon-doublon pairs) in one dimensional Mott insulator $\mathrm{ET}--{\mathrm{F}}_{2}\mathrm{TCNQ}$ as a function external pressure, which is used to tune electronic structure. At each pressure value, we first fit static optical properties and extract bandwidth $t$ intersite correlation energy $V$. then times correlate them with corresponding microscopic parameters. find that scale differently than for metals...
Photosensitive proteins embedded in the cell membrane (about 5 nm thickness) act as photoactivated proton pumps, ion gates, enzymes, or more generally, initiators of stimuli for activity. They are composed a protein backbone and covalently bound cofactor (e.g. retinal chromophore bacteriorhodopsin (BR), channel rhodopsin, other opsins). The light-induced conformational changes both at basis physiological functions photosensitive proteins. Despite dramatic development microscopy techniques,...
We report on resonance Raman spectroscopy measurements with excitation photon energy down to 1.16 eV graphene, study how low-energy carriers interact lattice vibrations. Thanks the close Dirac point at K, we unveil a giant increase of intensity ratio between double-resonant 2D and 2D′ peaks respect that measured in graphite. Comparing fully ab initio theoretical calculations, conclude observation is explained by an enhanced, momentum-dependent coupling electrons Brillouin zone-boundary...
We review the optical properties of three vanadium oxide compounds V2O3, VO2 and V3O5, belonging to so-called Magnéli phase. Their electrodynamics across a metal insulator transition is investigated as function both temperature pressure. analyse thoroughly results, with special emphasis on infrared spectral weight. This allows us discuss nature mechanisms driving phase transitions in compounds, pointing out role electron–electron electron–phonon interactions various cases.
The origin of the gap in NiS2 as well pressure- and doping-induced metal-insulator transition NiS2-xSex solid solutions are investigated both theoretically using first-principles band structures combined with dynamical mean-field approximation for electronic correlations experimentally by means infrared x-ray absorption spectroscopies. bonding-antibonding splitting S-S (Se-Se) dimer is identified main parameter controlling size charge gap. implications driven pressure Se doping discussed.
We investigate the pressure dependence of optical properties ${\mathrm{CeTe}}_{3}$, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in midinfrared spectral range room temperature and pressures between 0 9 GPa. The energy for single particle excitation across CDW gap decreases upon increasing applied pressure, similarly to chemical by rare-earth substitution. broadening bands lattice compression removes perfect nesting condition Fermi...
Heavily-boron-doped diamond films become superconducting with critical temperatures $T_c$ well above 4 K. Here we first measure the reflectivity of such a film down to 5 cm$^{-1}$, by also using Coherent Synchrotron Radiation. We thus determine optical gap, field penetration depth, range action Ferrell-Glover-Tinkham sum rule, and electron-phonon spectral function. conclude that behaves as dirty BCS superconductor.
Abstract Cell membranes are intrinsically heterogeneous, as the local protein and lipid distribution is critical to physiological processes. Even in template systems embedding a single type, like purple membranes, there can be different response external stimuli or environmental factors, resulting heterogeneous conformational changes. Despite dramatic advances of microspectroscopy techniques, identification conformation heterogeneity still challenging task. Tip‐enhanced infrared...
Recent efforts in the field of surface-enhanced spectroscopies have focused on paradigm "superchirality", entailing engineering local electromagnetic fields to boost enantiospecific interaction between light and chiral molecules. In this framework, approaches based both metallic dielectric nanostructures been proposed also recently extended vibrational circular dichroism mid-infrared. work, we design, fabricate, characterize a lattice plasmonic slits featuring enhanced We exploit collective...
We report the direct observation of transition from type I to II in (GaAs${)}_{\mathrm{m}}$/(AlAs${)}_{\mathrm{n}}$ ultra-short-period superlattices with m=n by means photoacoustic spectroscopy and high-excitation-intensity photoluminescence. The is found occur when constituent superlattice layers have a critical thickness about 12 monolayers (m=n=12). Different temperature dependences type-I type-II recombinations are observed, which tentatively ascribed thermal transfer carriers between...
In this work we present an integrated biosensor that enables FTIR (Fourier Transform-Infrared) detection of analytes contained in diluted solutions.
High n-type doping in germanium is essential for many electronic and optoelectronic applications especially high performance Ohmic contacts, lasing mid-infrared plasmonics.We report on the combination of in-situ excimer laser annealing to improve activation phosphorous germanium.An activated n-doping concentration 8.8x10 19 cm -3 has been achieved starting from an incorporated 1.1x10 20 .Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over 350 nm...
Vanadium sesquioxide V2O3 is considered a textbook example of Mott-Hubbard physics. In this paper we present an extended optical study its whole temperature/doping phase diagram as obtained by doping the pure material with M=Cr or Ti atoms (V1-xMx)2O3. We reveal that thermodynamically stable metallic and insulating phases, although macroscopically equivalent, show very different low-energy electrodynamics. The Cr drastically change both antiferromagnetic gap paramagnetic properties. A slight...