91 results on '"Domenico Pacifici"'
Search Results
2. Plasmonic Interferometers as TREM2 Sensors for Alzheimer’s Disease
- Author
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Dingdong Li, Rachel Odessey, Dongfang Li, and Domenico Pacifici
- Subjects
TREM2 sensors ,Alzheimer’s disease ,plasmonic interferometry ,optical biosensor ,surface functionalization ,Biotechnology ,TP248.13-248.65 - Abstract
We report an effective surface immobilization protocol for capture of Triggering Receptor Expressed on Myeloid Cells 2 (TREM2), a receptor whose elevated concentration in cerebrospinal fluid has recently been associated with Alzheimer’s disease (AD). We employ the proposed surface functionalization scheme to design, fabricate, and assess a biochemical sensing platform based on plasmonic interferometry that is able to detect physiological concentrations of TREM2 in solution. These findings open up opportunities for label-free biosensing of TREM2 in its soluble form in various bodily fluids as an early indicator of the onset of clinical dementia in AD. We also show that plasmonic interferometry can be a powerful tool to monitor and optimize surface immobilization schemes, which could be applied to develop other relevant antibody tests.
- Published
- 2021
- Full Text
- View/download PDF
3. Arrays of Plasmonic Nanostructures for Absorption Enhancement in Perovskite Thin Films
- Author
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Tianyi Shen, Qiwen Tan, Zhenghong Dai, Nitin P. Padture, and Domenico Pacifici
- Subjects
perovskite solar cells ,surface plasmon polaritons ,plasmonic nanostructures ,absorption enhancement ,FDTD simulations ,Chemistry ,QD1-999 - Abstract
We report optical characterization and theoretical simulation of plasmon enhanced methylammonium lead iodide (MAPbI 3 ) thin-film perovskite solar cells. Specifically, various nanohole (NH) and nanodisk (ND) arrays are fabricated on gold/MAPbI 3 interfaces. Significant absorption enhancement is observed experimentally in 75 nm and 110 nm-thick perovskite films. As a result of increased light scattering by plasmonic concentrators, the original Fabry–Pérot thin-film cavity effects are suppressed in specific structures. However, thanks to field enhancement caused by plasmonic resonances and in-plane interference of propagating surface plasmon polaritons, the calculated overall power conversion efficiency (PCE) of the solar cell is expected to increase by up to 45.5%, compared to its flat counterpart. The role of different geometry parameters of the nanostructure arrays is further investigated using three dimensional (3D) finite-difference time-domain (FDTD) simulations, which makes it possible to identify the physical origin of the absorption enhancement as a function of wavelength and design parameters. These findings demonstrate the potential of plasmonic nanostructures in further enhancing the performance of photovoltaic devices based on thin-film perovskites.
- Published
- 2020
- Full Text
- View/download PDF
4. High-purity red coloration via mode-selective absorption in a layered thin-film cavity
- Author
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De He, Zhijun Liu, Gustavo E. Fernandes, Tianyi Shen, Declan Oller, Domenico Pacifici, Jin Ho Kim, and Jimmy Xu
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Physics ,QC1-999 - Abstract
Physical coloration without chemicals offers a pathway to develop pollution-free coloration technology, and can be applied to colorimetric sensing of gases, toxic and chemical agents. In this paper, we report on realization of a high-purity red color using mechanism of mode-selective absorption in a thin-film optical cavity. By placing an ultra-thin absorber layer at the antinode of a targeted spectral band in a Fabry-Perot cavity, its otherwise conventional dichroic reflection spectrum is shaped into a broad rectangular flat-bottom one that gives the desired vivid red. The purity of our demonstrated red color reaches 76%, which is increased by 16% compared with those reported in prior thin-film structures. Our method of mode-selective absorption is adaptable to more general-purpose spectral shaping, and could be applied in producing other target colors as well as broadband light absorption for energy harvesting and infrared detection.
- Published
- 2018
- Full Text
- View/download PDF
5. Reduced angle sensitivity of structural coloration on an industrial aluminium platform
- Author
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Jin Ho Kim, De He, Declan Oller, Jimmy Xu, Domenico Pacifici, Tianyi Shen, and Rachel Odessey
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Materials science ,chemistry ,Chemistry (miscellaneous) ,Aluminium ,Materials Science (miscellaneous) ,General Chemical Engineering ,chemistry.chemical_element ,Sensitivity (control systems) ,Composite material ,Structural coloration - Published
- 2020
6. Plasmonic Interferometers as TREM2 Sensors for Alzheimer’s Disease
- Author
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Dongfang Li, Domenico Pacifici, Dingdong Li, and Rachel Odessey
- Subjects
Materials science ,Clinical Biochemistry ,Nanotechnology ,Article ,TREM2 sensors ,03 medical and health sciences ,0302 clinical medicine ,plasmonic interferometry ,Alzheimer Disease ,Astronomical interferometer ,Humans ,Receptors, Immunologic ,Plasmon ,030304 developmental biology ,surface functionalization ,0303 health sciences ,Membrane Glycoproteins ,optical biosensor ,TREM2 ,Brain ,General Medicine ,Interferometry ,Myeloid cells ,Surface modification ,Effective surface ,Biosensor ,Alzheimer’s disease ,TP248.13-248.65 ,030217 neurology & neurosurgery ,Biotechnology - Abstract
We report an effective surface immobilization protocol for capture of Triggering Receptor Expressed on Myeloid Cells 2 (TREM2), a receptor whose elevated concentration in cerebrospinal fluid has recently been associated with Alzheimer’s disease (AD). We employ the proposed surface functionalization scheme to design, fabricate, and assess a biochemical sensing platform based on plasmonic interferometry that is able to detect physiological concentrations of TREM2 in solution. These findings open up opportunities for label-free biosensing of TREM2 in its soluble form in various bodily fluids as an early indicator of the onset of clinical dementia in AD. We also show that plasmonic interferometry can be a powerful tool to monitor and optimize surface immobilization schemes, which could be applied to develop other relevant antibody tests.
- Published
- 2021
7. High-performance germanium quantum dot photodetectors in the visible and near infrared
- Author
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Dongfang Li, Alexander Zaslavsky, Aravind A.V.P.S, Stylianos Siontas, Haobei Wang, and Domenico Pacifici
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010302 applied physics ,Materials science ,business.industry ,Mechanical Engineering ,Photoconductivity ,Photodetector ,chemistry.chemical_element ,Germanium ,02 engineering and technology ,Specific detectivity ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Active layer ,chemistry ,Mechanics of Materials ,Quantum dot ,0103 physical sciences ,Figure of merit ,Optoelectronics ,General Materials Science ,Quantum efficiency ,0210 nano-technology ,business - Abstract
We present our work on high performance germanium (Ge) quantum dot (QD) photodetectors (PDs), fabricated on Si and Ge substrates, that operate via tunneling transport through a QD-containing active layer and feature high internal photoconductive gain. In the λ = 400–1100 nm range, the PDs fabricated on Si substrates exhibit room-temperature spectral responsivity ( R sp ) up to 4 A/W and internal quantum efficiency (IQE) up to 700%. At λ = 640 nm and 12 μ W of incident power, signal-to-noise ratio (SNR) of 7 × 10 6 and specific detectivity ( D * ) of 1.2×1011 cmHz1/2W−1 are obtained. The PDs demonstrate 3 dB bandwidths (f3dB) up to 10 MHz, corresponding to response times of ∼ 40 ns. When operated at 100 K temperature the performance improves, especially at low incident power, where at 10 nW D * increases to 2 × 10 13 cmHz1/2W−1, due to IQE in excess of 22000%. In order to extend the photoresponse into the near-infrared (near-IR), PDs were fabricated on Ge substrates, yielding room-temperature R sp = 1.5 A/W, IQE = 134% and f3dB = 10 kHz at the λ = 1550 nm telecommunication wavelength. Significant improvement to f3dB is expected in PDs employing thinner QD-containing layers. Lowering temperature to 50 K and incident power to 10 nW yield D* = 1013 cmHz1/2W−1, resulting from IQE exceeding 60000%. Based on the above figures of merit, as well as their Si technology compatibility, our Ge QD PDs appear promising for high-performance photodetectors working in the visible and near-IR.
- Published
- 2019
8. Highly stable and efficient all-inorganic lead-free perovskite solar cells with native-oxide passivation
- Author
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Tianyi Shen, Luis K. Ono, Yabing Qi, Alexander D. Carl, Hector F. Garces, Xiao Cheng Zeng, Domenico Pacifici, Ronald L. Grimm, Ming-Gang Ju, Zafer Hawash, Yuanyuan Zhou, Min Chen, Nitin P. Padture, and Yi Zhang
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0301 basic medicine ,Materials science ,Passivation ,Science ,General Physics and Astronomy ,chemistry.chemical_element ,Halide ,Germanium ,02 engineering and technology ,7. Clean energy ,Article ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,chemistry.chemical_compound ,Triiodide ,lcsh:Science ,Perovskite (structure) ,Multidisciplinary ,business.industry ,Photovoltaic system ,General Chemistry ,021001 nanoscience & nanotechnology ,030104 developmental biology ,chemistry ,Optoelectronics ,lcsh:Q ,Chemical stability ,0210 nano-technology ,business ,Tin - Abstract
There has been an urgent need to eliminate toxic lead from the prevailing halide perovskite solar cells (PSCs), but the current lead-free PSCs are still plagued with the critical issues of low efficiency and poor stability. This is primarily due to their inadequate photovoltaic properties and chemical stability. Herein we demonstrate the use of the lead-free, all-inorganic cesium tin-germanium triiodide (CsSn0.5Ge0.5I3) solid-solution perovskite as the light absorber in PSCs, delivering promising efficiency of up to 7.11%. More importantly, these PSCs show very high stability, with less than 10% decay in efficiency after 500 h of continuous operation in N2 atmosphere under one-sun illumination. The key to this striking performance of these PSCs is the formation of a full-coverage, stable native-oxide layer, which fully encapsulates and passivates the perovskite surfaces. The native-oxide passivation approach reported here represents an alternate avenue for boosting the efficiency and stability of lead-free PSCs., Replacing the toxic lead in the state-of-the-art halide perovskite solar cells is highly desired but the device performance and stability are usually compromised. Here Chen et al. develop inorganic cesium tin and germanium mixed-cation perovskites that show high operational stability and efficiency over 7%.
- Published
- 2019
9. Arrays of Plasmonic Nanostructures for Absorption Enhancement in Perovskite Thin Films
- Author
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Qiwen Tan, Nitin P. Padture, Tianyi Shen, Zhenghong Dai, and Domenico Pacifici
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Materials science ,business.industry ,General Chemical Engineering ,Energy conversion efficiency ,surface plasmon polaritons ,Surface plasmon polariton ,perovskite solar cells ,Article ,Light scattering ,FDTD simulations ,law.invention ,lcsh:Chemistry ,plasmonic nanostructures ,absorption enhancement ,lcsh:QD1-999 ,law ,Solar cell ,Optoelectronics ,General Materials Science ,Thin film ,business ,Absorption (electromagnetic radiation) ,Plasmon ,Perovskite (structure) - Abstract
We report optical characterization and theoretical simulation of plasmon enhanced methylammonium lead iodide (MAPbI 3 ) thin-film perovskite solar cells. Specifically, various nanohole (NH) and nanodisk (ND) arrays are fabricated on gold/MAPbI 3 interfaces. Significant absorption enhancement is observed experimentally in 75 nm and 110 nm-thick perovskite films. As a result of increased light scattering by plasmonic concentrators, the original Fabry&ndash, Pé, rot thin-film cavity effects are suppressed in specific structures. However, thanks to field enhancement caused by plasmonic resonances and in-plane interference of propagating surface plasmon polaritons, the calculated overall power conversion efficiency (PCE) of the solar cell is expected to increase by up to 45.5%, compared to its flat counterpart. The role of different geometry parameters of the nanostructure arrays is further investigated using three dimensional (3D) finite-difference time-domain (FDTD) simulations, which makes it possible to identify the physical origin of the absorption enhancement as a function of wavelength and design parameters. These findings demonstrate the potential of plasmonic nanostructures in further enhancing the performance of photovoltaic devices based on thin-film perovskites.
- Published
- 2020
- Full Text
- View/download PDF
10. Plasmon-Enhanced Thin-Film Perovskite Solar Cells
- Author
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Stylianos Siontas, Domenico Pacifici, and Tianyi Shen
- Subjects
chemistry.chemical_classification ,Materials science ,business.industry ,Iodide ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,General Energy ,chemistry ,Optoelectronics ,Physical and Theoretical Chemistry ,Thin film ,0210 nano-technology ,business ,Plasmon ,Perovskite (structure) - Abstract
We report on plasmon-enhanced hybrid organic–inorganic perovskite solar cells with methylammonium lead iodide (MAPbI3) as the active absorbing material. Three-dimensional finite-difference time-dom...
- Published
- 2018
11. Colour gamuts arising from absorber–dielectric–metal optical resonators
- Author
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Jin Ho Kim, De He, Domenico Pacifici, Jimmy Xu, Declan Oller, and Gustavo E. Fernandes
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Materials science ,business.industry ,Materials Science (miscellaneous) ,General Chemical Engineering ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,01 natural sciences ,010309 optics ,Metal ,Resonator ,Chemistry (miscellaneous) ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,Optoelectronics ,0210 nano-technology ,business - Published
- 2017
12. Scalable physical coloration
- Author
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Gustavo E. Fernandes, Jimmy Xu, Declan Oller, Domenico Pacifici, and Stylianos Siontas
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Materials science ,Anodizing ,business.industry ,Mechanical Engineering ,chemistry.chemical_element ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Resonant scattering ,0104 chemical sciences ,chemistry ,Colored ,Interference (communication) ,Mechanics of Materials ,Aluminium ,Optoelectronics ,General Materials Science ,0210 nano-technology ,Absorption (electromagnetic radiation) ,business ,Carbon ,Plasmon - Abstract
Methods to produce colored surfaces using physical mechanisms are proposed, with aluminum used as a demonstration vehicle. Our approach aims to achieve tunable, vibrant colors through the interaction of three well-established physical mechanisms of color formation, namely (1) resonant scattering and interference effects in a nano-structured surface (e.g. via anodization of aluminum), (2) plasmonic resonances in metal nanoparticles, and (3) spectrally selective absorption enhancement in ultrathin films, such as amorphous germanium and carbon. We provide proof-of-concept by fabricating and characterizing representative aluminum-based samples showing vivid colors throughout the visible spectral range.
- Published
- 2016
13. Revisiting the Photon-Drag Effect in Metal Films
- Author
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Cheng Zhang, Jared H. Strait, Henri J. Lezec, Domenico Pacifici, Amit Agrawal, Glenn Holland, and Wenqi Zhu
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Free electron model ,Physics ,Surface (mathematics) ,Photon ,Condensed matter physics ,Gold film ,Momentum transfer ,01 natural sciences ,010305 fluids & plasmas ,Metal ,Drag ,visual_art ,0103 physical sciences ,visual_art.visual_art_medium ,010306 general physics ,Sign (mathematics) - Abstract
We demonstrate that the sign of the photon-drag effect in smooth gold films is crucially dependent on the surface environment and contrary to the prevailing intuitive model of direct momentum transfer to free electrons.
- Published
- 2019
14. Determining the Nature of Optical Forces with the Photon-Drag Effect
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Wei Zhou, Jared H. Strait, Christian Haffner, B. Robert Ilic, Cheng Zhang, Amit Agrawal, Junyeob Song, Wenqi Zhu, Domenico Pacifici, Henri J. Lezec, and Glenn Holland
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Physics ,Electromagnetic theory ,Photon ,Optical force ,02 engineering and technology ,Mechanics ,021001 nanoscience & nanotechnology ,01 natural sciences ,010309 optics ,Momentum ,Radiation pressure ,Optical tweezers ,Drag ,Electric field ,0103 physical sciences ,0210 nano-technology - Abstract
The photovoltage generated in metal films conflicts with the prevailing intuitive model of light-metal momentum exchange, establishing the need for a new microscopic model of radiation pressure, and newly revealing the distribution of optical forces.
- Published
- 2019
15. High-performance germanium quantum dot photodetectors: Response to continuous wave and pulsed excitation
- Author
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Su-Fei Shi, Alexander Zaslavsky, and Domenico Pacifici
- Subjects
010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Photodetector ,02 engineering and technology ,Nanosecond ,021001 nanoscience & nanotechnology ,Laser ,01 natural sciences ,Active layer ,law.invention ,Quantum dot ,law ,0103 physical sciences ,Optoelectronics ,Continuous wave ,Figure of merit ,Quantum efficiency ,0210 nano-technology ,business - Abstract
Efficiency and response speed are key figures of merit for high-performance photodetectors, with high efficiency often obtained at the expense of slow photoresponse. Here, we report on germanium quantum dot photodetectors (Ge QD PDs) with a 25-nm-thick active layer that possesses both high internal quantum efficiency (IQE) and fast photoresponse, yet is still based on simple design and fabrication. We characterize these devices with continuous wave (CW) and pulsed excitation at room temperature as a function of incident power and applied bias. Under the reverse bias of –4 V, the IQE approaches ∼2000% over a broad spectral range (λ = 500–800 nm). The transient photoresponse speed to a 4.5 ns laser pulse at λ = 640 nm is under 20 ns. Furthermore, we observe an interesting phenomenon: by superimposing a weak CW HeNe laser beam ( λ = 632.8 nm) on the laser pulse, we obtain an optically tunable photoresponse while retaining fast speed. This study elucidates the role of photocarrier generation, trapping, and hopping in the percolative Ge QD oxide matrix and helps explain the observed high gain and fast response speed. The demonstrated IQE and nanosecond response time render our devices suitable for low-light detection and imaging.
- Published
- 2020
16. Measuring subwavelength spatial coherence with plasmonic interferometry
- Author
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Drew Morrill, Domenico Pacifici, and Dongfang Li
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Physics ,business.industry ,Surface plasmon ,Physics::Optics ,02 engineering and technology ,Degree of coherence ,Coherence (statistics) ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,010309 optics ,Interferometry ,Wavelength ,Optics ,0103 physical sciences ,Light beam ,Image sensor ,0210 nano-technology ,business ,Plasmon - Abstract
Optical interferometry has enabled quantification of the spatial and temporal correlations of electromagnetic fields, which laid the foundations for the theory of optical coherence. Despite significant advances in fundamental theories and applications, the measurement of nanoscale coherence lengths for highly incoherent optical fields has remained elusive. Here, we employ plasmonic interferometry (that is, optical interferometry with surface plasmons) to characterize the spatial degree of coherence of light beams down to subwavelength scales, with measured coherence lengths as low as ∼330 nm for an incident wavelength of 500 nm. Furthermore, we demonstrate a compact coherence meter that integrates this method with an image sensor. Precise determination of spatial coherence can advance high-resolution imaging and tomographic schemes, and provide an experimental platform for the development and testing of optical coherence theories at the nanoscale. Surface plasmon interferometry is used to measure the spatial coherence at subwavelength scales.
- Published
- 2016
17. Revisiting the Photon-Drag Effect in Metal Films
- Author
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Amit Agrawal, Bojan R. Ilic, Cheng Zhang, Wenqi Zhu, Domenico Pacifici, Jared H. Strait, Glenn Holland, and Henri J. Lezec
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Free electron model ,Physics ,Photon ,Momentum transfer ,General Physics and Astronomy ,FOS: Physical sciences ,01 natural sciences ,Signal ,Article ,Radiation pressure ,Drag ,0103 physical sciences ,Current (fluid) ,Atomic physics ,010306 general physics ,Sign (mathematics) ,Physics - Optics ,Optics (physics.optics) - Abstract
The photon-drag effect, the rectified current in a medium induced by conservation of momentum of absorbed or redirected light, is a unique probe of the detailed mechanisms underlying radiation pressure. We revisit this effect in gold, a canonical Drude metal. We discover that the signal for p-polarized illumination in ambient air is affected in both sign and magnitude by adsorbed molecules, opening previous measurements for reinterpretation. Further, we show that the intrinsic sign of the photon-drag effect is contrary to the prevailing intuitive model of direct momentum transfer to free electrons., Comment: 12 pages, 4 figures
- Published
- 2018
- Full Text
- View/download PDF
18. Probing Light-Metal Interaction with the Photon-Drag Effect
- Author
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Jared H. Strait, B. Robert Ilic, Amit Agrawal, Domenico Pacifici, Henri J. Lezec, and Glenn Holland
- Subjects
Physics ,Free electron model ,Photon ,Radiation pressure ,Drag ,Surface plasmon ,Momentum transfer ,Electron ,Polarization (waves) ,Molecular physics - Abstract
We demonstrate that the sign of the photon-drag effect in smooth metal films conflicts with the prevailing intuitive model of direct momentum transfer to free electrons, establishing the need for a new microscopic model of radiation pressure.
- Published
- 2018
19. Revisiting the Photon-Drag Effect in Thin Metal Films
- Author
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Cheng Zhang, Glenn Holland, Domenico Pacifici, R. Ilic, Amit Agrawal, Jared H. Strait, Henri J. Lezec, and Wenqi Zhu
- Subjects
Free electron model ,Quantum optics ,Materials science ,Photon ,Condensed matter physics ,Drag ,Condensed Matter::Superconductivity ,Momentum transfer ,Surface plasmon ,Electron ,Thin film - Abstract
Using pristine metal films of Au, Cu, and Ni-doped Ag, we show that light-induced current flow – photon drag – has a fundamental sign that contradicts the intuitive, prevailing model of direct momentum transfer to free electrons
- Published
- 2018
20. Revisiting the Photon-Drag Effect in Thin Metal Films
- Author
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Henri J. Lezec, Jared H. Strait, Amit Agrawal, Domenico Pacifici, B. Robert Hic, and Glenn Holland
- Subjects
Free electron model ,Materials science ,Photon ,Condensed matter physics ,Surface plasmon ,Momentum transfer ,Electron ,01 natural sciences ,010309 optics ,Drag ,0103 physical sciences ,Thin film ,010306 general physics ,Plasmon - Abstract
We demonstrate that the sign of the photon-drag effect in smooth gold films is crucially dependent on the surface environment and contrary to the prevailing intuitive model of direct momentum transfer to free electrons.
- Published
- 2018
21. The Role of Coherence in Plasmonic Interferometry
- Author
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Domenico Pacifici
- Subjects
Physics ,Spatial coherence ,Interferometry ,Optics ,business.industry ,Surface plasmon ,Physics::Optics ,Optoelectronics ,Photonics ,business ,Plasmon ,Coherence (physics) - Abstract
Here we discuss methods that employ surface plasmons to measure and strongly modulate the degree of optical spatial coherence of light, paving the way for multifunctional optical elements beyond conventional refractive- and diffractive-based photonics metasurfaces.
- Published
- 2017
22. Higher-Order Surface Plasmon Contributions to Plasmonic Interferometry
- Author
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Dongfang Li, Domenico Pacifici, and Jing Feng
- Subjects
Physics ,business.industry ,Surface plasmon ,Astrophysics::Instrumentation and Methods for Astrophysics ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surface plasmon polariton ,Discrete Fourier transform ,010309 optics ,Interferometry ,Optics ,Interference (communication) ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Optoelectronics ,Surface plasmon resonance ,0210 nano-technology ,business ,Plasmon ,Localized surface plasmon - Abstract
We experimentally unveiled up to the sixth-order surface plasmon contributions to hole-groove plasmonic interferometry using discrete Fourier transform. This method is further extended to double-slit plasmonic structures to deconvolve competing interference effects from asymmetric interfaces.
- Published
- 2017
23. A 'plasmonic cuvette': dye chemistry coupled to plasmonic interferometry for glucose sensing
- Author
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Jing Feng, Domenico Pacifici, Siu Vince, G. Tayhas R. Palmore, and Patrick W. Flanigan
- Subjects
diabetes ,business.industry ,Chemistry ,glucose sensing ,Physics ,QC1-999 ,Glucose sensing ,amplex red ,Atomic and Molecular Physics, and Optics ,plasmonics ,Electronic, Optical and Magnetic Materials ,Cuvette ,Interferometry ,plasmonic interferometry ,kinetics ,Optoelectronics ,Electrical and Electronic Engineering ,business ,Plasmon ,Biotechnology - Abstract
A non-invasive method for the detection of glucose is sought by millions of diabetic patients to improve personal management of blood glucose over a lifetime. In this work, the synergistic advantage of combining plasmonic interferometry with an enzyme-driven dye assay yields an optical sensor capable of detecting glucose in saliva with high sensitivity and selectivity. The sensor, coined a “plasmonic cuvette,” is built around a nano-scale groove-slit-groove (GSG) plasmonic interferometer coupled to an Amplex–red/Glucose–oxidase/Glucose (AR/GOx/Glucose) assay. The proposed device is highly sensitive, with a measured intensity change of 1.7×105%/m (i.e., one order of magnitude more sensitive than without assay) and highly specific for glucose sensing in picoliter volumes, across the physiological range of glucose concentrations found in human saliva (20–240 μm). Real-time glucose monitoring in saliva is achieved by performing a detailed study of the underlying enzyme-driven reactions to determine and tune the effective rate constants in order to reduce the overall assay reaction time to ∼2 min. The results reported suggest that by opportunely choosing the appropriate dye chemistry, a plasmonic cuvette can be turned into a general, real-time sensing scheme for detection of any molecular target, with high sensitivity and selectivity, within extremely low volumes of biological fluid (down to femtoliters). Hereby, we present the results on glucose detection in artificial saliva as a notable and clinically relevant case study.
- Published
- 2014
24. Higher-order surface plasmon contributions to passive and active plasmonic interferometry
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Dongfang Li, Jing Feng, and Domenico Pacifici
- Subjects
Materials science ,business.industry ,Scattering ,Surface plasmon ,technology, industry, and agriculture ,Physics::Optics ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Diffraction efficiency ,01 natural sciences ,Surface plasmon polariton ,Atomic and Molecular Physics, and Optics ,010309 optics ,Interferometry ,Optics ,Dispersion relation ,0103 physical sciences ,Optoelectronics ,Plasmonic lens ,0210 nano-technology ,business ,Plasmon - Abstract
We compare the intensity modulation of passive light transmission and active fluorescence emission in planar plasmonic interferometers consisting of a nano-scale hole flanked by circular grooves etched in a silver film. Discrete fast Fourier transform applied to plasmonic interferograms – i.e., optical interferograms obtained by varying the propagation phase of surface plasmon polaritons (SPPs) – reveals higher-order interference effects that can be enhanced by optimizing in-plane SPP scattering and reflection. The experimental SPP dispersion relations agree with finite-difference frequency-domain calculations. Finally, we show that odd-order SPP contributions can be suppressed by reducing the spatial coherence of the incident beam.
- Published
- 2016
25. Quasiperiodic plasmonic concentrators for enhanced light absorption in ultra-thin film solar cells
- Author
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Natalie G. Serrino, Zhen Ye, Aminy E. Ostfeld, Patrick W. Flanigan, and Domenico Pacifici
- Subjects
Optics ,Materials science ,Organic solar cell ,business.industry ,Quasiperiodic function ,Rotational symmetry ,Optoelectronics ,Plasmonic solar cell ,Hybrid solar cell ,Thin film ,business ,Absorption (electromagnetic radiation) ,Plasmon - Abstract
This report will demonstrate broadband, wide-angle, and polarization-insensitive absorption enhancement in ultra-thin films resting on metal substrates that have been etched with arrays of shallow sub-wavelength cylindrical holes. Absorption enhancement will be studied as a function of array geometry, with particular emphasis given to quasiperiodic arrays (a class of deterministic aperiodic arrays that were originally developed to tessellate 2-D planes with regular polygons). Through simulations and experimental data, it was found that absorption enhancement is heavily dependent on the rotational symmetry of the pattern of holes, as well as the inter-hole distance.
- Published
- 2013
26. Nanoscale optical interferometry with incoherent light
- Author
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Domenico Pacifici, Dongfang Li, and Jing Feng
- Subjects
Light ,Computer science ,Nanoparticle ,02 engineering and technology ,Biosensing Techniques ,01 natural sciences ,Article ,010309 optics ,Optics ,Nanosensor ,0103 physical sciences ,Astronomical interferometer ,Surface plasmon resonance ,Plasmon ,Multidisciplinary ,business.industry ,Surface plasmon ,Surface Plasmon Resonance ,021001 nanoscience & nanotechnology ,Data science ,Interferometry ,0210 nano-technology ,business ,Biosensor ,Coherence (physics) - Abstract
Optical interferometry has empowered an impressive variety of biosensing and medical imaging techniques. A widely held assumption is that devices based on optical interferometry require coherent light to generate a precise optical signature in response to an analyte. Here we disprove that assumption. By directly embedding light emitters into subwavelength cavities of plasmonic interferometers, we demonstrate coherent generation of surface plasmons even when light with extremely low degrees of spatial and temporal coherence is employed. This surprising finding enables novel sensor designs with cheaper and smaller light sources and consequently increases accessibility to a variety of analytes, such as biomarkers in physiological fluids, or even airborne nanoparticles. Furthermore, these nanosensors can now be arranged along open detection surfaces and in dense arrays, accelerating the rate of parallel target screening used in drug discovery, among other high volume and high sensitivity applications.
- Published
- 2016
27. ENGINEERING AND CLINICAL ASPECTS OF PHOTOPLETHYSMOGRAPHY
- Author
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Jennifer Racine, Oussama Fadil, Domenico Pacifici, and Roy K. Aaron
- Subjects
Materials science ,Photoplethysmogram ,Biomedical engineering - Published
- 2016
28. Strong Amplitude and Phase Modulation of Optical Spatial Coherence with Surface Plasmon Polaritons
- Author
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Dongfang Li and Domenico Pacifici
- Subjects
Electromagnetic field ,Physics::Optics ,FOS: Physical sciences ,Degree of coherence ,01 natural sciences ,010309 optics ,Optics ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,010306 general physics ,Computer Science::Databases ,Research Articles ,Physics ,Condensed Matter::Quantum Gases ,Multidisciplinary ,business.industry ,Condensed Matter::Other ,Surface plasmon ,SciAdv r-articles ,Ray ,Surface plasmon polariton ,Interferometry ,Applied Sciences and Engineering ,Optoelectronics ,Photonics ,business ,Phase modulation ,Physics - Optics ,Research Article ,Optics (physics.optics) - Abstract
Surface plasmon polaritons can make incoherent light coherent and vice versa., The degree of optical spatial coherence—a fundamental property of light that describes the mutual correlations between fluctuating electromagnetic fields—has been proven challenging to control at the micrometer scale. We use surface plasmon polaritons—evanescent waves excited on both surfaces of a thin metal film—as a means to mix the random fluctuations of the incident electromagnetic fields at the slit locations of a Young’s double-slit interferometer. Strong tunability of the complex degree of spatial coherence of light is achieved by finely varying the separation distance between the two slits. Continuous modulation of the degree of spatial coherence with amplitudes ranging from 0 to 80% allows us to transform totally incoherent incident light into highly coherent light and vice versa. These findings pave the way for alternative methods to engineer flat optical elements with multifunctional capabilities beyond conventional refractive- and diffractive-based photonic metasurfaces.
- Published
- 2016
- Full Text
- View/download PDF
29. Nanoscale Plasmonic Interferometers for Multispectral, High-Throughput Biochemical Sensing
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Siu Vince, Jing Feng, Domenico Pacifici, Steve Y. Rhieu, Vihang Mehta, Alec Roelke, and G. Tayhas R. Palmore
- Subjects
Silver ,Materials science ,business.industry ,Mechanical Engineering ,Microfluidics ,Multispectral image ,Bioengineering ,Biosensing Techniques ,General Chemistry ,Surface Plasmon Resonance ,Condensed Matter Physics ,Nanostructures ,Wavelength ,Interferometry ,Glucose ,Optics ,Astronomical interferometer ,Nanotechnology ,General Materials Science ,business ,Biosensor ,Refractive index ,Plasmon - Abstract
In this work, we report the design, fabrication, and characterization of novel biochemical sensors consisting of nanoscale grooves and slits milled in a metal film to form two-arm, three-beam, planar plasmonic interferometers. By integrating thousands of plasmonic interferometers per square millimeter with a microfluidic system, we demonstrate a sensor able to detect physiological concentrations of glucose in water over a broad wavelength range (400-800 nm). A wavelength sensitivity between 370 and 630 nm/RIU (RIU, refractive index units), a relative intensity change between ~10(3) and 10(6) %/RIU, and a resolution of ~3 × 10(-7) in refractive index change were experimentally measured using typical sensing volumes as low as 20 fL. These results show that multispectral plasmonic interferometry is a promising approach for the development of high-throughput, real-time, and extremely compact biochemical sensors.
- Published
- 2012
30. Broadband visible-to-telecom wavelength germanium quantum dot photodetectors
- Author
-
Alexander Zaslavsky, Haobei Wang, Domenico Pacifici, Dongfang Li, and Stylianos Siontas
- Subjects
010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,Silicon ,business.industry ,chemistry.chemical_element ,Photodetector ,Germanium ,02 engineering and technology ,Specific detectivity ,021001 nanoscience & nanotechnology ,01 natural sciences ,Photodiode ,law.invention ,Wavelength ,chemistry ,law ,Quantum dot ,0103 physical sciences ,Quantum efficiency ,0210 nano-technology ,Telecommunications ,business - Abstract
Germanium (Ge) quantum dot (QD) photodetectors (PDs) were fabricated on Ge substrates exhibiting a broadband, visible to near-infrared (near-IR) photoresponse in the λ = 400–1550 nm range. Room-temperature responsivities (Rsp) up to 1.12 A/W and internal quantum efficiency IQE = 313% were obtained, superior to conventional silicon and germanium photodiodes. Noise analysis was performed at visible λ = 640 nm and telecom λ = 1550 nm wavelengths, both yielding room-temperature specific detectivity D* ≃ 2 × 1010 cm Hz1/2 W−1. Lowering the operating temperature and incident power led to sharply enhanced performance, with D* = 1.1 × 1012 cm Hz1/2 W−1 and IQE = 1000% at T = 100 K for an incident power of 10 nW at λ = 1550 nm. Based on their simple fabrication and silicon technology compatibility, these Ge QD PDs represent a promising alternative for broadband, high-performance visible to near-IR detection.
- Published
- 2018
31. High-purity red coloration via mode-selective absorption in a layered thin-film cavity
- Author
-
Zhijun Liu, Domenico Pacifici, Tianyi Shen, Declan Oller, Jimmy Xu, De He, Gustavo E. Fernandes, and Jin Ho Kim
- Subjects
Materials science ,Infrared ,business.industry ,General Physics and Astronomy ,chemistry.chemical_element ,Germanium ,02 engineering and technology ,Spectral bands ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Dichroic glass ,01 natural sciences ,Red Color ,lcsh:QC1-999 ,0104 chemical sciences ,law.invention ,chemistry ,law ,Optical cavity ,Optoelectronics ,Thin film ,0210 nano-technology ,Absorption (electromagnetic radiation) ,business ,lcsh:Physics - Abstract
Physical coloration without chemicals offers a pathway to develop pollution-free coloration technology, and can be applied to colorimetric sensing of gases, toxic and chemical agents. In this paper, we report on realization of a high-purity red color using mechanism of mode-selective absorption in a thin-film optical cavity. By placing an ultra-thin absorber layer at the antinode of a targeted spectral band in a Fabry-Perot cavity, its otherwise conventional dichroic reflection spectrum is shaped into a broad rectangular flat-bottom one that gives the desired vivid red. The purity of our demonstrated red color reaches 76%, which is increased by 16% compared with those reported in prior thin-film structures. Our method of mode-selective absorption is adaptable to more general-purpose spectral shaping, and could be applied in producing other target colors as well as broadband light absorption for energy harvesting and infrared detection.Physical coloration without chemicals offers a pathway to develop pollution-free coloration technology, and can be applied to colorimetric sensing of gases, toxic and chemical agents. In this paper, we report on realization of a high-purity red color using mechanism of mode-selective absorption in a thin-film optical cavity. By placing an ultra-thin absorber layer at the antinode of a targeted spectral band in a Fabry-Perot cavity, its otherwise conventional dichroic reflection spectrum is shaped into a broad rectangular flat-bottom one that gives the desired vivid red. The purity of our demonstrated red color reaches 76%, which is increased by 16% compared with those reported in prior thin-film structures. Our method of mode-selective absorption is adaptable to more general-purpose spectral shaping, and could be applied in producing other target colors as well as broadband light absorption for energy harvesting and infrared detection.
- Published
- 2018
32. All-optical modulation by plasmonic excitation of CdSe quantum dots
- Author
-
Harry A. Atwater, Henri J. Lezec, and Domenico Pacifici
- Subjects
Quantum optics ,3D optical data storage ,Materials science ,business.industry ,Terahertz radiation ,Physics::Optics ,Surface plasmon polariton ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Biophotonics ,Optics ,Quantum dot ,Optoelectronics ,Photonics ,business ,Plasmon - Abstract
Photonics is a promising candidate technology for information processing, communication and data storage. Essential building blocks, such as logic elements and modulators, have been demonstrated. However, because of weak nonlinear light–matter interactions, these components typically require high power densities and large interaction volumes, limiting their application in dense chip-based integration. A solution may be found in surface plasmon polaritons (SPPs), guided electromagnetic waves that propagate with high field confinement along a metal–dielectric interface. We demonstrate an all-optical modulator in which efficient interaction between two light beams at different wavelengths is achieved by converting them into co-propagating SPPs interacting by means of a thin layer of CdSe quantum dots (QDs). The high SPP field confinement and high QD-absorption cross-section enable optical modulation at low power densities (~10^2 W cm^(-2)) in micrometre-scale planar devices.
- Published
- 2007
33. Electroluminescence properties of SiOx layers implanted with rare earth ions
- Author
-
Alessia Irrera, Maria Miritello, P.G. Fallica, G. Di Stefano, Fabio Iacona, Domenico Pacifici, Giorgia Franzò, Francesco Priolo, and Delfo Sanfilippo
- Subjects
Nuclear and High Energy Physics ,Materials science ,Annealing (metallurgy) ,business.industry ,Si nanocrystals ,electroluminescence ,rare earth ,optoelectronic devices ,Electroluminescence ,Nanoclusters ,Surface coating ,Ion implantation ,Optoelectronics ,Light emission ,Thin film ,Luminescence ,business ,Instrumentation - Abstract
In this work we have studied the structural, electrical and optical properties of MOS devices, where the dielectric layer consists of a SiOx (x < 2) thin film prepared by plasma enhanced chemical vapor deposition and implanted with rare earth ions. As deposited SiOx films were annealed at high temperature (> 1000 degreesC) to induce the separation of the Si and SiO2 phases with the formation of Si nanocrystals embedded in the insulating matrix. Devices based on this system present a strong light emission at room temperature at a wavelength of about 900 nm. Devices emitting at different wavelengths have been fabricated by implanting SiOx films with Er or Tin. Devices based on Er-doped Si nanoclusters film exhibit an intense 1.54 mum room temperature electroluminescence (EL). We have calculated the excitation cross-section for Er ions in presence of Si nanoclusters under electrical pumping and the value is similar to1 x 10(-14) cm(2), comparable to the value found for the electrical excitation of undoped Si nanocrystals. Finally, devices based on Tm-doped Si nanoclusters exhibit two EL peaks at 0.78 and 1.7 mum.
- Published
- 2004
34. Er doped Si nanostructures
- Author
-
Alessia Irrera, Francesco Priolo, Maria Miritello, Giorgia Franzò, Domenico Pacifici, Simona Boninelli, and Fabio Iacona
- Subjects
Materials science ,Annealing (metallurgy) ,Mechanical Engineering ,Doping ,Analytical chemistry ,Nanotechnology ,Condensed Matter Physics ,Ion ,Amorphous solid ,Nanoclusters ,Mechanics of Materials ,Excited state ,General Materials Science ,Light emission ,Luminescence - Abstract
In the present paper, we will review our recent work on Er-doped Si nanoclusters. We demonstrate that amorphous as well as crystalline Si clusters are efficient sensitizers for the Er 3+ luminescence at 1.54 μm. The samples have been obtained by implanting Er in a film containing pre-formed Si nanocrystals. After the implant, samples have been treated at 900 °C for 1 h, in order to activate Er 3+ . It is shown that this annealing temperature is not enough to re-crystallize all of the amorphized Si clusters. However, even if the Si nanoclusters are in the amorphous phase, they can still efficiently transfer the energy to nearby Er ions. We present a model based on an energy level scheme taking into account the coupling between each Si nanocluster and the neighboring Er ions. By fitting the data, we were able to determine a value of 3×10 −15 cm 3 s −1 for the Si nanocluster–Er coupling coefficient. Moreover, a strong cooperative up-conversion mechanism, active between two excited Er ions and characterized by a coefficient of 7×10 −17 cm 3 s −1 , will be shown to be active in the system, demonstrating that more than one Er ion can be excited by the same nanocluster. In addition, we found that the overall light emission yield of the Er related luminescence can be enhanced by using higher concentrations of very small nanoaggregates. Finally, room temperature operating electroluminescent devices based on Er-doped Si nanoclusters will be demonstrated.
- Published
- 2003
35. Stimulated emission in plasma-enhanced chemical vapour deposited silicon nanocrystals
- Author
-
Massimo Cazzanelli, Nicola Daldosso, Domenico Pacifici, Zeno Gaburro, Fabio Iacona, L. Dal Negro, Francesco Priolo, Giorgia Franzò, and Lorenzo Pavesi
- Subjects
OPTICAL GAIN ,Amplified spontaneous emission ,Materials science ,Silicon ,stimulated emission ,chemistry.chemical_element ,Chemical vapor deposition ,Rate equation ,Plasma ,Condensed Matter Physics ,Waveguide (optics) ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,Auger ,chemistry ,Silicon nanocrystals ,light amplification ,Stimulated emission ,Atomic physics - Abstract
Observation of optical gain in silicon nanocrystals (Si-nc) is critically dependent on a very delicate balance among the Si-nc gain cross-sections, the optical mode losses and confinement factors of the waveguide structures, the Si-nc concentration and the strongly competing fast non-radiative Auger processes. Here we report on optical gain measurements by variable stripe length (VSL) method on a set of silicon nanocrystals formed by thermal annealing at 1250°C of SiO x films with different silicon contents prepared by plasma-enhanced chemical vapour deposition. Time-resolved VSL has revealed fast component in the recombination dynamics under gain conditions. Fast lifetime narrowing and superlinear emission has been unambiguously observed. To explain our experimental results we propose a four levels recombination model. Within a phenomenological rate equations description including Auger processes and amplified spontaneous emission we obtained a satisfactory agreement with time-resolved experiments and explained the strong competition between stimulated emission and fast non-radiative Auger processes.
- Published
- 2003
36. Low-Temperature Operation of High-Efficiency Germanium Quantum Dot Photodetectors in the Visible and Near Infrared
- Author
-
Dongfang Li, Stylianos Siontas, Sartaj Aujla, Alexander Zaslavsky, Pei Liu, and Domenico Pacifici
- Subjects
010302 applied physics ,Materials science ,business.industry ,Near-infrared spectroscopy ,chemistry.chemical_element ,Photodetector ,Germanium ,02 engineering and technology ,Surfaces and Interfaces ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry ,Quantum dot ,0103 physical sciences ,Materials Chemistry ,Optoelectronics ,Electrical and Electronic Engineering ,0210 nano-technology ,business - Published
- 2017
37. Luminescence from Si Nanocrystals and Er3+ Ions Embedded in Resonant Cavities
- Author
-
Eduardo Ceretta Moreira, Giorgia Franzò, Fabio Iacona, Domenico Pacifici, and Francesco Priolo
- Subjects
Materials science ,Nanocrystal ,Inorganic chemistry ,General Materials Science ,Nanotechnology ,Silicon nanocrystals ,Condensed Matter Physics ,Luminescence ,Atomic and Molecular Physics, and Optics ,Ion - Published
- 2001
38. Role of the energy transfer in the optical properties of undoped and Er-doped interacting Si nanocrystals
- Author
-
Domenico Pacifici, Giorgia Franzò, Fabio Iacona, Vincenzo Vinciguerra, Francesco Priolo, and Alessia Irrera
- Subjects
Stretched exponential function ,Materials science ,Ion implantation ,Photoluminescence ,Plasma-enhanced chemical vapor deposition ,Excited state ,Doping ,Analytical chemistry ,General Physics and Astronomy ,Luminescence ,Molecular physics ,Ion - Abstract
In this article the luminescence properties of Si nanocrystals (nc) formed by plasma enhanced chemical vapor deposition and their interaction with Er ions introduced by ion implantation are investigated in detail. Si nc with different size distributions and densities were produced and all show quite intense room temperature luminescence (PL) in the range 700–1100 nm. It is shown that the time-decay of the luminescence follows a stretched exponential function whose shape tends towards a single exponential for almost isolated nc. This suggests that stretched exponential decays are related to the energy transfer from smaller towards larger nc. Indeed, by comparing samples with similar nc size distributions, but with very different nc densities, it is demonstrated that the PL has a quite strong redshift in the high density case, demonstrating a clear energy redistribution within the sample. Excitation cross sections have been measured in all samples yielding a value of ∼1.8×10−16 cm2 for isolated nc excited w...
- Published
- 2001
39. Role of Ge nanoclusters in the performance of photodetectors compatible with Si technology
- Author
-
C. Spinella, Salvatore Cosentino, Maria Miritello, Pei Liu, Domenico Pacifici, Sunghwan Lee, Salvo Mirabella, Giuseppe Nicotra, Antonio Terrasi, Son T. Le, David C. Paine, Isodiana Crupi, Alexander Zaslavsky, Cosentino, S., Mirabella, S., Liu, P., Le, S.T., Miritello, M., Lee, S., Crupi, I., Nicotra, G., Spinella, C., Paine, D., Terrasi, A., Zaslavsky, A., and Pacifici, D.
- Subjects
Nanocluster ,Materials science ,chemistry.chemical_element ,Photodetector ,Germanium ,Photoconductive gain ,Settore ING-INF/01 - Elettronica ,Nanoclusters ,Response time (computer systems), Germanium ,High-efficiency photodetector ,High-efficiency photodetectors ,Sparse array ,High-efficiency ,Response time ,Materials Chemistry ,Gain ,business.industry ,Photoconductivity ,Internal quantum efficiency ,Metals and Alloys ,Surfaces and Interfaces ,Photon ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Recombination center ,chemistry ,Semiconductor photodetector ,Optoelectronics ,Spectral response ,Quantum efficiency ,business ,Excitation ,Spectral responsivity, Nanocluster - Abstract
In this work, we investigate the spectral response of metal-oxide- semiconductor photodetectors based on Ge nanoclusters (NCs) embedded in a silicon dioxide (SiO2) matrix. The role of Ge NC size and density on the spectral response was evaluated by comparing the performance of PDs based on either densely packed arrays of 2 nm-diameter NCs or a more sparse array of 8 nm-diameter Ge NCs. Our Ge NC photodetectors exhibit a high spectral responsivity in the 500-1000 nm range with internal quantum efficiency of ~ 700% at - 10 V, and with NC array parameters such as NC density and size playing a crucial role in the photoconductive gain and response time. We find that the configuration with a more dispersed array of NCs ensures a faster photoresponse, due to the larger fraction of electrically-active NCs and the partial suppression of recombination centers. The photoconduction mechanism, assisted by trapping of photo-generated holes in Ge NCs, is discussed for different excitation power and applied bias conditions. Our results provide guidelines for further optimization of high-efficiency Ge NC photodetectors. © 2013 Elsevier B.V. All rights reserved.
- Published
- 2013
40. Noise performance of high-efficiency germanium quantum dot photodetectors
- Author
-
Alexander Zaslavsky, Domenico Pacifici, Stylianos Siontas, and Pei Liu
- Subjects
010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,business.industry ,Photodetector ,02 engineering and technology ,Specific detectivity ,021001 nanoscience & nanotechnology ,01 natural sciences ,Noise (electronics) ,Responsivity ,Optics ,Quantum dot ,0103 physical sciences ,Optoelectronics ,Figure of merit ,Quantum efficiency ,0210 nano-technology ,business ,Dark current - Abstract
We report on the noise analysis of high performance germanium quantum dot (Ge QD) photodetectors with responsivity up to ∼2 A/W and internal quantum efficiency up to ∼400%, over the 400–1100 nm wavelength range and at a reverse bias of −10 V. Photolithography was performed to define variable active-area devices that show suppressed dark current, leading to a higher signal-to-noise ratio, up to 105, and specific detectivity D*≃6×1012 cm Hz 1/2 W−1. These figures of merit suggest Ge QDs as a promising alternative material for high-performance photodetectors working in the visible to near-infrared spectral range.
- Published
- 2016
41. A spectroscopic refractometer based on plasmonic interferometry
- Author
-
Domenico Pacifici and Jing Feng
- Subjects
Plasmonic nanoparticles ,Materials science ,business.industry ,Physics::Optics ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Surface plasmon polariton ,010309 optics ,Interferometry ,Optics ,Refractometer ,0103 physical sciences ,Astronomical interferometer ,Optoelectronics ,Plasmonic lens ,Prism ,0210 nano-technology ,business ,Plasmon - Abstract
We describe the design, fabrication, and testing of a spectroscopic refractometer that employs plasmonic interferometry to measure the optical dielectric functions of materials in the visible range. The proposed device, dubbed a plasmonic refractometer, consists of an array of slit-groove plasmonic interferometers etched in a ∼300 nm-thick metal film (silver or gold) with arm lengths varying in steps of 25 nm up to ∼8 μm. The nano-groove in each interferometer is able to generate propagating surface plasmon polaritons efficiently in a broad wavelength range, without requiring prism- or grating-coupling configurations. An integrated microfluidic channel ensures uniform delivery of dielectric materials in liquid phase. Spectrally resolved plasmonic interferograms are generated by measuring light transmission spectra through the slit of each slit-groove plasmonic interferometer and plotting the normalized intensity as a function of arm length (0.26–8.16 μm) and incident wavelength (400–800 nm) for various co...
- Published
- 2016
42. Optical bandgap of single- and multi-layered amorphous germanium ultra-thin films
- Author
-
Alexander Zaslavsky, Paolo Longo, Domenico Pacifici, and Pei Liu
- Subjects
010302 applied physics ,Materials science ,genetic structures ,business.industry ,Band gap ,Superlattice ,technology, industry, and agriculture ,General Physics and Astronomy ,chemistry.chemical_element ,Germanium ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,eye diseases ,Optics ,chemistry ,Quantum dot ,Attenuation coefficient ,0103 physical sciences ,Tauc plot ,Transmittance ,sense organs ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) - Abstract
Accurate optical methods are required to determine the energy bandgap of amorphous semiconductors and elucidate the role of quantum confinement in nanometer-scale, ultra-thin absorbing layers. Here, we provide a critical comparison between well-established methods that are generally employed to determine the optical bandgap of thin-film amorphous semiconductors, starting from normal-incidence reflectance and transmittance measurements. First, we demonstrate that a more accurate estimate of the optical bandgap can be achieved by using a multiple-reflection interference model. We show that this model generates more reliable results compared to the widely accepted single-pass absorption method. Second, we compare two most representative methods (Tauc and Cody plots) that are extensively used to determine the optical bandgap of thin-film amorphous semiconductors starting from the extracted absorption coefficient. Analysis of the experimental absorption data acquired for ultra-thin amorphous germanium (a-Ge) l...
- Published
- 2016
43. Plasmonic concentrators for enhanced light absorption in ultra-thin film organic solar cells
- Author
-
Abigail Plummer, Aminy E. Ostfeld, Patrick W. Flanigan, Domenico Pacifici, Natalie G. Serrino, and Zhen Ye
- Subjects
Theory of solar cells ,Materials science ,genetic structures ,Organic solar cell ,business.industry ,technology, industry, and agriculture ,Hybrid solar cell ,Concentrator ,Polymer solar cell ,Optics ,Optoelectronics ,Plasmonic solar cell ,Thin film ,Absorption (electromagnetic radiation) ,business - Abstract
A plasmonic concentrator consisting of a quasi-periodic array of shallow sub-wavelength holes is considered for use in ultra-thin film organic solar cells. The level of absorption enhancement in the active layer will be studied as functions of array symmetry and planar hole density.
- Published
- 2012
44. Plasmonic interferometry for biosensing
- Author
-
Tayhas Palmore, Jing Feng, Steve Y. Rhieu, Alec Roelke, Domenico Pacifici, Vihang Mehta, and Siu Vince
- Subjects
Interferometry ,Wavelength ,Materials science ,Optics ,Nanosensor ,business.industry ,Microfluidics ,Astronomical interferometer ,business ,Biosensor ,Refractive index ,Plasmon - Abstract
In this work, we report the design, fabrication and characterization of novel biochemical sensors consisting of nanoscale grooves and slits milled in a metal film to form planar plasmonic interferometry. By integrating thousands of plasmonic interferometers per square millimeter with a microfluidic system, we demonstrate a sensor able to detect physiological concentrations of glucose in water over a broad wavelength range (400–800 nm). A wavelength sensitivity between 370–630 nm/RIU (RIU, Refractive Index Units), a relative intensity change between ∼103–106 %/RIU, and a resolution of ∼3×10−7 in refractive index change were experimentally measured using typical sensing volumes as low as 20 femtoliters. These results show that multispectral plasmonic interferometry is a promising approach for the development of high-throughput, real-time and extremely compact biochemical sensors.
- Published
- 2012
45. Transient photoresponse and incident power dependence of high-efficiency germanium quantum dot photodetectors
- Author
-
Salvatore Cosentino, Maria Miritello, Domenico Pacifici, Isodiana Crupi, Son T. Le, Alexander Zaslavsky, Sunghwan Lee, David C. Paine, Antonio Terrasi, Pei Liu, Salvo Mirabella, Liu, P., Cosentino, S., Le, S.T., Lee, S., Paine, D., Zaslavsky, A., Pacifici, D., Mirabella, S., Miritello, M., Crupi, I., and Terrasi, A.
- Subjects
Materials science ,Photoresponse ,Reverse bia ,General Physics and Astronomy ,chemistry.chemical_element ,Photodetector ,Germanium ,Optical power ,Photoconduction ,Time-resolved ,Settore ING-INF/01 - Elettronica ,Series resistance ,Optics ,Electrical resistance and conductance ,Equivalent series resistance ,Systematic study ,business.industry ,Photoconductivity ,Internal quantum efficiency ,Quantum-dot photodetector ,Photon ,Wavelength ,Semiconductor quantum dots, Germanium ,chemistry ,Quantum dot ,Transient current, Electric resistance ,Optoelectronics ,Incident power ,business - Abstract
We report a systematic study of time-resolved and power-dependent photoresponse in high-efficiency germanium quantum dot photodetectors (Ge-QD PDs), with internal quantum efficiencies greater than 100 over a broad wavelength, reverse bias, and incident power range. Turn-on and turn-off response times (τ on and τ off) are shown to depend on series resistance, bias, optical power, and thickness (W QD) of the Ge-QD layer, with measured τ off values down to ∼40 ns. Two different photoconduction regimes are observed at low and high reverse bias, with a transition around -3 V. A transient current overshoot phenomenon is also observed, which depends on bias and illumination power. © 2012 American Institute of Physics.
- Published
- 2012
46. Circular slit-groove plasmonic interferometers: a generalized approach to high-throughput biochemical sensing [Invited]
- Author
-
Dongfang Li, Domenico Pacifici, and Jing Feng
- Subjects
Materials science ,genetic structures ,business.industry ,Surface plasmon ,Astrophysics::Instrumentation and Methods for Astrophysics ,Rotational symmetry ,Physics::Optics ,Interference (wave propagation) ,Slit ,eye diseases ,Electronic, Optical and Magnetic Materials ,Light intensity ,Optics ,Astronomical interferometer ,Optoelectronics ,sense organs ,business ,Plasmon ,Groove (music) - Abstract
A class of plasmonic interferometers consisting of a circular slit flanked by a concentric circular groove is demonstrated. Laying in-between the conventional bullseye and the linear slit-groove interferometers, these circular slit-groove interferometers show a polarization-insensitive optical response (thanks to the rotational symmetry imposed by the circular geometry), and overall higher light transmission (due to the absence of a cutoff condition in the circular subwavelength slit). Light transmission and sensitivity can be further enhanced by the presence of plasmonic resonant modes excited by the circular slit. The proposed circular plasmonic interferometers can be employed to develop improved biochemical sensors.
- Published
- 2015
47. High-efficiency silicon-compatible photodetectors based on Ge quantum dots
- Author
-
Alexander Zaslavsky, Antonio Terrasi, Son T. Le, Maria Miritello, Pei Liu, David C. Paine, Salvatore Cosentino, Salvo Mirabella, Isodiana Crupi, Domenico Pacifici, Sunghwan Lee, Cosentino, S., Le, P., Lee, S., Paine, D., Zaslavsky, A., Pacifici, D., Mirabella, S., Miritello, M., Crupi, I., and Terrasi, A.
- Subjects
Amorphous silicon ,Materials science ,Thermal budget ,Physics and Astronomy (miscellaneous) ,Silicon ,Silicon Technologie ,Responsivity ,chemistry.chemical_element ,Settore ING-INF/01 - Elettronica ,chemistry.chemical_compound ,Metal/insulator/semiconductor ,Ge quantum dot ,Wavelength ranges, Amorphous silicon ,Photocurrent generation ,Photodetector ,Optoelectronic device ,Photocurrent ,Germanium ,business.industry ,Semiconductor quantum dot ,Internal quantum efficiency ,matrix ,TRANSPORT ,Semiconductor ,NANOCRYSTALS ,Silica, Quantum efficiency ,chemistry ,Quantum dot laser ,Quantum dot ,Optoelectronics ,Quantum efficiency ,Transport mechanism ,GAIN ,business ,NANOCRYSTALS, TRANSPORT, GAIN ,Fully compatible ,High efficiency - Abstract
We report on high responsivity, broadband metal/insulator/semiconductor photodetectors with amorphous Ge quantum dots (a-Ge QDs) as the active absorbers embedded in a silicon dioxide matrix. Spectral responsivities between 1-4 A/W are achieved in the 500-900 nm wavelength range with internal quantum efficiencies (IQEs) as high as ∼700%. We investigate the role of a-Ge QDs in the photocurrent generation and explain the high IQE as a result of transport mechanisms via photoexcited QDs. These results suggest that a-Ge QDs are promising for high-performance integrated optoelectronic devices that are fully compatible with silicon technology in terms of fabrication and thermal budget. © 2011 American Institute of Physics.
- Published
- 2011
48. ALL-OPTICAL PLASMONIC MODULATORS AND INTERCONNECTS
- Author
-
Domenico Pacifici, Henri J. Lezec, Luke A. Sweatlock, Chris de Ruiter, Vivian Ferry, and Harry A. Atwater
- Published
- 2010
49. Er3+ ions–Si nanocrystals interactions and their effects on the luminescence properties
- Author
-
Domenico Pacifici, Francesco Priolo, Fabio Iacona, Vincenzo Vinciguerra, and Giorgia Franzò
- Subjects
Photoluminescence ,Materials science ,Physics and Astronomy (miscellaneous) ,Nanocrystal ,Silicon ,chemistry ,Annealing (metallurgy) ,Analytical chemistry ,chemistry.chemical_element ,Chemical vapor deposition ,Thin film ,Luminescence ,Ion - Abstract
A detailed investigation on the interaction mechanisms between Er ions and Si nanocrystals (nc) is reported. Silicon nc were produced by high-temperature annealing of substoichiometric SiOx thin films grown by plasma-enhanced chemical vapor deposition. Subsequently, some of the samples were implanted by Er. These samples show intense room-temperature luminescence at both 1.54 and 0.98 μm. High-resolution luminescence spectra of Er-implanted Si nc suggest that the emitting Er ions are located in the SiO2 or at the Si nc/SiO2 interface. The pump-power dependence and the time decay of the 1.54 μm emission in Si nc with different Er contents have evidenced the presence of several nonradiative decay processes due to Er–Er and Er–Si nc interactions. Moreover, the number of Er ions per Si nc is shown to be a quite critical parameter in determining the final properties of the overall system.
- Published
- 2000
50. Plasmonic Nanostructure Design for Efficient Light Coupling into Solar Cells
- Author
-
Domenico Pacifici, Harry A. Atwater, Vivian E. Ferry, and Luke A. Sweatlock
- Subjects
Coupling ,Theory of solar cells ,Materials science ,business.industry ,Band gap ,Mechanical Engineering ,Bioengineering ,General Chemistry ,Condensed Matter Physics ,Optics ,Semiconductor ,General Materials Science ,Plasmonic solar cell ,Thin film ,Absorption (electromagnetic radiation) ,business ,Groove (music) - Abstract
We demonstrate that subwavelength scatterers can couple sunlight into guided modes in thin film Si and GaAs plasmonic solar cells whose back interface is coated with a corrugated metal film. Using numerical simulations, we find that incoupling of sunlight is remarkably insensitive to incident angle, and that the spectral features of the coupling efficiency originate from several different resonant phenomena. The incoupling cross section can be spectrally tuned and enhanced through modification of the scatterer shape, semiconductor film thickness, and materials choice. We demonstrate that, for example, a single 100 nm wide groove under a 200 nm Si thin film can enhance absorption by a factor of 2.5 over a 10 microm area for the portion of the solar spectrum near the Si band gap. These findings show promise for the design of ultrathin solar cells that exhibit enhanced absorption.
- Published
- 2008
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