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Nicola Donato


ndonato@unime.it

Journal articles

2012
V Modafferi, G Panzera, A Donato, P L Antonucci, C Cannilla, N Donato, D Spadaro, G Neri (2012)  Highly sensitive ammonia resistive sensor based on electrospun V2O5 fibers   SENSORS AND ACTUATORS B-CHEMICAL 163: 1. 61-68 MAR 1  
Abstract: A simple sol-gel based electrospinning method has been applied for the synthesis of vanadium oxide/polyvinyl acetate (V2O5/PVAC) fibers for gas sensing applications. The pure phase V2O5 has been subsequently obtained by removing the polymer phase via annealing of the composite fibers in air. The as-spun V2O5/PVAC composite fibers and related products of annealing have been widely studied to characterize their morphological and microstructural properties by TG-DSC, XRD, DRIFT and SEM investigations. The application of the produced V2O5 fibers as high performance ammonia resistive sensors has been demonstrated. Reversible electrical changes have been observed by exposing V2O5 fibers deposited on interdigited electrodes to sub-ppm concentrations of ammonia gas. The fabricated V2O5 sensor has shown the highest response to ammonia gas at 200-250 degrees C, with a response and recovery time of about 50 and 350 s, respectively. A linear dependence of the response value on the ammonia concentration has been observed in the range of 0.85-8.5 ppm, with an estimated lower detection limit of about 100 ppb. (C) 2012 Elsevier B.V. All rights reserved.
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Giovanni Neri, Antonio Lacquaniti, Giuseppe Rizzo, Nicola Donato, Mariangela Latino, Michele Buemi (2012)  Real-time monitoring of breath ammonia during haemodialysis: use of ion mobility spectrometry (IMS) and cavity ring-down spectroscopy (CRDS) techniques.   Nephrol Dial Transplant Apr  
Abstract: BACKGROUND: The diffusion of high-performance analytical technology has opened prospects for breath diagnosis as a non-invasive diagnostic tool. In this study, ion mobility spectrometry (IMS) and cavity ring-down spectroscopy (CRDS) techniques were used to analyse ammonia gas (NH(3)) in real-time in breath from patients undergoing haemodialysis (HD) treatment and any correlation with blood urea nitrogen (BUN) levels and Kt/V were investigated.METHODS: We studied 20 patients on intermittent HD treatment. The first breath samples were taken before the start of dialysis and further breath samples were taken every hour during the treatment and after the end of the session. An evaluation was also made of 20 healthy volunteers, acting as controls [healthy subjects (HS)].RESULTS: Breath ammonia concentrations were higher in CRDS-HD (914.5 ± 301.4 versus 280 ± 120 parts per billion (p.p.b.), P < 0.0001) and IMS-HD patients (964.4 ± 402.4 versus 280 ± 120 p.p.b., P < 0.0001) than in HS. We assessed real-time variations in the levels of NH(3) and showed a continuous decrease in the levels of NH(3). Expired NH(3) correlated directly with BUN levels, both in the IMS-HD (P = 0.002; r = 0.84; P = 0.009; r = 0.76) and in the CRDS-HD group (P = 0.005; r = 0.80; P = 0.008; r = 0.77), respectively, both before and at the end of dialysis. A direct correlation with Kt/V was found in both groups studied (IMS-HD: P = 0.003; r = 0.82; CRDS-HD: P = 0.006; r = 0.79).CONCLUSIONS: Breath monitoring of NH(3) with IMS and CRDS techniques could be useful to assess the real-time clinical status of patients during HD. By using pre-dialysis ammonia values, an approximate calculation of the Kt/V(urea) ratio can be established.
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L De Luca, A Donato, S Santangelo, G Faggio, G Messina, N Donato, G Neri (2012)  Hydrogen sensing characteristics of Pt/TiO2/MWCNTs composites   INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 37: 2. 1842-1851 JAN  
Abstract: Platinum-doped titanium-dioxide/multi-walled carbon nanotubes (Pt/TiO2/MWCNTs) composites were prepared by a sol-gel method and characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermo-gravimetry (TG) and micro-Raman spectroscopy (MRS). Regardless the nominal C/Ti molar ratio (0.3-17.0), only the anatase phase of TiO2 was detected. However, on the composite with the highest C/Ti molar ratio, the formation of a more structurally disordered and non-stoichiometric anatase phase seemed to be favored. Small Pt nanoparticles, whose size ranged from 1 to 10 nm, were observed dispersed on the surface of composite samples. Electrical characteristics and hydrogen sensing properties of Pt/TiO2/MWCNTs composite films deposited on inter-digitated ceramic substrates were analyzed in the temperature interval from room temperature (RT) to 100 degrees C. The electrical conductivity of the composite films was several orders of magnitude higher than that of pure titania, allowing electrical measurements at RT. Pt/TiO2/MWCNTs composite films showed a response to hydrogen concentration, up to 100%, in nitrogen even at RT. On the basis of the results obtained, a “spill-over” mechanism, in which hydrogen molecules are first chemisorbed and dissociated on platinum, and finally spill out of the Pt surface, diffusing into the TiO2 surface layer, with MWCNTs providing a preferential pathway to the current flow, can be proposed to explain the hydrogen sensing mechanism on these sensors. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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2011
T Krishnakumar, R Jayaprakash, T Prakash, D Sathyaraj, N Donato, S Licoccia, M Latino, A Stassi, G Neri (2011)  CdO-based nanostructures as novel CO(2) gas sensors   NANOTECHNOLOGY 22: 32. AUG 12  
Abstract: Crystalline Cd(OH)(2)/CdCO(3) nanowires, having lengths in the range from 0.3 up to several microns and 5-30 nm in diameter, were synthesized by a microwave-assisted wet chemical route and used as a precursor to obtain CdO nanostructures after a suitable thermal treatment in air. The morphology and microstructure of the as-synthesized and annealed materials have been investigated by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and thermogravimetry-differential scanning calorimetry. The change in morphology and electrical properties with temperature has revealed a wire-to-rod transformation along with a decreases of electrical resistance. Annealed samples were printed on a ceramic substrate with interdigitated contacts to fabricate resistive solid state sensors. Gas sensing properties were explored by monitoring CO(2) in synthetic air in the concentration range 0.2-5 v/v% (2000-50 000 ppm). The effect of annealing temperature, working temperature and CO(2) concentration on sensing properties (sensitivity, response/recovery time and stability) were investigated. The results obtained demonstrate that CdO-based thick films have good potential as novel CO(2) sensors for practical applications.
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N Donato, F Neri, G Neri, M Latino, F Barreca, S Spadaro, I Pisagatti, G Curro (2011)  CO sensing devices based on indium oxide nanoparticles prepared by laser ablation in water   THIN SOLID FILMS 520: 3. 922-926 NOV 30  
Abstract: A simple and effective solution route for synthesizing colloidal indium oxide (In(2)O(3)) nanocrystallites, i.e. laser ablation in liquid (LAL), is reported. The morphology and chemical structure of the as-prepared samples were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectra (XPS). The results showed the formation of In(2)O(3) nanoparticles with a bimodal distribution, consisting mainly of particles of small diameters (2-5 nm). Sensor devices prepared by spraying directly the LAL colloidal solutions on interdigitated alumina substrates exhibited good sensing properties for the detection of CO at very low concentrations. (C) 2011 Elsevier B.V. All rights reserved.
Notes: 7th International Workshop on Semiconductor Gas Sensors (SGS), Krakow, POLAND, SEP 12-16, 2010
Catherine Marichy, Nicola Donato, Marc-Georg Willinger, Mariangela Latino, Dmitry Karpinsky, Seung-Ho Yu, Giovanni Neri, Nicola Pinna (2011)  Tin Dioxide Sensing Layer Grown on Tubular Nanostructures by a Non-Aqueous Atomic Layer Deposition Process   ADVANCED FUNCTIONAL MATERIALS 21: 4. 658-666 FEB 22  
Abstract: A new atomic layer deposition (ALD) process for nanocrystalline tin dioxide films is developed and applied for the coating of nanostructured materials. This approach, which is adapted from non-hydrolytic sol-gel chemistry, permits the deposition of SnO(2) at temperatures as low as 75 degrees C. It allows the coating of the inner and outer surface of multiwalled carbon nanotubes with a highly conformal film of controllable thickness. The ALD-coated tubes are investigated as active components in gas-sensor devices. Due to the formation of a p-n heterojunction between the highly conductive support and the SnO(2) thin film an enhancement of the gas sensing response is observed.
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Sandra Lo Schiavo, Paola Cardiano, Nicola Donato, Mariangela Latino, Giovanni Neri (2011)  A dirhodium(II,II) complex as a highly selective molecular material for ammonia detection : QCM studies   JOURNAL OF MATERIALS CHEMISTRY 21: 44. 18034-18041  
Abstract: The well known axial coordination capabilities of dirhodium(II,II) complexes towards Lewis bases have been exploited for the development of functional molecular materials for selective ammonia monitoring. On the basis of literature data and experimental evidence, the [Rh(2)(form)(4)] (1) (form = N, N’-di-p-tolylformamidinate anion) complex has been selected, among a series of dirhodium(II, II) derivatives, as the most suitable for this aim. By exposure to gaseous ammonia, 1 readily reacts, both in solution and in the solid state, with the gas to afford the corresponding ammonia-axial adduct. The reaction is reversible and is accompanied by a significant color change from dark yellow-green to red-brown due to the adduct formation, as confirmed by RGB, UV-vis and FT-IR spectroscopic investigations. Solid state UV/vis spectra reveal that while ammonia coordination occurs steadily, as judged by the blue shift observed for the lambda(max) (470 for 1 vs. 430 nm for the adduct), its complete release, in free air, takes more than a week. The potentiality of 1 for the selective ammonia detection in the headspace of aqueous ammonia solutions has been examined by QCM investigations. The dynamic response obtained from such studies is consistent with a reversible binding process occurring at the layer surface, which is operating once a fraction of the analyte is “irreversibly” bound to the sensor layer. The QCM response shows an excellent linearity in a wide concentration range (1-30 wt%) without any saturation effect up to high ammonia levels and a high selectivity to ammonia among a wide range of interfering gases.
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2010
G Rizzo, A Arena, N Donato, M Latino, G Saitta, A Bonavita, G Neri (2010)  Flexible, all-organic ammonia sensor based on dodecylbenzene sulfonic acid-doped polyaniline films   THIN SOLID FILMS 518: 23. 7133-7137 SEP 30  
Abstract: A stable chlorobenzene dispersion of conducting polyaniline (PANI) has been obtained by doping emeraldine base with dodecylbenzene sulfonic acid (DBSA) and studied by spectrophotometric measurements in the UV-vis-IR range. The electrical properties of PANI: DBSA films obtained from the above dispersion have been investigated under different temperature and relative humidity conditions. All-organic chemoresistive devices have been developed by spin-coating the PANI: DBSA dispersion on flexible substrates, and then by depositing electrodes on the top, from a carbon nanotube conducting ink. Sensing tests performed under exposition to calibrated amounts of ammonia reveal that these simple and inexpensive sensors are able to detect ammonia at room temperature in a reliable way, with a sensitivity linearly related to concentration in the range between 5 ppm and 70 ppm. (C) 2010 Elsevier B.V. All rights reserved.
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G Rizzo, A Arena, A Bonavita, N Donato, G Neri, G Saitta (2010)  Gasochromic response of nanocrystalline vanadium pentoxide films deposited from ethanol dispersions   THIN SOLID FILMS 518: 23. 7124-7127 SEP 30  
Abstract: Vanadium pentoxide (V(2)O(5)) nanocrystals having few tens nanometers average size, are obtained ammonium metavanadate (NH(4)VO(3)) in the presence of oleic acid, and treating the reaction 400 degrees C. Nanocrystalline films, deposited from stable ethanol suspensions of the V(2)O(5) strongly to different kinds of substrates, without the need of any thermal post processing. temperature, the films are found to bleach when exposed to ammonia. Bleaching originates formation of ammonium metavandate, and is reversible, as after annealing in air at 350 C, metavanadate converts back to V(2)O(5). Formation of ammonium metavanadate, clearly remarkable changes in infrared spectrum of V(2)O(5) films exposed to ammonia, is a valuable mechanism, promising in view of developing highly selective ammonia sensors operating temperature. (C) 2010 Elsevier B.V. All rights reserved.
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S Santangelo, G Messina, G Faggio, A Donato, L De Luca, N Donato, A Bonavita, G Neri (2010)  Micro-Raman analysis of titanium oxide/carbon nanotubes-based nanocomposites for hydrogen sensing applications   JOURNAL OF SOLID STATE CHEMISTRY 183: 10. 2451-2455 OCT  
Abstract: Titanium oxide/carbon nanotubes-based nanocomposites (TiO(2)/CNTs, prepared by sal-gel method, and 2%Pt/TiO(2)/CNTs, obtained by wetness impregnation of the TiO(2)/CNTs base material with a solution of platinum acetylacetonate) have been recently used as active layer in hydrogen sensing devices at near room temperature, obtaining quite different responsiveness. The microstructure of these hybrid materials is here systematically investigated by micro-Raman spectroscopy at 2.41 eV. The results show that regardless of the nominal C/Ti molar ratio (3.6 or 17.0) only the anatase phase of titania is formed. Theoretical calculations demonstrate that phonon confinement is fully responsible for the large blue-shift (similar to 10 cm(-1)) and broadening (similar to 20 cm(-1)) of the lowest-frequency Raman mode with respect to bulk anatase. The average size (4.3-5.0 nm) of TiO(2) crystallites, resulting from Raman spectra fitting, is in excellent agreement with those inferred from transmission electron microscopy and X-ray diffraction measurements. (C) 2010 Elsevier Inc. All rights reserved.
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D Sathya Raj, T Krishnakumar, R Jayaprakash, N Donato, M Latino, G Neri (2010)  Synthesis and Characterization of Cd(OH)(2) Nanowires Obtained by a Microwave-Assisted Chemical Route   SCIENCE OF ADVANCED MATERIALS 2: 3, SI. 432-437 SEP  
Abstract: Cadmium hydroxide, Cd(OH)(2), nanowires were synthesized by a microwave-assisted chemical route. The morphology and microstructure of the synthesized material has been investigated by SEM, TEM, XRD, FT-IR and TG-DSC. Electron microscopy studies showed the formation of nanowires with length in the range from 0.3 up to several micron and 5-30 nm in diameter. X-ray diffraction pattern revealed the typical interplanar spacings corresponding to the pure hexagonal phase of Cd(OH)(2). UV-Vis measurements were also carried out to investigate the optical properties and the results obtained were interpreted on the basis of confinement effects due to the one-dimensional nature of the material synthesized. Electrical characteristics were also recognized, finalized to a possible use of cadmium-based nanostructures in the field of gas sensors.
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S Santangelo, G Messina, G Faggio, M G Willinger, N Pinna, A Donato, A Arena, N Donato, G Neri (2010)  Micro-Raman investigation of vanadium-oxide coated tubular carbon nanofibers for gas-sensing applications   DIAMOND AND RELATED MATERIALS 19: 5-6, SI. 590-594 MAY  
Abstract: Commercial tubular carbon nanofibers were uniformly coated with a 5 nm thick vanadium oxide layer via a modified approach to atomic layer deposition. The composition and microstructure of the resulting hybrid material was analyzed by micro-Raman spectroscopy. The effect of the post-synthesis thermal treatment in air at temperatures in the range of 25-375 degrees C was investigated in order to more deeply understand the behavior of the hybrid material in gas sensing devices. The obtained results demonstrate that the thermal treatment primarily affects the oxide coating-layer that is responsible for the sensing properties. The best sensor performance was obtained at the temperature at which the oxide layered-structure exhibits the highest structural order. (C) 2009 Elsevier B.V. All rights reserved.
Notes: 20th European Conference on Diamond, Diamond-Like Materials, Carbon Nanotubes and Nitrides, Athens, GREECE, SEP 06-10, 2009
Giovanni Neri, Anna Bonavita, Giuseppe Micali, Nicola Donato (2010)  Design and Development of a Breath Acetone MOS Sensor for Ketogenic Diets Control   IEEE SENSORS JOURNAL 10: 1. 131-136 JAN  
Abstract: The design of a handy and noninvasive measurement of acetone in the human breath, which is useful for ketosis monitoring and control, by means of MOS sensors is reported. For this aim, highly sensitive resistive sensors in thick film configuration, fabricated depositing sensing layers of In(2)O(3) and Pt-In(2)O(3) nanopowders by screen-printing, have been developed. The devices were calibrated using standard gases in the laboratory, showing high sensitivity and a linear response in the range of acetone concentration investigated (1-100 ppm). The results obtained indicate that MOS sensors based on Pt-In(2)O(3) nanopowders are promising as fast and quantifiable means of determining acetone in the breath, posing the advantages of real time measurements and low costs devices for the control of ketogenic diets.
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A Arena, N Donato, G Saitta, A Bonavita, G Rizzo, G Neri (2010)  Flexible ethanol sensors on glossy paper substrates operating at room temperature   SENSORS AND ACTUATORS B-CHEMICAL 145: 1. 488-494 MAR 4  
Abstract: Flexible sensors for the detection of ethanol at room temperature have been developed by depositing sensitive layers consisting of ITO nanopowder dispersed into poly-diallyldimethylammonium chloride (PDDAC), on the top of interdigitated electrodes based on conductive carbon nanotubes, previously printed onto flexible glossy paper substrates. The morphology and the microstructure of the interdigitated electrodes together with organic-inorganic sensing layer have been investigated by means of SEM, XRD and FT-IR. The electrical behaviour of the developed sensors at room temperature in response to low ethanol concentrations has been discussed as object of our research. The good ethanol sensing properties exhibited at room temperature by the composite film was supposed to originate from the electrostatic interaction occurring between the positively charged PDDAC polyelectrolyte and negatively charged ITO particles. (C) 2009 Elsevier B.V. All rights reserved.
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2009
A Arena, N Donato, G Saitta (2009)  Capacitive humidity sensors based on MWCNTs/polyelectrolyte interfaces deposited on flexible substrates   MICROELECTRONICS JOURNAL 40: 6. 887-890 JUN  
Abstract: Inexpensive humidity sensors operating at room temperature are developed by casting on glossy paper linearly shaped carbon nanotubes electrodes, spaced by few hundreds microns, and sensitive layers consisting of iron oxide nanopowder dispersed in a polyelectrolyte host. The electrical behaviour of the devices, investigated by using triangular voltage inputs, is found to be mainly capacitive. The humidity sensing functionality is demonstrated by a reversible change of the devices’ capacitance, from few tens pF to hundreds pF, as the relative humidity level changes from 35% to 60%. The average response and recovery time of the devices is found to be of the order of a few min. (C) 2009 Published by Elsevier Ltd.
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T Krishnakumar, R Jayaprakash, N Pinna, N Donato, A Bonavita, G Micali, G Neri (2009)  CO gas sensing of ZnO nanostructures synthesized by an assisted microwave wet chemical route   SENSORS AND ACTUATORS B-CHEMICAL 143: 1. 198-204 DEC 4  
Abstract: A simple wet chemical process assisted by microwave has been investigated for the synthesis of ZnO nanostructures for sensing applications. Characterization results have shown that microwave irradiation is able to quickly convert the reaction product zinc hydroxide into single phase crystalline ZnO. Different ZnO nanostructures (spherical-, flower- and star-like) have been prepared by adapting the experimental conditions. These ZnO nanostructures have been tested for CO gas monitoring by depositing them as thick films on an interdigitated alumina substrate and evaluating the surface resistance of the deposited layer as a function of operating temperature and CO concentrations. The gas sensitivity tests have demonstrated that the ZnO nanostructures, especially flower-like morphology, exhibit high sensitivity to CO proving their applicability in gas sensors. The role of the nanostructure on the sensing properties of ZnO is also discussed. (C) 2009 Elsevier B.V. All rights reserved.
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A Donato, F Della Corte, M Gioffre, N Donato, A Bonavita, G Micali, G Neri (2009)  RF sputtered ZnO-ITO films for high temperature CO sensors   THIN SOLID FILMS 517: 22. 6184-6187 SEP 30  
Abstract: In this work is reported the development of ceramic sensors based on ZnO-doped ITO thin films for engine diagnostics able to withstand the harsh environments associated with exhausts. ZnO-ITO films were deposited by RF-sputtering and have been employed in the development of thin films-based carbon monoxide resistive sensors operating at high temperature (500 degrees C). ZnO-ITO films, with different Zn/In ratio and thickness around 3 mu m., have been deposited by changing the power on the targets. The effects of both the working temperature and the ZnO loading on the sensors performances were investigated. Undoped ITO film has shown negligible response to CO, whereas ZnO-ITO films were found to be sensitive at the required working temperatures. The reported results show how the ZnO-ITO devices under study can be promising sensors for CO monitoring in real exhausts of car engines. (C) 2009 Elsevier B.V. All rights reserved.
Notes: 6th International Workshop on Semiconductor Gas Sensor, Zakopane, POLAND, SEP 14-19, 2008
2008
A Arena, N Donato, G Saitta, S Galvagno, C Milone, A Pistone (2008)  Photovoltaic properties of multi-walled carbon nanotubes deposited on n-doped silicon   MICROELECTRONICS JOURNAL 39: 12. 1659-1662 DEC  
Abstract: Multi-wall carbon nanotubes (MWCNTs), grown by catalytic chemical vapor deposition (CCVD) over Fe supported oil alumina catalyst, using isobutane as feedstock, are dispersed in aqueous solutions of sodium dodecyl sulfate. Stable and highly photosensitive heterojunctions are developed by liquid-phase deposition of MWCNTs/surfactant mixtures on the top of n-doped monocrystalline silicon wafers. Electrical measurements performed in the dark and under broad-band visible light, show that the hybrid solar cells, despite their non-optimized design, have conversion energy efficiency of the order of 3%. (C) 2008 Elsevier Ltd. All rights reserved.
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A Arena, N Donato, G Saitta (2008)  Photosensitive properties of Perylene-Oxazine films, solution-deposited on doped silicon   MATERIALS LETTERS 62: 15. 2388-2391 MAY 31  
Abstract: Liquid phase deposition of chlorobenzene solutions containing Perylene and Oxazine, is used to grow films made of quasi-parallel wire-like microstructures. Films form, when deposited on n-doped monocrystalline silicon wafers, photosensitive heterojunctions with a spectral response that closely resembles Perylene-Oxazine absorption. Photoelectric properties of the heterojunctions are investigated employing current versus voltage measurements, which are performed in the dark and under white light with a power density range of 0. 1 mW/cm(2) to 1.0 mW/cm(2). (c) 2007 Elsevier B.V. All rights reserved.
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2007
A Caddemi, F Catalfamo, N Donato (2007)  A neural network approach for compact cryogenic modelling of HEMTs   INTERNATIONAL JOURNAL OF ELECTRONICS 94: 9. 877-887  
Abstract: This paper reports on a procedure based on the use of artificial neural networks ( ANN) to fully model the performance of advanced high electron mobility transistors ( HEMT) operating down to cryogenic temperatures. By means of this procedure, we reproduce the DC behaviour and the scattering ( S-) parameters of the device under test ( DUT). The I- V curves and the S- parameters of the DUT have been compared with measurements, and a good agreement has been found for assessing the capability of the ANN structure to predict the full behaviour of the DUT. Furthermore, we have analysed in detail the performance of two typical parameters of HEMT’s, namely the transconductance and the output conductance. Their values have been derived from measured data and have been compared with those obtained by the ANN approach. Both the simulated DC and RF performance have shown an accuracy degree adequate to model the device properties down to cryogenic temperatures.
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A Arena, N Donato, G Saitta, G Pioggia, G Rizzo (2007)  All-organic electrochemical devices based on a tetracyanoquinodimethane complex   SOLID-STATE ELECTRONICS 51: 5. 639-643 MAY  
Abstract: A soluble charge-transfer complex is synthesized starting from 7,7’,8,8’-tetracyanoquinodimethane (TCNQ) and 2,5-dimercapto1,3,4-thiadiazole dipotassium salt, and characterized by means of spectrophotometric measurements. The material, deposited from the solution phase on the top of doped polythiophene electrodes, provides an elect rochemically reactive charge transport layer, achieving simple design all-organic electrochemical cells to be developed. The devices are characterized by rectification ratios up to 100 at a bias voltage of 3 V, and demonstrate humidity sensor functionality, as indicated by the ratio between the current in the 70% humidity condition and in the dry condition, which is found to reach values of the order of 10(5) at a bias voltage of 3 V. (c) 2007 Elsevier Ltd. All rights reserved.
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A Arena, N Donato, G Saitta (2007)  Electrical characterization of solid-state heterojunctions between PEDOT : PSS and an anionic polyelectrolyte   MICROELECTRONICS JOURNAL 38: 6-7. 678-681 JUN  
Abstract: Stable organic heterojunctions are developed by deposition of the anionic polyelectrolyte poly(4-lithium styrenesulfonic acid) (LiPSSA) on the top of poly(3,4-ethylendioxy hiophene)/poly(styrenesulfonate) (PEDOT:PSS) films. The electrical response of the heterojunctions to triangular voltage pulses in the range between -5 and + 5 V is characterized by hysteresis phenomena, observed for hundreds of cycles with low distortions, at scan rates between 1 and 100mV/s. The hysteresis is ascribed to the occurrence of redox transitions, evidenced by the presence of well-defined peaks in the current-voltage characteristics. The electrical behaviour of the PEDOT:PSS/LiPSSA devices is found to be mainly capacitive, and show humidity-sensitive functionality, demonstrated by the gradual and reversible increase of the area subtended by the J- V cycles as the relative humidity increases. (C) 2007 Elsevier Ltd. All rights reserved.
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A Arena, N Donato, G Saitta, G Rizzo, G Neri, G Pioggia (2007)  Photosensitive heterojunctions of silicon coated with sol-gel derived TiO2 dispersed in poly(3,4-ethylendi oxythiophene)/poly(styrenesulfonate)   JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY 43: 1. 41-46 JUL  
Abstract: Sol-gel derived aggregates of titania nanocrystals, synthesized starting from alcohol-water solutions of titanium isopropoxide, were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) measurements. The TiO2 powder was dispersed in aqueous solutions of poly(3,4-ethylendioxythiophene)/poly(styrenesulfonate) (PEDOT-PSS), and the blends were coated on n-doped silicon substrates to achieve simple design heterojunctions. Current versus voltage measurements performed both in the dark and under broad band light irradiation show that the nSi/PEDOT-PSS/TiO2 heterojunctions have remarkable photosensitive behaviour, promising in view of applications as hybrid photovoltaic cells.
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2006
A Arena, N Donato, G Pioggia, G Rizzo, G Saitta (2006)  Preparation and optical characterization of photosensitive multilayered structures based on polythiophenes and tetracyanoquinodimethane   MICROELECTRONICS JOURNAL 37: 11, SI. 1384-1388 NOV  
Abstract: Organic double layers obtained by electrodeposition of a substituted polythiophene followed by spin-coating of a Tetracyanoquinodimethane (TCNQ) electron acceptor layer, are characterized by means of spectrophotometric measurements carried out in the UV-VIS-IR range. According to the optical data, the electron acceptor molecules reduce to the singly ionized state as a consequence of a charge-transfer reaction that takes place at the interface with the electrodeposited polymer, which acts as an electron donor. Rectifying heterojunctions are obtained by depositing the double layers on the top of monocrystalline silicon wafers, and on the top of monocrystalline silicon wafers coated with electrochemically de-doped poly(3,4-ethylendioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS). Current versus voltage measurements performed in the dark and under halogen light irradiation show that the developed heterojunctions exhibit photosensitive charge transport features, promising in view of photovoltaic applications. (c) 2006 Elsevier Ltd. All rights reserved.
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Giovanni Neri, Anna Bonavita, Giuseppe Rizzo, Giuseppe Micali, Nicola Donato, Salvatore Ipsale (2006)  Investigation of permeation tubes for temperature-compensated gas-sensor calibrators   IEEE SENSORS JOURNAL 6: 5. 1120-1125 OCT  
Abstract: Ethanol permeation tubes have been proposed for a possible use in temperature-compensated gas-sensor calibrators. Two commercial tubes with a different geometric configuration of the polymeric membrane (wafer- and EL-type) have been tested. First, their permeation characteristics have been evaluated and, subsequently, their performances tested in an apparatus simulating programmed temperature cycles. Both tubes have shown a linear permeation rate in the range of temperature investigated and a low permeation temperature coefficient, with the EL-type tube showing also a very fast response to temperature variation. The integration of this latter tube with a flow-compensation controller has lead to the realization of a temperature-compensated calibrator device, allowing to maintain the ethanol concentration constant at the calibrator outlet by simply modulating the carrier flow through the permeation tube to compensate the temperature fluctuation. Results obtained in the generation of calibrated gas-phase ethanol concentrations, in the range from 1 to 500 ppm, suggest a promising use of these temperature-compensated permeation tubes as calibrators in portable gas-sensor devices.
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A Caddemi, G Crupi, N Donato (2006)  Microwave characterization and modeling of packaged HEMTs by a direct extraction procedure down to 30 K   IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 55: 2. 465-470 APR  
Abstract: The Knowledge of the small-signal equivalent circuit of microwave GaAs field effect transistors (FETs) is crucial for the design of low-noise amplifiers and is very useful to support the analysis of the transistor performance. This paper reports the results of our experimental activity concerning the application of an improved procedure for the direct extraction of the model element values from scattering (S-) parameter measurements. This analytical procedure was tested on low-noise pseudomorphic high electron mobility transistors (pHEMTs) up to 6 GHz and at cryogenic temperatures without any optimization or tuning adjustment. This paper reports the behavior of the intrinsic elements versus bias condition; the experimental results were found to match the theoretical expectations. The very good agreement between the simulated and measured S-parameters confirms the validity of the proposed method. To carry out the experimental activity, a properly designed cryogenic setup operating in our laboratory, which allows performing direct current (de) and microwave characterization down to 30 K, was employed.
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G Neri, A Bonavita, G Micali, N Donato, F A Deorsola, P Mossino, I Amato, B De Benedetti (2006)  Ethanol sensors based on Pt-doped tin oxide nanopowders synthesised by gel-combustion   SENSORS AND ACTUATORS B-CHEMICAL 117: 1. 196-204 SEP 12  
Abstract: The ethanol sensing properties of SnO2 powders prepared by a gel-combustion method have been investigated. SnO2 powders with different average crystallite size, (D), ranging from 6 up to 100 nm, were synthesized by this process starting from metallic tin as raw material and citric acid and/or urea as fuel substances. The average crystallite size of the synthesized powders was found to depend on the nature and loading of the fuel substance used in the combustion process. Thick film sensors based on the gel-combustion SnO2 powders, annealed at 600 degrees C, have shown good sensitivity to low concentrations of ethanol (50-200 ppm). The smaller particles have shown a higher sensitivity than the bigger ones. At the addition of 1 wt% Pt, a remarkable enhancement of the sensitivity to C2H5OH and response and recovery time was observed for the sample with smaller SnO2 particles. Pt was instead found to suppress CO sensitivity, thus increasing the selectivity towards ethanol. (c) 2005 Elsevier B.V. All rights reserved.
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A Caddemi, G Crupi, N Donato (2006)  Temperature effects on DC and small signal RF performance of AlGaAs/GaAs HEMTs   MICROELECTRONICS RELIABILITY 46: 1. 169-173 JAN  
Abstract: We here report on the DC and microwave performance of HEMTs tested on wafer under different temperature conditions. The relevant experimental data show that the most important electrical parameters, such as the output current, the threshold voltage, the transconductance and the forward transmission coefficient, are sensibly affected by thermal phenomena. We focused our attention on the variations of the above parameters with the temperature because such a detailed knowledge is essential to establish the optimum bias point for a given application. Furthermore, we analyze the influence of the DC quiescent point degradations, due to thermal phenomena, on the small signal equivalent circuit. Since the thermal behavior of the circuit model is a function of the bias, we examine the behavior of the circuit elements vs. temperature over a wide range of bias conditions. (c) 2005 Elsevier Ltd. All rights reserved.
Notes:
2005
G Neri, A Bonavita, S Galvagno, N Donato, A Caddemi (2005)  Electrical characterization of Fe2O3 humidity sensors doped with Li+, Zn2+ and Au3+ ions   SENSORS AND ACTUATORS B-CHEMICAL 111: SI. 71-77 NOV 11  
Abstract: Li-, Zn- and Au-doped Fe2O3 thin films have been investigated as humidity sensing materials. Their electrical properties have been studied in the 0-100% relative humidity (RH) range by means of electrochemical impedance spectroscopy (EIS). This has allowed to drawn an equivalent circuit which well fit experimental data obtained from the doped films. The resistive and capacitive elements of the equivalent circuit have been also calculated by a modeling procedure. Results indicate that the humidity characteristics of the doped sensing films are correlated to the charge density and surface concentration of the dopants. (c) 2005 Elsevier B.V. All rights reserved.
Notes: 18th Eurosensors Conference, Rome, ITALY, SEP 12-15, 2004
A Caddemi, G Crupi, N Donato (2005)  On the soft breakdown phenomenon in AlGaAs/InGaAs HEMT : An experimental study down to cryogenic temperature   SOLID-STATE ELECTRONICS 49: 6. 928-934 JUN  
Abstract: This work is focused on the investigation of the soft breakdown (or kink) phenomenon in AlGaAs/InGaAs HEMT down to cryogenic temperature. The kink effect in the output characteristics consists of an abrupt increase of the drain current at a given value of the drain-source voltage. This anomaly causes degradation in the performances of the transistors as it leads to a reduction in the gain and an increase in the level of noise. On the basis of our experimental data, we attribute the origin of the kink effect to trapping and subsequent field assisted detrapping mechanisms. Trap model allows us to explain the behavior of the kink effect with respect to the bias and the temperature, and also the difference between DC and RF output characteristics. By cooling the device, a negative charge accumulation, likely due to the reduction of the thermally activated electron detrapping phenomena, leads to the threshold voltage shift towards higher values. It results in a degradation of the transistor figures of merit, like the transconductance and the magnitude of the forward transmission parameter. (c) 2005 Elsevier Ltd. All rights reserved.
Notes:
M Alvaro, A Caddemi, G Crupi, N Donato (2005)  Temperature and bias investigation of self heating effect and threshold voltage shift in pHEMT’s   MICROELECTRONICS JOURNAL 36: 8. 732-736 AUG  
Abstract: In the present work we analyze the performance of power pseudomorphic HEMT’s having scaled gate widths (300, 600, 900 mu m) under a wide range of bias and temperature conditions to investigate the onset of an hot electron regime. These devices exhibit a negative slope of I-D with respect to V-DS and a subsequent negative differential resistance under high power dissipation conditions. This reduction in the drain current can be explained by a degradation of the carrier velocity in the two dimensional electron gas due to the self-heating effect. The output I-V characteristics of our devices are also affected by the threshold voltage shift. It results that the threshold voltage increases linearly by decreasing the temperature. This threshold voltage shift causes a decrease of the transconductance when the devices is biased closer to the pinch-off. Consequently, the forward transmission parameter S-21 at microwaves shows a degradation at lower temperatures despite the fact that the transport properties improve upon cooling. (c) 2004 Elsevier Ltd. All rights reserved.
Notes:
A Caddemi, F Catalfamo, N Donato (2005)  Cryogenic HEMT noise modeling by artificial neural networks   FLUCTUATION AND NOISE LETTERS 5: 3. SEP  
Abstract: In this paper we report the development of an artificial neural network to extract a 17-element small-signal circuit model of high electron mobility transistors (HEMTs) and one associated noise temperature value. By this procedure, we are able to reproduce the small-signal and noise performance of several device types from only one measured scattering parameter set, one frequency point and one noise figure value. The employed noise figure is measured in input matched conditions (i.e. 50 ohm source impedance), namely F-50. The output noise temperature is associated to the drain-source resistance in the HEMT equivalent circuit according to the noise temperature model by Pospieszalski. The noise parameters of the device under test are then calculated by CAD simulation of the circuit and compared with measurement results. The trained network outputs were used by means of a commercial CAD tool, to simulate and fit measurements performed down to cryogenic temperatures with very good agreement. We observed that the difference that occurs between the expected value of the noise temperature and the average value calculated by the neural network leads to negligible variations in the behavior of the simulated noise parameters.
Notes:
A Caddemi, G Crupi, N Donato (2005)  Impact of the self-generated heat on the scalability of HEMTs   MICROELECTRONIC ENGINEERING 82: 2. 143-147 OCT  
Abstract: This work is aimed at studying the influence of the self-heating effect on the scalability of HEMTs from an experimental point of view. To accomplish that, we analyze the DC and microwave performance of devices having scaled gate widths. Our experimental results show that the DC transconductance does not scale linearly with the gate periphery under high power dissipation condition. The observed degradation of the transconductance in larger devices can be explained by a reduction of the average carrier velocity due to the occurrence of self-heating. Thermal phenomena even affect the RF small signal performance of the devices under test as they influence the DC operating point. Therefore, the RF transconductance and the forward transmission coefficient are degraded when the dissipated power increases so that all the self-generated heat cannot be completely removed. (c) 2005 Elsevier B.V. All rights reserved.
Notes:
2004
G Giusi, N Donato, C Ciofi, F Crupi (2004)  A new technique for extracting the MOSFET threshold voltage using noise measurements   FLUCTUATION AND NOISE LETTERS 4: 4. DEC  
Abstract: In this work we propose a new technique for the evaluation of the threshold voltage of MOS transistors based on the measurement of the channel thermal noise. Since this new method allows the evaluation of the threshold voltage without any current flowing through the channel, it inherently eliminates the limitations coming from the need of using too approximate models for the interpretation of current-voltage measurements in MOS devices. The results of actual measurements on p-channel MOSFETs are reported that confirm the validity and the significance of the proposed approach.
Notes:
G Neri, A Bonavita, G Rizzo, S Galvagno, N Donato, L S Caputi (2004)  A study of water influence on CO response on gold-doped iron oxide sensors   SENSORS AND ACTUATORS B-CHEMICAL 101: 1-2. 90-96 JUN 15  
Abstract: A temperature programmed desorption (TPD) study of the water- and CO-interaction with the surface of gold-doped iron oxide sensors is presented. TPD data has shown that CO does not adsorb in the absence of water. The adsorption of CO occurs when water is present as coadsorbate, through the formation of a surface formate intermediate. TPReaction of CO with oxygen in both dry and wet air has shown that water also promotes CO oxidation, likely via the same formate intermediate. The effect of water on the CO sensing of Au/Fe2O3 Sensors was also investigated. Current response data at different temperatures and relative humidity were fitted by the equation S = I-CO/I-air = k[CO](beta), with the sensitivity (k) and exponential (beta) factors dependent on the temperature and relative humidity (RH). Moreover, in wet air, the maximum of response, T-M, shifts to higher temperature with respect to dry air. To explain the results of electrical tests two different sensing mechanisms which operate in dry and wet air, respectively, have been suggested. (C) 2004 Elsevier B.V. All rights reserved.
Notes:
A Caddemi, G Crupi, N Donato (2004)  A robust and fast procedure for the determination of the small signal equivalent circuit of HEMTs   MICROELECTRONICS JOURNAL 35: 5. 431-436 MAY  
Abstract: In this paper we present an analytical, fast, accurate and robust technique for the determination of the circuit model elements of HEMTs in the microwave range. By this method the values of the equivalent circuit parameters of the device under test are extracted using three measured scattering (S) parameter sets without any optimization. We also investigated the influence of the reverse transfer conductance Re(Y-12) on the modelling by means of a gate drain resistance R-dg. The validity of this method was verified upon a set of pseudomorphic HEMTs having different gate widths tested on wafer at several bias and temperature conditions. Very good agreement between the simulated and measured S-parameters has been obtained. The procedure has been implemented in Agilent VEE language as a fully automated tool to allow an accurate, fast and complete device characterization requiring no operator supervision. (C) 2004 Elsevier Ltd. All rights reserved.
Notes:
2003
A Caddemi, N Donato (2003)  Characterization techniques for temperature-dependent experimental analysis of microwave transistors   IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 52: 1. 85-91 FEB  
Abstract: Our recent research work has been focused upon the effects of temperature on the dc behavior, the small signal performance, and the noise properties of advanced transistors up to microwave frequencies. Several devices have been investigated by means of different experimental systems down to cryogenic levels (50 K). We here present the most interesting results of such ex. tensive investigation, together with the details of the experimental procedures followed. The on-wafer cooling setup was designed and realized in our laboratory. It exhibited a very good performance characterized by either a tight temperature control or a fast settling time over the 220-320 K temperature range. By this temperature-dependent analysis, interesting features of GaAs- and In-GaAs-HEMTs are shown and hereby discussed.
Notes:
2002
A Caddemi, N Donato (2002)  Temperature-dependent noise characterization and modeling of on-wafer microwave transistors   MICROELECTRONICS RELIABILITY 42: 3. 361-366 MAR  
Abstract: Thermal investigation is of basic importance to assess key aspects of the performance and the reliability of microwave devices and circuits operating in a critical environment. To this aim, we have designed and realized an efficient thermoelectric chuck for on-wafer probe stations featuring rapid and accurate temperature control over the 220-320 K range. The system has been exploited in the measurement of I-V characteristics, scattering parameters and noise figure of GaAs-based heterojunction devices up to 40 GHz. The results of the temperature-dependent characterization have been subsequently employed in the extraction of noisy electrical models useful for computer-aided design of low-noise microwave circuits. We here describe the details of this low-cost high-performance measurement system and its applications in investigating the temperature dependence of semiconductor device performances. (C) 2002 Elsevier Science Ltd. All rights reserved.
Notes:
G Ferrante, F Principato, A Caddemi, N Donato, G Tuccari (2002)  DC and 1/f noise characterization of cryogenically cooled pseudomorphic HEMT’s   JOURNAL DE PHYSIQUE IV 12: PR3. 117-120 MAY  
Abstract: Pseudomorphic (AlGaAs/InGaAs/GaAs) HEMT’s have exhibited the best noise performance over the entire LF-to-microwave frequency range if compared to MESFET’s and conventional GaAs HEMT’s, due to either a reduced flicker noise, a lower G/R contribution and a smaller high-field diffusion noise. We have recently investigated the microwave (up to 18 GHz) noise properties of packaged pseudomorphic HEMT’s from 290 K down to cryogenic temperature values. The current experimental work is aimed at extending such analysis to the LF noise range and at low temperatures. Cryogenic noise spectra (1 Hz to 100 KHz) and DC characteristics have therefore been recorded and the relevant observations on the device behavior are herewith reported.
Notes: 5th European Workshop on Low Temperature Electronics (WOLTE 5), GRENOBLE, FRANCE, JUN 19-21, 2002
G Neri, A Bonavita, S Galvagno, C Pace, N Donato (2002)  Preparation, characterization and CO sensing of Au/iron oxide thin films   JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 13: 9. 561-565 SEP  
Abstract: The preparation and characterization of Au-doped iron oxide thin films is reported. Doped-thin films have been prepared by a liquid-phase deposition (LPD) method from aqueous solutions in the presence of a reactive atmosphere containing NH3. The morphology and microstructure of the prepared films are described. The effect of some process parameters (precursor solution concentration, calcination temperature) on the film formation, thickness and microstructure are investigated. Sensor devices based on Au/Fe2O3 thin films deposited on alumina by the LPD method, are sensitive to CO at operating temperatures between 200-400 degreesC. (C) 2002 Kluwer Academic Publishers.
Notes:
2001
A Caddemi, N Donato (2001)  On the noise resistance of field-effect transistors at microwave frequencies   FLUCTUATION AND NOISE LETTERS 1: 3. SEP  
Abstract: Ibis paper presents a survey on the topical aspects of the noise resistance in field-effect transistors (FET) at microwave frequencies. Such noise parameter represents the sensitivity of the device noise figure to the departure from the minimum noise condition and is therefore important in all low-noise applications. The performance of the noise resistance in FETs has been reviewed since the first noise modeling analysis of short-gate devices were presented in the early ‘70s. The authors also comment and compare their own results on this subject as obtained by extensive experimental activity in the field of noisy device characterization vs. frequency, bias and temperature conditions.
Notes:

Conference papers

2010
S Lo Schiavo, L Livoti, A Calisto, A Bramanti, N Donato, M Latino, G Neri (2010)  Novel sensing materials for breath analysis devices   In: 2010 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) 670-673  
Abstract: The development of new transition metal complexes (TMCs) sensing materials, based on di-rhodium (II, II) complexes with a lantern structure, is investigated. Specifically, in this work is reported a study carried out with the Rh(2)(form)(4) complex having the formamidinate (form = N.N-p-tolylformamidinate anion) bridging ligand in the equatorial positions. Thick films of the complex have been deposited on interdigitated alumina substrate and their electrical characteristics have been evaluated. Rh2(form) 4 behaves as a p-type semiconductor, showing a large decrease in forward and reverse current in presence of ammonia vapors in air. The preliminary results reported promise a practical application of the developed devices in the breath analysis for clinical diagnostics.
Notes: 32nd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBC 10), Buenos Aires, ARGENTINA, AUG 30-SEP 04, 2010
2009
G Neri, G Micali, S Ipsale, N Donato, F Di Francesco, C Loccioni, G Pioggia, M Ferro, S Tabucchi, M Onor (2009)  DEVELOPMENT OF A SOLID STATE ANALYZER FOR BREATH ANALYSIS   In: PROCEEDINGS OF THE 13TH ITALIAN CONFERENCE ON SENSORS AND MICROSYSTEMS Edited by:C DiNatale, A DAmico, E Martinelli, R Paolesse. 243-248  
Abstract: Breath analysis is a non-invasive procedure for the potential diagnostics of a broad range of medical pathologies which could be easily performed at clinics and doctor rooms. The development of a breath analyzer based on MOS sensors and designed for this scope is here described. The developed analyzer should replace and improve the analytical procedures so far performed with conventional techniques (e.g, GC-MS) which are generally expensive and time consuming and therefore not suitable for routine analysis in clinical environment.
Notes: 13th Italian Conference on Sensors and Microsystems, Rome, ITALY, FEB 19-21, 2008
2007
G Neri, A Bonavita, S Ipsale, G Micali, G Rizzo, N Donato (2007)  Carbonyl sulphide (COS) monitoring on MOS sensors for biomedical applications   In: 2007 IEEE INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS, PROCEEDINGS, VOLS 1-8 2776-2781  
Abstract: Resistive metal-oxide semiconductor (MOS) sensors have been tested in the monitoring of carbonyl sulphide (COS), a biomarker for acute rejection (AR) in lung transplanted patients. COS concentration in the breath of these patients (about 0.5 ppm) is in fact more higher than that found in healthy peoples, making possible the real time diagnosis of this pathology by breath analysis. In2O3-based MOS resistive sensors have been therefore tested at different temperatures and COS concentrations in order to optimize the sensor response and response/recovery time. The ultimate aim of this work is to develop a simple and cost-effective breath test for the acute rejection in lung transplanted patients.
Notes: IEEE International Symposium on Industrial Electronics, Vigo, SPAIN, JUN 04-07, 2007
Alina Caddemi, Francesco Catalfamo, Nicola Donato (2007)  Two computational approaches for noise modeling of advanced microwave transistors   In: 2007 IEEE INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS, PROCEEDINGS, VOLS 1-8 239-244  
Abstract: A complete noise modeling of advanced microwave transistors is of great importance for the development of high sensitivity electronic systems. In the present paper, two computational approaches for modeling the noise performance of low noise microwave transistors are reported. The adopted techniques here presented involve the development of an artificial neural network tool and the implementation of an evolutionary algorithm. Each implemented approach is validated by a comparison between the expected values of the noise parameters (available from measurements) and the obtained data values. A thorough analysis of the results allows us to affirm that the application of these techniques quickly and originally solves the noise modeling task here examined.
Notes: IEEE International Symposium on Industrial Electronics, Vigo, SPAIN, JUN 04-07, 2007
2005
A Caddemi, F Catalfamo, N Donato (2005)  Artificial Neural Network-based procedure for cryogenic microwave noise characterization of HEMT’s   In: Proceedings of the 2005 IEEE International Conference on Computational Intelligence for Measurement Systems and Applications 285-289  
Abstract: In this paper we report on the development of ail Artificial Neural Network (ANN) software utility for the noise characterization of microwave transistors down to cryogenic temperatures. BY this procedure, jointly with an original characterization soft-are written in our lab, we are able to reproduce the noise performance of several device types from only one measured S-parameter set, one frequency point and one noise figure (namely, F-50) value. The noise parameters of the DUT (Device Under Test) are then compared with direct measured experimental data. A cryogenic temperature test is also performed leading to very good results. It can be seen that the difference occurring between the expected noise parameter values and the values calculated by the neural network does not evidence significant variations in the behavior of extracted noise parameters.
Notes: IEEE International Conference on Computational Intelligence for Measurement Systems and Applications, Messina, ITALY, JUL 20-22, 2005
A Caddemi, F Catalfamo, N Donato (2005)  Simulating noise performance of advanced devices down to cryogenic temperatures   In: Unsolved Problems of Noise and Fluctuations Edited by:, L Reggiani, C Pennetta, V Akimov, E Alfinito, M Rosini. 480-485  
Abstract: The aim of the present work is the development of a suitable neural network structure to compute the microwave noise parameters of High Electron Mobility Transistors (HEMT). The noise parameters (NP) here considered are the magnitude (vertical bar Gamma(opt)vertical bar) and phase (angle Gamma(opt)) of the optimum noise source reflection coefficient, the minimum noise figure (F-min) and the noise resistance (R-n). By this procedure, we are able to reproduce the above noise parameters of several device types from only one measured scattering parameter set, one frequency point and one generic noise figure value at different bias and/or temperature conditions. The employed noise figure is that measured in input matched conditions (i.e. 50 Omega source impedance), namely F-50. The trained network outputs were compared with data of noise measurements performed in our lab and the results have shown to be in a very good agreement. We observed that the difference occurring between the expected value of the noise parameters and the value calculated by the neural network is negligible. The procedure here presented is the most effective choice to avoid the need of any circuit simulations. Our neural network allows great time saving, thus leading to a rapid and complete characterization of the active microwave device under test with a remarkable generalization feature.
Notes: 4th International Conference on Unsolved Problems of Noise and Fluctuations in Physics, Biology and High Technology, Gallipoli, ITALY, JUN 06-10, 2005
2004
G Neri, A Bonavita, S Galvagno, N Donato, A Caddemi (2004)  Doped-Fe2O3 humidity sensors : An electrical modeling and circuit evaluation   In: SENSORS AND MICROSYSTEMS, PROCEEDINGS Edited by:, C DiNatale, A DAmico, G Soncini, L Ferrario, M Zen. 227-231  
Abstract: Li-, Zn- and Au-doped Fe2O3 thin films have been investigated as humidity sensing materials. Depending on the nature and loading of the dopant, microstructural modifications on the host metal oxide have been observed. The humidity sensing properties of these films were studied by means of Electrochemical Impedance Spectroscopy (EIS). Humidity sensing data have been then analysed by an electrical modeling and correlated to the microstructural characteristics.
Notes: 8th Italian Conference on Sensors and Microsystems, Trento, ITALY, FEB 12-14, 2003
G Neri, A Bonavita, G Rizzo, S Galvagno, N Donato, S Ipsale (2004)  Ternperature-independent permeation tubes for gas sensor calibrators   In: PROCEEDINGS OF THE IEEE SENSORS 2004, VOLS 1-3 Edited by:, D Rocha, P M Sarro, M J Vellekoop. 734-737  
Abstract: A new temperature-independent set-up for gas sensors calibration making use of permeation tubes is proposed. The control of the output gas-phase concentration from the calibrator was made modulating the carrier flow through the permeation tube as a function of the temperature and dynamic of the tube by an entirely computer-controlled system. The study and results related to generation of calibrated gas-phase ethanol concentrations (from 1 to 500 ppm) and the calibration of a MOS (Metal Oxide Semiconductor) gas sensor by this apparatus have been reported.
Notes: IEEE Sensors 2004 Conference, Vienna Univ Technol, Vienna, AUSTRIA, OCT 24-27, 2004
G Neri, A Bonavita, G Rizzo, S Galvagno, N Donato, C Pace (2004)  Study on the behaviour to humidity of Cr2-xTixO3 films prepared by sol-gel   In: SENSORS AND MICROSYSTEMS, PROCEEDINGS Edited by:, C DiNatale, A DAmico, G Soncini, L Ferrario, M Zen. 217-221  
Abstract: CTO powders and thin films have been prepared by a sol-gel route and subsequent thermal treatment at low temperature (<= 400 degrees C). The humidity characteristics of CTO thin films have been investigated. Results reported have shown that the humidity behaviour is related to the intergranulary porosity of the films. The Cr/Ti ratio and the role of alkaline impurities (Li+) was also studied with aim to clarify the mechanism of the surface conduction of CTO films in the presence of water vapor.
Notes: 8th Italian Conference on Sensors and Microsystems, Trento, ITALY, FEB 12-14, 2003
2003
A Caddemi, N Donato, G Crupi (2003)  A robust approach for the direct extraction of HEMT circuit elements vs. bias and temperature   In: TELSIKS 2003 : 6TH INTERNATIONAL CONFERENCE ON TELECOMMUNICATIONS IN MODERN SATELLITE, CABLE AND BROADCASTING SERVICE, VOLS 1 AND 2, PROCEEDINGS OF PAPERS 557-560  
Abstract: We here present the results of our most recent activity in the implementation of robust and easy-to-perform techniques for the extraction of reliable equivalent circuits for microwave transistors. Our effort also led to the development of a compact software tool written in Agilent VEE language for totally automated measurement and direct model extraction. Its effectiveness has been tested at several bias and temperature points and the modeling results have been compared with those obtained by application of other procedures. This procedure can be adopted for both Schottky-gate devices (MESFET’s, HEMT’s) and insulated gate devices (RF MOSFET’s, CMOS) since no direct polarization of the gate is requested.
Notes: 6th International Conference on Telecommunication in Modern Cable, Satellite and Broadcasting Services, NISH, YUGOSLAVIA, OCT 01-03, 2003
2002
A Bonavita, A Caddemi, N Donato (2002)  Thin-film sensors for industrial electronics : Performance evaluation by circuit model simulation   In: ISIE 2002 : PROCEEDINGS OF THE 2002 IEEE INTERNATIONAL SYMPOSIUM ON INDUSTRIAL ELECTRONICS, VOLS 1-4 388-392  
Abstract: Thin-films of pure and Li - or Au - doped iron oxide have been realized by liquid phase deposition (LPD). Supporting them over alumina substrates provided with gold interdigitated contacts, gas sensor devices in a layered configuration have been obtained. The sensor electrical response to CO and humidity in Air was evaluated. Furthermore, an impedance spectroscopy characterization over the whole 0 - 100 % RH humidity range was carried out. The results have been employed to extract accurate circuit models of the sensing films. Since each element of the equivalent circuit has a direct and univocal relationship with the different parts of the physical structure. such models have shown to be a basic tool for a deeper knowledge of the sensor performance by relating structural to electrical properties. In addition, their implementation gives useful indications on the changes that can be made to improve the sensor response. In the present paper, the performance of the sensors and the most interesting results of the model simulation are presented and discussed.
Notes: IEEE International Symposium on Industrial Electronics, L AQUILA, ITALY, JUL 08-11, 2002
2001
A Bonavita, A Caddemi, N Donato, P Accordino, S Galvagno, G Neri (2001)  Electrical characterization and modeling of thin-film humidity sensors   In: ICECS 2001 : 8TH IEEE INTERNATIONAL CONFERENCE ON ELECTRONICS, CIRCUITS AND SYSTEMS, VOLS I-III, CONFERENCE PROCEEDINGS 673-676  
Abstract: Undoped and Li-doped iron oxide thin films were investigated as humidity sensors. Large variations of the sensor resistance were observed by, changing the relative humidity (RH%) between 0 and 100%. The results of an electrochemical impedance spectroscopy (EIS) study performed by measuring the sensors complex impedance, Were analyzed and employed to extract equivalent circuit models. Such models have humidity-dependent element values and their structure has a direct relationship with the sensor physics. The performance of the films and the results of the model simulations are herewith presented and discussed.
Notes: 8th IEEE International Conference on Electronics, Circuits and Systems, ST JULIANS, MALTA, SEP 02-05, 2001
A Caddemi, N Donato, G Tuccari (2001)  Modeling the temperature noisy performance of low-noise III-V microwave devices down to cryogenic levels   In: EDMO 2001 : INTERNATIONAL SYMPOSIUM ON ELECTRON DEVICES FOR MICROWAVE AND OPTOELECTRONIC APPLICATIONS 267-272  
Abstract: We performed research work on the effects of temperature by investigating the DC behavior, the small signal and the noise performance of HEMT’s and HBT’s at microwave frequencies by means of different experimental systems down to cryogenic levels. The measurement data were then employed to extract temperature-dependent noisy models to be implemented in commercial CAD software. We here report the results of the modeling procedure with a special concern for the noise performance whose knowledge is of primary importance in the design of ultra high sensitivity receivers.
Notes: International Symposium on Electron Devices for Microwave and Optoelectronic Applications, VIENNA UNIV TECHNOL, VIENNA, AUSTRIA, NOV 15-16, 2001
2000
A Caddemi, N Donato, M Sannino (2000)  Low-noise device and circuit characterization at cryogenic temperatures for high sensitivity microwave receivers   In: 8TH IEEE INTERNATIONAL SYMPOSIUM ON HIGH PERFORMANCE ELECTRON DEVICES FOR MICROWAVE AND OPTOELECTRONIC APPLICATIONS 89-94  
Abstract: The present paper focuses on the small-signal and noise characterization of microwave transistors and circuits at temperatures ranging from 290 to 90 K, in the 6-18 GHz frequency band. We here report on the measurement procedure adopted and the relevant experimental results, including also detailed linear circuit modeling to determine the temperature dependence of basic physical parameters of the tested pseudomorphic HEMT’s. We have already worked at moderately low temperatures (down to 220 K) on either packaged and on wafer microwave transistors and present results at lower temperatures confirm what has been previously found.
Notes: 8th IEEE International Symposium on High Performance Electron Devices for Microwave and Optoelectronic Applications (EDMO 2000), UNIV GLASGOW, GLASGOW, SCOTLAND, 2000
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