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1. Short Term Reliability and Robustness of ultra-thin barrier, 110 nm-gate AlN/GaN HEMTs

Author

Gao, Zhan, Meneghini, Matteo, Harrouche, Kathia, Kabouche, Riad, Chiocchetta, Francesca, Marcon, Daniele, Okada, Etienne, Rampazzo, Fabiana, De Santi, Carlo, Medjdoub, Farid, Meneghesso, Gaudenzio, and Zanoni, Enrico

Subjects
Physics - Applied Physics
Abstract

Short-term reliability and robustness of 110 nm AlN/GaN HEMTs has been evaluated by means of off-state, semi-on state and on-state step stress tests on devices having different gate-drain distance, LGD. While breakdown voltages and critical voltages scale almost linearly with LGD, failure mode remains almost unchanged in all tested devices, and consists in an increase of gate leakage, accompanied by a positive shift of threshold voltage. In off-state, electroluminescence images detect the presence of localized leakage paths which may act as preferential paths for electron trapping. Degradation does not depend on dissipated power and is preliminary attributed to hot-electron trapping, enhanced by electric fields., Comment: ["European Union (EU)" & "Horizon 2020"]["Euratom" & Euratom research & training programme 2014-2018"][EUGANIC][EDA Contract B 1447 IAP1 GP][5G_GaN_2]

Published
2021
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2. Turning bad into good: a water-splitting-active hole transporting material to preserve the performance of perovskite solar cells in humid environments

Author

Kim, Min, Alfano, Antonio, Perotto, Giovanni, Serri, Michele, Dengo, Nicola, Mezzetti, Alessandro, Gross, Silvia, Prato, Mirko, Salerno, Marco, Sorrentino, Roberto, Meneghesso, Gaudenzio, Di Fonzo, Fabio, Petrozza, Annamaria, Gatti, Teresa, and Lamberti, Francesco

Subjects
Physics - Applied Physics, Condensed Matter - Materials Science
Abstract

Lead halide perovskite-based photoactive layers are nowadays employed for a large number of optoelectronic applications, from solar cells to photodetectors and light-emitting diodes, because of their excellent absorption, emission and charge-transport properties. Unfortunately, their commercialization is still hindered by an intrinsic instability towards classical environmental conditions. Water in particular promotes fast decomposition, leading to a drastic decrease in device performance. An innovative functional approach to overcome this major issue could derive from integrating water-splitting active species within charge extracting layers adjacent to the perovskite photoactive layer, converting incoming water molecules into molecular oxygen and hydrogen before they reach this last one, thus preserving device performance in time. In this work we report for the first time on a perovskite-ancillary layer based on CuSCN nanoplateletes dispersed in a p-type semiconducting polymeric matrix, combining hole extraction/transport properties with good water-oxidation activity, that transforms incoming water molecules and further triggers the in situ p-doping of the conjugated polymer by means of the produced dioxygen, further improving transport of photogenerated charges. This composite layer enables the long-term stabilization of a mixed cation lead halide perovskite within a direct solar cell architecture, maintaining a stable performance for 28 days in high-moisture simulated conditions. Our findings demonstrate that the engineering of a hole extraction layer with water-splitting active additives represent a valuable strategy to mitigate the degradation of perovskite solar cells exposed to atmospheric humidity. A similar approach could be employed in the future to improve stabilities of other optoelectronic devices based on water-sensitive species.

Published
2020

3. V-Pits and Trench-Like Defects in High Periodicity MQWs GaN-Based Solar Cells: Extensive Electro-Optical Analysis

Author

Nicoletto, Marco, primary, Caria, Alessandro, additional, Rampazzo, Fabiana, additional, De Santi, Carlo, additional, Buffolo, Matteo, additional, Rossi, Francesca, additional, Huang, Xuanqui, additional, Fu, Houqiang, additional, Chen, Hong, additional, Zhao, Yuji, additional, Gasparotto, Andrea, additional, Becht, Conny, additional, Schwarz, Ulrich T., additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, and Meneghini, Matteo, additional

Published
2024
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5. Correlating Interface and Border Traps With Distinctive Features of C–V Curves in Vertical Al2O3/GaN MOS Capacitors

Author

Zagni, Nicolò, primary, Fregolent, Manuel, additional, Verzellesi, Giovanni, additional, Marcuzzi, Alberto, additional, De Santi, Carlo, additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, Treidel, Eldad Bahat, additional, Brusaterra, Enrico, additional, Brunner, Frank, additional, Hilt, Oliver, additional, Meneghini, Matteo, additional, and Pavan, Paolo, additional

Published
2024
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7. Modeling the Electrical Degradation of Micro-transfer-Printed 845 nm VCSILs for Silicon Photonics

Author

Zenari, Michele, primary, Buffolo, Matteo, additional, De Santi, Carlo, additional, Goyvaerts, Jeroen, additional, Grabowski, Alexander, additional, Gustavsson, Johan, additional, Baets, Roel, additional, Larsson, Anders, additional, Roelkens, Günther, additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, and Meneghini, Matteo, additional

Published
2024
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8. Fast Characterization of Power LEDs: Circuit Design and Experimental Results

Author

Roccato, Nicola, primary, Piva, Francesco, additional, Buffolo, Matteo, additional, Trivellin, Nicola, additional, Santi, Carlo De, additional, Narduzzi, Claudio, additional, Fraccaroli, Riccardo, additional, Caria, Alessandro, additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, and Meneghini, Matteo, additional

Published
2024
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13. Understanding the Optical Degradation of 845 nm Micro-Transfer-Printed VCSILs for Photonic Integrated Circuits

Author

Zenari, Michele, primary, Buffolo, Matteo, additional, Fornasier, Mirko, additional, De Santi, Carlo, additional, Goyvaerts, Jeroen, additional, Grabowski, Alexander, additional, Gustavsson, Johan, additional, Kumari, Sulakshna, additional, Stassren, Andim, additional, Baets, Roel, additional, Larsson, Anders, additional, Roelkens, Günther, additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, and Meneghini, Matteo, additional

Published
2023
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15. Positive VTH Shift in Schottky p-GaN Gate Power HEMTs: Dependence on Temperature, Bias and Gate Leakage

Author

Modolo, Nicola, De Santi, Carlo, Sicre, Sebastien, Minetto, Andrea, Meneghesso, Gaudenzio, Zanoni, Enrico, and Meneghini, Matteo

Abstract

In this article, we present an extensive analysis of the positive threshold voltage instability in Schottky p-GaN gate enhancement-mode devices, investigated by a custom setup allowing an extended observation window, from the microsecond to hundreds of seconds. We show that a matrix of experiments can be specifically designed to investigate the voltage, temperature and leakage dependence of the threshold voltage instability induced by a positive gate bias, and to identify them. The original results indicate that the observed positive threshold voltage shift can be ascribed to the trapping of electrons at defects located in the AlGaN barrier. Remarkably, the trapping rate is strongly dependent on temperature at low bias, while it is not temperature-dependent at high bias, indicating the existence of both temperature and leakage-assisted trapping processes. This result was confirmed by investigating the correlation between dc leakage measurements and the time constant of threshold voltage transients. On the other hand, the recovery process is found to be thermally activated, with an activation energy of 0.26 eV: the trapped electrons are thermally emitted into the conduction band and are pushed toward the channel by the intrinsic electric field.

Published
2024
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16. Correlating Interface and Border Traps With Distinctive Features of C–V Curves in Vertical Al2O3/GaN MOS Capacitors

Author

Zagni, Nicolo, Fregolent, Manuel, Verzellesi, Giovanni, Marcuzzi, Alberto, De Santi, Carlo, Meneghesso, Gaudenzio, Zanoni, Enrico, Treidel, Eldad Bahat, Brusaterra, Enrico, Brunner, Frank, Hilt, Oliver, Meneghini, Matteo, and Pavan, Paolo

Abstract

In this article, we present an analysis of the correlation between interface traps (ITs) and border traps (BTs) on distinctive features of ${C}$ – ${V}$ curves in vertical Al2O3/gallium-nitride (GaN) MOS capacitors. First, pulsed ${C}$ – ${V}$ curves were characterized during the application of quiescent gate bias stresses of different magnitudes and signs. This characterization revealed four main distinctive features: 1) rightward rigid shift; 2) leftward rigid shift; 3) decrease of the $\Delta {C}$ – $\Delta {V}$ slope; and 4) formation of a hump in a gate bias range before the accumulation of electrons at the oxide/semiconductor interface. By means of a combined experimental/simulation analysis, these features were univocally attributed to specific ITs or BTs in the overall trap distribution. The simulation-aided analysis enhances the physical understanding of the ${C}$ – ${V}$ curves features and increases the dependability of the adopted IT measurement technique, allowing for a more rapid process optimization and device technology development.

Published
2024
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17. Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

Author

Zanoni, Enrico, De Santi, Carlo, Gao, Zhan, Buffolo, Matteo, Fornasier, Mirko, Saro, Marco, De Pieri, Francesco, Rampazzo, Fabiana, Meneghesso, Gaudenzio, Meneghini, Matteo, Zagni, Nicolo, Chini, Alessandro, and Verzellesi, Giovanni

Abstract

Application of gallium nitride high-electron-mobility transistors (GaN HEMTs) to millimeter-wave power amplifiers requires gate length scaling below 150 nm: in order to control short-channel effects, the gate-to-channel distance must be decreased, and the device epitaxial structure has to be completely redesigned. A high 2-D electron gas (2DEG) carrier density can be preserved even with a very thin top barrier layer by substituting AlGaN with AlN, InAl(Ga)N, or ScAlN. Moreover, to prevent interaction of hot electrons with compensating impurities and defects in the doped GaN buffer, the latter has to be separated from the channel by a back barrier. Other device designs consist in adopting a graded channel (which controls the electric field) or to adopt nitrogen-polar (N-polar) GaN growth (which decreases the distance between gate and channel, thus attenuating short-channel effects). The aim of this article is to review the various options for controlling short-channel effects, improve off-state characteristics, and reduce drain–source leakage current. Advantages and potential drawbacks of each proposed solution are analyzed in terms of current collapse (CC), dispersion effects, and reliability.

Published
2024
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18. Dynamic Behavior of Threshold Voltage and ID–VDS Kink in AlGaN/GaN HEMTs Due to Poole–Frenkel Effect

Author

Gao, Zhan, De Santi, Carlo, Rampazzo, Fabiana, Saro, Marco, Fornasier, Mirko, Meneghesso, Gaudenzio, Meneghini, Matteo, Chini, Alessandro, Verzellesi, Giovanni, and Zanoni, Enrico

Abstract

The kink effect in field-effect transistors (FETs) consists in a sudden increase in drain current, ${I}_{\text {D}}$ , during a drain voltage sweep and leading to a higher ${I}_{\text {D}}$ saturation value. We report new experimental data concerning the dynamic behavior of the “kink” in AlGaN/GaN HEMTs and correlate them with deep levels. The results demonstrate the role of the Poole–Frenkel effect in determining the occurrence of the kink and identify the experimental conditions that make it observable.

Published
2023
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19. Transconductance Overshoot, a New Trap-Related Effect in AlGaN/GaN HEMTs

Author

Zhan, Gao, primary, Rampazzo, Fabiana, additional, Santi, Carlo De, additional, Fornasier, Mirko, additional, Meneghesso, Gaudenzio, additional, Meneghini, Matteo, additional, Blanck, Hervé, additional, Grünenpütt, Jan, additional, Sommer, Daniel, additional, Chen, Ding Yuan, additional, Wen, Kai-Hsin, additional, Chen, Jr-Tai, additional, and Zanoni, Enrico, additional

Published
2023
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20. Degradation of GaN-Based Multiple Quantum Wells Solar Cells Under Forward Bias: Investigation Based on Optical Measurements and Steady-State Photocapacitance

Author

Caria, Alessandro, primary, Santi, Carlo De, additional, Buffolo, Matteo, additional, Nicoletto, Marco, additional, Huang, Xuanqi, additional, Fu, Houqiang, additional, Chen, Hong, additional, Zhao, Yuji, additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, and Meneghini, Matteo, additional

Published
2023
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21. Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

Author

Zanoni, Enrico, primary, Santi, Carlo De, additional, Gao, Zhan, additional, Buffolo, Matteo, additional, Fornasier, Mirko, additional, Saro, Marco, additional, Pieri, Francesco De, additional, Rampazzo, Fabiana, additional, Meneghesso, Gaudenzio, additional, Meneghini, Matteo, additional, Zagni, Nicolò, additional, Chini, Alessandro, additional, and Verzellesi, Giovanni, additional

Published
2023
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22. Status of Performance and Reliability of 265 nm Commercial UV-C LEDs in 2023

Author

Piva, Francesco, Buffolo, Matteo, Santi, Carlo De, Meneghesso, Gaudenzio, Zanoni, Enrico, Meneghini, Matteo, and Trivellin, Nicola

Abstract

In the last years, the research on ultraviolet-C (UV-C) light emitting diodes (LEDs) focused its efforts on the solution of major problems that limited the emitted optical power (OP) and that caused the sudden failure of the devices. This led to the availability in the market of some devices with interesting electro-optical characteristics and promising lifetimes. In this article, we decided to study the reliability of four commercial UV-C LEDs with a nominal wavelength of 265 nm, in order to study their lifetime and their possible implementation in disinfection systems. We submitted the devices to an accelerated lifetime test of 20000 min, at the absolute maximum current indicated in their respective datasheets. During the tests, we carried out electrical and optical measurements, and we evaluated their spectral characteristics before and after aging. Once identified the best sample, we compared it with the best sample at 275 nm studied in our previous work, in order to show all the problems to consider if these LEDs have to be used in machinery that will be placed on the market.

Published
2023
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31. Challenges and Perspectives for Vertical GaN-on-Si Trench MOS Reliability: From Leakage Current Analysis to Gate Stack Optimization

Author

Mukherjee, Kalparupa, primary, De Santi, Carlo, additional, Borga, Matteo, additional, Geens, Karen, additional, You, Shuzhen, additional, Bakeroot, Benoit, additional, Decoutere, Stefaan, additional, Diehle, Patrick, additional, Hübner, Susanne, additional, Altmann, Frank, additional, Buffolo, Matteo, additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, and Meneghini, Matteo, additional

Published
2021
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32. Inactivating SARS-CoV-2 Using 275 nm UV-C LEDs through a Spherical Irradiation Box: Design, Characterization and Validation

Author

Trivellin, Nicola, primary, Buffolo, Matteo, additional, Onelia, Francesco, additional, Pizzolato, Alberto, additional, Barbato, Marco, additional, Orlandi, Viviana Teresa, additional, Del Vecchio, Claudia, additional, Dughiero, Fabrizio, additional, Zanoni, Enrico, additional, Meneghesso, Gaudenzio, additional, Crisanti, Andrea, additional, and Meneghini, Matteo, additional

Published
2021
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33. Understanding the Leakage Mechanisms and Breakdown Limits of Vertical GaN-on-Si p+n−n Diodes: The Road to Reliable Vertical MOSFETs

Author

Mukherjee, Kalparupa, primary, De Santi, Carlo, additional, Buffolo, Matteo, additional, Borga, Matteo, additional, You, Shuzhen, additional, Geens, Karen, additional, Bakeroot, Benoit, additional, Decoutere, Stefaan, additional, Gerosa, Andrea, additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, and Meneghini, Matteo, additional

Published
2021
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35. Analysis of the role of current, temperature, and optical power in the degradation of InGaN-based laser diodes

Author

Meneghini, Matteo, Trivellin, Nicola, Orita, Kenji, Yuri, Masaaki, Ueda, Daisuke, Zanoni, Enrico, and Meneghesso, Gaudenzio

Subjects
Gallium compounds -- Electric properties, Indium -- Electric properties, Semiconductor lasers -- Electric properties, Semiconductor lasers -- Thermal properties, Business, Electronics, Electronics and electrical industries
Abstract

The degradation of InGaN-based laser diodes for Blu-ray technology is described. The observed degradation of the laser is attributed to an electrothermally activated process that induces an increase in the nonradiative recombination rate with subsequent decrease in the optical efficiency of the active layer.

Published
2009

40. Reducing the EMI susceptibility of a Kuijk bandgap

Author

Orietti, Enrico, Montemezzo, Nicola, Buso, Simone, Meneghesso, Gaudenzio, Neviani, Andrea, and Spiazzi, Giorgio

Subjects
Electromagnetic interference -- Research, Circuit components -- Analysis, Semiconductor device, Business, Computers, Electronics, Electronics and electrical industries
Abstract

In this paper, the susceptibility of a Kuijk bandgap voltage reference to electromagnetic interferences (EMIs) superimposed to the power supply is investigated. A model of the bandgap circuit is derived from experimental tests consisting of scattering parameters and susceptibility measurements on a test chip. The model is able to correctly predict the susceptibility of the circuit by means of SPICE transient simulations. The simulations identify the fundamental stray components responsible for EMI coupling that are usually not taken into account in postlayout analyses. From the EMI point of view, the rectification phenomenon of bipolar transistors, used in the bandgap cell, and the operational amplifier (op-amp) input distortion are shown to cause the voltage reference performance degradation. In particular, for the first time, the importance of the bandgap cell is pointed out, suggesting that the measures to reduce the susceptibility of the op-amp may not be sufficient to guarantee the bandgap immunity. Moreover, the analyses of main parasitic paths (from the power supply net to the more sensitive nodes) demonstrate the relevance of paths that are not commonly considered during the design phase and that may lead to an immunity degradation. Possible solutions to reduce the bandgap susceptibility are also explored, suggesting design criteria, filtering techniques, and layout variations. A second test chip is designed and manufactured to validate the suggested improvements and verify the critical role of the bandgap cell. Finally, a simplified theoretical analysis, which allows a fast bandgap susceptibility evaluation, is presented. This tool is used to point out the importance of the rectification phenomenon compared to the op-amp differential pair distortion. Index Terms--Differential pair distortion, Kuijk bandgap, RF interference, rectification, stray components.

Published
2008

41. Investigation of high-electric-field degradation effects in AlGaN/GaN HEMTs

Author

Faqir, Mustapha, Verzellesi, Giovanni, Meneghesso, Gaudenzio, Zanoni, Enrico, and Fantini, Fausto

Subjects
Gallium compounds -- Electric properties, Gate arrays -- Analysis, High-electron-mobility transistors -- Evaluation, Field programmable gate array, Business, Electronics, Electronics and electrical industries
Abstract

High-electric-field degradation phenomena in GaN-capped AlGaN/GaN high-electron mobility transistors (HEMTs) are examined. Findings reveal the amplification of gate-lag effects and a decline in the reverse gate leakage current.

Published
2008

43. Reversible degradation of ohmic contacts on p-GaN for application in high-brightness LEDs

Author

Meneghini, Matteo, Trevisanello, Lorenzo-Roberto, Zehnder, Ulrich, Meneghesso, Gaudenzio, and Zanoni, Enrico

Subjects
Decomposition (Chemistry) -- Research, Electrical conductivity -- Electric properties, Electrical conductivity -- Research, Light-emitting diodes -- Design and construction, Light-emitting diodes -- Comparative analysis, Business, Electronics, Electronics and electrical industries
Abstract

The high-temperature long-term stability of ohmic contacts on p-type gallium nitride (p-GaN) is examined. Findings reveal that thermal treatment at 250 degree Celsius was instrumental in inducing the worsening of the electrical properties of the ohmic contacts.

Published
2007

44. High-temperature degradation of GaN LEDs related to passivation

Author

Meneghini, Matteo, Trevisanello, Lorenzo-Roberto, Zehnder, Ulrich, Zahner, Thomas, Strauss, Uwe, Meneghesso, Gaudenzio, and Zanoni, Enrico

Subjects
Gallium compounds -- Thermal properties, Gallium compounds -- Chemical properties, Light-emitting diodes -- Usage, Silicon nitride -- Thermal properties, Silicon nitride -- Chemical properties, Business, Electronics, Electronics and electrical industries
Abstract

The thermally activated failure mechanisms of GaN light-emitting diode test structures related with the presence of a hydrogen-rich SiN passivation layer is described. It is shown that the properties of the passivation layer can remarkably affect devices' stability during high-temperature stress and the degradation mechanisms consist of radiative efficiency loss, emission crowding, and forward-current decrease.

Published
2006

45. Current collapse and high-electric-field reliability of unpassivated GaN/AlGaN/GaN HEMTs

Author

Meneghesso, Gaudenzio, Rampazzo, Fabiana, Kordos, Peter, Verzellesi, Giovanni, and Zanoni, Enrico

Subjects
Gallium compounds -- Atomic properties, Gallium compounds -- Electric properties, Electric fields -- Research, Electron mobility -- Research, Business, Electronics, Electronics and electrical industries
Abstract

Long-term ON-state and OFF-state high-electric-field stress results are presented for unpassivated GaN/AlGaN/GaN high-electron-mobility transistors (HEMTs) on SiC substrates. Devices show minimal current-collapse effect prior to high-electric-field stress, despite the fact that they are not passivated due to the thin GaN cap layer.

Published
2006

49. Impact of Residual Carbon on Avalanche Voltage and Stability of Polarization-Induced Vertical GaN p-n Junction

Author

Fabris, Elena, primary, De Santi, Carlo, additional, Caria, Alessandro, additional, Mukherjee, Kalparupa, additional, Nomoto, Kazuki, additional, Hu, Zongyang, additional, Li, Wenshen, additional, Gao, Xiang, additional, Marchand, Hugues, additional, Jena, Debdeep, additional, Xing, Huili Grace, additional, Meneghesso, Gaudenzio, additional, Zanoni, Enrico, additional, and Meneghini, Matteo, additional

Published
2020
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