Ahmad Hajjar

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Address: Limoges, France

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Nicole Herbots

Arizona State University

PROF. OM PRAKASH SINHA

Amity University

Suseendran Jayachandran

IMEC

Prof.Dr. İbrahim USLU

Gazi University

Kiran Dasari

University of Illinois at Urbana-Champaign

Wolfgang Tremel

Johannes Gutenberg-Universität Mainz

Franz Giessibl

University of Regensburg

Eko Rahardjo

University of Indonesia

Alex Dommann

University of Bern

Jean-Yves Fortin

Centre National de la Recherche Scientifique / French National Centre for Scientific Research

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Papers by Ahmad Hajjar

Identification de pièges dans le buffer des HEMTs AlGaN/GaN basée sur des mesures de paramètres S basse fréquence et sur des simulations physiques

— Dans ce papier, la determination du type, de l'energie d'activation (E a) et de la sect... more — Dans ce papier, la determination du type, de l'energie d'activation (E a) et de la section de capture (σ n) des pieges de buffer des transistors HEMTs AlGaN/GaN est presentee. Les caracteristiques des pieges, extraites a partir de mesures de parametres S basse frequence, sont validees par des simulations physiques a deux dimensions. En outre, cette etude conclut sur la presence de pieges de buffer GaN de type accepteurs, ayant une concentration de 5.0×10 16 cm −3 et un niveau d'energie d'activation de 0.4 eV en dessous de la bande de conduction du GaN.

Millimeter-wave power amplifier linearity characterization using Unequally Spaced Multi-Tone stimulus

2020 IEEE/MTT-S International Microwave Symposium (IMS), 2020

This paper presents an implementation of Ka band linearity measurement. In this paper large signa... more This paper presents an implementation of Ka band linearity measurement. In this paper large signal measurements using the innovative Unequally Spaced Multi-Tone (USMT) wideband test signal have been performed in order to assess the in-band linearity degradation of non-linear microwave power devices. The proposed test bench is suitable for both on-wafer and connectorized devices characterization, using a sub-6GHz source and an RF mixer to up convert the signal into Ka band. In this paper a first result of comparison between NPR with a notch and USMT test signal has been demonstrated; it shows very similar behavior using similar signal statistics, bandwidth, peak-to-average, etc… at a 6 GHz frequency carrier. This comparison has been done with simulations and experimentally on the same test bench, to ensure the same conditions.

Characterization and Electrical Modeling Including Trapping Effects of A1n/GaN HEMT 4⨯50μmon Silicon Substrate

2018 48th European Microwave Conference (EuMC), 2018

This paper reports the full characterization and modeling of novel A1N/GaN HEMTs on silicon using... more This paper reports the full characterization and modeling of novel A1N/GaN HEMTs on silicon using a short gate length. This device has been optimized for high frequency analog circuits applications. The presented model includes DC and small-signal modeling steps taking into account the trapping effects. It contains a trap model inside the current source which allows to accurately predict gate-lag transient response and low frequency dispersion of the output admittance. The model is validated by comparing the 4 GHz load-pull measurement results with the simulation ones.

Low Frequency Drain Noise Characterization of Different Technologies of GaN HEMTs:Investigation of Trapping Mechanism

2018 International Workshop on Integrated Nonlinear Microwave and Millimetre-wave Circuits (INMMIC), 2018

In this paper, we attempt to characterize the low-frequency (LF) drain noise characteristics of 0... more In this paper, we attempt to characterize the low-frequency (LF) drain noise characteristics of 0.25- μ m ultra-short gate length GaN HEMT devices fabricated using different transistor technology. LF drain noise characteristics have been measured using the dedicated test-bench over the frequency range of 100 Hz to 1 MHz and for varying chuck temperatures (Tchuck) ranging between 25 ° C and 125 ° C. The measurement characteristics demonstrate the existence of two traps in both the AlN/GaN and AlGaN/GaN HEMT transistor technologies grown on SiC substrate. Interestingly, no signature of trapping mechanism has been observed in InAlN/GaN HEMT transistor technology.

Caractérisation basse fréquence et simulation physique de transistors bipolaires hétérojonction en vue de l'analyse du bruit GR assisté par pièges

Ce travail presente le developpement d’un banc de mesure thermique, pour la mesure : de reseaux I... more Ce travail presente le developpement d’un banc de mesure thermique, pour la mesure : de reseaux I (V), d’impedance basse frequence et de bruit basse frequence des composants semi-conducteurs. Le banc de mesure de bruit BF est compose d’un amplificateur de tension faible bruit, d’un amplificateur transimpedance, d’un analyseur FFT et d’un support thermique. Ce banc a permis d’extraire les sources de bruit en courants equivalentes aux acces du transistor pour differentes densites de courant et a differentes temperatures. Dans le but de calculer l’energie d’activation et la section de capture des pieges grâce a la localisation des frequences de coupures de bruit GR dans la technologie du TBH InGaP/GaAs. Dans un deuxieme temps, nous avons etudie le bruit basse frequence dans le transistor InGaP/GaAs et les jonctions base emetteur, base collecteur et la resistance TLM par le moyen de simulation physique et de mesure de densite spectrale de puissance de bruit basse frequence. Grâce a ces ...

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Caractérisation et modélisation non-linéaire du HEMT AlN/GaN sur substrat silicium et validation par mesure Load-Pull

– Cet article decrit la caracterisation et la modelisation grand-signal d'un transistor HEMT ... more – Cet article decrit la caracterisation et la modelisation grand-signal d'un transistor HEMT AlN/GaN sur substrat silicium de developpement 2x50 µm avec une longueur de grille ultra courte du laboratoire IEMN de Lille. Ce composant a ete optimise pour la conception de circuits analogiques haute frequence. Les differentes etapes de caracterisation et de modelisation sont presentees ainsi que la validation du modele grand-signal en comparant les resultats de simulations avec des mesures Load-Pull. Le modele employe prend en compte les effets de pieges, il est valide par comparaison avec des mesures qui mettent en evidence leurs effets.

Novel AlN/GaN HEMT Electrical Model including Trapping Effects

This paper reports the full characterization and modeling of novel AlN/GaN HEMTs on silicon using... more This paper reports the full characterization and modeling of novel AlN/GaN HEMTs on silicon using a short gate length. This device has been optimized for high frequency analog circuits applications. The presented model includes DC and small-signal modeling steps taking into account the trapping effects. It contains a trap model inside the current source which allows to accurately predict gate-lag transient response and low frequency dispersion of the output admittance. The model is validated by comparing the 4 GHz load-pull measurement results with the simulation ones.

Identification of GaN buffer traps in Microwave Power AlGaN/GaN HEMTs through Low Frequency S-parameters Measurements and TCAD-based Physical Device Simulations

IEEE Journal of the Electron Devices Society, 2017

In this paper, the type, activation energy (E a) and cross section (σ n) of the GaN buffer traps ... more In this paper, the type, activation energy (E a) and cross section (σ n) of the GaN buffer traps existing in the AlGaN/GaN high-electron mobility transistors are investigated through low frequency (LF) S-parameters measurements. Furthermore, we present the 2-D physics based TCAD numerical simulation analysis of this device. The dc simulation results are calibrated to match with the experimentally measured I-V characteristics and this allows to qualitatively estimate the concentration of traps (N T) present in the GaN buffer. Knowing the measured trap energy level and the estimated trap concentration N T , TCAD physical simulations are performed at various temperatures in order to extract the LF-Y 22 admittance parameter. Interestingly, the LF-Y 22 simulation results are found to be in good agreement with the measurements and this result strongly suggests that LF admittance dispersion is an effective tool in identifying the traps present in the GaN buffer. Moreover, this paper reveals that acceptor-like traps with an apparent concentration of 5.0 × 10 16 cm −3 and with the apparent trap energy level of 0.4 eV below the conduction band are located in the GaN buffer. INDEX TERMS Gallium-nitride (GaN), high electron mobility transistor (HEMT), buffer traps, TCAD simulation, low frequency S-parameters.

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Low-Frequency Noise Characterization in GaN HEMTs: Investigation of Deep Levels and Their Physical Properties

IEEE Electron Device Letters

In this letter, traps-related dispersion phenomenon of GaN/AlGaN/GaN high electron mobility trans... more In this letter, traps-related dispersion phenomenon of GaN/AlGaN/GaN high electron mobility transistor grown on the SiC substrate is investigated through low-frequency noisemeasurements. Low-frequency drain noise measurements are performed over the frequency range of 20 Hz–1MHz and for varying chuck temperatures (<inline-formula> <tex-math notation="LaTeX">${T}_{\text {chuck}})$ </tex-math></inline-formula> ranging between 25 °C and 125 °C. This letter demonstrates that two prominent deep levels are present in the device-under-testwith apparent activation energies (<inline-formula> <tex-math notation="LaTeX">${E}_{a})$ </tex-math></inline-formula> of 0.51 and 0.57 eV, respectively. Moreover, signatures of deep level with <inline-formula> <tex-math notation="LaTeX">${E}_{a}$ </tex-math></inline-formula> of 0.57 eV become visible only at higher operating temperatures, due to the fact that traps dispersion occurs at very low frequencies, which is confirmed through TCAD physical simulations.

Identification de pièges dans le buffer des HEMTs AlGaN/GaN basée sur des mesures de paramètres S basse fréquence et sur des simulations physiques

Millimeter-wave power amplifier linearity characterization using Unequally Spaced Multi-Tone stimulus

2020 IEEE/MTT-S International Microwave Symposium (IMS), 2020

Characterization and Electrical Modeling Including Trapping Effects of A1n/GaN HEMT 4⨯50μmon Silicon Substrate

2018 48th European Microwave Conference (EuMC), 2018

Low Frequency Drain Noise Characterization of Different Technologies of GaN HEMTs:Investigation of Trapping Mechanism

2018 International Workshop on Integrated Nonlinear Microwave and Millimetre-wave Circuits (INMMIC), 2018

Caractérisation basse fréquence et simulation physique de transistors bipolaires hétérojonction en vue de l'analyse du bruit GR assisté par pièges

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Caractérisation et modélisation non-linéaire du HEMT AlN/GaN sur substrat silicium et validation par mesure Load-Pull

Novel AlN/GaN HEMT Electrical Model including Trapping Effects

Identification of GaN buffer traps in Microwave Power AlGaN/GaN HEMTs through Low Frequency S-parameters Measurements and TCAD-based Physical Device Simulations

IEEE Journal of the Electron Devices Society, 2017

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Low-Frequency Noise Characterization in GaN HEMTs: Investigation of Deep Levels and Their Physical Properties

IEEE Electron Device Letters

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