Article
Engineering, Electrical & Electronic
Yan Wang, Wenhao Zheng, Shuman Mao, Bo Yan, Qingzhi Wu, Yuehang Xu
Summary: This study investigates the degradation of flexible AlGaN/GaN HEMTs under bending tensile strain for the first time. The traps locations were identified and characterized, and the results have important implications for further application of GaN technology in flexible electronics.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Joao L. Gomes, Luis C. Nunes, Filipe M. Barradas, Adam Cooman, Aryan E. F. de Jong, Rob M. Heeres, Jose C. Pedro
Summary: This article investigates the impact of the emission time constant of deep-level traps on the achievable linearity of gallium nitride high electron mobility transistor (GaN HEMT) power amplifiers. It is found that when the emission rate is comparable to the signal bandwidth, the linearity degrades significantly, but improves when they differ. Additionally, self-heating plays a major role in the degradation of linearity due to the strong temperature dependence of the emission time constant. Experimental results using different trap activation energies further highlight the importance of the coupling between these two effects on the linearity.
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
(2022)
Article
Engineering, Electrical & Electronic
Injun Hwang, Soogine Chong, Younghwan Park, Sun-Kyu Hwang, Boram Kim, Joonyong Kim, Jaejoon Oh, Jun Hyuk Park, Dong-Chul Shin, Min Chul Yu, Jai Kwang Shin, Jongseob Kim
Summary: This study focuses on the transient measurement of the drift region potential in AlGaN/GaN HEMT under high power state, revealing that the propagation speed of high electric field in the device is influenced by the drift region voltage, and proposing that trapping of hot channel electrons is causing this effect.
IEEE ELECTRON DEVICE LETTERS
(2021)
Proceedings Paper
Engineering, Electrical & Electronic
Matteo Meneghini, Nicola Modolo, Arianna Nardo, Carlo De Santi, Andrea Minetto, Luca Sayadi, Christian Koller, Sebastien Sicre, Gerhard Prechtl, Gaudenzio Meneghesso, Enrico Zanoni
Summary: Gallium nitride has emerged as an excellent semiconductor for power device fabrication due to its high breakdown field, high saturation velocity, and wide energy gap. Large-wafer processing on silicon substrates allows cost reduction and yield improvement, while the potential for monolithic integration could lead to fast and compact integrated circuits based on gallium nitride, contributing to the widespread adoption of this technology.
2021 IEEE BICMOS AND COMPOUND SEMICONDUCTOR INTEGRATED CIRCUITS AND TECHNOLOGY SYMPOSIUM (BCICTS)
(2021)
Article
Engineering, Electrical & Electronic
Rana ElKashlan, Ahmad Khaled, Raul Rodriguez, Arturo Sibaja-Hernandez, Uthayasankaran Peralagu, AliReza Alian, Nadine Collaert, Piet Wambacq, Bertrand Parvais
Summary: This paper reports the linearity trade-offs associated with T-gate geometries of AlGaN/GaN HEMTs on Si, specifically the impact of gate extensions as field plates on large-signal performance. Small-signal characterization and modeling, along with TCAD simulations, provide initial guidelines for optimal dimensions of gate field plates based on the ratio of f(T) and the product of gate resistance and gate-to-drain capacitance. Various characterization methods, including nonlinear vector network analyzer and load-pull, are used to quantify amplitude and phase distortion and their impact on large-signal metrics under different conditions. The influence of gate field plates on amplitude and phase distortion is found to be significant, especially under matched conditions.
INTERNATIONAL JOURNAL OF MICROWAVE AND WIRELESS TECHNOLOGIES
(2023)
Article
Engineering, Electrical & Electronic
Shijie Pan, Shiwei Feng, Xuan Li, Kun Bai, Xiaozhuang Lu, Yamin Zhang, Lixing Zhou, Erming Rui, Qiang Jiao, Yu Tian
Summary: This paper investigates trapping effect in AlGaN/GaN high-electron-mobility transistors using pulsed current-voltage characterization, drain voltage transient (DVT) measurement, and capacitance deep-level transient spectroscopy (C-DLTS). Three electron traps with different energy levels were identified, and the correlation of different techniques was demonstrated to investigate the physical origin of traps.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Injun Hwang, Soogine Chong, Dong-Chul Shin, Sun-Kyu Hwang, Younghwan Park, Boram Kim, Joonyong Kim, Jaejoon Oh, Jun Hyuk Park, Min Chul Yu, Woochul Jeon, Jai Kwang Shin, Jongseob Kim
Summary: The research suggests using wafer level transient voltage measurement (WLTVM) to estimate the short circuit capability of AlGaN/GaNHEMT devices. The study found that short circuit failure is mainly attributed to degradation in the drift region. By measuring transient potential changes, it is possible to predict short circuit failures and take timely action.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Bhishma Pandit, Hyeon-Sik Jang, Yunjo Jeong, Sangmin An, S. Chandramohan, Kyung Kyu Min, Sang Min Won, Chel-Jong Choi, Jaehee Cho, Seongin Hong, Keun Heo
Summary: The presence of 2D electron gas at the AlGaN/GaN interface has attracted significant interest in GaN-based ultraviolet photodetector technology. However, the high dark current reduces the performance of the photodetector. This study demonstrates enhanced performance by using interdigitated p-GaN finger structure on top of the AlGaN/GaN heterostructure, resulting in a reduction of dark current and the realization of ultraviolet photodetectors with superior sensitivity and detectivity.
ADVANCED MATERIALS INTERFACES
(2023)
Proceedings Paper
Engineering, Multidisciplinary
Qihao Song, Joseph P. Kozak, Yunwei Ma, Jingcun Liu, Ruizhe Zhang, Roman Volkov, Daniel Sherman, Kurt V. Smith, Wataru Saito, Yuhao Zhang
Summary: This study investigates the overvoltage robustness and surge energy of GaN power HEMTs, revealing the parametric shift and recovery during repetitive overvoltage switching. The research demonstrates the good performance of GaN MIS-HEMTs and suggests the significance of hole dynamics in overvoltage switching.
2022 IEEE INTERNATIONAL RELIABILITY PHYSICS SYMPOSIUM (IRPS)
(2022)
Article
Engineering, Electrical & Electronic
Nahid Sultan Al-Mamun, Maxwell Wetherington, Douglas E. Wolfe, Aman Haque, Fan Ren, Stephen Pearton
Summary: The performance and reliability of microelectronic devices, particularly AlGaN/GaN high electron mobility transistors (HEMTs), were found to be significantly affected by even small localized strains. The reduction of strain by 0.02% was shown to decrease the overall output saturation current up to approximately 20%.
MICROELECTRONIC ENGINEERING
(2022)
Article
Engineering, Electrical & Electronic
Peng Xue, Francesco Iannuzzo
Summary: This article presents a comprehensive study on the occurrence mechanism, instability analysis, and suppression methods of self-sustained turn-OFF oscillation that occurs on cascode gallium nitride high electron mobility transistors (cascode GaN HEMTs). It analyzes the oscillation waveforms to determine the occurrence of the oscillation is due to test circuit instability and identifies the impact of load current, dc bus voltage, and gate resistance on the oscillation through double pulse tests. A small-signal ac model of the resonant circuit is derived to investigate its instability and analyze the influences of various parameters on the self-sustained oscillation. The article reveals possible methods to suppress the oscillation, which are validated by experimental data and simulation results.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Nanoscience & Nanotechnology
I. S. Ezubchenko, E. M. Kolobkova, A. A. Andreev, M. Ya. Chernykh, Yu. V. Grishchenko, P. A. Perminov, I. A. Chernykh, M. L. Zanaveskin
Summary: Microwave transistors based on AlN/GaN heterostructures on silicon substrates were fabricated and studied. The results showed that these transistors exhibit high specific saturation current, good transconductance, and excellent frequency performance.
NANOBIOTECHNOLOGY REPORTS
(2022)
Article
Metallurgy & Metallurgical Engineering
Bhubesh Chander Joshi
Summary: AlGaN/GaN heterostructures are promising for high-speed and high-power electronic devices. Due to the lack of native substrates, they are grown on foreign materials using two-step growth techniques. In this study, test structures, TLM pads, FET structure, ohmic contacts, and Schottky contacts were fabricated on AlGaN/GaN heterostructure. Transmission line measurement and current voltage measurement were used for characterization.
INTERNATIONAL JOURNAL OF MATERIALS RESEARCH
(2023)
Article
Materials Science, Multidisciplinary
Stefan Moench, Stefan Mueller, Richard Reiner, Patrick Waltereit, Heiko Czap, Michael Basler, Jan Hueckelheim, Lutz Kirste, Ingmar Kallfass, Ruediger Quay, Oliver Ambacher
Summary: Experimental comparison between a high-voltage AlN/GaN superlattice (SL) buffer and a step-graded AlGaN/GaN buffer for monolithic AlGaN/GaN power circuits showed that the SL buffer performs better in mitigating negative back gating effects and leakage at positive substrate voltage, making it more suitable for high-voltage power topology operation. Additionally, HEMTs on the SL buffer exhibited minimal threshold voltage shift at negative substrate bias, allowing for efficient operation of monolithic high-voltage power topologies.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2021)
Article
Engineering, Electrical & Electronic
Pengfei Wan, Jianqun Yang, He Lv, Enhao Guan, Huyang Li, Ling Lv, Xiaodong Xu, Yadong Wei, Yang Song, Weiqi Li, Xingji Li
Summary: This article investigates the displacement damage on AlGaN/GaN HEMTs using 30-MeV fluorine ions. By combining experimental data with multiscale simulation, the study reveals the impact of different defects on the performance of the devices.
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2022)
Article
Engineering, Electrical & Electronic
Marco Nicoletto, Alessandro Caria, Carlo De Santi, Matteo Buffolo, Xuanqui Huang, Houqiang Fu, Hong Chen, Yuji Zhao, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: In this article, we extensively investigate the degradation of gallium nitride (GaN)-based high periodicity indium GaN (InGaN)-GaN multiple quantum well (MQW) solar cells under optical stress at high excitation intensity and high temperature. The obtained results suggest that the degradation originates from the diffusion of hydrogen, and the proposed analytical methodology provides insight into MQW solar cell degradation.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Gao Zhan, Fabiana Rampazzo, Carlo De Santi, Mirko Fornasier, Gaudenzio Meneghesso, Matteo Meneghini, Herve Blanck, Jan Gruenenpuett, Daniel Sommer, Ding Yuan Chen, Kai-Hsin Wen, Jr-Tai Chen, Enrico Zanoni
Summary: DC characteristics of AlGaN/GaN HEMTs with different thickness values of the undoped GaN channel layer were compared. An abnormal transconductance (gm) overshoot accompanied by a negative threshold voltage (V-TH) shift was observed during IDS-V-GS sweep in devices with thinner GaN layer. At the same time, a non-monotonic increase in gate current was observed. In OFF-state, electron trapping occurs in the undoped GaN layer or at the GaN/AlN interface, leading to a positive VTH shift. When the device is turning on at a sufficiently high V-DS, electron de-trapping occurs due to trap impact-ionization; consequently, V-TH and therefore ID suddenly recovers, leading to the gm overshoot effect. These effects are attributed to electron trap impact-ionization and consequent modulation of the device's electric field.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Materials Science, Multidisciplinary
Nicola Trivellin, Francesco Piva, Davide Fiorimonte, Matteo Buffolo, Carlo De Santi, Enrico Zanoni, Gaudenzio Meneghesso, Matteo Meneghini
Summary: This study reports on the reliability of commercial ultraviolet-C (UV-C) light-emitting diodes (LEDs) under constant current stress. Electrical, optical, and spectral analyses were conducted on UV-C LEDs with a peak emission at 275 nm and a nominal power of 12 mW at 100 mA. Degradation tests were performed at maximum rated current, double the maximum, and three times the maximum. The results show that LED lifetime is inversely proportional to the stress current density, potentially due to high-energy electrons from Auger-Meitner recombination.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Michele Zenari, Matteo Buffolo, Mirko Fornasier, Carlo De Santi, Jeroen Goyvaerts, Alexander Grabowski, Johan Gustavsson, Sulakshna Kumari, Andim Stassren, Roel Baets, Anders Larsson, Gunther Roelkens, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: This study investigates the optical degradation of VCSILs designed for operation at 845 nm in PICs. The degradation is related to impurity diffusion, which affects device characteristics in different ways depending on the migration region. Understanding the root cause of physical degradation is crucial for improving the lifetime of these novel optical sources.
IEEE JOURNAL OF QUANTUM ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Alessandro Caria, Carlo De Santi, Matteo Buffolo, Marco Nicoletto, Xuanqi Huang, Houqiang Fu, Hong Chen, Yuji Zhao, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: The aim of this article is to investigate the degradation mechanisms of GaN solar cells under harsh conditions, specifically forward current stress. The results indicate that the main parameters of the cells decrease under this stress, and there is a correlation between the charge distribution inside the active region and the concentration of trap states. The decrease in power conversion efficiency is attributed to a redistribution of charge in the active region, resulting in an increase in midgap states density. These findings fill the gap in the literature regarding the long-term reliability of GaN solar cells under harsh conditions.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Energy & Fuels
Marco Nicoletto, Alessandro Caria, Fabiana Rampazzo, Carlo De Santi, Matteo Buffolo, Giovanna Mura, Francesca Rossi, Xuanqui Huang, Houqiang Fu, Hong Chen, Yuji Zhao, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: This study investigates the influence of V-pits on the electrical performance of high periodicity InGaN-GaN multiple quantum wells solar cells. Through combined electrical analysis, microscopy investigation, and simulations, it is found that V-pits can affect the turn-on voltage and current-voltage characteristics of the solar cells. The presence of V-pits allows for a closer connection between the quantum well region and the p-side contact. These findings provide insight into the role of V-pits in the electrical performance of high-periodicity quantum well devices.
IEEE JOURNAL OF PHOTOVOLTAICS
(2023)
Article
Engineering, Electrical & Electronic
Nicola Modolo, Carlo De Santi, Giulio Baratella, Andrea Minetto, Luca Sayadi, Sebastien Sicre, Gerhard Prechtl, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: Ideally, the emission profile in semiconductors should follow a pure exponential decay, but complex devices often exhibit a strongly stretched exponential shape. Conventional methodologies for mapping capture/emission time constants may lead to inaccuracies. In this article, a new methodology based on the double inverse Laplace transform is introduced to accurately extract the capture-emission time map of defects. The proposed approach is compared with conventional approximations, providing insight into the accuracy of simplified methods. The method is tested on custom-generated functions and successfully applied to extract the capture/emission time map from a power GaN HEMT subjected to positive bias instability test.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Alessandro Caria, Carlo De Santi, Marco Nicoletto, Matteo Buffolo, Xuanqi Huang, Houqiang Fu, Hong Chen, Yuji Zhao, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: GaN-based multi-quantum wells solar cells have potential for extreme applications. In this study, we performed stress experiments on samples to investigate degradation mechanisms. Results showed that increased current led to changes in resistance and decreased efficiency. Measurements also revealed the generation of defects and correlated variations in charge density and conversion efficiency. These defects may migrate through the devices, as detected at different times by different measurements.
GALLIUM NITRIDE MATERIALS AND DEVICES XVIII
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Marco Nicoletto, Alessandro Caria, Carlo De Santi, Matteo Buffolo, Xuanqi Huang, Houqiang Fu, Hong Chen, Yuji Zhao, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: This study investigates the degradation of high-periodicity GaN-based InGaN-GaN multiple quantum wells (MQWs) solar cells under stress conditions. The findings suggest the presence of a thermally-activated diffusion process of impurities that increases the SRH recombination rate. By analyzing the time-variation of non-radiative Shockley-Read-Hall lifetime, the diffusion coefficient and activation energy of the defect involved in the degradation are determined.
GALLIUM NITRIDE MATERIALS AND DEVICES XVIII
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
F. Piva, M. Buffolo, C. De Santi, M. Pilati, N. Roccato, A. Muhin, N. Susilo, D. Hauer Vidal, L. Sulmoni, T. Wernicke, M. Kneissl, G. Meneghesso, E. Zanoni, M. Meneghini
Summary: The market for ultraviolet (UV) light emitting diodes (LEDs) is expected to grow due to their disinfection properties, but a thorough study of the reliability-limiting processes is needed. This study investigates the degradation mechanisms of AlGaN-based UV single quantum well (SQW) LEDs, revealing increased subthreshold leakage currents and decreased optical output power as major causes of degradation. C-DLTS measurements identify three defects, including one with an activation energy of 700 meV, suggesting gallium vacancies or nitrogen antisites.
GALLIUM NITRIDE MATERIALS AND DEVICES XVIII
(2023)