Article
Engineering, Electrical & Electronic
Vipin Joshi, Rajarshi Roy Chaudhuri, Sayak Dutta Gupta, Mayank Shrivastava
Summary: This study reveals a channel electric field modulation induced by buffer capacitive action in AlGaN/GaN HEMTs fabricated on a carbon-doped GaN-on-Si buffer. Experimental measurements show that devices have a higher breakdown voltage when subjected to faster slew rates. The observed breakdown behavior is attributed to the field rearrangement in the GaN channel under different slew rates.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Physics, Applied
Xin Chen, Yaozong Zhong, Shumeng Yan, Xiaolu Guo, Hongwei Gao, Xiujian Sun, Haodong Wang, Fangqing Li, Yu Zhou, Meixin Feng, Ercan Yilmaz, Qian Sun, Hui Yang
Summary: The characteristics of an AlGaN/GaN high-electron-mobility transistor buffer structure are studied and optimized by employing an AlN/GaN superlattice (SL) structure. The influence of buffer traps on carrier transport behaviors and electrical performance for SL buffer structures under a high electric field is analyzed. The AlN/GaN SL buffer structures are further optimized with various AlN/GaN thickness ratios and their total thickness, achieving a high breakdown voltage and suppressing the buffer trapping effect.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
M. -A. Jaud, W. Vandendaele, B. Rrustemi, A. G. Viey, S. Martin, C. Le Royer, L. Vauche, S. Martinie, R. Gwoziecki, R. Modica, F. Iucolano, T. Poiroux
Summary: Unexpected threshold voltage behaviors were observed in GaN-on-Si MOSc-HEMTs, attributed to conduction band confinement, especially at gate corners, which is influenced by the fully recessed gate configuration and back-barrier efficiency.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Aniruddhan Gowrisankar, Vanjari Sai Charan, Hareesh Chandrasekar, Anirudh Venugopalarao, R. Muralidharan, Srinivasan Raghavan, Digbijoy N. Nath
Summary: This article reports the performance of compensation doping-free aluminum gallium-nitride (AlGaN)/gallium nitride (GaN) high-electron mobility transistors (HEMTs) on Silicon for RF applications using a polarization-graded buffer scheme. A resistive buffer is engineered using a compositionally reverse-graded AlGaN (g-AlGaN) layer, eliminating the need for compensation dopants. Transistors with 0.35 μm gate length and source-connected field plates showed a maximum drain current of 1 A/mm and OFF-state breakdown voltage of 144 V. RF performance of HEMTs on these polarization-graded buffers achieved a peak ft/fmax of 49.2/86.4 GHz.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Vipin Joshi, Sayak Dutta Gupta, Rajarshi Roy Chaudhuri, Mayank Shrivastava
Summary: Using a well-calibrated computational framework, this study reveals the complex interplay between device design and epi-stack parameters in AlGaN GaN HEMTs. The role of surface traps, piezoelectric polarization, and passivation thickness in determining electron injection and trapping is explored. Optimizing buffer doping can minimize electron trapping and increase breakdown voltage.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Huaxing Jiang, Qifeng Lyu, Renqiang Zhu, Peng Xiang, Kai Cheng, Kei May Lau
Summary: This article demonstrates the research results of p-GaN gate HEMTs with ultrahigh breakdown voltage and excellent performance on silicon, proving their great potential for applications beyond 600V.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Computer Science, Information Systems
Yuchen Li, Sen Huang, Xinhua Wang, Qimeng Jiang, Xinyu Liu
Summary: In this study, the temperature-dependent ON-state breakdown BVON of AlGaN/GaN HEMTs with an AlGaN back barrier was investigated using the gate current extraction technique. It was found that the impact ionization of acceptor-like traps is responsible for the ON-state breakdown in HEMTs when the 2DEG channel is marginally turned on. Additionally, the characteristic electric field of impact ionization was extracted and shown to have a U-shaped temperature dependence.
Article
Chemistry, Analytical
Yuan Lin, Min-Lu Kao, You-Chen Weng, Chang-Fu Dee, Shih-Chen Chen, Hao-Chung Kuo, Chun-Hsiung Lin, Edward-Yi Chang
Summary: Investigated the effects of substrate voltage on the power performance of GaN-on-Si HEMTs, finding that different V-SUB can influence the concentration of donor and acceptor traps, thereby affecting breakdown voltage and dynamic R-on degradation.
Article
Engineering, Electrical & Electronic
Sheng Gao, Yi Huang, Hongsheng Zhang, Hong Yang, Bin Liu
Summary: This study presents a novel method for fabricating Schottky/ohmic drain for GaN HEMTs, which enables the production of Schottky/ohmic drain without the need for secondary photolithography or metal evaporation steps. By adjusting the direction of the electron beam evaporation, different metal/semiconductor interfaces can be formed simultaneously, enhancing the shielding effect of the rough ohmic-drain metal morphology and modulating the electric field distribution on the drain side. The use of Schottky/ohmic drain technology improves the breakdown voltage and enhances the offstate reliability characteristics of GaN HEMTs.
IEEE ELECTRON DEVICE LETTERS
(2022)
Review
Physics, Applied
Michael J. Uren, Martin Kuball
Summary: This article examines the impact of buffer doping on the critical performance issues of GaN high electron mobility transistors, showing that carbon can lead to the epitaxial buffer becoming p-type and electrically isolated from the two-dimensional electron gas. Simulation models are used to explain a wide range of experimental observations related to current-collapse and dynamic R-ON in power switches, as well as other phenomena in RF GaN-on-SiC devices.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Li Zhang, Zheyang Zheng, Song Yang, Wenjie Song, Sirui Feng, Kevin J. Chen
Summary: Reconstructing the surface of the p-GaN layer into GaON enhances the immunity to hot electron bombardment in HEMTs, improving long-term reliability. This is achieved through a high-temperature thermal process and remote oxygen plasma treatment for surface reconstruction.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Feiyuan Yang, Manikant Singh, Michael J. Uren, Trevor Martin, Hassan Hirshy, Michael A. Casbon, Paul J. Tasker, Martin Kuball
Summary: The breakdown mechanism in 0.25-μm gate length AlGaN/GaN-on-SiC transistors is investigated using the drain current injection technique. The results show that breakdown can be divided into two stages, which are related to gate voltage levels and material characteristics.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Hao Lu, Bin Hou, Ling Yang, Meng Zhang, Longge Deng, Mei Wu, Zeyan Si, Sen Huang, Xiaohua Ma, Yue Hao
Summary: This work presents recent advancements in the sub-6 GHz power performance of GaN-based HEMTs grown on high resistivity silicon substrates using the passivation implanted termination (PIT) process. The fabricated HEMTs exhibit a low leakage current, a high ON/OFF current ratio, and improved breakdown voltage. They also demonstrate a high power-added efficiency (PAE), drain efficiency (DE), and output power density (P-out). The findings suggest that the PIT process could be a promising technique to enhance the application of high-performance GaN-on-Si HEMTs in 5G wireless base stations.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Rajarshi Roy Chaudhuri, Vipin Joshi, Sayak Dutta Gupta, Mayank Shrivastava
Summary: In this study, we investigated the time-dependent evolution of drain current and hot electron distribution along the width of AlGaN/GaN HEMTs on C-doped GaN buffer during semi-ON state stressing. The drain current exhibited two distinct phases, with reduction at lower stress times and increase for longer stress times. The transition in hot electron distribution from being uniform to confined near the center of the device was observed. The reduction in drain current was found to be due to gate-stack-dependent threshold voltage shift, while the increase in drain current and hot electron confinement were observed in both Schottky and MIS-gated devices. The nonuniform temperature distribution along the device width was identified as the cause of experimental observations.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Wei-Min Wu, Ming-Dou Ker, Shih-Hung Chen, Arturo Sibaja-Hernandez, Sachin Yadav, Uthayasankaran Peralagu, Hao Yu, AliReza Alian, Vamsi Putcha, Bertrand Parvais, Nadine Collaert, Guido Groeseneken
Summary: Gallium nitride (GaN) technologies play an important role in commercial advanced RF systems, but face challenges in reliability due to electrostatic discharge (ESD). A mis-correlation between standard-defined human body model (HBM) ESD robustness and commonly used transmission line pulse (TLP) failure current was observed in GaN high electron mobility transistors (HEMTs). A discharge model is proposed to explain the mechanism, and simulations confirm that the mis-correlation is due to 2-dimensional electron gas (2DEG) resistance modulation in response to HBM ESD transient voltage waveforms.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Alessandro Caria, Carlo De Santi, Matteo Buffolo, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: The degradation of InGaN-GaN LEDs under high photon densities has been studied, revealing optically-induced processes that decrease internal quantum efficiency. Measurements show a shallow level related to defects which result in an increase in yellow luminescence.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Julien Bassaler, Remi Comyn, Catherine Bougerol, Yvon Cordier, Farid Medjdoub, Philippe Ferrandis
Summary: This study focuses on the material investigation of an Al0.9Ga0.1N/GaN heterostructure, identifying various defects in the GaN channel that may contribute to reduced mobility and are linked to the quality of the channel interfaces.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Computer Science, Information Systems
Nicola Trivellin, Davide Fiorimonte, Francesco Piva, Matteo Buffolo, Carlo De Santi, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: This study reports on the reliability of recent commercial UVC LED devices and their efficacy in antiviral technologies for COVID-19. An in-depth analysis of four different state-of-the-art commercial LEDs suitable for disinfection applications indicates limited reliability possibly related to an increase in Shockley-Read-Hall (SRH) recombination. Suggestions for product design improvements will be proposed based on the results of this work.
Article
Chemistry, Analytical
Claudia Casu, Matteo Buffolo, Alessandro Caria, Carlo De Santi, Enrico Zanoni, Gaudenzio Meneghesso, Matteo Meneghini
Summary: This study investigates the defectiveness and degradation mechanisms of InGaN-based quantum wells. By designing a color-coded structure and using numerical simulations, it is found that an increase in traps in the active region is the main cause of degradation. The degradation process consists of two phases, with the first phase occurring in the quantum well closer to the p-contact. The stronger degradation in this well may be due to a lowering of injection efficiency or an increase in SRH recombination.
Article
Physics, Applied
Kathia Harrouche, Srisaran Venkatachalam, Francois Grandpierron, Etienne Okada, Farid Medjdoub
Summary: This article reports on the design optimization of vertically scaled AlN/GaN high electron mobility transistor technology for millimeter-wave applications. The thickness of the undoped GaN channel and the carbon concentration in the buffer were extensively varied and systematically characterized. It was found that a thin GaN channel improves electron confinement but increases trapping effects, especially with shorter gate lengths. Moreover, high carbon concentration in the buffer enables high electron confinement and low leakage current under high electric field, at the expense of trapping effects.
APPLIED PHYSICS EXPRESS
(2022)
Article
Chemistry, Analytical
Idriss Abid, Youssef Hamdaoui, Jash Mehta, Joff Derluyn, Farid Medjdoub
Summary: We report on the fabrication and electrical characterization of AlGaN/GaN normally off transistors on silicon designed for high-voltage operation. The normally off configuration was achieved with a p-gallium nitride (p-GaN) cap layer below the gate, enabling a positive threshold voltage higher than +1 V. The buffer structure was based on AlN/GaN superlattices (SLs), delivering a vertical breakdown voltage close to 1.5 kV with a low leakage current all the way to 1200 V.
Article
Chemistry, Analytical
Kathia Harrouche, Srisaran Venkatachalam, Lyes Ben-Hammou, Francois Grandpierron, Etienne Okada, Farid Medjdoub
Summary: This paper presents an enhancement of mm-wave power performances using a vertically scaled AlN/GaN heterostructure. The introduction of an AlGaN back barrier underneath a non-intentionally doped GaN channel layer prevents punch-through effects and drain leakage current, while maintaining a moderate carbon concentration in the buffer layer. By carefully tuning the Al concentration in the back barrier layer, the optimized heterostructure provides electron confinement and low trapping effects up to high drain bias for a gate length as short as 100 nm. Load-Pull measurements at 40 GHz showed outstanding performances with a record power-added efficiency of 70% (66%) under high output power density at V-DS = 20 V. These results demonstrate the potential of this approach for future millimeter-wave applications.
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
Physics, Applied
Reda Elwaradi, Jash Mehta, Thi Huong Ngo, Maud Nemoz, Catherine Bougerol, Farid Medjdoub, Yvon Cordier
Summary: In this study, two series of AlGaN/GaN/AlN high electron mobility transistor (HEMT) heterostructures were grown using molecular beam epitaxy. The effects of reducing the GaN channel thickness and varying the AlGaN barrier thickness and composition on the structural and electrical properties of the heterostructures were investigated. Material analysis techniques such as high-resolution x-ray diffraction, atomic force microscopy, and cross-sectional transmission electron microscopy were employed. The results showed that reducing the GaN channel thickness led to a decrease in GaN strain relaxation rate, but also caused degradation in crystal quality and electron mobility, along with an increase in sheet resistance. However, a trade-off was observed for a specific HEMT structure with a 50 nm width GaN channel, which exhibited a moderate sheet resistance and a high three-terminal breakdown voltage.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Zeyu Chi, Tamar Tchelidze, Corinne Sartel, Tsotne Gamsakhurdashvili, Ismail Madaci, Hayate Yamano, Vincent Sallet, Yves Dumont, Amador Perez-Tomas, Farid Medjdoub, Ekaterine Chikoidze
Summary: Spinel zinc gallate ZnGa2O4 is a ternary complex oxide with the widest gap where bipolar conductivity has been demonstrated among emerging ultra-wide bandgap semiconductors. This study used metal organic chemical vapor deposition to grow highly resistive p-type ZnGa2O4 thin films on sapphire and Si substrates to determine its critical electric field and vertical breakdown voltage. The average E-CR was estimated to be at least 5.3 MV cm(-1), which is significantly larger than SiC and GaN.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(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)
Editorial Material
Materials Science, Multidisciplinary
Michael Kneissl, Juergen Christen, Axel Hoffmann, Bo Monemar, Tim Wernicke, Ulrich Schwarz, Asa Haglund, Matteo Meneghini
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Computer Science, Information Systems
Elodie Carneiro, Stephanie Rennesson, Sebastian Tamariz, Kathia Harrouche, Fabrice Semond, Farid Medjdoub
Summary: Sub-micron-thick AlN/GaN transistors (HEMTs) grown on a silicon substrate for high-frequency power applications were reported. An innovative ultrathin step-graded buffer with a total stack thickness of 450 nm was used, which enabled excellent electron confinement and low leakage current. State-of-the-art GaN-on-silicon power performances were achieved at 40 GHz, with a combination of high power-added efficiency and saturated output power density. This is the first demonstration of high RF performance achieved with sub-micron-thick GaN HEMTs grown on a silicon substrate.
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)
Article
Computer Science, Information Systems
Alexander Herzog, Simon Benkner, Babak Zandi, Matteo Buffolo, Willem D. Van Driel, Matteo Meneghini, Tran Quoc Khanh
Summary: This study reports on the degradation mechanisms and dynamics of silicone encapsulated high-power ultraviolet A (UV-A) light-emitting diodes (LEDs) with a peak wavelength of 365 nm. Stress tests were conducted for 8665 hours at forward currents ranging from 350 mA to 700 mA and junction temperatures up to 132 degrees C. The results showed a significant decrease in optical power, with faster degradation at higher operating conditions. The degradation mechanisms were analyzed, and a degradation model was proposed to estimate the device lifetime under different operating parameters. Additional stress test data was used to validate the accuracy of the model's lifetime predictions.
Article
Engineering, Electrical & Electronic
Zhiqiang Wang, Siyang Dai, Yao Zhao, Guofeng Li, Bing Ji, Volker Pickert, Bowen Gu, Shuai Ding
Summary: This paper proposes a lumped-charge model for IEGT single chip, considering the effect of carrier injection enhancement in the emitter. The parasitic inductance of the parallel branches in PP-IEGT is extracted using Ansys simulation, and the validity of Ansys simulation is verified. Furthermore, the switching inconsistency is evaluated by combining the electrical model and the effect of mutual inductance, and it is found that mutual inductance is an important factor influencing electrical parameter distribution.
MICROELECTRONICS RELIABILITY
(2024)
Article
Engineering, Electrical & Electronic
Sankha Subhra Ghosh, Surajit Chattopadhyay, Arabinda Das, Nageswara Rao Medikondu, Abdulkarem H. M. Almawgani, Adam R. H. Alhawari, Sudipta Das
Summary: This article describes a method for identifying the IGBT switch breakdown failure in a 3-phase, 3-level Voltage Source Converter linked to the photovoltaic grid. Comparative learning has been used to detect the specific parameter suitable for the detection of the failure.
MICROELECTRONICS RELIABILITY
(2024)
Article
Engineering, Electrical & Electronic
Milad Khajehvand, Henri Seppanen, Panthea Sepehrband
Summary: Using SEM/EDX analysis, microscale fracture at the bond-pad is detected during the wedge bonding process of Cu wire to a Cu or Al substrate. It is observed that the fracture of the bond leads to the formation of a bulge on the wire and a cavity in the substrate, causing fracture in the original substrate. 3D optical profiler reveals that the depth, radius, and surface area of the cavity increase with bond time for a constant bond force and power. These metrics are suggested as new factors for optimizing the wedge bonding process. The optimal bonding parameters should maximize the cavity's surface area (related to bond's pull force) while minimizing the cavity's depth relative to the substrate's thickness to avoid substrate damage. Furthermore, Molecular Dynamics simulations propose a potential plastic deformation mechanism for bond-pad damage, suggesting the benefits of using a small-grain-sized substrate, low transducer's vibration amplitude, and high transducer's frequency to minimize the cavity's depth.
MICROELECTRONICS RELIABILITY
(2024)
