Article
Engineering, Electrical & Electronic
Ahtisham Ul Haq Pampori, Sheikh Aamir Ahsan, Yogesh Singh Chauhan
Summary: This article presents an engineering approach to model the current and charge characteristics of an AlGaN/GaN Fin-HEMT, and validates the model against experimental data. The research on this model is of great importance for the development of advanced GaN Fin-HEMT technology.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
R. Singh, T. R. Lenka, D. K. Panda, H. P. T. Nguyen, N. El Boukortt, G. Crupi
Summary: This paper presents a physics-based analytical model for describing the charge density and current in AlN/beta-Ga2O3 high electron mobility transistors (HEMTs) using two-dimensional Poisson equations. The model is validated through comparison with numerical simulations and experimental results, showing good consistency. The developed model can serve as a reference for beta-Ga2O3-based HEMTs.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2022)
Article
Engineering, Electrical & Electronic
Jie Yang, Junxian Zhu
Summary: In this paper, a novel extended-temperature current-voltage (I-V) model for GaN HEMT devices is proposed. The proposed model, revised from the traditional Materka nonlinear model, considers the selfheating and trapping effects, resulting in improved accuracy in both the saturation region and the knee region. A sequential temperature-dependent modeling approach is also proposed to reduce temperature regression errors. The proposed model is validated through the construction and testing of a simple class-A amplifier circuit.
SOLID-STATE ELECTRONICS
(2022)
Article
Materials Science, Multidisciplinary
Makoto Miyoshi, Sakura Tanaka, Tomoyuki Kawaide, Akiyoshi Inoue, Takashi Egawa
Summary: In this study, a strain-engineered quaternary AlGaInN barrier layer and an unintentionally doped GaN channel layer structure of high-electron-mobility transistors (HEMTs) were grown on a single-crystal AlN substrate using metal-organic chemical vapor deposition. The fabricated HEMTs showed good current-voltage characteristics without large negative resistance, even at high-current operations, according to DC static measurement results. Pulse I-V measurements indicated that the devices exhibited low-drain-current collapse similar to unpassivated GaN HEMTs, which was further improved by applying an Al2O3 surface passivation. These results demonstrate the promising prospects of AlGaInN/GaN HEMTs on SC-AlN for future high-power radio-frequency applications.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Fredo Chavez, Devin T. Davis, Nicholas C. Miller, Sourabh Khandelwal
Summary: This paper presents a fast and accurate deep learning-based ASM-HEMT I-V model parameter extraction method. By using a large training dataset and Monte Carlo simulations, the proposed method successfully models multiple GaN HEMTs and achieves a good fit with the actual data.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Computer Science, Information Systems
Martin Florovic, Jaroslav Kovac, Ales Chvala, Jaroslav Kovac, Jean-Claude Jacquet, Sylvain Laurent Delage
Summary: This article introduces a differential analysis method using a device analytical spatial electrical model to explore the impact of temperature profile and trapping phenomena on electrical attributes. Through experimental and theoretical analysis, the average temperature of the device was determined and compared with the threshold voltage shift of HEMT.
Article
Astronomy & Astrophysics
Sydney A. Jenkins, Ting S. Li, Andrew B. Pace, Alexander P. Ji, Sergey E. Koposov, Burcin Mutlu-Pakdil
Summary: In this study, we performed consistent reductions and measurements for three ultra-faint dwarf galaxies using VLT/GIRAFFE spectrograph data. We identified new members, refined physical parameters, and conducted a comparative analysis of previously discovered members. Additionally, we found new binary stars in Leo IV and Leo V, and reanalyzed the metallicity distribution function in Bootes I, leading to insights that will contribute to future dark matter studies.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
H. Elabidi, S. Sahal-Brechot, M. S. Dimitrijevic, W. Belhadj, R. Hamdi
Summary: This paper presents new Stark broadening parameters for Ga IV, Ga V, Ge IV, and Ge V ions. The calculations were performed using a quantum mechanical method. Only the Stark broadening results for Ge IV ion were available, obtained through semiclassical perturbation and modified semi-empirical methods. For the other three ions, no data have been found. Theoretical evaluations and measurements of atomic and Stark broadening data play a crucial role in stellar atmosphere modeling.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Computer Science, Information Systems
Wei Wang, Yan Liang, Minghui Zhang, Fang Lin, Feng Wen, Hongxing Wang
Summary: The study investigates the dynamic on-resistance (R-ON) behavior of a commercial GaN HEMT device with p-GaN gate under hard-switching conditions. Results show non-monotonic performance of dynamic R-ON with off-state voltage ranging from 50 to 400 V, attributed to the leaky dielectric model. The highest normalized R-ON value of 1.22 appears at 150 and 200 V. The device shows gradual increase and maximum of dynamic R-ON under prolonged stress time, due to longer trapping time related to deep acceptors and donors, with no obvious degradation at higher V-DS. The dynamic R-ON is insensitive to frequency, with leakage under source and drain contact identified as a key issue in resistance degradation.
Article
Engineering, Electrical & Electronic
Zhen-Wei Qin, Wen-Hsuan Tsai, Wei-Chia Chen, Hao-Hsuan Lo, Yue-Ming Hsin
Summary: This study investigates the I-V behaviors of various E-mode GaN-based transistors under gate floating and zero gate bias. The high off-state drain current is observed under gate floating except for Cascode GaN FETs based on the measured I-V characteristics. The devices will induce false-turn-on and reverse conduction loss during switching under gate floating due to the capacitance charging effect between the drain and the gate electrodes.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2022)
Article
Chemistry, Analytical
Yu-Lin Song, Manoj Kumar Reddy, Luh-Maan Chang, Gene Sheu
Summary: This study presents an analysis of the physics-based TCAD simulation procedure for GaN/AlGaN/GaN HEMT device structures grown on Si (111) substrate, calibrated against measurement data. The study investigates the impact of traps on device performance and the complexity of identifying their source and position in the device. The research focuses on key parameters for tuning threshold voltage in GaN transistors and demonstrates good agreement with experimental data.
Article
Optics
Zhan Li, Shuaishuai Yang, Qi Xiao, Tianyu Zhang, Yong Li, Lu Han, Dean Liu, Xiaoping Ouyang, Jianqiang Zhu
Summary: A spectrum series learning-based model is proposed for mode-locked fiber laser state searching and switching. The model combines deep reinforcement learning and long short-term memory networks to obtain the mode-locked operation search policy. The switch of the mode-locked state is realized by a predictive neural network that controls the pump power. Experimental results show that this new method achieves high efficiency and accuracy in searching and switching mode-locked states.
PHOTONICS RESEARCH
(2022)
Article
Chemistry, Multidisciplinary
Xingjie Wang, Kieran Brunson, Haomiao Xie, Ian Colliard, Megan C. Wasson, Xinyi Gong, Kaikai Ma, Yufang Wu, Florencia A. Son, Karam B. Idrees, Xuan Zhang, Justin M. Notestein, May Nyman, Omar K. Farha
Summary: New Ce12V6 oxo clusters with different capping ligands were designed and synthesized, showing enhanced solubility and catalytic activity compared to the nonporous Ce12V6-SO4. The introduction of organic ligands improved the accessibility of catalytic sites and influenced the electronic environment, affecting the reactivity of the cluster. This study provides a strategy to fully utilize the catalytic sites within inorganic sulfate capped clusters through the introduction of organic ligands.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Energy & Fuels
Yajing Zhang, Jianguo Li, Jiuhe Wang, Trillion Q. Zheng, Pengyu Jia
Summary: In this paper, the dynamic process of a photovoltaic inverter based on GaN HEMT is analyzed in detail, and the influence of parasitic parameters on the performance is considered. The correctness of theoretical and simulation analysis is verified through experiments.
Article
Electrochemistry
Monja Schilling, Michael Braig, Kerstin Koeble, Roswitha Zeis
Summary: New energy storage technologies are required to balance the intermittent power supply of renewable energy sources due to increasing global energy demand and the urgency to act against climate change. The vanadium redox flow battery (VRFB) shows promise for large-scale energy storage, but challenges in lifetime and efficiency persist. Therefore, conducting experiments that closely mimic operating conditions is crucial for gaining new insights into the reactions and transport processes of a VRFB.
ELECTROCHIMICA ACTA
(2022)
Article
Engineering, Electrical & Electronic
Jiejie Zhu, Yingcong Zhang, Xiaohua Ma, Siyu Liu, Siqi Jing, Qing Zhu, Minhan Mi, Bin Hou, Ling Yang, Michael J. Uren, Martin Kuball, Yue Hao
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2020)
Article
Physics, Applied
Jiejie Zhu, Yingcong Zhang, Michael J. Uren, Siyu Liu, Pengfei Wang, Minhan Mi, Bin Hou, Ling Yang, Martin Kuball, Xiaohua Ma, Yue Hao
APPLIED PHYSICS LETTERS
(2020)
Article
Chemistry, Physical
Matthew D. Smith, Xu Li, Michael J. Uren, Iain G. Thayne, Martin Kuball
APPLIED SURFACE SCIENCE
(2020)
Article
Engineering, Electrical & Electronic
Filip Wach, Michael J. Uren, Benoit Bakeroot, Ming Zhao, Stefaan Decoutere, Martin Kuball
IEEE ELECTRON DEVICE LETTERS
(2020)
Article
Engineering, Electrical & Electronic
Durgesh C. Tripathi, Michael J. Uren, Dan Ritter
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2020)
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
Markus Wohlfahrt, Michael J. Uren, Felix Kaess, Oleg Laboutin, Hassan Hirshy, Martin Kuball
Summary: AlGaN/GaN High Electron Mobility Transistors (HEMTs) exhibit a UV-induced persistent photoconductivity (PPC) effect, which is related to changes in electronic band bending in the buffer layer. This effect is significant only in p-type buffers and allows for quantification of deep-level doping density, with recovery times extending to several days.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Thomas Gerrer, James Pomeroy, Feiyuan Yang, Daniel Francis, Jim Carroll, Brian Loran, Larry Witkowski, Marty Yarborough, Michael J. Uren, Martin Kuball
Summary: The reliable operation of high-power GaN amplifiers depends on the mutual optimization of design parameters and a defined thermal budget. Finite element simulations provide design rules for GaN-on-diamond amplifier structures, showcasing better performance compared to GaN-on-SiC. Diamond substrates demonstrate superior heat dissipation capabilities, resulting in lower peak channel temperatures.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Stefano Dalcanale, Michael J. Uren, Josephine Chang, Ken Nagamatsu, Justin A. Parke, Robert S. Howell, Martin Kuball
Summary: A novel noise analysis method was used to study leakage current during time-dependent dielectric degradation under bias stress, showing that an additional low bias noise test can detect the onset of permanent localized breakdown earlier.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Feiyuan Yang, Michael J. Uren, Mark Gajda, Stefano Dalcanale, Serge Karboyan, James W. Pomeroy, Martin Kuball
Summary: This study investigates charge trapping in power AlGaN/GaN high electron mobility transistors, finding that high Si concentration passivation can suppress charge trapping and stress can induce negative charge trapping in the gate-drain access region. Electroluminescence (EL) measurements reveal that EL emitted near the drain edge might be obscured by the field plates, cautioning against using EL alone to locate high field regions in the device. Temperature-dependent dynamic R (ON) transient measurements suggest 'trap' responses with an activation energy of around 0.48 eV and located in the heavily carbon-doped GaN layer, explained by the leaky dielectric model.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2021)
Article
Engineering, Electrical & Electronic
Yuke Cao, James W. Pomeroy, Michael J. Uren, Feiyuan Yang, Martin Kuball
Summary: Electric-field-induced second harmonic generation is utilized to map the electric field distribution in the device channel of GaN-based high-electron-mobility transistors. The study shows that changes in carbon dopant concentration can significantly affect the electric field distribution in the devices, highlighting the role of dopants in altering the device characteristics. Additionally, dislocation-related leakage paths can lead to inhomogeneity in the electric field within the devices.
NATURE ELECTRONICS
(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
Physics, Applied
Yuke Cao, James W. Pomeroy, Michael J. Uren, Feiyuan Yang, Jingshan Wang, Patrick Fay, Martin Kuball
Summary: The electric field distribution of GaN-on-GaN p-n diodes with partially compensated ion-implanted edge termination (ET) was characterized using an electric field induced second harmonic generation technique (EFISHG). The effectiveness of the ET structure was confirmed by the distributed electric field from the anode to the outer edge of the ET. However, the effectiveness was found to be strongly dependent on the acceptor charge distribution in the partially compensated layer (PC) of the ET.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
Zequan Chen, Abhishek Mishra, Aditya K. Bhat, Matthew D. Smith, Michael J. Uren, Sandeep Kumar, Masataka Higashiwaki, Martin Kuball
Summary: The frequency dispersion of impedance in lateral beta-Ga2O3 MOSFETs has been studied and a model has been developed to explain the phenomenon. The dispersion is caused by the resistive and capacitive coupling between the terminal contact pads and the buried conducting layer at the unintentionally-doped epitaxy/substrate interface, which also leads to a buried parallel leakage path. It is shown that the dispersion is not related to gate dielectric traps, as commonly assumed. A generalized equivalent circuit model is proposed to explain the experimental results.
APPLIED PHYSICS EXPRESS
(2023)
Article
Engineering, Electrical & Electronic
Akhil S. Kumar, Michael J. Uren, Justin Parke, H. George Henry, Robert S. Howell, Martin Kuball
Summary: Multichannel RF power amplifiers provide high frequency operation, high current and RF power, and excellent linearity. By using 3D and 2D simulations, the impact of device architecture on linearity and off-state reliability can be investigated, leading to an improved linear design without compromising reliability. Linearity is assessed using a 2D approximation which is computationally efficient, while off-state reliability is evaluated using a full 3D simulation to measure peak electric field. The study suggests that introducing channel number-dependent doping can enhance transconductance-linearity, and increasing gate dielectric thickness or fin width leads to a strong increase in third order intercept, while maintaining reliability requires increased fin height to reduce electric field.
SEMICONDUCTOR SCIENCE AND TECHNOLOGY
(2023)