Article
Engineering, Electrical & Electronic
Chien-Hung Yeh, Po-Hsun Chen, Ting-Chang Chang, Kai-Chun Chang, Yu-Xuan Wang, Ting-Tzu Kuo, Yong-Ci Zhang, Jia-Hong Lin, Ya-Huan Lee, Hung-Ming Kuo, Wei-Ting Yen, I-Ting Tsai, Simon M. Sze
Summary: In order to reduce drain leakage current, carbon doping is introduced into the GaN layer of the p-GaN HEMT device. This study focuses on discussing the abnormal current behavior that occurs in the saturation region of carbon-doped p-GaN HEMT. The abnormal phenomenon disappears when the device is heated up to 150 °C. The abnormal current behavior corresponds to the hot electron stress result, indicating that electron trapping causes this abnormal current behavior. An energy band is proposed to describe the lesser trapping effect in the saturation region.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Physics, Applied
Subhajit Ghosh, Kai Fu, Fariborz Kargar, Sergey Rumyantsev, Yuji Zhao, Alexander A. Balandin
Summary: In this study, low-frequency noise characteristics of vertical GaN PIN diodes were investigated with a focus on diode design, current, and temperature effects. Most devices exhibited a 1/f spectrum at high currents, while some showed generation-recombination bulges at low currents. All tested GaN PIN diodes had low noise spectral densities at room temperature, with temperature, current, and frequency dependencies indicating a recombination noise mechanism. Noise measurements at low currents were proposed as efficient tools for assessing diode quality.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Jianghua Yang, Zewen Ji, Shujuan Zhang
Summary: Defects were introduced in carbon nitride (CN) by adjusting the ratio of acetylacetone (AcAc) and urea. The resulting modified CNs (AxCN) with dual defects (C doping and surface -OH modification) exhibited higher photocatalytic production rate and selectivity of H2O2, attributed to the synergistic roles of the dual defects in oxygen reduction reactions. This finding provides insights into defect engineering for environmentally friendly generation of H2O2.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Computer Science, Information Systems
Wei Lin, Maojun Wang, Haozhe Sun, Bing Xie, Cheng P. Wen, Yilong Hao, Bo Shen
Summary: This paper proposes an HEMT structure with a source-connected p-GaN embedded in a carbon-doped semi-insulating buffer to suppress the buffer-induced current collapse effect. Two-dimensional transient simulation demonstrates the successful suppression of current collapse in SCPG-HEMTs compared to conventional HEMTs. The mechanism of ejecting holes from SCPG into the high resistive buffer layer after off-state stress is illustrated to potentially solve the buffer-induced degradation of dynamic on-resistance in GaN power devices.
Article
Chemistry, Physical
Qinglun You, Chunsheng Zhang, Min Cao, Bin Wang, Jun Huang, Yujue Wang, Shubo Deng, Gang Yu
Summary: In this study, a modified g-C3N4 (SCBCN0.4) was successfully synthesized using a triple strategy of defect controlling, element doping, and crystallinity improving. The research revealed that SCBCN0.4 has optimized microstructure and electronic structure, improved light-harvesting capability, and enhanced carrier separation efficiency. SCBCN0.4 demonstrated excellent performance in pollutant degradation and in-situ H2O2 generation, and showed detoxification, reusability, and stability.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2023)
Article
Computer Science, Information Systems
Martin Doublet, Nicolas Defrance, Etienne Okada, Loris Pace, Thierry Duquesne, Bouyssou Emilien, Arnaud Yvon, Nadir Idir, Jean-Claude De Jaeger
Summary: This paper proposes a methodology for studying the current collapse effects of GaN power diodes and its consequences on dynamic RON. Due to the increasing interest in GaN-based high frequency power conversion, it is important to accurately characterize and understand the behavior of GaN devices before developing power converters. This study aims to model observed trap effects and improve the equivalent electrical model. By applying high voltage stresses at various temperatures, the current-collapse phenomenon inherent to GaN diodes is studied, and useful data on activation energy and capture cross section of electrical defects linked to dynamic RON are extracted. The origins of these defects are discussed and attributed to carbon-related defects.
Article
Chemistry, Multidisciplinary
Timofei Eremin, Valentina Eremina, Yuri Svirko, Petr Obraztsov
Summary: Covalent functionalization of single-walled carbon nanotubes (SWCNTs) can greatly enhance their photoluminescent (PL) brightness, making them suitable for infrared light emitters.
Article
Chemistry, Physical
Shengjiong Yang, Shengshuo Xu, Jiayao Tong, Dahu Ding, Gen Wang, Rongzhi Chen, Pengkang Jin, Xiaochang C. Wang
Summary: The study uncovered the role of nitrogen dopant in carbon catalysts, where nitrogen is partially evaporated at high temperature to form topological intrinsic defects, promoting the activation of peroxymonosulfate and organic degradation through an electron-transfer mechanism. The findings suggest that surface-activated PMS complex is the main reactive oxidation species for organic degradation.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2021)
Article
Chemistry, Analytical
Nicolo Zagni, Alessandro Chini, Francesco Maria Puglisi, Paolo Pavan, Giovanni Verzellesi
Summary: The intentional doping of lateral GaN power HEMTs with carbon impurities can reduce buffer conductivity and increase breakdown voltage, but also leads to current collapse. By modeling the donor/acceptor compensation ratio, it is found that the total trap concentration determines breakdown voltage, requiring a significant compensation ratio to quantitatively explain both phenomena.
Article
Chemistry, Multidisciplinary
Min-Ken Li, Adnan Riaz, Martina Wederhake, Karin Fink, Avishek Saha, Simone Dehm, Xiaowei He, Friedrich Schoeppler, Manfred M. Kappes, Han Htoon, Valentin N. Popov, Stephen K. Doom, Tobias Hertel, Frank Hennrich, Ralph Krupke
Summary: This work demonstrates that electroluminescence excitation is selective towards neutral defect-state configurations with the lowest transition energy, which, combined with gate control, leads to high spectral purity.
Article
Automation & Control Systems
Rustam Kumar, Arnab Sarkar, Sandeep Anand, Amit Verma, Tian-Li Wu
Summary: This article presents a measurement circuit for evaluating the dynamic on-state resistance of gallium nitride high electron mobility transistors. The circuit allows independent control over the testing conditions and measurement of forward and reverse conduction modes.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)
Review
Chemistry, Multidisciplinary
Charalampos A. Londos, Alexander Chroneos, Efstratia N. Sgourou, Ioannis Panagiotidis, Theoharis Angeletos, Marianna S. Potsidi
Summary: Crystalline silicon is a crucial material in the semiconductor industry, and impurities and defects can affect its properties. This review focuses on the impact of isovalent doping on oxygen-related and carbon-related defects in electron-irradiated silicon, discussing recent experimental results and theoretical studies.
APPLIED SCIENCES-BASEL
(2022)
Article
Engineering, Electrical & Electronic
Zhan Gao, Carlo De Santi, Fabiana Rampazzo, Marco Saro, Mirko Fornasier, Gaudenzio Meneghesso, Matteo Meneghini, Alessandro Chini, Giovanni Verzellesi, Enrico Zanoni
Summary: This article reports new experimental data on the dynamic behavior of the kink effect in AlGaN/GaN HEMTs and correlates them with deep levels. The results demonstrate the importance of the Poole-Frenkel effect in determining the occurrence of the kink and identify the experimental conditions that make it observable.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Marine
Hang Wu, Haisheng Zhao, Xin Li, Xin Feng, Yanfei Chen
Summary: This study investigates the collapse behavior and modes of pipelines with multiple corrosion defects under external pressure through experiments and finite element simulations. The influence of defect dimensions and distribution on the interaction of the pipeline is analyzed, and an estimation formula for collapse pressure is proposed for pipelines with dual corrosion defects.
Article
Engineering, Electrical & Electronic
Luca Nela, Halil Kerim Yildirim, Catherine Erine, Remco Van Erp, Peng Xiang, Kai Cheng, Elison Matioli
Summary: The study presents a new surface passivation technology for multi-channel power devices, utilizing SiO2 and Si3N4 layers to effectively reduce electron traps and improve dynamic performance, resulting in significant reduction of dynamic on-resistance even under large off-state voltages. This approach demonstrates the potential of multi-channel technology for future power electronic applications by offering reduced current collapse and comparable dynamic performance with passivated single-channel devices.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Feiyuan Yang, Stefano Dalcanale, Mark Gajda, Serge Karboyan, Michael J. Uren, Martin Kuball
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2020)
Article
Nanoscience & Nanotechnology
Matthew D. Smith, Jerome A. Cuenca, Daniel E. Field, Yen-chun Fu, Chao Yuan, Fabien Massabuau, Soumen Mandal, James W. Pomeroy, Rachel A. Oliver, Michael J. Uren, Khaled Elgaid, Oliver A. Williams, Iain Thayne, Martin Kuball
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)