Article
Engineering, Electrical & Electronic
Baoxing Duan, Luoyun Yang, Yandong Wang, Yintang Yang
Summary: This article introduces a depletion-mode AlGaN/GaN HEMTs with a partial GaN cap, which optimizes the surface electric field and 2DEG distribution through the electric field modulation effect. The improved breakdown voltage and slightly increased output current result from the optimized surface electric field with the partial GaN cap.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Jingyu Shen, Chao Yang, Liang Jing, Jingwei Guo, Ping Li, Hao Wu, Shengdong Hu
Summary: In this study, an enhancement mode p-GaN gate HEMT with selective regrowth and strain engineering has been proposed. The device shows improved 2DEG density and surface electric field distribution, leading to significant improvements in ON-resistance and breakdown voltage.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Multidisciplinary Sciences
Weicheng Cao, Chunyan Song, Hui Liao, Ningxuan Yang, Rui Wang, Guanghui Tang, Hongyu Ji
Summary: Carbon doping has a significant impact on the leakage current and breakdown voltage in GaN-on-Si epitaxial layers. However, the complex occupancy forms caused by carbon make it difficult to analyze the leakage/breakdown mechanisms. This study simulates the space charge distribution and intensity in GaN-on-Si epitaxial layers and investigates the capture and release behaviors of CN at different positions in carbon-doped GaN.
SCIENTIFIC REPORTS
(2023)
Article
Engineering, Electrical & Electronic
Marcello Cioni, Nicolo Zagni, Ferdinando Iucolano, Maurizio Moschetti, Giovanni Verzellesi, Alessandro Chini
Summary: Dynamic R-ON dispersion in GaN power HEMTs is a known issue caused by buffer traps, affecting performance and stability. Research shows that R-ON reaches a maximum for some OFF-state voltage values and then partially recovers. This behavior is attributed to the charging/discharging dynamics of C-related buffer traps, with R-ON increasing up to 60% and partially recovering to about 30% for certain voltage values.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Crystallography
Peiran Wang, Chenkai Deng, Hongyu Cheng, Weichih Cheng, Fangzhou Du, Chuying Tang, Chunqi Geng, Nick Tao, Qing Wang, Hongyu Yu
Summary: In this study, the DC, transient, and RF performances of AlGaN/GaN HEMTs with different field plate structures were investigated using SILVACO ATLAS 2D TCAD. It was found that the double floating field plate structure (2FFP) effectively alleviated the peak electric fields under the gate, improving the breakdown voltage (BV) and suppressing current collapse. The 2FFP structure also exhibited lower parasitic capacitance and higher cut-off frequency and oscillation frequency compared to the conventional gate field plate structure (GFP). These results demonstrate the superiority of the 2FFP structure for RF GaN HEMTs and its potential for integrated RF GaN devices.
Article
Engineering, Electrical & Electronic
Bingxian Ou, Ning Jin, Yancheng Li, Xiaohong Yan, Jian Xu, Yang Li, Jinping Ao, Dawei Yan
Summary: The charge transport and breakdown mechanisms of gate leakage current in lattice-matched In0.17Al0.83 N/GaN high electron mobility transistors (HEMTs) were investigated. The excessive Fowler-Nordheim (FN) tunneling current at high reverse biases was observed and the dislocation-related charge transport processes were described. The reduced effective bandgap and decreased breakdown electric field at the dislocation site were proposed as causes for premature current breakdown.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Chao Liu, Xinghuan Chen, Ruize Sun, Jingxue Lai, Wanjun Chen, Yajie Xin, Fangzhou Wang, Xiaoming Wang, Zhaoji Li, Bo Zhang
Summary: In this study, the abnormal reduction and recovery of dynamic R-ON are observed in Schottky p-GaN gate HEMTs under unclamped-inductive-switching (UIS) stress. The reduction of R-ON_dyn is found to be positively correlated with UIS stress (V-PEAK, peak voltage). By utilizing Sentaurus simulation, the underlying physical mechanism is revealed to be the trapping and faster detrapping of electrons compared to holes during UIS stress, resulting in the reduction of R-ON_dyn. Furthermore, a mathematic model of R-ON_dyn after UIS stress is developed and validated through measurement. This work provides practical guidance for reducing the RON and conduction loss of GaN HEMTs during UIS operation setup.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Yixu Yao, Sen Huang, Qimeng Jiang, Xinhua Wang, Lan Bi, Wen Shi, Fuqiang Guo, Tiantian Luan, Jie Fan, Haibo Yin, Ke Wei, Yingkui Zheng, Jingyuan Shi, Yankui Li, Qian Sun, Xinyu Liu
Summary: A drain-controlled current-mode deep level transient spectroscopy (I-DLTS) was developed to investigate the Semi-ON-state current collapse in AlGaN/GaN high electron mobility transistors (HEMTs). By inserting a graded AlGaN back-barrier, the charging of buffer traps induced by hot-electron effect was effectively blocked, resulting in a suppressed current collapse in AlGaN/GaN HEMTs under Semi-ON-state stress.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Joseph P. Kozak, Qihao Song, Ruizhe Zhang, Yunwei Ma, Jingcun Liu, Qiang Li, Wataru Saito, Yuhao Zhang
Summary: This article presents a comparative study of the parametric shift and recovery of three mainstream GaN HEMTs in repetitive overvoltage switching. The study shows that the devices exhibit shifts in threshold voltage and saturation current during the switching process, and these shifts saturate in a short period of time. The recovery process is dominated by hole detrapping and through-gate removal, with the gate stack playing a significant role. The article also suggests effective methods for poststress recovery.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2023)
Article
Engineering, Electrical & Electronic
Nengtao Wu, Ling Luo, Zhiheng Xing, Shanjie Li, Fanyi Zeng, Ben Cao, Changtong Wu, Guoqiang Li
Summary: This article investigates a low-leakage-current and high-breakdown-voltage normally OFF p-GaN gate HEMT on a Si substrate with low-damage NH3 plasma pretreatment. The NH3 plasma pretreatment effectively removes surficial oxides and other impurities, suppresses interface traps, and reduces the overall drain leakage current. The NH3 plasma pretreated p-GaN gate HEMTs exhibit a high ON/OFF-current ratio, low reverse gate leakage current, high gate breakdown voltage, and high breakdown voltage at 1 mu A/mm.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
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
Engineering, Electrical & Electronic
Shradha Gupta, Janesh K. Kaushik, Ankur Gupta
Summary: A physical model is proposed to explain the breakdown of the virtual gate region and the complex contour of kink in AlGaN/GaN HEMTs output I-V characteristics, taking into account the impact ionization and multiphonon assisted ionization of surface traps.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Lian Zhang, Zhe Cheng, Yawei He, Jianxing Xu, Lifang Jia, Xinyuan Wang, Shiyong Zhang, Wei Tan, Yun Zhang
Summary: This study focuses on the electron concentration and mobility of SAG n(+)-GaN on InAlN/GaN HEMTs using MOCVD, revealing that the electron mobility of SAG GaN is significantly affected by thickness. A gas flow model is proposed to guide the regrowth for improving electron mobility. High mobility and low resistance are achieved in the SAG GaN, contributing to the performance of the HEMTs.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Fuchun Jia, Xiaohua Ma, Ling Yang, Bin Hou, Meng Zhang, Qing Zhu, Mei Wu, Minhan Mi, Jiejie Zhu, Siyu Liu, Yue Hao
Summary: The study indicates that a combination of UID GaN layer and thinner Fe doping buffer layer can accelerate the slope rate of Fe concentration in the UID GaN layer, leading to improved device performance. By reducing the concentration of deep traps introduced by Fe doping, the device demonstrates excellent DC and RF characteristics. Controlling the Fe doping tail is crucial for designing GaN-based power amplifiers with high P-sat and PAE.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(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.
Review
Engineering, Electrical & Electronic
Nicolo Zagni, Francesco Maria Puglisi, Paolo Pavan, Muhammad Ashraful Alam
Summary: This article reviews the relevant literature on the reliability of doped hafnium oxide (HfO2) based ferroelectric transistors (FeFETs), focusing on the reliability physics of ferroelectric capacitors and the key reliability metrics of FeFETs. The integrative approach connects seemingly unrelated reliability issues and suggests mitigation strategies at the device, circuit, or system level. The article concludes by proposing research opportunities for future development in this field.
PROCEEDINGS OF THE IEEE
(2023)
Article
Engineering, Electrical & Electronic
Alessandro Chini, Nicolo Zagni, Giovanni Verzellesi, Marcello Cioni, Giovanni Giorgino, Maria Concetta Nicotra, Maria Eloisa Castagna, Ferdinando Iucolano
Summary: In this letter, we investigate the on-resistance instability in p-GaN power HEMTs induced by gate bias following the application of a quasi-static initialization voltage. The transient behavior of this instability was characterized at different temperatures. Both R-ON increase/decrease were found to be thermally activated and with same activation energy, attributed to the charging/discharging of hole traps present in the AlGaN barrier below the gate.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Physics, Applied
Sara Vecchi, Paolo Pavan, Francesco Maria Puglisi
Summary: As electronic devices continue to shrink, understanding the defects in high-kappa dielectrics is crucial for improving performance and reducing reliability issues. This study investigates the Random Telegraph Noise (RTN) in a TiN/(4 nm)HfO2/TiN stack and shows that the noise properties vary with the applied bias due to the influence of oxygen vacancies (V(+)) and oxygen ions (O(0)). The study demonstrates the importance of considering trapped charge in accurately estimating the RTN parameters and explains the mechanisms behind the complex RTN signals.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Analytical
Andrea Amidei, Susanna Spinsante, Grazia Iadarola, Simone Benatti, Federico Tramarin, Paolo Pavan, Luigi Rovati
Summary: The majority of car accidents worldwide are caused by drowsy drivers. Therefore, it is important to be able to detect drowsiness in drivers to prevent serious accidents. This study focuses on using a wrist device and analyzing the skin conductance signal to detect drowsiness. The results show that it is possible to identify drowsiness accurately using only signals from the wrist, encouraging further research for a real-time warning system.
Article
Chemistry, Multidisciplinary
Pavan Pujar, Haewon Cho, Young-Hoon Kim, Nicolo Zagni, Jeonghyeon Oh, Eunha Lee, Srinivas Gandla, Pavan Nukala, Young-Min Kim, Muhammad Ashraful Alam, Sunkook Kim
Summary: The study demonstrates the stabilization of the ferroelectric orthorhombic phase in doped-hafnia films by growing large-grained La-doped HfO2 films directly on silicon with minimal carbonaceous impurities. The well-distributed La dopant generates uniformly populated oxygen vacancies, eliminating the need for oxygen-scavenging electrodes. These oxygen-deficient films exhibit high remnant polarization and can withstand large fields. The results also show the improvement of MOSFET switching using the doped HfO2 film in series with Al2O3.
Article
Instruments & Instrumentation
M. Menichelli, M. Bizzarri, M. Boscardin, L. Calcagnile, M. Caprai, A. P. Caricato, G. A. P. Cirrone, M. Crivellari, I. Cupparo, G. Cuttone, S. Dunand, L. Fano, B. Gianfelici, O. Hammad, M. Ionica, K. Kanxheri, M. Large, G. Maruccio, A. G. Monteduro, F. Moscatelli, A. Morozzi, A. Papi, D. Passeri, M. Pedio, M. Petasecca, G. Petringa, F. Peverini, G. Quarta, S. Rizzato, A. Rossi, G. Rossi, A. Scorzoni, L. Servoli, C. Talamonti, G. Verzellesi, N. Wyrsch
Summary: Hydrogenated amorphous silicon is commonly used in radiation-resistant detectors for particle beam flux measurements and space solar panels. This study focuses on p-i-n and charge selective contacts planar diode detectors with a thickness of 10 μm, which were irradiated with neutrons at two fluence values. The radiation resistance of the detectors was evaluated by measuring leakage current and response to x-ray photons. The results show that the leakage current increased by a factor of 2 after irradiation at 1016 neq/cm2, but was completely recovered after annealing for p-i-n devices. X-ray dosimetric sensitivity degraded after irradiation, but partially recovered for charge selective contact devices and increased for p-i-n devices after annealing. For the irradiation test at 5 x 1016 neq/cm2, noticeable degradation in leakage current and x-ray sensitivity was observed after storage, with a small recovery after annealing.
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Andrea Amidei, Pierangelo Maria Rapa, Giuseppe Tagliavini, Roberto Rabbeni, Paolo Pavan, Simone Benatti
Summary: The automotive industry recognizes the importance of human-machine interaction for enhancing the driving experience and improving driver safety. Monitoring the driver's physiological signals, such as Photoplethysmography (PPG), can provide valuable information about the driver's state. This study introduces ANGELS, an embedded system that utilizes PPG signals to monitor drivers in a non-invasive way. Experimental assessments demonstrate that ANGELS is a reliable and promising solution for improving driver safety, with accurate heart rate detection, low latency, and low power consumption.
2023 9TH INTERNATIONAL WORKSHOP ON ADVANCES IN SENSORS AND INTERFACES, IWASI
(2023)
Proceedings Paper
Engineering, Multidisciplinary
Sara Vecchi, Paolo Pavan, Francesco Maria Puglisi
Summary: The implementation of high-kappa dielectrics, such as HfO2, is necessary in nanoscale devices to meet market demands for device scaling. However, HfO2 exhibits stronger and more complex Random Telegraph Noise (RTN) compared to SiO2, which is a significant reliability issue for ultra-thin oxides. This study provides a unified and physics-based framework for analyzing RTN in different devices, which is crucial for designing new devices and circuits for emerging RTN-based applications.
2023 IEEE INTERNATIONAL RELIABILITY PHYSICS SYMPOSIUM, IRPS
(2023)
Article
Engineering, Electrical & Electronic
Nicolo Zagni, Manuel Fregolent, Giovanni Verzellesi, Alberto Marcuzzi, Carlo De Santi, Gaudenzio Meneghesso, Enrico Zanoni, Eldad Bahat Treidel, Enrico Brusaterra, Frank Brunner, Oliver Hilt, Matteo Meneghini, Paolo Pavan
Summary: In this article, the correlation between interface traps (ITs) and border traps (BTs) on distinctive features of C-V curves in vertical Al2O3/GaN MOS capacitors is analyzed. Experimental and simulation analysis is used to attribute specific features in the C-V curves to ITs or BTs in the trap distribution. The simulation-aided analysis enhances the understanding of C-V curve features and improves the reliability of IT measurement technique.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
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, Electrical & Electronic
Enrico Zanoni, Carlo De Santi, Zhan Gao, Matteo Buffolo, Mirko Fornasier, Marco Saro, Francesco De Pieri, Fabiana Rampazzo, Gaudenzio Meneghesso, Matteo Meneghini, Nicolo Zagni, Alessandro Chini, Giovanni Verzellesi
Summary: This article reviews various options for controlling short-channel effects, improving off-state characteristics, and reducing drain-source leakage current. The advantages and potential drawbacks of each proposed solution are analyzed in terms of current collapse, dispersion effects, and reliability.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Tommaso Zanotti, Paolo Pavan, Francesco Maria Puglisi
Summary: In this study, a self-consistent automated parameter extraction procedure is proposed for the UniMORE RRAM compact model. The procedure can be easily calibrated by performing a few common experiments and its effectiveness is validated on various RRAM technologies.
ESSDERC 2022 - IEEE 52ND EUROPEAN SOLID-STATE DEVICE RESEARCH CONFERENCE (ESSDERC)
(2022)
Proceedings Paper
Engineering, Electrical & Electronic
Sara Vecchi, Paolo Pavan, Francesco Maria Puglisi
Summary: This paper investigates the effect of atomic species' motion on RTN phenomena, and demonstrates that complex RTN signals can naturally emerge from the combination of the Coulomb field due to trapped charge at defects and the field-assisted motion. It is shown that multilevel RTN signals conventionally attributed to several defects can actually result from atomic species' motion.
ESSDERC 2022 - IEEE 52ND EUROPEAN SOLID-STATE DEVICE RESEARCH CONFERENCE (ESSDERC)
(2022)