Article
Materials Science, Coatings & Films
Stefan Schmult, Pascal Appelt, Claudia Silva, Steffen Wirth, Andre Wachowiak, Andreas Grosser, Thomas Mikolajick
Summary: Inconsistencies in the concentrations of unintentional donor impurities and free charge carriers in GaN/AlGaN layer stacks containing a two-dimensional electron gas (2DEG) can be explained by the measurement procedure and the method of extracting the free charge carrier concentration. When the 2DEG acts as the bottom electrode in capacitance versus voltage measurements, unphysically low concentrations of free charges are calculated due to the depletion of the 2DEG and the disappearance of the bottom electrode. It is shown that, for the case of a defined (non-vanishing) bottom electrode, the levels of donor impurities and resulting free charges consistently match.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
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)
Article
Biochemical Research Methods
Yahong Chen, Mengyu Zhao, Yifan Ouyang, Suhui Zhang, Zhihan Liu, Kexin Wang, Zhaoxuan Zhang, Yingxia Liu, Chaoyong Yang, Wei Sun, Jie Shen, Zhi Zhu
Summary: Structural DNA nanotechnology can be used to program complex designer structures with molecular precision, directing a wide range of materials. In this protocol, carbon nanotubes are used as model semiconductors to build ultra-scaled, high-performance field-effect transistors from micron-scale DNA templates. The approach enables the assembly of CNT arrays with uniform pitches and clean interfaces, displaying superior performance compared to previous examples of biotemplated electronics.
Article
Physics, Applied
Md Abu Jafar Rasel, Ryan Schoell, Nahid Sultan Al-Mamun, Khalid Hattar, C. Thomas Harris, Aman Haque, Douglas E. Wolfe, Fan Ren, Stephen J. Pearton
Summary: This study investigated the effects and mechanism of IL-37 on pyroptosis in RA-FLSs induced by TNF-a. It was found that IL-37 inhibited inflammation and reduced pyroptosis-related protein expression in RA-FLSs. The study also revealed that IL-37 alleviates TNF-a-induced pyroptosis in RA-FLSs by inhibiting NF-?B/GSDMD signaling.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Zihong Shen, Zunxian Yang, Yuanqing Zhou, Yuliang Ye, Bingqing Ye, Qiaocan Huang, Wenbo Wu, Hongyi Hong, Zeqian Hong, Zongyi Meng, Zhiwei Zeng, Songwei Ye, Zhiming Cheng, Qianting Lan, Jiaxiang Wang, Ye Chen, Hui Zhang, Tailiang Guo, Yun Ye, Zhenzhen Weng, Yongyi Chen
Summary: Artificial photonic synapses, with their high sensitivity and low power consumption, have been developed as new sensors for the IoT and ANNs. This study successfully fabricates photonic synaptic transistors using ternary organic array films, which exhibit both short-term and long-term plasticity. The low power consumption and wireless optical communication capabilities make these synapses highly valuable for next-generation human-computer interaction sensors.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Engineering, Electrical & Electronic
Yaru Ding, Chu Yan, Yiming Qu, Yi Zhao
Summary: This study experimentally investigates the channel length dependence of hot carrier degradation (HCD) in ultra-scaled nFinFETs with the self-heating correction. The novel insight into the HCD mechanism is proposed by considering the trap behaviors, including both interface traps and oxide traps. The experimental results show that the proportion of interface traps in total traps strongly depends on the channel length, and the interface traps induced by HCD are located near the source side in ultra-scaled nFinFETs.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Chemistry, Inorganic & Nuclear
Hang Liu, Ruofan Sun, Xu Lu
Summary: This study successfully synthesized Bi2O2Te nanosheets and controlled their thickness by adjusting the growth conditions. The experimental results showed that Bi2O2Te exhibited exceptional electrical performance, especially with ultrahigh mobility at low temperatures. This suggests that Bi2O2Te is a promising candidate for highly efficient electronic devices.
INORGANIC CHEMISTRY
(2023)
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
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
Engineering, Electrical & Electronic
Yaozong Zhong, Shuai Su, Xin Chen, Yu Zhou, Hongwei Gao, Xiaoning Zhan, Xiaolu Guo, Shuming Zhang, Qian Sun, Hui Yang
Summary: The reliability and degradation mechanism of normally OFF high-electron-mobility transistors (HEMTs) with regrown p-GaN gates and AlN/SiNx stack passivation were studied. It was found that the Schottky junction fails first, leading to a sudden increase in gate current, highlighting the need for improving gate breakdown voltage and lifetime. The analyses suggest the feasibility of using regrown p-GaN gates and AlN/SiNx stack passivation in practical applications.
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
(2021)
Article
Materials Science, Multidisciplinary
Xia-Xi Zheng, Chun Wang, Jian-Hao Huang, Jen-Yao Huang, Daisuke Ueda, Krishna Pande, Chang Fu Dee, Ching Ting Lee, Edward-Yi Chang
Summary: This paper investigates the influence of group-III precursor injection rate on the material and electrical properties of InAlGaN/GaN heterostructures grown by Metalorganic Chemical Vapor Phase Deposition. It is demonstrated that high-quality GaN layers can be achieved by using the sputtered AlN/sapphire templates and optimized group-III injection rate, while maintaining high crystallinity and smooth surface of InAlGaN barrier layer.
Article
Engineering, Electrical & Electronic
Shijie Pan, Shiwei Feng, Xuan Li, Xiang Zheng, Xiaozhuang Lu, Chaoxu Hu, Guojian Shao, Gang Lin
Summary: The effects of high-energy electron irradiation on the electrical and trapping properties of AlGaN/GaN HEMTs were systematically investigated. The study found that irradiation induced strain relaxation in the HEMT, resulting in improved electrical characteristics and reduced trap density. Additionally, traps in the device were identified and their behaviors were observed to change after irradiation.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
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
Physics, Applied
Jeffrey A. Smith, Kai Ni, Hideki Takeuchi, Robert J. Stephenson, Yi-Ann Chen, Marek Hytha, Shuyi Li, Paul E. Nicollian, Robert J. Mears, Suman Datta
Summary: The insertion of oxygen (OI) layers in silicon effectively reduces the intermixing phenomenon between titanium nitride/hafnium oxide film layers, modifying the film properties and reducing the formation of interfacial charge dipoles. This discovery offers a new technique for tuning the electrical characteristics of high-k dielectric/metal gate (HKMG) stacks.
JOURNAL OF APPLIED PHYSICS
(2021)
Review
Chemistry, Multidisciplinary
Yuqiu Lei, Peiyun Li, Yuting Zheng, Ting Lei
Summary: Organic electrochemical transistors (OECTs) have shown great potential in various applications due to their high transconductance, low operating voltages, and good biocompatibility. However, the development of n-type and ambipolar OECT materials has lagged behind, which has limited the advancement of OECT-based logic circuits.
MATERIALS CHEMISTRY FRONTIERS
(2023)
Article
Engineering, Electrical & Electronic
Elahe Yarmoghaddam, Nazila Haratipour, Steven J. Koester, Shaloo Rakheja
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2020)
Article
Physics, Applied
Ankit Shukla, Arun Parthasarathy, Shaloo Rakheja
PHYSICAL REVIEW APPLIED
(2020)
Article
Engineering, Electrical & Electronic
Saptarshi Mukherjee, Karen Dowling, Yicong Dong, Kexin Li, Adam Conway, Shaloo Rakheja, Lars Voss
Summary: With the advancement of optoelectronic device technology, a Prony-based curve-fitting method has been proposed to characterize RF pulse measurements from these devices. The method shows high accuracy in measurement data and is capable of extracting key pulse parameters, providing insights into the physics of optoelectronic devices.
IEEE SIGNAL PROCESSING LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Karen Dowling, Yicong Dong, David Hall, Saptarshi Mukherjee, Joseph D. Schneider, Stefan Hau-Riege, Sara E. Harrison, Laura Leos, Adam Conway, Shaloo Rakheja, Lars Voss
Summary: This work presents a new optoelectronic device that has the potential to be used as a high-frequency, high-power RF source or amplifier. By introducing optical illumination into a small gap in the signal trace of a gallium-arsenide coplanar waveguide, a confined charge cloud is generated. The phenomenon of negative differential mobility is utilized to achieve pulse compression, resulting in a temporally compressed output electrical pulse compared to the input optical pulse. Experimental results demonstrate a 66% reduction in the full-width at half-maximum of the electrical pulse, relative to the input optical pulse. This novel coupled optoelectronic device opens up possibilities for high-frequency, high-power, compact devices that could enhance satellite communication systems.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Koon Hoo Teo, Yuhao Zhang, Nadim Chowdhury, Shaloo Rakheja, Rui Ma, Qingyun Xie, Eiji Yagyu, Koji Yamanaka, Kexin Li, Tomas Palacios
Summary: GaN technology is expanding rapidly in various application areas, including digital and quantum computing electronics. Developing new GaN devices for higher-voltage and ultra-low-voltage power applications is crucial. GaN CMOS technology is expected to play a key role in realizing a full GaN platform.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Yicong Dong, Karen M. Dowling, Stefan P. Hau-Riege, Adam Conway, Lars F. Voss, Shaloo Rakheja
Summary: This paper presents the physics and design-space exploration of a novel pulse compression photoconductive switch (PCPS) using semi-insulating gallium arsenide (GaAs) operating in the negative differential mobility (NDM) regime of electron transport. The relationship between PCPS performance and various design options is quantified, and the optimal design parameters for higher electron confinement and superior radio-frequency (RF) metrics are discussed. The results provide guidance for experimentalists in fine-tuning the PCPS design parameters and serve as a theoretical basis for measurements of PCPS devices using GaAs and other NDM materials.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Ankit Shukla, Shaloo Rakheja
Summary: We theoretically and numerically study terahertz auto-oscillations in thin-film metallic noncollinear coplanar antiferromagnets and provide insights into the dynamics and design of the auto-oscillators. We analyze the input current requirements, oscillation frequency, and output power and efficiency of the auto-oscillator. Our results can be used as a starting point for experimental setups and have potential applications in terahertz sensing, imaging, and neuromorphic computing.
PHYSICAL REVIEW APPLIED
(2022)
Article
Physics, Applied
Ashwin Tunga, Kexin Li, Ethan White, Nicholas C. Miller, Matt Grupen, John D. Albrecht, Shaloo Rakheja
Summary: This study uses various simulations to investigate the behaviors of two different energy-transport models in GaN HEMT devices. The results show that the Fermi kinetics transport model exhibits faster and more stable numerical convergence, whereas the hydrodynamics transport model shows slower convergence and certain anomalous behaviors.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Ashwin Tunga, Zijing Zhao, Ankit Shukla, Wenjuan Zhu, Shaloo Rakheja
Summary: In this work, the charge transport in 2-D Schottky barrier field-effect transistors (SB-FETs) is described, focusing on carrier injection at the Schottky contacts. A numerical model is developed for thermionic and field-emission processes of carrier injection, which is then simplified to an analytic equation for current versus voltage (I-V) in the SB-FET. The model incorporates the physics of various injection processes and is validated against measurement data and TCAD simulation data.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Editorial Material
Physics, Applied
Shaloo Rakheja, Zhihong Chen, Ching-Tzu Chen
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Yicong Dong, Karen Dowling, Soroush Ghandiparsi, Lars Voss, Shaloo Rakheja
Summary: In this work, we study the deep-level defect physics of semi-insulating gallium arsenide bulk photoconductive semiconductor switches (PCSS) with gap sizes of 10 µm and 25 µm in dark-mode operation. By solving for the trap dynamics of the PCSS, we propose two semi-analytical models with impact ionization effects, one involving ground state interactions and the other involving direct electron excitation and relaxation processes. Experimental measurements confirm that the latter model provides a better fit with near-bistable features. The validity of the second model is further confirmed through measurements at higher bias voltages on a 10 µm PCSS. The importance of including defect interactions and defect avalanche effects in illuminated operation of PCSS is also discussed.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2023)
Article
Computer Science, Information Systems
Nikhil Rangarajan, Satwik Patnaik, Johann Knechtel, Ramesh Karri, Ozgur Sinanoglu, Shaloo Rakheja
Summary: The era of globalization has brought about hardware-centric security threats in the IC supply chain. This paper introduces dynamic camouflaging as a technique to protect against IP reverse engineering at all stages of the supply chain. By leveraging the properties of spin-based devices, dynamic camouflaging is resilient against attacks and has potential for energy, performance, and area savings.
IEEE TRANSACTIONS ON EMERGING TOPICS IN COMPUTING
(2022)
Article
Materials Science, Multidisciplinary
S. M. Farzaneh, Shaloo Rakheja
Summary: Using density functional theory, this study quantifies the spin-dependent properties of group 14 elemental monolayers, finding that silicene, germanene, and stanene transition from a quantum spin Hall insulator to an ordinary band insulator under applied electric fields, while plumbene's spin Hall conductivity remains robust to external electric fields.
Article
Engineering, Electrical & Electronic
Shaloo Rakheja, Kexin Li, Karen M. Dowling, Adam M. Conway, Lars F. Voss
Summary: Gallium Nitride (GaN) has emerged as the dominant material for high-electron mobility transistors (HEMTs) and photoconductive switches (PCSS) in RF electronics. Operating GaN PCSS in the regime of negative differential mobility significantly benefits its high-frequency performance. By generating optically excited carriers in the middle of the active region, the device can achieve a bandwidth of approximately 600 GHz, output power exceeding 800 mW, and a power gain greater than 35 dB. Additional enhancements can be achieved by increasing the optical bias to further boost the performance of GaN PCSS under high optical bias.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2021)
Article
Materials Science, Multidisciplinary
Arun Parthasarathy, Egecan Cogulu, Andrew D. Kent, Shaloo Rakheja
Summary: This study discusses the precession and stability of the Neel order of antiferromagnets subjected to spin torque, focusing on the requirements for in-plane and normal components of spin polarization. The precessional motion is described as a damped-driven pendulum with hysteresis, showing critical values and frequency dependencies on the spin current.