Article
Engineering, Electrical & Electronic
Stefan Moench, Richard Reiner, Patrick Waltereit, Fouad Benkhelifa, Jan Hueckelheim, Dirk Meder, Martin Zink, Thomas Kaden, Stefan Noll, Sebastian Mansfeld, Nicola Mingirulli, Ruediger Quay, Ingmar Kallfass
Summary: The study achieved a low-inductive half-bridge and gate driver package through a beneficial combination of PCB embedding and monolithic circuit integration, addressing the interconnection challenge with external capacitors.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2021)
Article
Physics, Applied
Abu Bashar Mohammad Hamidul Islam, Tae Kyoung Kim, Dong-Soo Shin, Jong-In Shim, Joon Seop Kwak
Summary: This study investigates the effect of current stress on InGaN/GaN multiple-quantum-well flip-chip blue micro light-emitting diodes (mu-LEDs) and reveals the mechanisms of defect aggregation and generation that cause changes in the optoelectronic performance of the devices. The aging test shows that the improvement in crystal quality due to defect aggregation initially enhances the light output power and external quantum efficiency (EQE), but the generation of sidewall point defects eventually leads to performance degradation. The findings highlight the importance of both defect aggregation and generation in understanding the degradation mechanisms of mu-LEDs.
APPLIED PHYSICS LETTERS
(2022)
Article
Physics, Applied
F. Piva, M. Grigoletto, R. Brescancin, C. De Santi, M. Buffolo, J. Ruschel, J. Glaab, D. Hauer Vidal, M. Guttmann, J. Rass, S. Einfeldt, N. Susilo, T. Wernicke, M. Kneissl, G. Meneghesso, E. Zanoni, M. Meneghini
Summary: We investigated the impact of Mg-doping on the performance and degradation kinetics of AlGaN-based UV-C LEDs. Higher Mg-doping in the electron-blocking layer (EBL) resulted in higher optical power at low current levels due to increased hole injection efficiency. The reduction of optical power followed a non-exponential trend and could be explained by the generation/activation of defects within the quantum wells. Higher Mg-doping in the EBL mitigated the degradation rate, potentially due to the presence and movement of hydrogen reducing the de-hydrogenation rate of point defects in the active region.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Ah Hyun Park, Seungjae Baek, Go Bong Choi, Yoong Ahm Kim, Jinsub Lim, Tae Hoon Seo
Summary: In this study, green light emitting diodes (LEDs) with Au nanoclusters in a micro-hole patterned p-GaN layer (ANCs-MHPP) were demonstrated to have higher internal quantum efficiencies and faster decay times compared to conventional green LEDs. The remarkable opto-electronic performance of green LEDs with ANCs-MHPP is attributed to exciton-surface plasmon coupling and surface texturing effect caused by the micro-hole patterned p-GaN layer.
APPLIED PHYSICS LETTERS
(2021)
Article
Physics, Applied
Zhen Huang, Renchun Tao, Duo Li, Zexing Yuan, Tai Li, Zhaoying Chen, Ye Yuan, Junjie Kang, Zhiwen Liang, Qi Wang, Pengfei Tian, Bo Shen, Xinqiang Wang
Summary: In this work, a method is proposed to improve the modulation bandwidth of green mu-LEDs by enhancing p-type conductivity. The polarization-induced p-type doping with graded AlGaN significantly enhances the conductivity of the p-type layer, leading to improved light output power and modulation bandwidth.
APPLIED PHYSICS LETTERS
(2022)
Article
Optics
Katarzyna Pieniak, Witold Trzeciakowski, Grzegorz Muziol, Anna Kafar, Marcin Siekacz, Czeslaw Skierbiszewski, Tadeusz Suski
Summary: The study examined electroluminescence from In0.17Ga0.83N/GaN quantum wells of LEDs and LDs, finding a transition from ground-states recombination to excited states recombination with increasing QW width. The effect is accompanied by partial or complete screening of the built-in electric field with increasing driving current, which was studied using a high pressure method. Investigations were supported by simulations of the variation with driving current of electron and hole wavefunctions overlap affecting the recombination channel and built-in electric field.
Article
Optics
A. Pandey, Y. Malhotra, P. Wang, K. Sun, X. Liu, Z. Mi
Summary: This paper demonstrates the performance of N-polar InGaN/GaN nanowire sub-microscale red light emitting diodes (LEDs) for the first time. These LEDs exhibit higher efficiency and brightness compared to conventional red-emitting micro-LEDs. In-situ annealing significantly enhances the optical emission intensity, and the fabricated LED sizes are extremely small.
PHOTONICS RESEARCH
(2022)
Review
Materials Science, Multidisciplinary
Matteo Buffolo, Alessandro Caria, Francesco Piva, Nicola Roccato, Claudia Casu, Carlo De Santi, Nicola Trivellin, Gaudenzio Meneghesso, Enrico Zanoni, Matteo Meneghini
Summary: This paper reviews the main factors and mechanisms that limit the reliability of gallium nitride (GaN)-based light-emitting diodes (LEDs). It provides an overview of the relevant defects characterization techniques for wide-bandgap diodes, and presents a catalogue of traps and deep levels in GaN along with computer-aided simulations to identify the defects that negatively affect the radiative efficiency of the devices. The paper also analyzes gradual degradation mechanisms and examines the commonly used lifetime estimation methods and standards for solid-state luminaires. Additionally, it discusses the typical degradation and failure mechanisms exhibited by LEDs under electrical overstress.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2022)
Article
Optics
Jacob J. Ewing, Cheyenne Lynsky, Matthew S. Wong, Feng Wu, Yi Chao Chow, Pavel Shapturenka, Michel Iza, Shuji Nakamura, Steven P. Denbaars, James S. Speck
Summary: This article studied the method of achieving highly efficient long-wavelength InGaN LEDs through V-defect engineering, which utilized naturally occurring V-defects for lateral injection and improved the external quantum efficiency.
Article
Engineering, Electrical & Electronic
Yan Guo, Sai Pan, Danfeng Pan, Chaojun Xu, Yugang Zhou, Rong Zhang, Youdou Zheng
Summary: The Mg/Al bilayer achieves high-reflectivity ohmic contact for n-GaN, but annealing temperature significantly affects the contact resistivity and reflectivity. Annealing below 300 degrees Celsius maintains high reflectivity, while excessively high temperatures deteriorate the ohmic characteristics.
IEEE PHOTONICS TECHNOLOGY LETTERS
(2021)
Article
Optics
Jinpeng Huang, Zelin Hu, Xiang Gao, Yi Xu, Liancheng Wang
Summary: This study proposes a single-chip micro-LED display technology with unidirectional emission through the integration of a resonant cavity and metasurface, which can achieve efficient naked-eye 3D display with a wide viewing angle and multiple viewpoints. The research promotes the application of GaN-based micro-LEDs in displays, especially in 3D displays.
Article
Nanoscience & Nanotechnology
K. Khan, S. Diez, Kai Sun, C. Wurm, U. K. Mishra, E. Ahmadi
Summary: This study reports the observation of self-assembled InGaN/(In)GaN superlattice structure in InGaN film grown on N-polar GaN substrate, with varying In content in each layer depending on growth temperature. By increasing the substrate temperature, a periodic structure was achieved, offering a new pathway for designing and fabricating electronic and optoelectronic devices with enhanced performance.
Article
Chemistry, Multidisciplinary
Sukho Song, Sagar Joshi, Jamie Paik
Summary: The latest research in digital fluidic circuits aims to create electronics-free controllers for soft robots, but faces challenges in adjusting digital logic operations. A new approach has been presented to design a circuit with digitized fluidic gates that can actively tune fluidic characteristics for improved control. This work has successfully modeled a pressure-controlled oscillator, showcasing its ability to modulate frequency and control the motion of soft robotic systems.
Article
Multidisciplinary Sciences
Po-Wei Chen, Po-Wen Hsiao, Hsuan-Jen Chen, Bo-Sheng Lee, Kai-Ping Chang, Chao-Chun Yen, Ray-Hua Horng, Dong-Sing Wuu
Summary: The mechanism of carrier recombination in downsized mu-LED chips was investigated, showing that the smallest chip size exhibited the highest ideality factor due to carrier recombination in high-defect-density zones. The use of a passivation layer and a maskless technology improved the performance and efficiency of the mu-LED chips. The blue-shift phenomenon in the electroluminescence spectrum was attributed to carrier screening and band filling effects, with high EQE values observed in the high current density region for the 10 x 10 μm(2) mu-LED chip.
SCIENTIFIC REPORTS
(2021)
Article
Chemistry, Physical
Giane B. Damas, Karl Ronnby, Henrik Pedersen, Lars Ojamae
Summary: This report investigates the reaction pathways and mechanisms involved in the crystal growth of indium nitride (InN) thin film in atomic layer deposition (ALD) techniques using trimethylindium (TMI) and ammonia (NH3) precursors. The study provides important insights for the optimization of InN film preparation.
APPLIED SURFACE SCIENCE
(2022)
Article
Engineering, Electrical & Electronic
Lang Chen, Hang Liu, Jefferson Hora, J. Andrew Zhang, Kiat Seng Yeo, Xi Zhu
Summary: This article introduces a method of designing power amplifiers (PA) using load-modulated balanced amplifier (LMBA) architecture. PAs designed with this method show excellent performance in terms of high efficiency, high output power, and support for multiple signal modulation schemes.
IEEE JOURNAL OF SOLID-STATE CIRCUITS
(2021)
Article
Engineering, Electrical & Electronic
Hao-wei Lu, Xiao-Peng Yu, Si-Qi Wang, Yu-Yan Liu, Zhen-Yan Huang, Zheng-Hao Lu, Kiat-Seng Yeo, Jer-Ming Chen
Summary: This paper proposes a new digital background calibration scheme for non-linearity of high-resolution SAR ADC, which improves the performance of ADC by training the real weight of more significant bits and implementing calibration table in the digital domain, suitable for some detection applications in specific circumstances.
MICROELECTRONICS JOURNAL
(2021)
Article
Engineering, Electrical & Electronic
Hang Liu, Xi Zhu, Yisheng Wang, Kai Men, Kiat Seng Yeo
Summary: The developed 60 GHz fully-integrated 8-way power amplifier shows excellent performance characteristics, including high gain, linearity, and efficiency, while meeting all channel requirements specified in the IEEE 802.11ad standard.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2021)
Article
Computer Science, Information Systems
Bithin Alangot, Daniel Reijsbergen, Sarad Venugopalan, Pawel Szalachowski, Kiat Seng Yeo
Summary: Clients of permissionless blockchain systems, like Bitcoin, need to connect to at least one honest peer to avoid eclipse attacks. This paper proposes two methods for detecting eclipse attacks and discusses an implementation without introducing any dedicated infrastructure or changes to the Bitcoin protocol and network.
IEEE TRANSACTIONS ON NETWORK AND SERVICE MANAGEMENT
(2021)
Editorial Material
Engineering, Electrical & Electronic
Fanyi Meng, Chenfei Wang, Ziheng Liu, Kaixue Ma, Don Disney, Kiat Seng Yeo
IEEE POWER ELECTRONICS MAGAZINE
(2021)
Article
Computer Science, Information Systems
Samuel B. S. Lee, Kiat Seng Yeo
Summary: This letter introduces an inductorless transimpedance amplifier for visible light communication, fabricated using the UMC 40 nm CMOS process. The amplifier features a wide gain range and bandwidth, as well as functions such as peaking variation and dynamic range.
Article
Computer Science, Information Systems
Maoyang Xiang, Tee Hui Teo
Summary: This paper proposes a novel approach for implementing Binarized Neural Networks (BNN) on embedded systems, which preserves low-level features and requires minimal operations through optimization of hardware structure and BNN topology. Experimental results on the CIFAR-10 dataset demonstrate that the proposed method outperforms current BNN designs in terms of efficiency and accuracy.
Article
Nanoscience & Nanotechnology
Aasish Boora, Bharatha Kumar Thangarasu, Kiat Seng Yeo
IEEE NANOTECHNOLOGY MAGAZINE
(2022)
Article
Engineering, Electrical & Electronic
Nagarajan Mahalingam, Hang Liu, Yisheng Wang, Kiat Seng Yeo, Chien- Chou, Hung-Yu Tsai, Kun-Hsun Liao, Wen-Shan Wang, Ka-Un Chan, Ying-Hsi Lin
Summary: This letter presents a digital transmitter for NB-IoT applications, which achieves a large dynamic range, high-speed RF-DACs, and low power consumption. The transmitter incorporates integrated baluns and a reconfigurable interpolater to ensure efficient operation and meet the requirements of NB-IoT.
IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Ziheng Liu, Fanyi Meng, Kaixue Ma, Kiat Seng Yeo
Summary: This article presents a new design theory named current harmonics analysis (CHA) for designing load-independent zero voltage switching (LI-ZVS) single-switch resonant dc/dc converters. The proposed CHA adopts frequency-domain harmonic analysis to eliminate the mathematical iterations and improves ZVS load variation range.
IEEE TRANSACTIONS ON POWER ELECTRONICS
(2022)
Article
Computer Science, Information Systems
J. Jithish, Bithin Alangot, Nagarajan Mahalingam, Kiat Seng Yeo
Summary: The smart grid integrates Information and Communication Technologies (ICT) into the traditional power grid to manage the generation, distribution, and consumption of electrical energy. Machine learning (ML)-based techniques on smart meter data has shown remarkable results in anomaly detection. However, traditional ML-based anomaly detection requires smart meters to share local data with a central server, which raises concerns regarding data security and user privacy. Motivated by these concerns, we propose a Federated Learning (FL)-based smart grid anomaly detection scheme where ML models are trained locally in smart meters without sharing data with a central server, thus ensuring user privacy.
Article
Engineering, Electrical & Electronic
Liying Cai, Xiong Song, Zhenghao Lu, Xiao-Peng Yu, Kiat-Seng Yeo, Jer-Ming Chen, Bharatha Kumar Thangarasu
Summary: This paper presents a reconfigurable fully integrated automatic gain control (AGC) amplifier based on a dual mode continuous gain adjustment variable-gain amplifier (VGA). The VGA is implemented using a current-steering structure to achieve linear-in-dB gain tuning. A current division active load is proposed to provide additional gain control range and gain robustness. The proposed VGA achieves a total gain range of 68.2 dB and independent adjustment of bandwidth and gain. The AGC is implemented in UMC 55-nm CMOS technology with a core area of 0.026 mm².
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2023)
Article
Engineering, Electrical & Electronic
Nagarajan Mahalingam, Hang Liu, Yisheng Wang, Bharatha Kumar Thangarasu, Kiat Seng Yeo, Chien- Chou, Hung-Yu Tsai, Kun-Hsun Liao, Wen-Shan Wang, Ka-Un Chan, Ying-Hsi Lin
Summary: This article introduces a pulling mitigation scheme implemented in a frequency synthesizer integrated with a dual-band NB-IoT transmitter (TX). The scheme utilizes a hybrid phase compensation and sampled filter to mitigate the pulling effects caused by the transmitter. The synthesizer covers frequencies from 700-900 MHz and 1.7-2 GHz in the low and high bands respectively, meeting the dual-band NB-IoT frequency tuning specifications. The proposed pulling mitigation improves the EVM by 11.5% with 16QAM modulation, achieving a pulling suppression of 24 dB in single-tone measurements. Implemented in 40 nm CMOS, the pulling mitigation occupies a small area of 0.18 x 0.18 mm² and consumes 1 mW of DC power with a 1.1 V supply voltage.
IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES
(2023)
Article
Engineering, Electrical & Electronic
Xin Wang, Genyin Ma, Fanyi Meng, Shilin Shi, Keping Wang, Kaixue Ma, Kiat Seng Yeo
Summary: This letter presents a 0.5-4.5-GHz watt-level SPDT switch designed in 0.13-mu m CMOS SOI technology. By using stacked FETs with independent biasing, the power handling capacity of the switch is improved. The switch features low insertion loss and good isolation, making it suitable for the fifth-generation communication system.
IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS
(2023)
Article
Computer Science, Artificial Intelligence
Wei Ming Tan, T. Hui Teo
Summary: This paper proposes a Multi-variable Time Series (MTS) focused approach to prognostics, utilizing a lightweight Convolutional Neural Network (CNN) to enhance accuracy and training speed for the estimation of Remaining Useful Life (RUL). The deployment of the network on a lightweight hardware platform demonstrates compactness and efficiency in resource-restricted environments.
