Article
Chemistry, Multidisciplinary
Dong Un Lim, Sae Byeok Jo, Jeong Ho Cho
Summary: Organic electrochemical transistors (OECTs) are a promising candidate for printable electronics, offering chemical versatility and a unique redox-based operating principle. This study presents a simple strategy to achieve monolithic multi-valued logic transistors, an important branch of transistor technology. The introduction of a vertically stacked heterogenous dual-channel architecture and patterned reference electrode enables the manifestation of stable ternary logic states with reduced transistor footprint. The dual-ion-penetration mechanism and ultrashort vertical channel also allow for high-frequency accessing of multiple logic states.
ADVANCED MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Antonino Scandurra, Matteo Testa, Giorgia Franzo, Giuseppe Greco, Fabrizio Roccaforte, Maria Eloisa Castagna, Cristiano Calabretta, Andrea Severino, Ferdinando Iucolano, Elena Bruno, Salvatore Mirabella
Summary: This study investigated the electrical isolation of 2DEG achieved through Ar ion implantation. The results showed that Ar ion implantation caused crystal lattice damage and significant reduction in 2DEG carrier density. Furthermore, the electrical isolation was found to be stable at high temperatures.
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
(2023)
Review
Physics, Applied
Maciej Matys, Kazuki Kitagawa, Tetsuo Narita, Tsutomu Uesugi, Michal Bockowski, Jun Suda, Tetsu Kachi
Summary: This review briefly summarizes the major challenges and recent progress in the development of GaN Junction Barrier Schottky (JBS) diodes using selective-area p-type doping with ion implantation and ultra high-pressure annealing (UHPA) process. The high-performance JBS diodes demonstrated superior electrical characteristics and nondestructive breakdown.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
Sang Young Jeong, Jung Woo Moon, Soonyong Lee, Ziang Wu, Sung Hyeon Park, Jeong Ho Cho, Han Young Woo
Summary: In this study, a quasi-solid-state ion gel-gated vertical-type OECT (v-OECT) and NOT logic gate are successfully demonstrated by combining both p-type and n-type v-OECTs for the first time. Compared to aqueous devices, an enlarged electrochemical window and improved operational stability are observed. Logic gates are successfully demonstrated using p- and n-type v-OECTs, suggesting the potential of OECT-based next-generation electronics.
ADVANCED ELECTRONIC MATERIALS
(2023)
Article
Physics, Applied
Dolar Khachariya, Shane Stein, Will Mecouch, M. Hayden Breckenridge, Shashwat Rathkanthiwar, Seiji Mita, Baxter Moody, Pramod Reddy, James Tweedie, Ronny Kirste, Kacper Sierakowski, Grzegorz Kamler, Michal Bockowski, Erhard Kohn, Spyridon Pavlidis, Ramon Collazo, Zlatko Sitar
Summary: We report a novel vertical GaN junction barrier Schottky (JBS) diode with low ON-resistance and high breakdown voltage, demonstrating that high-performance GaN JBS can be achieved using Mg implantation and high-temperature UHP post-activation anneal.
APPLIED PHYSICS EXPRESS
(2022)
Article
Multidisciplinary Sciences
Reem B. Rashid, Weiyuan Du, Sophie Griggs, Iuliana P. Maria, Iain McCulloch, Jonathan Rivnay
Summary: The study introduces an active sensing node and inverter based on OECTs for signal amplification in bioelectronic sensing, providing new opportunities to improve signal quality and reduce the burden of signal transmission, while also demonstrating compatibility with nontraditional fabrication methods.
Article
Physics, Applied
Praneeth Ranga, Arkka Bhattacharyya, Adrian Chmielewski, Saurav Roy, Rujun Sun, Michael A. Scarpulla, Nasim Alem, Sriram Krishnamoorthy
Summary: This study reports on the growth and characterization of metalorganic vapor-phase epitaxy-grown beta-(AlxGa1-x)(2)O-3/beta-Ga2O3 modulation-doped heterostructures. An electron channel is achieved in the heterostructure by utilizing a delta-doped beta-(AlxGa1-x)(2)O-3 barrier, with characteristics studied using various measurement methods. The fabricated transistor demonstrates high peak current and on-off ratio, while the electron channel in beta-(AlxGa1-x)(2)O-3 displays promising charge density and mobility at room temperature.
APPLIED PHYSICS EXPRESS
(2021)
Article
Physics, Applied
Yuta Itoh, Hirotaka Watanabe, Yuto Ando, Emi Kano, Manato Deki, Shugo Nitta, Yoshio Honda, Atsushi Tanaka, Nobuyuki Ikarashi, Hiroshi Amano
Summary: In the process of Mg ion implantation into GaN at a high temperature of 1100 degrees C, low-beam-current implantation can reduce defect formation and activate Mg more effectively. By decreasing the density of Mg segregation defects with inactive Mg and increasing the density of intrinsic dislocation loops, the densities of Ga and N vacancies are reduced. The formation of these defects depends on beam current, an important parameter for defect suppression.
APPLIED PHYSICS EXPRESS
(2022)
Article
Physics, Applied
Yiyang Luo, Kairong Huang, Xiaoci Liang, Hanjing Ke, Sujuan Hu, Qian Wu, Baiquan Liu, Chuan Liu
Summary: Vertical static induction transistors (SITs) have gained new attention due to their suitability for flexible substrates and hybrid integration with light-emitting diodes. However, understanding of them has been hindered by Schottky gate leakage. In this study, concise expressions for the channel potential and current-voltage characteristics of ideal SITs are derived, and the theory is verified through simulation and experimental results. The proposed theories connect the device structure and electrical characteristics of SITs concisely.
PHYSICAL REVIEW APPLIED
(2023)
Article
Biophysics
Xian Wei, Jiyang Ma, Sujie Ma, Pinduo Liu, Hong Qing, Qing Zhao
Summary: Magnesium and its alloys have promising mechanical properties and biocompatibility, but their fast corrosion rate hinders their development in the biomedical field. This study used less-toxic hydroxyl ion implantation to form a functionalized oxide layer on the magnesium alloy surface, which significantly improved the corrosion resistance and biocompatibility of the material.
COLLOIDS AND SURFACES B-BIOINTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Marco Hoeppner, Bahman Kheradmand-Boroujeni, Joern Vahland, Michael Franz Sawatzki, David Kneppe, Frank Ellinger, Hans Kleemann
Summary: The high-frequency and low-voltage operation of organic thin-film transistors (OTFTs) is crucial for the commercial success of flexible electronics. While significant progress has been made, technology maturity remains a key challenge, including scalability, integrability, and device reliability.
Article
Physics, Applied
Shinji Yamada, Hideki Sakurai, Yamato Osada, Kanji Furuta, Toshiyuki Nakamura, Ryuichiro Kamimura, Tetsuo Narita, Jun Suda, Tetsu Kachi
Summary: A dry-etching technique using inductively coupled plasma reactive ion etching (ICP-RIE) was developed to form an optimal trench shape with highly vertical sidewalls and rounded corners, with SiCl4 reactive gas mixed with Cl-2 gas contributing to the highly vertical trench formation. The optimization of bias power was key to suppressing the formation of subtrenches and achieving natural formation of rounded corners. Multistep-bias etching technique was applied to reduce etching-induced damage, showing promising results for GaN-based vertical T-MOSFETs.
APPLIED PHYSICS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Yongjian Ma, Xuanze Zhou, Wenbo Tang, Xiaodong Zhang, Guangwei Xu, Li Zhang, Tiwei Chen, Shige Dai, Chunxu Bian, Botong Li, Zhongming Zeng, Shibing Long
Summary: In this work, a high-performance beta-Ga2O3 U-shaped trench-gate metal-oxide-semiconductor field-effect transistor (UMOSFET) was demonstrated. Nitrogen ions were used to create a current blocking layer, which allowed electrons to accumulate near the U-shaped groove and form a conductive channel, promoting current generation. By modulating the concentration of implanted nitrogen ions, a UMOSFET with an applicable threshold voltage of 4.2 V was achieved. When the N ions concentration was 5 x 10^18 cm^-3, a high current density of 702.3 A/cm^2, a low on-resistance of 10.4 m Omega.cm^2, and a decent breakdown voltage of 455 V (at V_G =0 V) were obtained. The UMOSFET in this study offers great advantages in the fabrication of high-performance E-mode vertical beta-Ga2O3 MOSFETs and facilitates the development of beta-Ga2O3 power electronics devices.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Jiadong Yao, Wenxuan Guo, Yali Liu, Xinyue Niu, Mengge Li, Xiaoxiang Wu, Ying Yu, Tianjian Ou, Jian Sha, Yewu Wang
Summary: A MoS2/GeSe2 vertical heterostructure with type I band alignment was built in this study, exhibiting a large hysteresis voltage attributed to charge transfer between MoS2 and GeSe2 layers. This understanding can improve device performance and aid in the development of new van der Waals heterostructure devices.
JOURNAL OF MATERIALS CHEMISTRY C
(2021)
Article
Chemistry, Multidisciplinary
Jung Woo Moon, Dong Un Lim, Young No Kim, Jung Hyun Kim, Jin Hyeon Kim, Sae Byeok Jo, Jeong Ho Cho
Summary: The emergence of organic electrochemical transistors (OECTs) has opened a new era of printable electronics and bioelectronics due to their unique advantages. However, their insufficient operation speeds and short compatibilities to scaling-down have hindered advanced integrations beyond biosensing and biosignal amplifications. A 3D-construction-dependent operational analysis of OECTs is reported, enabling high operating speed and easy expansion to large-area and high-density 3D crossbar arrays. Various printed logic circuit arrays, including NOT, NAND, and NOR gates, have been achieved with high stability and reproducibility.
ADVANCED FUNCTIONAL MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Zhengliang Bian, Ke Zeng, Srabanti Chowdhury
Summary: A novel edge termination method has been reported for a 2.8 kV avalanche-capable vertical gallium nitride pn diode. By depositing a field plate on top of a hydrogen-plasma passivated p-type GaN layer, better electric field management was achieved to mitigate peak electric fields in the diode. Avalanche behavior was confirmed by the positive temperature coefficient of the breakdown voltage.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Physics, Applied
Kelly Woo, Mohamadali Malakoutian, Benjamin A. Reeves, Srabanti Chowdhury
Summary: Diamond, as an ultrawide-bandgap semiconductor, is suitable for high power devices. Various diamond structures were investigated for extrinsic photoconductive semiconductor switches, and some preliminary results were obtained.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Siwei Li, Burcu Ercan, Chenhao Ren, Hirotaka Ikeda, Srabanti Chowdhury
Summary: The impact of dislocation density on off-state leakage current in avalanche-capable GaN vertical p-n diodes was experimentally demonstrated and studied. The results showed that devices with higher dislocation density had higher leakage current and a more variable-range-hopping-dominated leakage process, while devices with lower dislocation density were more influenced by the Poole-Frenkel effect.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Seungbin Jeong, Kwangjae Lee, Jaeyi Chun, Rohith Soman, Srabanti Chowdhury
Summary: GaN vertical FinFETs on a bulk GaN substrate were fabricated and their self-heating and DC-RF dispersion were investigated. The devices showed high drain current density and low gate leakage with low-temperature post-gate processes. The specific on-resistance was one of the lowest values reported, and low dispersion was observed for devices away from the wafer edge. The influence of self-heating was more significant as the fin width scaled down or the number of fingers increased.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Rafael Perez Martinez, David J. Munzer, Bhawani Shankar, Boris Murmann, Srabanti Chowdhury
Summary: There is a significant disconnect between the linearity metrics used by device and circuit engineers in GaN technology, which degrades its maximum performance. A detailed linearity analysis is conducted on four different GaN device variants using derivative superposition (DS) method to evaluate amplifier performance under modulated conditions. Conventional linearity metrics at the device level, such as output third-order intercept point (OIP3) and output 1-dB compression point (OP1 dB), are compared with communication standard-based metrics, including adjacent channel power ratio (ACPR) and error vector magnitude (EVM), to provide best practices for quantifying power amplifier (PA) linearity. The study reveals that employing more devices primarily improves the input-bias range of the device, not the peak amplifier performance under modulation. This work provides device engineers with a circuit-level perspective on linearity to enhance RF performance for practical deployment.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Editorial Material
Materials Science, Multidisciplinary
Grace Xing, Zetian Mi, Srabanti Chowdhury
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Crystallography
Xinyi Wen, Kwang Jae Lee, Yusuke Nakazato, Jaeyi Chun, Srabanti Chowdhury
Summary: For the first time, a low-temperature GaN (LT-GaN) layer prepared by MOCVD regrowth was used as a Mg stopping layer (MSL) for a GaN trench CAVET with p-GaN as a CBL. The MSL effectively suppresses Mg out-diffusion into the regrown AlGaN/GaN channel, enhancing the current capability of the GaN vertical devices. The study investigates the influence of MSL regrowth temperature and thickness on device performance and demonstrates that LT-GaN as the MSL is a promising approach for isolating Mg from subsequent layers in GaN vertical devices with a Mg-doped p-type layer.
Article
Physics, Applied
Maliha Noshin, Xinyi Wen, Rohith Soman, Xiaoqing Xu, Srabanti Chowdhury
Summary: In this study, N-polar AlGaN channel HEMT structures with varying Al mole fraction were grown using MOCVD. The high-quality morphology and Al composition of the structures were confirmed using atomic force microscopy and x-ray diffraction spectra. The results showed a decreasing trend in mobility with increasing Al mole fraction, which can be attributed to a combination of alloy-scattering and optical phonon-scattering mechanisms. HEMTs fabricated from these structures exhibited a drain current of 320 mA/mm for a 4 μm long-channel device.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Maliha Noshin, Rohith Soman, Srabanti Chowdhury
Summary: Devices made from ultrawide bandgap materials are being widely investigated for high-power and RF electronics. Nitrogen-polar GaN channel HEMTs exhibit better performance compared to their metal-polar counterparts. In this work, the first experimental demonstration of N-polar all-AlGaN HEMT devices with different Al compositions (20% and 30%) in the channel is reported. These devices showed high drive current, low leakage current, large on/off ratio, and high breakdown voltage without field plate structures.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Sudip K. Mazumder, Lars F. Voss, Karen M. Dowling, Adam Conway, David Hall, Robert J. Kaplar, Gregory W. Pickrell, Jack Flicker, Andrew T. Binder, Srabanti Chowdhury, Victor Veliadis, Fang Luo, Sameh Khalil, Thomas Aichinger, Sandeep R. Bahl, Matteo Meneghini, Alain B. Charles
Summary: This article provides an overview of power semiconductor devices (PSDs) for the distributed energy resource (DER) system. It begins with an introduction to electrically triggered silicon carbide (SiC) and gallium nitride (GaN) devices, followed by a brief explanation of ultrawide bandgap (UWBG) PSDs. Additionally, it discusses optically activated PSDs such as photoconductive semiconductor switches (PCSS) and optical bipolar PSDs, and concludes with an overview of PSD packaging and reliability considerations.
IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS
(2023)
Proceedings Paper
Computer Science, Interdisciplinary Applications
Rafael Perez Martinez, Masaya Iwamoto, Jianjun Xu, Philipp Pahl, Srabanti Chowdhury
Summary: This paper compares the accuracy and attributes of different FET models in the context of GaN HEMT modeling. Three FET models implemented within PathWave Advanced Design System are compared, with a focus on analyzing the use of neural networks for modeling I-V and Q-V relations. The models are validated and benchmarked using data from a specific GaN-on-SiC HEMT, showing the power of neural network technology for accurately modeling thermal and trapping effects of GaN HEMTs.
2023 IEEE RADIO FREQUENCY INTEGRATED CIRCUITS SYMPOSIUM, RFIC
(2023)
Proceedings Paper
Engineering, Electrical & Electronic
Yuke Cao, James W. Pomeroy, Jingshan Wang, Patrick Fay, Bhawani Shankar, Srabanti Chowdhury, Martin Kuball
Summary: Semiconductor device developments are guided by simulations and comparing measured and simulated IV curves is a common method to assess device performance. However, the problem of low breakdown voltage due to different implantation or doping levels lacks guidance for mitigation. We present a technique based on EFISHG to directly measure electric strength in vertical GaN-on-GaN pn junctions with submicron resolution, which aids in improving device design and reducing product development cycles.
GALLIUM NITRIDE MATERIALS AND DEVICES XVIII
(2023)
Article
Materials Science, Multidisciplinary
Mohamadali Malakoutian, Rohith Soman, Kelly Woo, Srabanti Chowdhury
Summary: The increasing power demands of electronic applications, including 5G/6G, have made thermal management crucial. Enhancing heat transfer using thermally conductive materials like diamond is important to address the performance degradation and early failure caused by Joule heating in the device channel due to higher power. Diamond integration onto the device's top, near the channel, can be achieved through direct chemical vapor deposition.
Proceedings Paper
Computer Science, Artificial Intelligence
Dennis Rich, Anna Kasperovich, Mohamadali Malakoutian, Robert M. Radway, Shiho Hagiwara, Takahide Yoshikawa, Srabanti Chowdhury, Subhasish Mitra
2023 60TH ACM/IEEE DESIGN AUTOMATION CONFERENCE, DAC
(2023)
Proceedings Paper
Engineering, Multidisciplinary
Bhawani Shankar, Zhengliang Bian, Ke Zeng, Chuanzhe Meng, Rafael Perez Martinez, Srabanti Chowdhury, Brendan Gunning, Jack Flicker, Andrew Binder, Jeramy Ray Dickerson, Robert Kaplar
Summary: This study investigates the avalanche behavior and failure mechanism of 3 kV GaN-on-GaN vertical P-N diodes, aiming to identify issues with the device design and provide feedback for improvement based on the specific avalanche characteristics and failure mechanism.
2022 IEEE INTERNATIONAL RELIABILITY PHYSICS SYMPOSIUM (IRPS)
(2022)
