Article
Engineering, Electrical & Electronic
Chin-Sheng Pang, Peng Wu, Joerg Appenzeller, Zhihong Chen
Summary: Ultrascaled WS2 field-effect transistors (FETs) with exfoliated multilayer channels exhibit excellent ON-state and OFF-state performance, achieving high ON-state current and ultralow contact resistance. The study shows that a WS2 body thickness of 2.1 nm (three layers) performs the best in both ON-state and OFF-state.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Tsung-En Lee, Kasidit Toprasertpong, Mitsuru Takenaka, Shinichi Takagi
Summary: In this study, ultrathin equivalent oxide thickness scaling of TiN/Y2O3/SiGe gate stacks using a trimethylaluminum (TMA) treatment was investigated. The EOT was scaled down to 1 nm with low interface trap densities, and the stress-induced degradation at the SiGe interface from constant gate biasing was found to be suppressed by scaling the thickness of Y2O3.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Nanoscience & Nanotechnology
Parminder Kaur, Balwinder Raj, Sandeep Singh Gill
Summary: This study presents the design and optimization of ZnO thin film transistors, with observed improvements in device performance through optimizing dielectric layer thickness and replacing SiO2 with high-k dielectric material.
Article
Chemistry, Physical
Yuan-Ming Chen, Hsien-Cheng Lin, Kuan-Wei Lee, Yeong-Her Wang
Summary: An inverted-type InAlAs/InAs MOS-HEMT with LPO InAlAs as the gate insulator has been demonstrated, showing improved device performance compared to the conventional Schottky-gate HEMT. By inserting a thin InAs layer in the sub-channel layers of InGaAs, this MOS-HEMT exhibits enhanced drain current density, transconductance, leakage current density, noise figures suppression, and associated gain. The use of LPO to form MOS structure improves surface states and energy barrier, making the proposed device a potential alternative option for applications.
Article
Physics, Applied
Kentaro Onishi, Takuma Kobayashi, Hidetoshi Mizobata, Mikito Nozaki, Akitaka Yoshigoe, Takayoshi Shimura, Heiji Watanabe
Summary: By sputter deposition of SiO2, we minimized the formation of unstable GaO x layer, as confirmed by negligible GaO x growth even after post-deposition oxygen annealing up to 600 degrees C. A MOS device with negligible capacitance-voltage hysteresis, stable flat-band voltage, and low leakage current was demonstrated by performing oxygen and forming gas annealing at temperatures of 600 degrees C and 400 degrees C, respectively.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Engineering, Electrical & Electronic
Ken Kudara, Shoichiro Imanishi, Atsushi Hiraiwa, Yuji Komatsuzaki, Yutaro Yamaguchi, Yoshifumi Kawamura, Shintaro Shinjo, Hiroshi Kawarada
Summary: This study reports on the high operation voltage large-signal performance of two-dimensional hole gas diamond MOSFETs with thick ALD-Al2O3, demonstrating superior output power density at both 1 GHz and 3.6 GHz frequencies.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Materials Science, Multidisciplinary
Duy Phong Pham, Hongrae Kim, Jiwon Choi, Donghyun Oh, Yung-Bin Chung, Woo-Seok Jeon, Jungyun Jo, Vinh-Ai Dao, Suresh Kumar Dhungel, Junsin Yi
Summary: We propose an in-situ stoichiometric SiO2 layer deposition using plasma-enhanced chemical vapor deposition (PECVD) to replace outside SiO2 deposition for semiconductor devices. The addition of argon gases in the plasma environment promotes the dissociation of SiH4 and CO2, resulting in an increase in the deposition rate and a decrease in the refractive index of SiO2. The in-situ PECVD-based stoichiometric SiO2 layer is expected to simplify the semiconductor device procedure.
Article
Engineering, Electrical & Electronic
Hyun-Joo Ryoo, Hyun-Min Ahn, Nak-Jin Seong, Kyu-Jeong Choi, Chi-Sun Hwang, Sung-Jin Chang, Sung-Min Yoon
Summary: A nanoscale vertical-channel thin film transistor (V-TFT) with a channel length shorter than 160 nm was successfully fabricated and characterized. The prototype device demonstrated sound transistor operation and robust stabilities under positive/negative bias stresses. Further analysis revealed insights into the implementation of nanoscale oxide V-TFTs.
ACS APPLIED ELECTRONIC MATERIALS
(2021)
Article
Engineering, Electrical & Electronic
Ajit Kumar, Pramod Kumar Tiwari, J. N. Roy
Summary: A comprehensive subthreshold model of asymmetric gate all around (GAA) junctionless (JL) FETs with scaled equivalent oxide thickness is developed in this work. The perimeter weighted sum approach is used to model the channel potential and threshold voltage of the device. A novelty in the perimeter weighted approach is proposed to model subthreshold slope of the device. Different gate dielectric materials are studied to investigate the scaling of equivalent oxide thickness, and the characteristics of asymmetric devices due to dielectric thickness asymmetry are analyzed.
MICROELECTRONICS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Yu Fu, Shozo Kono, Hiroshi Kawarada, Atsushi Hiraiwa
Summary: MOS capacitors with C-Si-O diamond as semiconductors and SiO2/Al2O3 as gate insulators were fabricated and characterized, showing excellent electrical performance.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Nanoscience & Nanotechnology
James Huang, Yunil Cho, Zichen Zhang, Antony Jan, Keith T. Wong, Srinivas D. Nemani, Ellie Yieh, Andrew C. Kummel
Summary: Highly selective and smooth TiO2/Al2O3 and HfO2/Al2O3 nanolaminates were successfully deposited by water-free pulsed CVD, achieving high selectivity and smooth films on a nanoscale pattern.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Engineering, Electrical & Electronic
Zhiyu Guo, Zhi He, Fengxuan Wang, Jingmin Wu, Xiang Yang, Zhongchao Fan, Fuhua Yang
Summary: This work investigates the characteristics of trench sidewall capacitance in a 4H-SiC stepped thick-oxide trench MOS structure. Different test patterns of SiC trench MOS capacitors with varying structures and geometric parameters were designed and fabricated. The results show significant positive shifts in the flat-band voltages of the MOS from the upper and lower parts of trench sidewall step, indicating the presence of a large number of negative charges in the sidewall oxide film. The net oxide charge density of the MOS in the lower part of sidewall step was smaller, potentially due to the presence of massive shallow states in the oxide and the poor quality of the thick-oxide film. This study provides a convenient technology to monitor the trench MOS structure during SiC trench MOSFET fabrication.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Joao L. Gomes, Filipe M. Barradas, Luis C. Nunes, Jose C. Pedro
Summary: This article addresses the issue of reconciling a non-reciprocal capacitance formulation in the equivalent circuit model of field-effect transistors (FETs) with the energy conservation principle. It demonstrates that the nonreciprocity of the C(v) matrix is a collateral effect from using the standard pi equivalent circuit to fit the measured Y-parameters of the FET. The conductive and capacitive elements representing the FET's channel are externally mixed together due to the Y-parameters formulation, resulting in extracted nonlinear capacitances that do not abide by the energy conservation principle.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Environmental
Busuyi O. Adebayo, Han Yu, Ali A. Rownaghi, Xinhua Liang, Fateme Rezaei
Summary: In this study, Pt nanoparticles were loaded on SiO2, TiO2-SiO2, or ZrO2-SiO2 particles to investigate their performance in sequential adsorption and desorption/catalytic oxidation of benzene. The results showed that Pt nanoparticles and ZrO2 exhibited synergistic effects in catalytic oxidation.
CHEMICAL ENGINEERING JOURNAL
(2022)
Article
Computer Science, Information Systems
Ya-Wen Ho, Tejender Singh Rawat, Zheng-Kai Yang, Sparsh Pratik, Guan-Wen Lai, Yen-Liang Tu, Albert Lin
Summary: Artificial neural networks and multilayer perceptrons are efficient in designing semiconductor device models, but require a large number of parameters and longer simulation time. Optimizing network architecture for better learning is important yet tedious. Neuro-evolution method can achieve lower RMSE and faster convergence for semiconductor device compact models compared to traditional MLP models.
Article
Materials Science, Ceramics
Kyusung Kim, Pil Gyu Choi, Toshio Itoh, Yoshitake Masuda
Summary: This study investigated the gas sensitivity of ZnO nanostructures on different exposed surfaces, demonstrating that ZnO-whisker exhibited superior sensing performance in all ranges compared to ZnO-rod. The results were attributed to the different electron distribution in oxygen vacancy sites on the exposed surfaces, with ZnO-whisker showing higher sensitivity due to easier electron provision.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2022)
Article
Materials Science, Multidisciplinary
Kyusung Kim, Sangwoo Chae, Yoshitake Masuda, Nagahiro Saito
Summary: In this study, the morphology of ZnO nanostructures was controlled using solution plasma process without chemical additives, resulting in the synthesis of nanorod and nanosheet-type ZnO with Zn and W electrodes, respectively. The unique reaction between ions and radicals at the plasma/liquid interface was responsible for the fabrication of ZnO nanostructures, with Zn(OH)(4)(2-) ions promoting rod structure and WO42- ions inhibiting growth in the [001] direction to form sheet structure.
Article
Chemistry, Analytical
Chunyan Li, Pil Gyu Choi, Kyusung Kim, Yoshitake Masuda
Summary: This paper discusses the direct fabrication of ultrathin Ni(OH)2 nanosheets on substrates via a solvothermal process. The thickness and morphology of the nanosheets can be controlled by manipulating the ethanol content in the solvent. The 75% ethanol-based NiO gas sensor demonstrates ultrahigh acetone sensitivity, ultralow detection limit, good stability, and superior acetone selectivity. Low cost NiO nanosheets fabricated via a simple process could be considered as potential candidates for commercial acetone sensing applications.
SENSORS AND ACTUATORS B-CHEMICAL
(2022)
Article
Environmental Sciences
Toshio Itoh, Yoshitake Masuda, Ichiro Matsubara, Junichirou Arai, Woosuck Shin
Summary: This study analyzed the temporal variation of VOCs composition in four essential oils. The results revealed that the concentration level of VOCs in the oils varied with diffusion time and equilibrium concentration with the liquid phase. It was confirmed that the total concentration of VOCs diffused by the ultrasonic diffuser in room air was very low.
INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH
(2022)
Article
Chemistry, Analytical
Yoshitake Masuda
Summary: This review focuses on tin oxide nanomaterials, which are actively researched as semiconductor-type gas sensors. The development and applications of novel tin oxide nanomaterials in the past decade are discussed, with a focus on how dimensions and morphology affect sensing performance. The dendritic structure formed by 2D nanosheets connected by crystal growth points towards future sensor development, while the high gas adsorption performance and reactivity of metastable crystal planes provide guidance for future sensor development.
SENSORS AND ACTUATORS B-CHEMICAL
(2022)
Article
Chemistry, Multidisciplinary
Chunyan Li, Pil Gyu Choi, Yoshitake Masuda
Summary: NiO nanosheets were synthesized using a facile solvothermal method and used as gas sensors to analyze the exhaled biomarker of psychological stress, allyl mercaptan (AM) gas. MnO2 nanosheets were also synthesized onto the surfaces of the NiO nanosheets to enhance gas-sensing performance. The gas-sensing response of the NiO nanosheet sensor was found to be higher compared to the MnO2@NiO nanosheet sensor.
Article
Materials Science, Ceramics
Kyusung Kim, Pil Gyu Choi, Toshio Itoh, Yoshitake Masuda
Summary: Atomic defects can enhance the catalytic efficiency of metal oxides, making chemical reactions easier. In this study, porous ZnO nanobelts with atomic step structures were fabricated for ultrasensitive gas sensing of acetone, ethanol, and isoprene at the parts-per-billion level.
INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY
(2023)
Article
Materials Science, Ceramics
Yoshitake Masuda
Summary: Cold crystallization and morphology control have been achieved for ZnO nanostructures, which can be used in various devices such as sensors, batteries, and catalysts.
INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Pil Gyu Choi, Yoshitake Masuda
Summary: Mental stress management is crucial for human health as excessive and sustained mental stress can cause harm. This study focuses on allyl mercaptan, a biomarker associated with mental stress, and utilizes a nanosheet-type tin oxide gas sensor array to detect it. Gas classification models are built using supervised learning algorithms and principal component analysis, providing accurate forecasts for allyl mercaptan.
SCIENTIFIC REPORTS
(2022)
Article
Materials Science, Ceramics
Kyusung Kim, Pil Gyu Choi, Toshio Itoh, Yoshitake Masuda
Summary: By changing the supply rate of hydroxide ions, we can control the morphology of ZnO nanomaterial and improve the sensitivity of metal-oxide-semiconductor gas sensors.
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Krishnaprasanth Alageshwaramoorthy, Pandian Mannu, Seetha Mahalingam, Ta Thi Thuy Nga, Han-Wei Chang, Yoshitake Masuda, Chung-Li Dong
Summary: In this study, the novel CuTa2O6 phase was synthesized by hydrothermal and calcination processes. X-ray diffraction confirmed the presence of different phases, with a phase transition to cubic crystal structure at high temperatures. Optical studies and FESEM images provided further characterization of the material. The photocatalytic activity of CuTa2O6 was evaluated for the degradation of MO dye and showed promising results.
FRONTIERS IN CHEMISTRY
(2023)
Article
Chemistry, Physical
Pil Gyu Choi, Yoshitake Masuda
Summary: A thin film of nanosheet-type tin oxide (SnO2) was synthesized on a sensor chip using an aqueous solution process. Au-Pd was then loaded onto the film's surface through ion sputtering. The sensor signal response of the Au-Pd loaded tin oxide to hydrogen was higher than that of the bare tin oxide, while its response to methane gas decreased. The designed nanosheet has potential applications as a hydrogen sensor array.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
Article
Engineering, Environmental
Chunyan Li, Pil Gyu Choi, Yoshitake Masuda
Summary: Gas sensors with high sensitivity and selectivity are crucial for practical applications, such as distinguishing target molecules in volatile organic compound detection, real-time security alerts, and clinical diagnostics. In this study, a large-lateral-area SnO2 nanosheet sensor was successfully synthesized via a one-step aqueous solution process. The SnO2 sensor exhibited remarkable sensitivity and anti-interference ability towards acetone, with excellent reproducibility and long-term stability. The ultrasensitive response of the SnO2 nanosheets can be attributed to their specific loose structure, small grain size, and metastable crystal facets.
JOURNAL OF HAZARDOUS MATERIALS
(2023)
Article
Chemistry, Analytical
Toshio Itoh, Yutaro Koyama, Yuichi Sakumura, Takafumi Akamatsu, Akihiro Tsuruta, Yoshitake Masuda, Woosuck Shin
Summary: We investigated the discriminant method for identifying volatile organic compounds (VOCs) in exhaled breath under both contaminated and purified air conditions using multiple semiconductive gas sensors and linear discriminant analysis (LDA) technique. Our developed discriminant method was used to analyze the resistance changes in sensor signals in the LDA space. The target gases were discriminated based on the angle of the locus of the test data in the 2-D LDA space. Our results demonstrated the feasibility of this method in discriminating target gases under contaminated air conditions.
SENSORS AND ACTUATORS B-CHEMICAL
(2023)
Article
Chemistry, Physical
Kyusung Kim, Pil Gyu Choi, Toshio Itoh, Yoshitake Masuda
Summary: By decorating ZnO nanobelts with atomic step structures, the gas sensing performance can be improved to detect acetone at the ppt level. The atomic step edges promote electron transfer and restrict gas diffusion on the flat surface to achieve sensitivity.
JOURNAL OF MATERIALS CHEMISTRY A
(2022)
