Article
Materials Science, Multidisciplinary
S. Sai Guru Srinivasan, B. Govardhanan, M. Ashok, M. C. Santhosh Kumar
Summary: Nanocrystalline single-phase Cu2O thin films were deposited on a glass substrate by RF reactive sputtering, exhibiting excellent photocatalytic activity. As the deposition time increases, the crystallite size and surface roughness also increase.
Article
Materials Science, Ceramics
Hailong Liang, Bo Zhang, Yuanyuan Guo, Xintao Guo, Shiqiang Ren, Yan Li, Yanqing Lu, Runlong Lang
Summary: In this work, Y-doped HfO2 thin films with ferroelectric properties were successfully prepared by ion beam assisted RF magnetron sputtering, achieving a high coercive field and remanent polarization. The structural and electrical properties of the films were found to be strongly dependent on the energy of the applied ion beam, with a model of phase transition kinetics introduced to explain the variations. The bombardment of the Ar ion beam provided extra energy to facilitate atomic diffusion and overcome potential barriers, showing great potential for ferroelectric device applications.
CERAMICS INTERNATIONAL
(2021)
Article
Nanoscience & Nanotechnology
Ding Wang, Ping Wang, Shubham Mondal, Subhajit Mohanty, Tao Ma, Elaheh Ahmadi, Zetian Mi
Summary: This paper reports on the resistive switching behavior and memory effect in an ultrawide-bandgap ferroelectric ScAlN/GaN heterostructure. The structure exhibits stable ON and OFF states that last for months at room temperature, and shows stable operation at high temperatures close to or even above the Curie temperature. The underlying mechanism is directly related to charge reconstruction induced by the ferroelectric field effect at the hetero-interface. The polar heterostructure demonstrates robust resistive switching landscape and electrical polarization engineering capability, and has the potential to integrate with both silicon and GaN technologies, enabling a wide range of multifunctional applications.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Engineering, Electrical & Electronic
Mingyo Park, Jialin Wang, Azadeh Ansari
Summary: This study presents the first demonstration of thin-film ferroelectric Aluminum Scandium Nitride (AlScN)-on-silicon composite resonators, achieving high-overtone resonance modes with a high figure of merit (FoM). The research shows that the addition of a passive Si device layer underneath the thin piezo-stack results in improved quality factor (Q), structural robustness, and overall FoM. High k(t)(2) values and FoM are reported for the TE resonant frequency, showing a significant improvement compared to the co-fabricated AlScN-only FBARs.
IEEE ELECTRON DEVICE LETTERS
(2021)
Article
Chemistry, Analytical
Hui Wang, Linwei Zhang, Zhixin Zhou, Liang Lou
Summary: The temperature performance of AlN-SAW resonators and AlScN-SAW resonators was studied in this paper. They were simulated using COMSOL Multiphysics, and their modes and S11 curve were analyzed. The two devices were fabricated using MEMS technology and tested using VNA, and the test results were consistent with the simulation results. Temperature experiments were conducted with temperature control equipment, and the changes in S11 parameters, TCF coefficient, phase velocity, and quality factor Q with temperature were analyzed. The results showed that both the AlN-SAW resonator and the AlScN-SAW resonator exhibited excellent temperature performance, with good linearity. Additionally, the AlScN-SAW resonator had a 9.5% higher sensitivity, 15% higher linearity, and 11.1% higher TCF coefficient. It is therefore more suitable as a temperature sensor.
Article
Nanoscience & Nanotechnology
Jose P. B. Silva, Raluca F. Negrea, Marian C. Istrate, Sangita Dutta, Hugo Aramberri, Jorge Iniguez, Fabio G. Figueiras, Corneliu Ghica, Koppole C. Sekhar, Andrei L. Kholkin
Summary: Zirconia- and hafnia-based thin films have attracted significant attention due to their ferroelectric behavior at the nanoscale. This study reveals a new ferroelectric rhombohedral phase of ZrO2 in thin films grown on (111)-Nb:SrTiO3 substrates, exhibiting high ferroelectric polarization and low coercive field with characteristics in agreement with the nucleation limited switching (NLS) model for ferroelectric domain reversal.
ACS APPLIED MATERIALS & INTERFACES
(2021)
Article
Materials Science, Multidisciplinary
Takanori Mimura, Reijiro Shimura, Akinori Tateyama, Yoshiko Nakamura, Takahisa Shiraishi, Hiroshi Funakubo
Summary: This study investigates the deposition of thin films using a no-heating method, and finds that some of these films exhibit ferroelectric and piezoelectric properties.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Review
Materials Science, Multidisciplinary
Jacob M. M. Wall, Feng Yan
Summary: This article reviews several key sputtering parameters for the deposition of ScxAl1-xN, including target design, sputtering atmosphere, sputtering power, and substrate temperature. These parameters play a crucial role in achieving satisfactory films with desired stoichiometry and film thickness, as well as impacting the crystal quality and surface characteristics of the deposited films. The goal of this paper is to analyze the impacts of these sputtering parameters in detail and provide some overarching themes to assist future researchers in optimizing their sputtering processes for optimum results.
Article
Chemistry, Physical
Khagesh Tanwar, Xin Tan, Md Mokhlesur Rahman, Srikanth Mateti, Pavel Cizek, Paramita Koley, Chunping Hou, Sean C. Smith, Ying (Ian) Chen
Summary: The novel molybdenum sulfide-carbon composite thin film electrodes exhibit excellent cycling performance and rate capability in Li-MSx cells, without any shuttle effect.
JOURNAL OF POWER SOURCES
(2021)
Article
Chemistry, Analytical
Daniel Drury, Keisuke Yazawa, Andriy Zakutayev, Brendan Hanrahan, Geoff Brennecka
Summary: Currently, there is a lack of nonvolatile memory (NVM) technology that can operate continuously at temperatures > 200 degrees C. This study demonstrates how AlScN can enable high-temperature (>200 degrees C) nonvolatile memory, showing promise for potential high-temperature operation.
Article
Materials Science, Ceramics
Xinkun Liu, Ying Dai, Xinmei Pei, Wen Chen
Summary: Lead-free Sr-doped BCZT thin films were successfully prepared and their structure, electric properties and ECE were investigated. The results show that the phase transition temperatures of the films change with increasing Sr content and merge at room temperature. The BCZT-0.05Sr film exhibits a giant ECE near room temperature.
CERAMICS INTERNATIONAL
(2023)
Article
Optics
S. R. Cynthia, R. Sivakumar, C. Sanjeeviraja
Summary: The ternary CuO:SnO2:ZnO (1:1:1) thin films prepared by radio frequency magnetron sputtering technique showed good sensing characteristics towards NH3 gas detection, with excellent crystalline nature and surface morphology variation. The films exhibited a highest optical transmittance of 87% in the visible region, and excellent sensitivity and stability towards NH3 gas detection at room temperature.
Article
Multidisciplinary Sciences
Taketo Handa, Ruito Hashimoto, Go Yumoto, Tomoya Nakamura, Atsushi Wakamiya, Yoshihiko Kanemitsu
Summary: This article introduces a metal-free ferroelectric perovskite material, MDABCO-ammonium triiodide, which exhibits both ferroelectricity and visible photoluminescence. It is found that the intensity of the photoluminescence is strongly related to the polarization of the excitation light. These results suggest that the photoluminescent property can be tuned by external fields in response to its ferroelectric state.
Article
Chemistry, Physical
N. Ziani, E. Aubry, N. Martin, L. Hirsinger, A. Billard, P. Briois, M. S. Belkaid, M. Arab Pour Yazdi
Summary: Delafossite CuFeO2 films were synthesized by reactive magnetron sputtering at different substrate temperatures ranging from 380 to 550 degrees C. The films exhibited a rhombohedral structure and showed partial dissociation of the delafossite phase into FCC Cu and Fe3O4 magnetite phases at the highest temperature, as well as changes in preferential orientation and optical properties with temperature.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Chemistry, Multidisciplinary
Daoqin Wang, Zongjin Jiang, Linhan Li, Deliang Zhu, Chunfeng Wang, Shun Han, Ming Fang, Xinke Liu, Wenjun Liu, Peijiang Cao, Youming Lu
Summary: H doping can enhance the performance of ZnO thin-film transistors, and the design of double active layers further improves device performance. In this study, ZnO:H/ZnO-TFT with a hydrogen flow ratio of 0.13% exhibited the best overall performance, with higher mobility, on/off current ratio, subthreshold swing, and threshold voltage compared to single active layer ZnO:H-TFTs. The transport mechanism in double active layer devices is more complex, with increased hydrogen flow ratio suppressing defect states and electron accumulation at the interface providing an additional pathway for carrier transport. This research demonstrates the fabrication of high-performance ZnO-based TFTs and provides reference value for the development of flexible devices.
Article
Engineering, Electrical & Electronic
Hua-Lun Ko, Quang Ho Luc, Ping Huang, Si-Meng Chen, Jing-Yuan Wu, Che-Wei Hsu, Nhan-Ai Tran, Edward Yi Chang
Summary: In this study, InGaAs FinFETs with (010) orientation channel and nitrogen post remote plasma treatment were fabricated, demonstrating a peak transconductance of 2727 S-μ/(μm) and improved subthreshold performances. These results were achieved through strong electrostatic control, scaled fin width, and RP passivation, leading to superior high-kappa /InGaAs interface quality.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Ryota Shibukawa, Sung-Lin Tsai, Takuya Hoshii, Hitoshi Wakabayashi, Kazuo Tsutsui, Kuniyuki Kakushima
Summary: The sputtering power dependence of 40 nm thick Al0.7Sc0.3N ferroelectric properties was investigated. Higher sputtering power resulted in better orientation growth along the c-axis and improved leakage current and breakdown field. High remnant polarization and low coercive field were achieved, and a wake-up effect was observed.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Si-Meng Chen, Sung-Lin Tsai, Kazuto Mizutani, Takuya Hoshii, Hitoshi Wakabayashi, Kazuo Tsutsui, Edward Yi Chang, Kuniyuki Kakushima
Summary: A method for shifting the threshold voltage (Vth) in GaN high electron mobility transistors using self-upward polarized Al1-xScxN gate dielectrics is proposed. The direction of spontaneous polarization is controlled by inserting an Al2O3 layer. A Vth shift of 8 V is achieved by changing the polarization direction. The thickness scaling in the Al1-xScxN layer shows a linear relationship to Vth, indicating a high spontaneous polarization. With the combination of a recess process, it is feasible to achieve a high positive Vth for enhancement-mode operation.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
M. Nishizawa, T. Hoshii, H. Wakabayashi, K. Tsutsui, Y. Daigo, I Mizushima, T. Yoda, K. Kakushima
Summary: This paper proposes a method for using device simulation to extract the hole lifetime of a thin n-type SiC epitaxial layer. By correlating the voltage drop across a forward-biased pn diode and parallel pn diodes at the same current density with the defined hole lifetime, the hole lifetime can be extracted. It was found that there was a severe error in the extraction of the voltage drop, which was attributed to surface recombination. The introduction of a field-plate between the anodes recovered the extraction error, achieving an extraction accuracy of 99% even with a high surface recombination velocity.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Physics, Applied
Atsuki Miyata, T. Hoshii, H. Wakabayashi, K. Tsutsui, K. Kakushima
Summary: This paper investigates a photodetector based on an AlGaN/GaN high electron mobility transistor on Si, which exhibits long decay time after removal of light irradiation, making it unsuitable for applications requiring fast response. The decay time is successfully suppressed from 75 to 2 seconds by modulating the substrate voltage.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
P. Huang, M. Y. Chen, Q. H. Luc, J. Y. Wu, N. A. Tran, E. Y. Chang
Summary: This study investigates the performance comparison between InGaAs MOSFETs and ferroelectric field-effect transistors (FEFETs) as a function of channel length (L-ch) using a technology computer-aided design (TCAD) simulator. The results show that at relatively long L-ch, the RF characteristics and energy efficiencies of FE-FETs are comparable or inferior to conventional MOSFETs. However, as L-ch is scaled down, significant performance enhancement is observed in FE-FETs. The superior RF properties in FE-FETs can be attributed to higher effective electron velocity (V-eff), better gate controllability, and reduced gate resistance (Rg).
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Physics, Applied
Masaki Otomo, Masaya Hamada, Ryo Ono, Iriya Muneta, Kuniyuki Kakushima, Kazuo Tsutsui, Hitoshi Wakabayashi
Summary: ZrS2, a high-mobility next-generation channel material, is stabilized in the air by a ZrO2 film, which acts as a high-k film in MISFET. We examined the chemical properties of high-k/PVD-ZrS2 stacks with a self-oxidized ZrO2 film as an interfacial layer to understand the impact of fabrication processes on ZrS2 under the oxide film. The results showed that sulfur vapor annealing (SVA) is crucial for producing high-quality PVD ZrS2 films and that the surface potential change of ZrS2 films due to interface dipoles is suppressed with scaling of high-k thickness. The SVA with high-k films also enhances the quality of ZrS2 films without affecting their surface potential.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Materials Science, Coatings & Films
Tsu-Ting Lee, Kashi Chiranjeevulu, Sireesha Pedaballi, Daire Cott, Annelies Delabie, Chang-Fu Dee, Edward Yi Chang
Summary: In this study, the nucleation, growth, and development of Al2O3 atomic layer deposition (ALD) on a polycrystalline WS2 monolayer created by metal-organic chemical vapor deposition (MOCVD) were investigated. The results provide insights into the intrinsic reactivity of WS2 and the influence of ALD on the growth of WS2, which are crucial for further exploration of the structure and properties of TMD monolayers.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Engineering, Electrical & Electronic
Ping-Hsun Lee, Yueh-Chin Lin, Heng-Tung Hsu, Yi-Fan Tsao, Chang-Fu Dee, Pin Su, Edward Yi Chang
Summary: In this study, tall-gate-stem structures were used to improve the power performance of AlGaN/GaN HEMTs in the Ka-band. A film thinning process was also adopted to reduce parasitic capacitance. The results showed that devices with tall-gate-stem structures and film thinning process had higher cut-off frequency and maximum oscillation frequency values with lower parasitic capacitance. Load-pull measurement results demonstrated improved output power density and power added efficiency for the AlGaN/GaN HEMT with a tall gate stem at Ka-band.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2023)
Review
Materials Science, Multidisciplinary
Jui-Sheng Wu, You-Chen Weng, Tsung-Ying Yang, Chia-Hsun Wu, Chih-Chieh Lee, Hiroshi Iwai, Edward Yi Chang
Summary: Aluminum gallium nitride/gallium nitride (AlGaN/GaN) heterostructure devices have shown superior performance in high-frequency power amplifiers and power switching applications compared to traditional silicon technology and other advanced semiconductor technologies. The development of enhancement-mode AlGaN/GaN high electron mobility transistors (HEMTs) and metal-insulator-semiconductor HEMTs (MIS-HEMTs) has gained attention due to their potential applications. The hybrid ferroelectric charge storage gate (FEG) GaN HEMT, based on a flash-memory-like structure, has become of interest for its ability to achieve E-mode operations. This article reviews the latest progress in this technology and discusses future challenges for E-mode FEG-HEMTs.
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Engineering, Electrical & Electronic
Shivendra K. Rathaur, Jui-Sheng Wu, Tsung-Ying Yang, Asifa Amin, Abhisek Dixit, Edward Yi Chang
Summary: This article investigates the performance of a hybrid ferroelectric charge trap (HFCT)-based HfZrO4/HfOXNY/Al2O3/AlGaN/GaN gate-stack under constant positive gate voltage stress over time and temperature variability. The experimentally determined breakdown (BD) analysis suggests a thermally assisted tunneling (TAT) BD mechanism due to the negative temperature coefficient of BD voltage. The step gate stress results in a lower BD voltage compared to the linear gate stress, indicating performance degradation. The HFCT gate-stack demonstrates robustness and superior reliability, with a single degradation mechanism leading to time-dependent gate dielectric breakdown.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Ming-Wen Lee, Yueh-Chin Lin, Po-Sheng Chang, Yi-Fan Tsao, Heng-Tung Hsu, Chang-Fu Dee, Edward Yi Chang
Summary: This study presents the fabrication of AlGaN/GaN high-electron-mobility transistors (HEMTs) using Stepper Lithography on a 4-inch wafer for Ka-Band applications. A small gate length of 100 nm was achieved through a 2-Step Photolithography Process, and the gate region of the AlGaN/GaN HEMT was defined using two lithography steps to form gamma-shaped gates. The results demonstrate high electrical performance uniformity and excellent RF performance, indicating the potential of AlGaN/GaN HEMT fabrication with high yield for 5G applications using Stepper Lithography.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2023)
Article
Engineering, Electrical & Electronic
Takamasa Kawanago, Ryosuke Kajikawa, Kazuto Mizutani, Sung-Lin Tsai, Iriya Muneta, Takuya Hoshii, Kuniyuki Kakushima, Kazuo Tsutsui, Hitoshi Wakabayashi
Summary: In this study, we demonstrated the concept of doping-free Tungsten Diselenide (WSe2) complementary metal-oxide-semiconductor (CMOS) inverter by using alloys and compound metals as source/drain (S/D) contacts. The use of Aluminum - scandium alloy (AlSc) and tungsten oxide (WOx)-based S/D contacts facilitated efficient electron and hole injection into WSe2 for n-type and p-type FET operation. By utilizing a dual-gate bias architecture, the fabricated WSe2 CMOS inverter showed higher gain and operated at a low power supply voltage (V-dd) of 0.5 V.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2023)
Article
Engineering, Electrical & Electronic
P. Huang, Q. H. Luc, A. Sibaja-Hernandez, H. L. Ko, J. Y. Wu, N. A. Tran, N. Collaert, E. Y. Chang
Summary: This work demonstrates the high-frequency characteristics of scaled In0.53Ga0.47As nanowires through TCAD simulations. The study reveals that reducing the wire width leads to higher cut-off frequency due to the volume inversion effects caused by strong quantum confinement. Additionally, the channel charging delay increases with narrower wire width due to the increase in source/drain resistance.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2022)
Article
Engineering, Electrical & Electronic
Jui-Sheng Wu, Chih-Chieh Lee, Chia-Hsun Wu, Cheng-Jun Huang, Yan-Kui Liang, You-Chen Weng, Edward Yi Chang
Summary: This study systematically investigated FEG-HEMTs with different Hf-based and Zr-based charge trapping layers. The results showed that FEG-HEMT with nitrogen incorporated HfO2 as the charge trapping layer exhibited the highest E-mode operation threshold voltage and lower gate leakage, as well as better charging process and stability.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2022)
