Article
Engineering, Electrical & Electronic
Hao Huang, Ying Wang, Ke-Han Chen, Xin-Xing Fei
Summary: This study investigates the deposition of high-k dielectric materials, Al2O3 and HfO2, on 4H-SiC for metal-oxide-semiconductor applications using atomic layer deposition. The HfO2/SiO2/Al2O3/4H-SiC structure shows lower interface state density (Dit) and reduced number of fixed interface trap charges (Neff) compared to the HfO2/Al2O3/SiO2/4H-SiC structure. Interface properties degrade significantly when annealed at 400 degrees C. Transmission electron microscopy analysis reveals an inhomogeneous SiO2/SiC surface with carbon clusters and a more uniform Al2O3/SiC interface. The high-k dielectric stacked structure exhibits reduced leakage current (10-11 A/cm(2)) and a breakdown electric field of 9.6 MV/cm.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2023)
Article
Physics, Multidisciplinary
Zewei Shao, Hongyi Xu, Hengyu Wang, Na Ren, Kuang Sheng
Summary: High-k materials have the potential to enhance the conduction capability and reduce defects in SiC power devices, but they also induce significant leakage currents at the SiC interface due to their lower energy band gap. By inserting a SiO2 layer, the leakage current can be effectively reduced. This study determined the optimal thickness of the intercalated SiO2 by investigating the dielectric breakdown voltage and interfacial defects of a dielectric stack.
Article
Physics, Applied
Zhen Wang, Zhaofu Zhang, Sheng Liu, Chen Shao, John Robertson, Yuzheng Guo
Summary: In this article, five types of carbon-carbon defects introduced to the SiO2/4H-SiC (0001) interface are systematically investigated through first-principle calculations. The thermal oxidation process of 4H-SiC is analyzed, and it is found that oxygen-poor condition effectively suppresses the formation of carbon-carbon defects. The electronic structure and distribution of electron states for the carbon-carbon defects are obtained, revealing that they cause gap states near the conduction band minimum and act as acceptors.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Physics, Applied
Suman Das, Hengfei Gu, Lu Wang, Ayayi Ahyi, Leonard C. Feldman, Eric Garfunkel, Marcelo A. Kuroda, Sarit Dhar
Summary: We propose an N-2 based annealing treatment to eliminate interface traps in 4H-SiC. The treatment shows potential as a safer and more cost-effective alternative to nitric oxide. The effectiveness of the treatment varies between n- and p-type devices, with N-2 annealing being more effective for p-type devices. The breakdown voltages of the devices also differ between the two treatments, with N-2 annealed devices having lower breakdown voltages.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Physics, Applied
Naoki Komatsu, Mizuho Ohmoto, Mitsuharu Uemoto, Tomoya Ono
Summary: This study proposes the atomic structures of the 4H-SiC/SiO2 interface after NO annealing, with a preference for forming at the topmost layers of the SiC side and accumulation of N atoms at the interface. The areal N-atom density and electronic structure results are consistent with experimental findings, suggesting that NO annealing can reduce interface defects by forming a nitride layer.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Engineering, Electrical & Electronic
Ming Li, Xin Xia, Kunpeng Li, Shuxian Wu, Jie Zou, Kunfeng Chen, Gongbin Tang
Summary: SAW resonators based on 36 degrees YX-LiTaO3/SiO2/4H-SiC multilayer substrates are fabricated in this work to effectively suppress acoustic energy leakage. By using interdigital transducers (IDT) with a tilted angle, a multilayer resonator with transverse mode suppression is achieved. The results show that the multilayer resonator exhibits extremely high Bode-Q and impedance ratio, and achieves a high figure of merit.
IEEE ELECTRON DEVICE LETTERS
(2022)
Article
Engineering, Mechanical
Kun Tang, Wangping Ou, Cong Mao, Jie Liang, Moke Zhang, Mingjun Zhang, Yongle Hu
Summary: This study investigated the single-crystal silicon carbide (SiC) using nanoindentation testing method, and analyzed the material removal characteristics and crack situation. The results showed that the Si-plane and edge forward indenter direction were most suitable for material removal and machining. Additionally, the normal loading rate had little effect on the scratch depth, but a lower loading rate increased the ductile region and critical depth of transition. The increase in scratch interval weakened the interaction and fluctuation of the depth-distance curves of the second scratch, resulting in material fractures and chip accumulation.
CHINESE JOURNAL OF MECHANICAL ENGINEERING
(2023)
Article
Materials Science, Multidisciplinary
Mitsuhiro Saito, Hongping Li, Kazutoshi Inoue, Hirofumi Matsuhata, Yuichi Ikuhara
Summary: Optimizing wet oxidation conditions is crucial for obtaining excellent electronic properties in 4H-SiC MOSFET devices, with differences in oxidation rates between Si-face and C-face due to interface structure variations. The formation of an oxidation front by oxygen atom ordering ultimately suppresses interface defects or residual carbon, providing important insights for designing high-performance 4H-SiC MOSFET devices.
Article
Materials Science, Ceramics
Xiaotian Guo, Jie Tang, Haotian Chang, Yunzhou Zhu, Yuquan Wei, Xiulan Hu, Zhengren Huang, Yong Yang
Summary: This study successfully prepared SiC ceramic composites with complex shapes and high flexural strength by combining digital light processing (DLP) and reactive solution infiltration process (RMI). A low-absorbance SiO2 cladding layer was formed on the surface of SiC powder, and a photosensitive ceramic slurry with improved curing properties was formulated. Ceramic green bodies were molded using DLP, and then sintered and densified to obtain SiC ceramic composites with desired properties. This approach can effectively reduce the manufacturing cycle and cost of SiC ceramic composites.
CERAMICS INTERNATIONAL
(2023)
Article
Engineering, Electrical & Electronic
Baohua Tian, Haiping Shang, Dahai Wang, Yang Liu, Weibing Wang
Summary: This paper proposes an in situ extraction method to determine the piezoresistive coefficients of n-type 4H-SiC and fabricates two piezoresistive pressure sensors based on SiC sealed cavity structure for characterization. By fitting the experimental data and numerical calculation results, the longitudinal and transverse piezoresistive coefficients are obtained and the reliability of the extraction method is verified. This research is of significant value for understanding the piezoresistive effect in materials and guiding the design and performance optimization of SiC-based sensors.
IEEE SENSORS JOURNAL
(2022)
Article
Physics, Applied
Hidetoshi Nakanishi, Tatsuhiko Nishimura, Iwao Kawayama, Masayoshi Tonouchi, Takuji Hosoi, Takayoshi Shimura, Heiji Watanabe
Summary: Terahertz emission spectroscopy (TES) is used to evaluate interface properties between thermally grown oxides and 4H-SiC(0001) substrates. By measuring the emitted THz signal, information on the surface potential change of SiC MOS structures can be obtained, allowing for comparisons between structures with different interface qualities and investigation of the mechanism of THz emission.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Nanoscience & Nanotechnology
Mitsuru Sometani, Yusuke Nishiya, Ren Kondo, Rei Inohana, Hongyu Zeng, Hirohisa Hirai, Dai Okamoto, Yu-ichiro Matsushita, Takahide Umeda
Summary: The electric properties of the carbon dangling-bond (P-bC) center at a thermally oxidized 4H-SiC(0001)/SiO2 interface were investigated, and the energy levels of the associated interface states were determined. The impacts of the P-bC center on power device operations were evaluated. It was found that the P-bC center has larger correlation energy compared to the silicon dangling-bond (P-b) center, and it influences both p- and n-channel devices.
Article
Materials Science, Ceramics
Guanghui Feng, Hejun Li, Xiyuan Yao, Jia Sun, Yujun Jia
Summary: In this study, a multilayer coating with different sublayer thicknesses was fabricated on SiC-coated C/C composites using plasma spraying. The relationship between sublayer thickness and thermal stress was investigated through finite element analysis and practical experiments, showing a close connection among sublayer thickness, residual stress, and ablation behavior.
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
(2022)
Article
Chemistry, Physical
K. Idczak, E. Wachowicz
Summary: This study demonstrates that intercalated gadolinium atoms can significantly affect the electronic properties of graphene and the buffer layer, and temperature-induced intercalation can cause the buffer layer to decouple and transform into a new graphene layer.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Analytical
Chia-Yuan Chen, Yun-Kai Lai, Kung-Yen Lee, Chih-Fang Huang, Shin-Yi Huang
Summary: This research proposes a novel 4H-SiC power device structure called different concentration floating superjunction MOSFET (DC-FSJ MOSFET), which has a higher breakdown voltage and lower forward specific on-resistance compared to traditional vertical MOSFET. By optimizing the depth, concentration, and thickness of the floating P-type structure, DC-FSJ MOSFET achieves a breakdown voltage over 3300V and reduced R-on,R-sp. Additionally, the Baliga Figure of Merit (BFOM) of DC-FSJ MOSFET increases by 27% and R-on,R-sp is 25% less than traditional vertical MOSFET under the same conditions.
Article
Nanoscience & Nanotechnology
Kung-Chu Chen, Jenn-Gwo Hwu
Article
Engineering, Electrical & Electronic
Chen-Yun Huang, Jenn-Gwo Hwu
Summary: This article investigates a concentric metal-insulator-semiconductor (MIS) structure as a photo sensor, achieving improved photo-sensitivity under extremely weak light by changing the sensing method and roles of the inner and outer rings, which also leads to reduced power consumption.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Jian-Yu Lin, Jenn-Gwo Hwu
Summary: In this study, a new type of trench MIS TD was investigated, showing lower reverse bias current and stronger transient current compared to traditional planar structure MIS TDs. The trench devices exhibited better memory retention and memory endurance, with a potential to serve as memory devices due to their enhanced transient behavior.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Kung-Chu Chen, Jenn-Gwo Hwu
Summary: By utilizing the Schottky barrier height modulation mechanism, metal-insulator-semiconductor tunnel diodes (MISTD) achieve high photon current gain, with the operation voltage being able to go down and assist in high-speed applications.
IEEE SENSORS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Jen Hao Chen, Kung Chu Chen, Jenn Gwo Hwu
Summary: A multilevel open-circuit voltage sensor was developed based on the coupling mechanism between Al/SiO2/Si(p) metal-insulator-semiconductor tunneling diodes, achieving multiple levels of V-out-V-in curves and proposing a novel concept of logic gates. A 2-D TCAD simulation was implemented to confirm the feasibility of this concept, which is believed to overcome the complexity of conventional CMOS circuit and be beneficial for logic computation on electronics chip in the future.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Sung-Wei Huang, Jenn-Gwo Hwu
Summary: In this study, the steady-state and transient behavior of metal-insulator-semiconductor tunnel diodes with high-low (H/L) oxide layers were investigated through experiments and simulations. The use of H/L oxide layers was found to reduce leakage or tunneling current at reverse bias by reducing minority carrier density near the gate edge. Characteristics of devices with various parameters were studied to identify conditions for tunneling current reduction, leading to enhanced transient current and capacitance change. The simulation confirmed the observed phenomena, including the existence of lateral electron current flow reducing minority carrier density near the gate edge. A memory operation using the H/L device showed improved read current and stable performance, making it a potential future volatile memory application.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Nanoscience & Nanotechnology
Jen-Hao Chen, Kung-Chu Chen, Jenn-Gwo Hwu
Summary: This study investigates the coupling phenomenon between two Al/SiO2/Si(p) metal-insulator-semiconductor tunneling diodes, revealing that the coupling effect occurs earlier with thinner oxide thickness and the coupling sensitivity is enhanced.
Article
Materials Science, Multidisciplinary
Kuan-Wun Lin, Jenn-Gwo Hwu
Summary: This study investigated the influence of local oxide thinning (LOT) spots on the electrostatics of MOS capacitors, finding that the introduction of LOT spots causing significant gate leakage leads to severe deep depletion (DD) above threshold, making the capacitors inapplicable for MOSFETs. The research also analyzed the effects of capacitor size, spot size, and spot thickness on the DD behavior, demonstrating the high impact of LOT spots on device operations and emphasizing the importance of controlling oxide structural defects.
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2022)
Article
Engineering, Electrical & Electronic
Sung-Wei Huang, Jenn-Gwo Hwu
Summary: This study demonstrates the effect of oxide local thinning (OLT) on the increase in current two states in metal-insulator-semiconductor (MIS) tunnel diodes for dynamic memory usage. The improvement in the read current window is significant. Soft breakdown (SBD) is observed in the MIS sample after performing the deep depletion stress (DDS), indicating local thinning of the oxide. Pulsed voltage programming results in a larger magnitude of transient read current for OLT MIS, leading to improved current two states characteristics.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Sung-Wei Huang, Jenn-Gwo Hwu
Summary: This work proposes a metal-insulator-semiconductor (MIS) antifuse with three stable and highly distinguishable current states obtained through dielectric breakdown (BD) under electrical stress with opposite polarities. The device shows nonvolatile properties and is immune to read and write disturb at specific voltages. The idea of forming dielectric BD under opposite polarities for different current states could be beneficial for the design of one-time programmable multilevel memory.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Sung-Wei Huang, Jenn-Gwo Hwu
Summary: This article provides a detailed description of the behavior of two-state transient currents in metal-insulator-semiconductor tunnel diodes (MISTDs) through experiments and simulations. It reveals that transient currents at a timescale of 50 ms saturate after large voltage pulses with both polarities, and the read current is determined by the number of minority carriers regardless of the switching condition. The article also highlights the strong dependence of the read current on the oxide thickness and suggests optimal parameters based on experimental results for different design considerations.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Computer Science, Information Systems
Kung-Chu Chen, Kuan-Wun Lin, Jenn-Gwo Hwu
Summary: In this study, the current and capacitance characteristics of Al/SiO2/Si(p) MISTD with oxide thickness ranging from 2-4 nm were investigated. It was observed that the saturation reverse bias current increases with oxide thickness due to varying levels of SBHM. This non-intuitive phenomenon allows majority carriers to inject from metal to semiconductor, leading to stronger SBHM at thicker oxide thickness.
Article
Engineering, Electrical & Electronic
Sung-Wei Huang, Jenn-Gwo Hwu
Summary: Metal-insulator-semiconductor tunnel diodes with ultra thin metal surrounded gate (UTMSG) show improved transient current behavior, with resistance inducing delay of inversion carriers. The devices can only read capacitance under the surrounding gate in inversion regime.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2021)
Article
Materials Science, Multidisciplinary
Yung-Chun Yang, Kuan-Wun Lin, Jenn-Gwo Hwu
ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY
(2020)
Article
Engineering, Electrical & Electronic
Kung-Chu Chen, Kuan-Wun Lin, Sung-Wei Huang, Jian-Yu Lin, Jenn-Gwo Hwu
Summary: This study investigated the influence of oxide charges on the capacitance and conductance of metal-insulator-semiconductor (MIS) devices, proposing a model that takes into account various factors. Experimental and TCAD simulation results confirmed the model's accuracy in calculating capacitance for MIS devices with oxide charges. While heavily doped substrates may deviate from the model due to quantum effects, the overall trend of capacitance values can still be estimated using this approach.
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY
(2022)
