Papers by Keyword: MOS

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Authors: Sei Hyung Ryu, Craig Capell, Charlotte Jonas, Michael J. O'Loughlin, Jack Clayton, Edward van Brunt, Khiem Lam, Jim Richmond, Arun Kadavelugu, Subhashish Bhattacharya, Albert A. Burk, Anant Agarwal, Dave Grider, Scott T. Allen, John W. Palmour
Abstract: A 1 cm x 1 cm 4H-SiC N-IGBT exhibited a blocking voltage of 20.7 kV with a leakage current of 140 μA, which represents the highest blocking voltage reported from a semiconductor power switching device to this date. The device used a 160 μm thick drift layer and a 1 μm thick Field-Stop buffer layer, and showed a VF of 6.4 V at an IC of 20 A, and a differential Ron,sp of 28 mΩ-cm2. Switching measurements with a supply voltage of 8 kV were performed, and a turn-off time of 1.1 μs and turn-off losses of 10.9 mJ were measured at 25°C, for a 8.4 mm x 8.4 mm device with 140 μm drift layer and 2 μm F-S buffer layer. The turn-off losses were reduced by approximately 50% by using a 5 μm F-S buffer layer. A 55 kW, 1.7 kV to 7 kV boost converter operating at 5 kHz was demonstrated using the 4H-SiC N-IGBT, and an efficiency value of 97.8% was reported.
Authors: Jean Lorenzzi, Romain Esteve, Nikoletta Jegenyes, Sergey A. Reshanov, Adolf Schöner, Gabriel Ferro
Abstract: In this work we report on the growth and preparation of 3C-SiC(111) material for metal-oxide-semiconductor (MOS) application. In order to achieve reasonable material quality to prepare MOS capacitors several and crucial steps are needed: 1) heteroepitaxial growth of high quality 3C-SiC(111) layer by vapour-liquid-solid mechanism on 6H-SiC(0001) substrate, 2) surface polishing, 3) homoepitaxial re-growth by chemical vapour deposition and 4) use of an advanced oxidation process combining plasma enhanced chemical vapour deposition (PECVD) SiO2 and short post-oxidation steps in wet oxygen. Combining all these processes the interface traps density (Dit)can be drastically decreased down to 1.2  1010 eV-1cm-2 at 0.63 eV below the conduction band. To our knowledge, these values are the best ever reported for SiC material in general and 3C-SiC in particular.
Authors: T. Hirao, Hiroshi Yano, Tsunenobu Kimoto, Hiroyuki Matsunami, Hiromu Shiomi
Authors: H.Ö. Ólafsson, Christer Hallin, Einar Ö. Sveinbjörnsson
Authors: Tian Yun Yan
Abstract: A new system model for objective speech quality evaluation based on the improved recurrent generalized congruence neural network (RGCNN/OSQE) is proposed. The performance of the RGCNN model is compared with the most commonly used RBFNN (radial basis function neural network) model in objective speech quality evaluation. Comparison results show that the RGCNN model has higher correlation coefficient, less deviation, and saves about half training time, i.e., the RGCNN model has obvious advantages over the RBFNN model. Therefore, the novel RGCNN model for objective speech quality evaluation is feasible and effective.
Authors: Yan Ming, Li Zhen Wang, Xu Jiu Xia
Abstract: A 4kbps vocoder based on MELP is presented in this paper. It uses the parameter encoding and mixed excitation technology to ensure the quality of speech. Through adopting the scalar quantization of Line Spectrum Frequency (LSF), the algorithm reduces the storage and computational complexity. Meanwhile, 4kbps vocoder adds a new frame type-transition frame. The classifier can reduce the U/V decision errors and avoid excessive switching between voiced frame and unvoiced frame. A modified bit allocation table is introduced and the PESQ-MOS and coding time test shows that the synthetic speech quality has been improved and reached the quality of communication.
Authors: Fredrik Allerstam, Einar Ö. Sveinbjörnsson
Abstract: This study is focused on characterization of deep energy-level interface traps formed during sodium enhanced oxidation of n-type Si face 4H-SiC. The traps are located 0.9 eV below the SiC conduction band edge as revealed by deep level transient spectroscopy. Furthermore these traps are passivated using post-metallization anneal at 400°C in forming gas ambient.
Authors: H.Ö. Ólafsson, Einar Ö. Sveinbjörnsson, T.E. Rudenko, V.I. Kilchytska, I.P. Tyagulski, I.N. Osiyuk
Authors: Xue Hui Wei, Meng Zhao
Abstract: Video quality assessment can be gotten by combination the distortion in the space area and the time area. As we all known that edge information is one of the most important features in image quality estimation. Based on the edge model in the perceived image quality estimation, we used it in the space and time area in the video, and get the edge information distorted model in space area and time area of the video. Using multilinear regression to combine the two models, we can get the video quality assessment model based on edge information. The proposed model only uses the edge information, and the consumption in both areas is small. After compared with other methods given by video quality estimation group, it’s found that our method is convenient and good at the 50 Hz video sequence of low bit rate(768kb/s -4.5 Mb/s).
Authors: Takuji Hosoi, Makoto Harada, Yusuke Kagei, Yuu Watanabe, Takayoshi Shimura, Shuhei Mitani, Yuki Nakano, Takashi Nakamura, Heiji Watanabe
Abstract: We propose the use of an aluminum oxynitride (AlON) gate insulator for 4H-SiC MIS devices. Since direct deposition of AlON on 4H-SiC substrate generates a large amount of interface charge due to an interfacial reaction, a thick AlON layer was deposited on underlying thin SiO2 thermally grown in N2O ambient. To reduce the negative fixed charge density in the aluminum oxide (Al2O3) film, we used reactive sputtering of Al in an N2/O2 gas mixture. The fabricated MIS capacitor with AlON/SiO2 stacked gate dielectric shows no flat band voltage shift and negligible capacitance-voltage hysteresis (30 mV), indicating the dielectric is almost free from both fixed charges and electrical defects. Owing to the high dielectric constant of AlON (k=6.9), as compared to single N2O-SiO2 gate insulator, significant gate leakage reduction was achieved by AlON/SiO2 stacked gate dielectrics even at high-temperature, especially in a high electric field condition (>5 MV/cm).
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