Papers by Keyword: Interface Properties

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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).
Authors: Rüdiger Rentsch, Olaf Grohmann, Alwin Schulz, Volker Uhlenwinkel
Abstract: In modern manufacture, like in automotive industry, high quality products and high output rates as well as low costs are achieved by highly efficient processes. Optimized tool design represents a key factor for such processes, leading to long tool life and hence to low tooling costs. Early in the industrial manufacturing chain of roller bearings for example, hot bars are sheared into billets, which are subsequently transported automatically to the first forming stage of a press. The shear blades should have a high wear resistance at high temperatures. In this study the first bi-metal composite shear blade made by spray-forming has been developed and tested in industrial environment. The composite tool has been deposited in a co-spray forming process to directly combine a hard-facing alloy layer with a hot working steel body in order to take advantage of the high microstructural homogeneity and the low segregation generated in spray forming. After machining, heat treating and quality inspection of the new material composite, the hot working tool was used in manufacture to prove its wear resistance and durability. The results show that the interface properties of the composite are of high quality and the material has a lower vulnerability to cracks after use in production than the conventional tool, respectively material. Only the porous zone near the interface leads to fissures which are partially going deep into the tool. Hence the parameters of the co-spray forming process need to be improved.
Authors: César A.C. Sequeira, Diogo M.F. Santos
Abstract: In this paper, current-voltage (i-Vg) results from different kinds of n-type InP Schottky diodes are reported. The diodes were fabricated on an unintentionally doped n-type (100) indium phosphide substrate, and the i-Vg characteristics were measured in the temperature range 100 300 K. For the ideality factor, n always exhibited a small (1) but continuous increase with the voltage. At higher forward voltage, slightly higher values of n were due to series resistance effect; in other words, the interface state density always remained small. However, it was possible to obtain some information in the case of discrete interface traps. It was shown that i-Vg measurements can be used as a fast method to determine the densities of the interface states when they equilibrate with the semiconductor.
Authors: Xiu Fang Cui, Guo Jin, Qing Fen Li
Abstract: The deposition process and interface properties of electro-thermal explosion sprayed WC/Co coating were studied by numerical simulation and experimental observation in this paper. The variety rule of the deposition particles / metal substrates interface temperature, the critical remelting condition of the substrates surface, and the interface removment speed of deposition particles were numerical simulated by finite element method. Results show that the remelting depth of the substrate increased with increasing spraying particle temperature and particle size. Structures and interface properties of the electro-thermal explosion sprayed WC/Co coating was analysed based on the numerical results. The morphologies, AES patterns, element distributions, TEM micrographs were experimentally observed and compared with the simulatin results. Which show that the finite element analysis is in good agreement with the experimental results, suggesting that the analysis in the present work is reliable.
Authors: Bouchra Hassoune-Rhabbour, Laurence Poussines, Valérie Nassiet
Abstract: There are several models on the relationship structures and properties of the composite fiber / matrix interface [1]. Including literature proposes the development of micromechanical tests suitable for assessing the shear strength of the interface fiber / polymer matrix. The first test which allowed to characterize the fiber / matrix interface is the pull-out test developed by Broutman [2]. It consists in extracting the fiber from the matrix that can be in block form, gout or disk of resin. To reduce the variation in results due to the geometries used, it was agreed to use a drop of resin with small dimensions. The test is to characterize the fiber / matrix interface of natural thermosetting or thermoplastic by determining the shear stress.
Authors: Dan Guo, Jia Xiao, Chen Jing, Xin An Zeng, Han Zhong
Abstract: Effects of pulsed electric fields (PEF) treatment on interface properties of phospholipids dispersion were studied. Results showed that the conductivity of solutions with different concentration after PEF treatment increased while surface tension value decreased with increasing electric field strength. The absolute value of zeta potential firstly increased when the field intensity was within 0~20 kV/cm, and then decreased if the field intensity increased further. It can be inferred that the torque of phospholipids molecule may have changed and phospholipids molecule have rearranged after PEF treatment. Moreover, as a resemblance to biological membrane structure, the phospholipid molecules of cell membrane may generate micropores after rearrangement, which result in the cell electroporation.
Authors: E. Bouarroudj, Wahiba Bouzidi, O. Menchi, S. Abdi
Abstract: The present investigation attempts to understand the friction welding characteristics of Aluminum alloy AlCu and steel AISI 4140. In spite, many trials were applied to achieve the sound weld zone of direct bonding between Aluminum and steel. The formation of intermetallic phase and crack in the near weld zone resulted in a lower tensile strength of joints relative to those of other welding technique. Therefore, to prevent intermetallic phase and crack formation at the interface, pure copper was used as insert powders for stress relief buffer layer. This study also envisages the influence of process parameters which include resident preform densities, friction pressure, upset pressure, and burn-off length on microstructure and mechanical properties of the welds. This work consolidates information on the aspects of diffusion joining of steel, copper and Aluminum component with wrought materials for practical execution. In the view point of tensile strength, the highest tensile strength between AlCu and AISI 4140 was acquired by using pure copper as insert powder.
Authors: Si Feng Zhang, Jian Xiang Feng, Rui Han, Zhi Gang Sun
Abstract: Geotechnical prestressed anchorage structures are widely used in high slope, deep foundation pit, dam and other geotechnical reinforcement engineerings. Under the influence of the outside environment, its pretensioned force is not fixed, but presents a kind of approximate closed cyclic loading mode, under which the development and evolution regularity of the interface shear stress for the inner bond section of geotechnical prestressed anchorage structure is directly related to the ultimate bearing capacity and its long-term durability. In the experiment, the means of indoor model test was adopted, in which the different loading scheme and loading amplitude were taken into account and the interfaces mechanical properties of inner bond section for geotechnical prestressed anchorage structures under cyclic loading were studied. According to the test results, the development and evolution regularity of the interface shear strain for the inner bond section is revealed, and the long-term durability of the geotechnical anchorage bolt under cycle loading is put forward.
Authors: Xiao Zhi Hu, H. Wang
Authors: Heiji Watanabe, Yuu Watanabe, Makoto Harada, Yusuke Kagei, Takashi Kirino, Takuji Hosoi, Takayoshi Shimura, Shuhei Mitani, Yuki Nakano, Takashi Nakamura
Abstract: We propose a treatment combining nitrogen plasma exposure and forming gas annealing (FGA) to improve the electrical properties of SiO2/SiC interfaces. Although conventional FGA at 450°C alone is not effective for reducing interface traps and fixed charges, our combination treatment effectively reduces both even at moderate temperatures. We achieved further improvement by applying our treatment at higher (over 900°C) FGA temperatures, including lower interface state density (Dit) values for both deep and shallow energy levels (1 - 4 x 1011 cm-2eV-1). Considering that nitrogen incorporation promotes hydrogen passivation of interface defects, a possible mechanism for the improved electrical properties is that interface nitridation eliminates carbon clusters or Si-O-C bonds, which leads to the formation of simple Si and C dangling bonds that can be readily terminated by hydrogen. We therefore believe that our treatment is a promising method for improving the performance of SiC-based MOS devices.
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