Papers by Keyword: Dislocation

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Authors: Fujio Abe
Abstract: The effect of fine precipitates, excess dislocations and sub-boundary hardening on creep strain behavior in the transient region has been investigated for tempered martensitic 9%Cr steel at 600 and 650oC. The fine precipitates that form during tempering or during creep decrease the creep rate in the transient region, while excess dislocations produced by cold rolling promote the recovery of dislocations during creep, resulting in higher creep rates. The sub-boundary hardening is enhanced by fine precipitates along lath and block boundaries, which retards the onset of acceleration creep. The movement and annihilation process of dislocations in the transient region is controlled by not only the movement of dislocations in the matrix but also the absorption of dislocations at boundaries. The minimum creep rate is basically determined by the time to minimum creep rate.
Authors: Yoshiji Miyamura, Hirofumi Harada, Karolin Jiptner, Jun Chen, Ronit R. Prakash, Jian Yong Li, Takashi Sekiguchi, Takuto Kojima, Yoshio Ohshita, Atsushi Ogura, Masayuki Fukuzawa, Satoshi Nakano, Bing Gao, Koichi Kakimoto
Abstract: To get the optimized condition and ideal furnace structure, we have performed seed cast growth of mono-crystalline Si by using unidirectional solidification furnace. More than 20 ingots of 10 cm diameter and 10 cm height were grown under different growth conditions. The quality of ingots was characterized by using Fourier transform infrared spectroscopy (FTIR), infrared microscopy, scanning infrared polariscope (SIRP), X-ray topography, etc. We have realized reduction of carbon, residual strain and extended defects, which may contribute the increase of solar cell efficiency.
Authors: R.T. Leonard, Y. Khlebnikov, Adrian R. Powell, C. Basceri, M.F. Brady, I. Khlebnikov, Jason R. Jenny, D.P. Malta, Michael J. Paisley, Valeri F. Tsvetkov, R. Zilli, E. Deyneka, H.McD. Hobgood, Vijay Balakrishna, Calvin H. Carter Jr.
Abstract: Recent advances in PVT c-axis growth process have shown a path for eliminating micropipes in 4HN-SiC, leading to the demonstration of zero micropipe density 100 mm 4HN-SiC wafers. Combined techniques of KOH etching and cross-polarizer inspections were used to confirm the absence of micropipes. Crystal growth studies for 3-inch material with similar processes have demonstrated a 1c screw dislocation median density of 175 cm-2, compared to typical densities of 2x103 to 4x103 cm-2 in current production wafers. These values were obtained through optical scanning analyzer methods and verified by x-ray topography.
Authors: Yu Qiang Gao, Hong Yan Zhang, Yan Min Zong, Huan Huan Wang, Jianqiu Guo, Balaji Raghothamachar, Michael Dudley, Xi Jie Wang
Abstract: 150 mm diameter 4H-SiC boules were grown by the physical vapor transport (PVT) method. Synchrotron white beam X-ray topography (SWBXT) was carried out to investigate the distribution of defects in axial slices cut from the boule. It was found that an increase of dislocations and micropipes was mainly induced by inclusions. After eliminating these inclusions, which were formed in the mid to late stage of the crystal growth, both the screw dislocation density and base plane dislocation density could be decreased down to a magnitude of 102 cm-2, which is comparable to that of high quality 100 mm diameter SiC substrates.
Authors: Kazutoshi Kojima, Hajime Okumura, Satoshi Kuroda, Kazuo Arai, Akihiko Ohi, Hiroyuki Akinaga
Abstract: Homoepitaxial growth was carried out on 4H-SiC on-axis substrate by horizontal hot wall chemical vapor deposition. By using carbon face substrate, specular surface morphology of a wide area of up to 80% of a 2-inch epitaxial wafer was obtained at a low C/Si ratio growth condition of 0.6. The Micropipe in on-axis substrate was indicated to be filled with spiral growth and to be dissociated into screw dislocations during epitaxial growth. It was found that the appearance of basal plane dislocations on the epitaxial layer surface can be prevented by using an on-axis substrate.
Authors: G.R. Canova, Yves Bréchet, L.B. Kubin, Benoit Devincre, Vassilis Pontikis, M. Condat
Authors: Ladislas P. Kubin, Benoit Devincre, G.R. Canova, Yves Bréchet
Authors: Y. Yanagisawa, Tomoaki Hatayama, Hiroshi Yano, Yukiharu Uraoka, Takashi Fuyuki
Abstract: Propagations of dislocations in 4H-SiC were evaluated three-dimensionally by a planar mapping EBIC method with the control of accelerating voltages. Screw dislocation (SD), edge dislocation (ED), and basal plane dislocation (BPD) were clearly observed through the 20nm-thick Ni Schottky contact on SiC. From the analysis of BPD extended on {0001}, the intensity of EBIC signals was proportional to the depth position of defect. In addition, the information of the decomposition and combination for dislocations can be obtained from the fluctuation of EBIC signal along the scanning position.
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