Synchrotron white beam topography studies of screw dislocations in 6H-SiC single crystals

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[唯一标识符]:CDSITC.AEROSPACE.A96-21859
[文献来源]:美国航空航天数据库(aerospace)
[资源原始索取号]:A1996-21859; Reference AN: A96-21859
[标题]:Synchrotron white beam topography studies of screw dislocations in 6H-SiC single crystals
[作者]:Wang S; Dudley M; Carter C H Jr; Tsvetkov V F; Fazi C
[书名]:IN: Applications of synchrotron radiation techniques to materials science II; Proceedings of the Symposium, Boston, MA, Nov. 17-Dec. 2, 1994 (A96-21851 04-23), Pittsburgh, PA, Materials Research Society (MRS Symposium Proceedings. Vol. 375), 1995, p. 281-
[文摘]:Synchrotron white beam X-ray topography, along with optical microscopy and SEM, has been used to characterize structural defects which are potentially detrimental to device performance in PVT 6H-SiC single crystals. Line defects running along the 0001-line axis, known as 'micropipes', were studied extensively. Detailed analysis of topographic image contrast associated with 'micropipes', based on the kinematical theory of XRD, established that the 'micropipes' are screw dislocations with large Burgers vectors. (Author)
[关键词]:SYNCHROTRON RADIATION; TOPOGRAPHY ; CRYSTAL DISLOCATIONS; SILICON CARBIDES; SINGLE CRYSTALS; CRYSTAL GROWTH; X RAY DIFFRACTION; BURGER EQUATION; VAPOR DEPOSITION; MICROCRACKS ; MICROSTRUCTURE
[出版年份]:1995
[专业领域]:SOLID STATE PHYSICS
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[唯一标识符]:CDSITC.AEROSPACE.A98-27825
[文献来源]:美国航空航天数据库(aerospace)
[资源原始索取号]:A1998-27825; Reference AN: A98-27825
[标题]:Using the Oklahoma Mesonetwork to develop and test a practical sampling error statistic for meteorological time series
[作者]:Morrissey Mark L; Greene J S
[来源]:Journal-of-Geophysical-Research. 1998 April; vol. 103, no. D8: 8979-8984
[文摘]:The error variance based upon sampling in time, which accounts for the missing values in meteorological and climatological averages in a time series, is developed. This statistic can be substituted for those already developed which assume a random or uniform distribution of discrete measurements in time. The statistic is unique from other error statistics developments published in the meteorological literature in that it relates the error variance of local time averages (e.g., monthly) around the local population averages rather than the long-term mean and allows for missing data or unevenly sampled data. A comparison of theoretical values with those derived from an autoregressive time series and a nonstationary reference data set indicate that the statistic can be appropriately used to provide researchers with a quantitative measure of the usefulness of their data. (Author)
[关键词]:VARIANCE ; TIME SERIES ANALYSIS; ERROR ANALYSIS; METEOROLOGY ; CLIMATOLOGY ; METHODOLOGY ; AUTOREGRESSIVE PROCESSES; DATA ACQUISITION
[出版年份]:1998
[专业领域]:METEOROLOGY AND CLIMATOLOGY
[唯一标识符]:CDSITC.AEROSPACE.A95-25289
[文献来源]:美国航空航天数据库(aerospace)
[资源原始索取号]:A1995-25289; Reference AN: A95-25289
[标题]:Diffractive optical reflection elements for the infrared based on artificial dielectrics
[作者]:Kipfer P; Collischon M ; Haidner H; Schwider J
[书名]:IN: Infrared technology XX; Proceedings of the Meeting, San Diego, CA, July 25-28, 1994 (A95-25226 06-35), Bellingham, WA, Society of Photo-Optical Instrumentation Engineers (SPIE Proceedings. Vol. 2269), 1994, p. 791-799
[文摘]:A novel design for imitating continuous phase profiles by binary subwavelength structures is presented. The continuous phase profiles, in general phase structures, are required to achieve high diffraction efficiencies. The working principle has recently been shown for regular gratings like beam deflectors or polarizing beam-splitters. The subjects of this paper are the transferring of this principle to nonstrictly-periodic gratings (such as lenses) and to avoid strong polarization dependence by using 2D modulated subwavelength structures. A further event of this paper is to examine the origin of this effect. Two possibilities are open: the resonance effect, because the structure size is nearly as big as the wavelength, and the averaging effect, which should be responsible if the light cannot resolve the small structures. (Author)
[关键词]:OPTICAL REFLECTION; BEAM SPLITTERS; DIELECTRICS ; OPTICAL WAVEGUIDES; INFRARED INSTRUMENTS; GRATINGS SPECTRA; BIREFRINGENCE ; FRESNEL REGION
[出版年份]:1994
[专业领域]:OPTICS