Spatially resolved observation of charge transfer across single grain boundaries in YBaCuO films

It has long been known that the addition of Cu to Al interconnects improves the resistance to electromigration failure. It is generally accepted that this improvement is the result of Cu segregation to Al grain boundaries. The exact mechanism by which segregated Cu increases service lifetime is not understood, although it has been suggested that the formation of thin layers of θ-CuA12 (or some metastable substoichiometric precursor, θ’ or θ”) at the boundaries may be necessary. This paper reports measurements of the local electronic structure of Cu atoms segregated to Al grain boundaries using spatially resolved EELS in a UHV STEM. It is shown that segregated Cu exists in a chemical environment similar to that of Cu atoms in bulk θ-phase precipitates.Films of 100 nm thickness and nominal composition Al-2.5wt%Cu were deposited by sputtering from alloy targets onto NaCl substrates. The samples were solution heat treated at 748K for 30 min and aged at 523K for 4 h to promote equilibrium grain boundary segregation. EELS measurements were made using a Gatan 666 PEELS spectrometer interfaced to a VG HB501 STEM operating at 100 keV. The probe size was estimated to be 1 nm FWHM. Grain boundaries with the narrowest projected width were chosen for analysis. EDX measurements of Cu segregation were made using a VG HB603 STEM.

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Grain Boundary Atomic Structures in SrTiO3 and BaTiO3

Materials Science Forum ◽

10.4028/www.scientific.net/msf.558-559.851 ◽

2007 ◽

Vol 558-559 ◽

pp. 851-856 ◽

Cited By ~ 1

Author(s):

Takahisa Yamamoto ◽

Teruyasu Mizoguchi ◽

S.Y. Choi ◽

Yukio Sato ◽

Naoya Shibata ◽

...

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Annealing Temperature ◽

Unit Length ◽

Rate Dependency ◽

Atomic Structures ◽

Current Voltage ◽

Single Grain ◽

Current Voltage Characteristics ◽

Theoretical Results

SrTiO3 bicrystals with various types of grain boundaries were prepared by joining two single crystals at high temperature. By using the bicrystals, we examined their current-voltage characteristics across single grain boundaries from a viewpoint of point defect segregation in the vicinity of the grain boundaries. Current-voltage property in SrTiO3 bicrystals was confirmed to show a cooling rate dependency from annealing temperature, indicating that cation vacancies accumulate due to grain boundary oxidation. The theoretical results obtained by ab-initio calculation clearly showed that the formation energy of Sr vacancies is the lowest comparing with Ti and O vacancies in oxidized atomosphere. The formation of a double Schottky barrier (DSB) in n-type SrTiO3 is considered to be closely related to the accumulation of the charged Sr vacancies. Meanwhile, by using three types of low angle boundaries, the excess charges related to one grain boundary dislocation par unit length was estimated. In this study, we summarized our results obtained in our group.

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Single-Grain Boundaries in PTC Resistors

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.1996.tb08538.x ◽

1996 ◽

Vol 79 (4) ◽

pp. 997-1001 ◽

Cited By ~ 53

Author(s):

Makoto Kuwabara ◽

Ken-ichiro Morimo ◽

Tatsuya Matsunaga

Keyword(s):

Grain Boundaries ◽

Single Grain

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Pressure-Induced Increase inJcacross Single Grain Boundaries in YBa2Cu3Ox

Journal of the Physical Society of Japan ◽

10.1143/jpsjs.76sa.118 ◽

2007 ◽

Vol 76 (Suppl.A) ◽

pp. 118-119

Author(s):

Takahiro Tomita ◽

James S. Schilling ◽

Lihura Chen ◽

Boyd W. Veal ◽

Helmut Claus

Keyword(s):

Grain Boundaries ◽

Single Grain

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Chemistry of grain boundaries in calcia doped silicon nitride studied by spatially resolved electron energy-loss spectroscopy

Analytica Chimica Acta ◽

10.1016/0003-2670(94)00058-1 ◽

1994 ◽

Vol 297 (1-2) ◽

pp. 97-108 ◽

Cited By ~ 23

Author(s):

John Bruley ◽

I. Tanaka ◽

H.-J. Kleebe ◽

M. Rühle

Keyword(s):

Silicon Nitride ◽

Energy Loss ◽

Grain Boundaries ◽

Electron Energy ◽

Electron Energy Loss Spectroscopy ◽

Spatially Resolved ◽

Doped Silicon ◽

Electron Energy Loss

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Location Control of Laterally Columnar Si Grains by Dual-Beam Excimer-Laser Melting of Si Thin-Film

MRS Proceedings ◽

10.1557/proc-621-q9.4.1 ◽

2000 ◽

Vol 621 ◽

Cited By ~ 7

Author(s):

Ryoichi Ishihara

Keyword(s):

Thin Film ◽

Grain Boundary ◽

Heat Source ◽

Grain Boundaries ◽

Excimer Laser ◽

Laser Melting ◽

Dual Beam ◽

Single Grain ◽

Free Area ◽

Si Thin Film

ABSTRACTThe offset of the underlying TiW is introduced in the island of Si, SiO2 and TiW on glass. During the dual-beam excimer-irradiation to the Si and the TiW, the offset in TiW acts as an extra heat source, which melts completely the Si film near the edge, whereas the Si inside is partially melted. The laterally columnar Si grains with a length of 3.2 μm were grown from the inside of the island towards the edge. By changing the shape of the edge, the direction of the solidification of the grain was successfully controlled in such a way that the all grain-boundaries are directed towards the edge and a single grain expands. The grain-boundary-free area as large as 4 μm × 3 μm was obtained at a predetermined position of glass.

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