58 research outputs found
Short note on parallel illumination in the TEM
No full textShort note on parallel illumination in the TEM
D. Eyidi a, C. Hébert b and P. Schattschneider a, b
a University Service Center for Transmission Electron Microscopy, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria
b Institute for Solid State Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10, A-1040 Wien, Austria
Received 20 September 2005; revised 16 February 2006; accepted 5 April 2006. Available online 5 July 2006.
Abstract
Parallel illumination conditions are required for several experiments in the transmission electron microscope (TEM).
The image rotation induced by the helical trajectory of electrons passing through the magnetic field of the TEM lenses inevitably induces an inclination of the beam relative to the optical axis in the object plane-even for an electron which travels parallel to the optical axis in the far field. This angle (shear angle) is vectorially added to the convergence angle; it depends both on the distance to the optical axis and the magnetic field.
By using a beam tilt compensation method, the minimum shear angle is found to be of the order of 1 mrad for a field of view of 2 μm in a 200 kV TEM. In practice, "parallel illumination" can only be obtained for fields of view <= 1 μm.
Keywords: Image rotation; Convergence angle; Magnetic field; Tilt angle; Helical distortion
PACS classification codes: 41.75.Fr; 61.14.Lj; 07.78; 14.60.C
Line defects in epitaxial silicon films grown at 560°C
No full textLine defects in epitaxial silicon films grown at 560°C
K. Petter a, D. Eyidi b, M. Stöger-Pollach b, I. Sieber a, P. Schubert-Bischoff a, B. Rau a, A.T. Tham c, 1, P. Schattschneider b, S. Gall a, K. Lips a and W. Fuhs a
a Hahn-Meitner-Institut, Kekuléstr. 5, D-12489 Berlin, Germany
b Technische Universität Wien, USTEM, Wiedner Hauptstr. 8-10, A-1040 Wien, Austria
c Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
Available online 27 January 2006.
Abstract
We present an investigation of line defects in epitaxially grown silicon layers using Secco defect etching and transmission electron microscopy (TEM). 1 μm thick layers were deposited onto Si (1 0 0) wafers at a substrate temperature of 560°C electron cyclotron resonance chemical vapour deposition (ECRCVD). Defect etching reveals a variety of etch pits related to extended defects. A detailed analysis of the orientations and shapes of etch pits related to line defects is carried out. Using this information it is then possible to assign different types of etch pits to line defects observed by TEM. The investigations show, that one type of defect are extended dislocations parallel to , while the direction of two other types are as well as , a direction uncommon for line defects in silicon.
Keywords: Silicon; Epitaxy; Defect etching
PACS: 61.72.Ff; 81.15.G
Helium irradiation effects in polycrystalline Si, silica, and single crystal Si
No full textTransmission electron microscopy (TEM) has been used to investigate the effects of room temperature 6 keV helium ion irradiation of a thin (≈55 nm thick) tri-layer consisting of polycrystalline Si, silica, and single-crystal Si. The ion irradiation was carried out in situ within the TEM under conditions where approximately 24% of the incident ions came to rest in the specimen. This paper reports on the comparative development of irradiation-induced defects (primarily helium bubbles) in the polycrystalline Si and single-crystal Si under ion irradiation and provides direct measurement of a radiation-induced increase in the width of the polycrystalline layer and shrinkage of the silica layer. Analysis using TEM and electron energy-loss spectroscopy has led to the hypothesis that these result from helium-bubble-induced swelling of the silicon and radiation-induced viscoelastic flow processes in the silica under the influence of stresses applied by the swollen Si layers. The silicon and silica layers are sputtered as a result of the helium ion irradiation; however, this is estimated to be a relatively minor effect with swelling and stress-related viscoelastic flow being the dominant mechanisms of dimensional change
Electron energy-loss spectroscopy investigations of the electron density in ErMn₂ and ErMn₂D₂ compounds
No full textElectron energy-loss spectroscopy investigations of the electron density in ErMn₂and ErMn₂D₂ compound
Influence of the magnetic field on the wear behavior of a cutting tool during the turning operations
No full textThis study concerns tests carried out without lubrication on a universal lathe to study the influence of the magnetic field on the wear of a cutting tool made of metallic carbide. The tests parameters are: the intensity of the magnetic field (from 0 to 28.5 kA.m-1), the cutting speed (from 6 to 136 m.min-1), the advance speed and the cut depth (pass). Both of the previous parameters are fixed respectively at 0.125 mm.rev-1 and 0.5 mm. The material being cut is made of XC38 steel. The tool wear is evaluated by weighing method (before and after each test). The results showed that the magnetic field has an influence on wear and that there is a critical value (H = 16.5 kA.m-1) for which wear is minimum. Also, the scanning electron microscope (SEM) and optical microscope observations revealed the existence of three types of wear that are: flank wear, crater wear and wear by plastic deformation. Moreover, we concluded that, the increase of the magnetic field modifies the shape and the morphology of chips and rises the contact temperature.</jats:p
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