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MI: Fachverband Mikrosonden
MI 3: TEM- and SEM-based Material Analysis
MI 3.5: Vortrag
Montag, 14. März 2011, 16:30–16:45, BEY 81
Indentation-induced dislocations and cracks in GaN bulk crystals — •Ingmar Ratschinski1, Hartmut S. Leipner1, Frank Heyroth1, Wolfgang Fränzel2, and Frank Habel3 — 1Interdisziplinäres Zentrum für Materialwissenschaften, Martin-Luther-Universität Halle-Wittenberg, Heinrich-Damerow-Straße 4, D-06120 Halle, Germany — 2Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 3, D-06120 Halle, Germany — 3Freiberger Compound Materials GmbH, Am Junger-Löwe-Schacht 5, D-09599 Freiberg, Germany
GaN bulk crystals with a density of in-grown dislocations in the magnitude of 106 cm−2 have been deformed at room temperature using a Vickers indenter. The (0001) surface has been indented with loads in the range from 0.02 N to 4.90 N with two different orientations of the indenter. Dislocations and cracks at the indentations were observed by means of optical microscopy, scanning electron microscopy and cathodoluminescence. Dislocations occur at all indentations for the loads used in the investigations. The dislocation arrangement corresponds to the symmetry of the indented surface. Higher loads lead to radial cracks at the corners of the indentations as well as lateral cracks beneath the surface. The crack system is determined predominantly by the symmetry and orientation of the indenter. Geometrical relations have been found between dislocations and cracks.