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MI: Fachverband Mikrosonden

MI 4: Analytische Elektronenmikroskopie

MI 4.3: Vortrag

Montag, 11. März 2013, 16:15–16:30, H5

Generation and propagation of dislocations and cracks in GaN single crystals — •Ingmar Ratschinski¹, Hartmut S. Leipner¹, Wolfgang Fränzel², Gunnar Leibiger³, Frank Habel³, William Mook⁴, and Johann Michler⁴ — ¹Interdisziplinäres Zentrum für Materialwissenschaften, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany — ²Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany — ³Freiberger Compound Materials GmbH, 09599 Freiberg, Germany — ⁴Laboratory for Mechanics of Materials and Nanostructures, EMPA Materials Science & Technology 3602 Thun, Switzerland

(0001) GaN single crystals have been deformed at room temperature using different indenter types (Vickers, Berkovich, cube corner) in a load range from 5 mN to 4.9 N. The investigations range from the generation of dislocations at the pop-in event to the formation and propagation of radial and lateral cracks. Dislocations and cracks at the indentations were investigated by optical microscopy as well as scanning electron microscopy in secondary electron contrast and by cathodoluminescence (CL). The dislocation arrangement conforms to the symmetry of the indented surface, whereas the crack formation depends on the shape and the orientation of the indenter. Furthermore, the propagation of dislocations in the strain field of indentations was analyzed by heating and subsequent CL imaging at seven temperature levels up to 1000 °C.