Cracks and dislocations at Vickers, Berkovich and cube corner indentations in (0001) GaN single crystals

Abstract

(0001) GaN single crystals having a thickness of 3.4 mm and a density of in‐grown dislocations of 3.5 x 106 cm‐2 have been deformed at room temperature using a cube corner, a Berkovich and a Vickers indenter, respectively. Cube corner indentations were performed in a scanning electron microscope in order to observe the deformation in situ. Subsequently, cracks and dislocations at the indentations were investigated by means of optical microscopy, scanning electron microscopy in secondary electron contrast and cathodoluminescence imaging. The arrangement of dislocations is determined by the symmetry of the indented surface. In contrast, the formation of cracks depends on both the shape and the orientation of the indenter. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Deformation and fracture in (0001) and (10-10) GaN single crystals

“…The majority of studies on mechanical properties concern GaN thin film, with limited number of investigations of c-plane GaN single crystals describing separately either crack formation at higher loads or dislocations and mechanical properties [14][15][16][17][18]. Nonpolar orientations for GaN thick films or single crystals have received less attention [19,20], while there has been a recent publication that studies the main dislocation slip system in bulk GaN [21].…”