Size of dislocation patterns induced by Vickers indentation in hydride vapor-phase epitaxy GaN

Abstract

3D dislocation structures induced by Vickers indentation depending on the imprint size are precisely investigated using an alternation of cathodoluminescence and chemical mechanical polishing (CMP), multiphoton excitation photoluminescence, and (scanning) transmission electron microscopy under a load range within a constant Vickers hardness. The dislocation structures are composed of a rosette pattern, a flower pattern, and a triangular area. The flower pattern distribution is dispersive along the z direction. The determined penetration depth of the dislocations by practical CMP is almost the same as the length of the imprint diagonal (d1). The dimensions of the individual patterns in the dislocation structure can be described as multiples of d1. That is, the geometric similarity between the imprint size and the dimensions of the dislocation structure is confirmed. This suggests that the dimensions of the dislocation structures induced under scratch can be estimated by measuring the width of the scratch. This shows that a simple method may be developed to determine the maximum thickness of the affected layer over the entire wafer area and the ability to develop low-cost GaN wafers free of affected layers.