Shock-induced brittle cracking in HVPE-GaN processed by laser lift-off techniques

作者：Xujun Su, Kun Xu, Yi‐Shi Xu, Gaoyuan Ren, J. C. Zhang, J. F. Wang, Hua Yang · 发表于：Journal of Physics D Applied Physics · 年份：2013 · DOI：10.1088/0022-3727/46/20/205103 · 被引用次数：29 · 研究领域：Semiconductor materials and devices、Diamond and Carbon-based Materials Research、Integrated Circuits and Semiconductor Failure Analysis

A study on brittle cracking in GaN films processed by laser lift-off is presented. Two kinds of cracks were found in the N-polar face of GaN after the laser lift-off process, namely perpendicular cracks along the {1 −1 0 0} planes and lateral cracks along the (0 0 0 −1) plane, respectively. Single-shot laser damage is studied to understand the cracking mechanism. The damage morphology indicates that the GaN material on the edge of the laser ablation area experiences three loading modes: shear stress P S , longitudinal compressive stress P L and transverse tensile stress P T . Under shock P L , lateral cracks likely appear and extend from the illuminated region along the interface in mode I. Furthermore, two different kinds of perpendicular cracks were found, namely shear cracks (PC I) and deflection cracks (PC II). A strong P S gives rise to PC I while a cooperative action of P L and P T results in PC II. In addition, there exist a critical effective spot size d Pth and a critical ratio of the laser spot size d L to the effective spot size d P , when cracks occur over them.