Point defect detection and strain mapping in Si single crystal by two-dimensional multiplication moiré method.

Although defect detection is critical for evaluating the manufacturing processes of semiconductor materials and metals, the detection of crystal defects, especially point defects, over a large field of view still faces considerable challenges. Herein, we report on the development of a two-dimensional (2D) multiplication moiré method using digital image processing to simultaneously detect point and line defects in a wide field of view. Defect locations were automatically detected by employing the concept of a hybrid strain, that is, the absolute value of the product of the strain distributions in different principal directions. To demonstrate a typical application of the proposed method, the hybrid strain distribution in a Si single crystal was measured, and point defects were successfully detected by transmission electron microscopy. The effectiveness of the proposed method was experimentally verified based on the enlarged views of atomic structures at several detected defect locations. This method is capable of visualizing defects by magnifying the lattice distortion in situ, which is a good solution to the problem faced by traditional methods in detecting point defects. This study paves the way for the detection of vacancies, interstitial atoms, substitutional atoms, dislocations, slips, and interfaces in various crystal structures and 2D materials.