Attempt to correlate dislocations network and distribution to macroscale plane rotations in <001> cast-mono ingots

Abstract

This work aims to contribute to the understanding of the mechanisms behind electrically active crystalline defect formation in cast-mono (cm) ingots grown along the <001> axis. Both the spatial distributions of background dislocations in the cellular dislocation array and the driving force for dislocation multiplication in the sub-grains are not perfectly understood. Macroscale length crystal rotations are here characterized by the (θ/2θ) X-ray diffraction (XRD) method at different ingot heights and along two perpendicular sample axes. XRD measurements show the presence of crystal rotations in the large single grain domain. Two orthogonal misorientations components are found to evolve linearly along each sample axis forming plane orientation gradients up to (0.05 ± 0.02) degree/cm extending over 12 cm inside the cast-mono grain. (001) crystal structure deformation are also analysed by rocking curve imaging (RCI) using synchrotron radiation on wafers of a neighboring brick. First, results confirm the presence of the plane orientation gradient measured by XRD and its order of magnitude. Second, RCI results demonstrate that the plane orientation gradient is associated to the cellular dislocation network. Therefore, these results strongly suggest that background dislocations network of a cellular form can create an organized orientation gradient at large distance within the ingot. The involvement of the characterized orientation gradients in the formation and extension of electrically active SGBs in cast-mono ingots is discussed. • Crystal structure deformation measurements of cm-Si ingots. • Evidence of the presence of {001} planes orientation gradients. • Plane orientation gradients almost constant along the sample axes. • Orientation gradients increase with the ingot height. • Orientation gradients associated to the cellular network of dislocations.