X-ray determination of stresses distribution in a coarse grained silicon billet

摘要

The present study concerns residual stresses analysis in polycrystalline solar silicon materials, which is continuously cast in a cold crucible. The observation of cracks and a modeling of thermal stresses suggest us that stresses in the center region are tensile and the ones in the peripheral region are compressive. X-ray measurement of stresses would be an experimental proof of the observations and an evaluation of the stresses levels. Unfortunately, the obtained material exhibits coarse grains with the size of up to one millimeter. In this case, where only a few crystals are irradiated by the incident X-ray beam, the classical sin~2 PSI method is no longer valid. A specific analysis must be carried out. The results are of good accuracy comparing the low stress levels observed. The measured stress distribution on a radius of the billet is not always in good agreement with the analytical calculus.