Skip to Main content Skip to Navigation
Theses

On the fracture of solar grade crystalline silicon wafer

Abstract : The profitability of silicon solar cells is a critical point for the PV market and it requires improved electrical performance, lower wafer production costs and enhancing reliability and durability of the cells. Innovative processes are emerging that provide thinner wafers with less raw material loss. But the induced crystallinity and distribution of defects compared to the classical wafers are unclear. It is therefore necessary to develop methods of microstructural and mechanical characterization to assess the rigidity and mechanical strength of these materials. In this work, 4-point bending tests were performed under quasi-static loading. This allowed to conduct both the stiffness estimation and the rupture study. A high speed camera was set up in order to track the fracture process thanks to a 45° tilted mirror. Fractographic analysis were performed using confocal optical microscope, scanning electron microscope and atomic force microscope. Electron Back-Scatter Diffraction and Laue X-Ray diffraction were used to explore the relationship between the microstructural grains orientations/textures of our material and the observed mechanical behavior. Jointly, finite element modeling and simulations were carried out to provide auxiliary characterization tools and help to understand the involved fracture mechanism. Thanks to the experiment-simulation coupled method, we have assessed accurately the rigidity of silicon wafers stemming from different manufacturing processes. A fracture origin identification strategy has been proposed combining high speed imaging and post-mortem fractography. Fracture investigations on silicon single crystals have highlighted the deflection free (110) cleavage path, the high initial crack velocity, the velocity dependent crack front shape and the onset of front waves in high velocity crack propagation. The investigations on the fracture of multi-crystalline wafers demonstrate a systematic transgranular cracking. Furthermore, thanks to twin multi-crystalline silicon plates, we have addressed the crack path reproducibility. A special attention has been paid to the nature of the cleavage planes and the grain boundaries barrier effect. Finally, based on these observations, an extended finite element model (XFEM) has been carried out which fairly reproduces the experimental crack path.
Complete list of metadatas

Cited literature [174 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-02004451
Contributor : Abes Star :  Contact
Submitted on : Friday, February 1, 2019 - 5:43:36 PM
Last modification on : Wednesday, July 8, 2020 - 12:42:36 PM
Long-term archiving on: : Friday, May 3, 2019 - 1:27:58 AM

File

these.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02004451, version 1

Citation

Lv Zhao. On the fracture of solar grade crystalline silicon wafer. Mechanics [physics.med-ph]. Université de Lyon, 2016. English. ⟨NNT : 2016LYSEI134⟩. ⟨tel-02004451⟩

Share

Metrics

Record views

140

Files downloads

41