Abstract: | |
In order to reduce the silicon consumption in the production of crystalline silicon solar cells, the improvement of sawing techniques or the use of a kerf-less process are possible solutions. This study focuses on a particular kerf-less technique based on thermally-induced spalling of thin silicon layers joined to aluminum. Via a controlled temperature variation we demonstrate that it is possible to drive an initially sharp crack, introduced by laser, into the silicon substrate and obtain the detachment of ultra-thin silicon layers. A numerical approach based on the finite element method (FEM) and Linear Elastic Fracture Mechanics (LEFM) is herein proposed to compute the Stress Intensity Factors (SIFs) that characterize the stress field at the crack tip and predict crack propagation of an initial notch, depending on the geometry of the specimen and on the boundary conditions. We propose a parametric study to evaluate the dependence of the crack path on the following parameters: (i) the distance between the notch and the aluminum-silicon interface, (ii) the thickness of the stressor (aluminum) layer, and (iii) the applied load. The results for the cooling process here analyzed show that ΔT >43 K and a ratio λ=0.65 between the thickness of the stressor layer and the distance of the initial notch from the interface are suitable values to achieve a steady-state propagation in case of a ratio λ0=0.115 between the in plane thickness of the silicon substrate and the aluminum thickness, a value typically used in applications.
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License of this version: | CC BY-NC-ND 4.0 Unported - https://creativecommons.org/licenses/by-nc-nd/4.0/ |
Publication type: | Article |
Publishing status: | publishedVersion |
Publication date: | 2015 |
Keywords english: | delamination, Finite element method, kerf-less technique, Linear Elastic Fracture Mechanics, silicon, thin film solar cells, Aluminum, Brittle fracture, Computational geometry, Crack propagation, Crack tips, Cracks, Delamination, Failure (mechanical), Fracture, Fracture mechanics, Interface states, Interfaces (materials), Numerical methods, Silicon, Silicon solar cells, Spalling, Stress intensity factors, Stresses, Controlled temperature, Crystalline silicon solar cells, kerf-less technique, Linear elastic fracture mechanics, Modelling and validation, Numerical approaches, Steady-state propagation, Thin film solar cells, Finite element method |
DDC: | 620 | Ingenieurwissenschaften und Maschinenbau |
Controlled keywords(GND): | Konferenzschrift |
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