TY  - JOUR
A1  - Berardone, Irene
A1  - Kajari-Schröder, Sarah
A1  - Niepelt, R
A1  - Hensen, J
A1  - Steckenreiter, V
A1  - Paggi, Marco
SP  - 855
Y1  - 2015///
PB  - Elsevier
EP  - 862
VL  - 77
SN  - 1876-6102
JF  - Energy Procedia
N2  - 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 ?T >43 K and a ratio ?=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 ?0=0.115 between the in plane thickness of the silicon substrate and the aluminum thickness, a value typically used in applications.
KW  - Finite element method; Linear Elastic Fracture Mechanics; kerf-less technique; delamination; silicon; thin film solar cells
UR  - http://www.sciencedirect.com/science/article/pii/S1876610215008899
TI  - Numerical modelling and validation of thermally-induced spalling
ID  - eprints2761
AV  - none
ER  -