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Influence of high aluminium content on the mechanical properties of directionally solidified multicrystalline silicon


The purpose of this research is the mechanical characterisation of multicrystalline silicon crystallised from silicon feedstock with a high content of aluminium for photovoltaic applications. The mechanical strength, fracture toughness and elastic modulus were measured at different positions within the multicrystalline silicon block to quantify the impact of the segregation of impurities on these mechanical properties. Aluminium segregated to the top of the block and caused extensive micro-cracking of the silicon matrix due to the thermal mismatch between silicon and the aluminium inclusions. Silicon nitride inclusions reduced the fracture toughness and caused failure by radial cracking in its surroundings due to its thermal mismatch with silicon. However, silicon carbide increased the fracture toughness and elastic modulus of silicon.

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The authors would like to deeply thank M. Kwiatkowska, F. Boldt, F. Haas, P. Häuber, M. Schumann, J. Zielonka and M. Winterhalder from Fraunhofer ISE and W. Fütterer from the TU Bergakademie for their valuable work that made this research possible. This work was supported by the Fraunhofer Society with the project Si-Beacon, the Ministerio de Economía y Competitividad, MAT2009-13979-C03, and the Comunidad de Madrid, S-S2009/MAT-1585-ESTRUMAT2.

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Correspondence to T. Orellana.

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Orellana, T., Tejado, E.M., Funke, C. et al. Influence of high aluminium content on the mechanical properties of directionally solidified multicrystalline silicon. J Mater Sci 49, 4905–4918 (2014).

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  • Fracture Toughness
  • Stress Intensity Factor
  • Silicon Nitride
  • Weibull Modulus
  • Residual Thermal Stress