Observatorio de I+D+i UPM

Memorias de investigación
Research Publications in journals:
How do Impurity Inclusions Influence the Mechanical Properties of Multicrystalline Silicon?
Year:2015
Research Areas
  • Engineering
Information
Abstract
The purpose of this research is to characterise the mechanical properties of multicrystalline silicon for photovoltaic applications that was crystallised from silicon feedstock with a high content of several types of impurities. The mechanical strength, fracture toughness and elastic modulus were measured at different positions within a multicrystalline silicon block to quantify the effect of impurity segregation on these mechanical properties. The microstructure and fracture surfaces of the samples was exhaustively analysed with a scanning electron microscope in order to correlate the values of mechanical properties with material microstructure. Fracture stresses values were treated statistically via the Weibull statistics. The results of this research show that metals segregate to the top of the block, produce moderate microcracking and introduce high thermal stresses. Silicon oxide is produced at the bottom part of the silicon block, and its presence significantly reduces the mechanical strength and fracture toughness of multicrystalline silicon due to both thermal and elastic mismatch between silicon and the silicon oxide inclusions. Silicon carbide inclusions from the upper parts of the block increase the fracture toughness and elastic modulus of multicrystalline silicon. Additionally, the mechanical strength of multicrystalline silicon can increase when the radius of the silicon carbide inclusions is smaller than ~10 µm. The most damaging type of impurity inclusion for the multicrystalline silicon block studied in this work was amorphous silicon oxide. The oriented precipitation of silicon oxide at grain and twin boundaries eases the formation of radial cracks between inclusions and decreases significatively the mechanical strength of multicrystalline silicon. The second most influencing type of impurity inclusions were metals like aluminium and copper, that cause spontaneous microcracking in their surroundings after the crystallisation process, therefore reducing the mechanical response of multicrystalline silicon. Therefore, solar cell producers should pay attention to the content of metals and oxygen within the silicon feedstock in order to produce solar cells with reliable mechanical properties.
International
Si
JCR
No
Title
International Journal of Metallurgical & Materials Engineering
ISBN
2455-2372
Impact factor JCR
Impact info
Volume
1
Journal number
101
From page
1
To page
11
Month
SIN MES
Ranking
Participants
  • Autor: T. Orellana (1 Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110 Freiburg, Germany)
  • Autor: Elena Maria Tejado Garrido (UPM)
  • : C. Funke (1 Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110 Freiburg, Germany)
  • Autor: W. Fütterer (Institute for Experimental Physics, TU Bergakademie Freiberg, Leipziger Strasse 23, D-09599 Freiberg, Germany)
  • Autor: S. Riepe (Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110 Freiburg, Germany)
  • Autor: H.J. Moller (Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110 Freiburg, Germany)
  • Autor: Jose Ignacio Pastor Cańo (UPM)
Research Group, Departaments and Institutes related
  • Creador: Grupo de Investigación: Materiales Estructurales Avanzados y Nanomateriales
  • Departamento: Ciencia de Materiales
S2i 2021 Observatorio de investigación @ UPM con la colaboración del Consejo Social UPM
Cofinanciación del MINECO en el marco del Programa INNCIDE 2011 (OTR-2011-0236)
Cofinanciación del MINECO en el marco del Programa INNPACTO (IPT-020000-2010-22)