Raman Study of Multicrystalline Silicon Wafers Produced by the RST Process

A. Tejeroa, E. Tupinb, M.A. Gonzáleza, O. Martíneza, J. Jiméneza, C. Belouetb and C. Baillisc aGdS-Optronlab, Dpto. Física Materia Condensada, Parque Científico Univ. de Valladolid, 47011 Valladolid, Spain bSolarforce, 1 rue du Dauphin, 38300 Bourgoin-Jallieu, France cEC2-Modélisation, 66 bd Niels Bohr CS 52132, 69603 Villeurbanne, France

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In the silicon ribbon on a sacrificial template process silicon is deposited on both sides of a carbon ribbon, thus forming a Si/carbon/Si trilayer. The fast cooling of the ribbon in large temperature gradients generates stresses that are detrimental to both the electrical performance and the mechanical behaviour of the wafers. The assessment of the stresses is crucial for the setting-up of thermal treatments allowing for the stress relaxation of the wafers, prior to the cell fabrication. We present an analysis of the stress in the as-grown trilayer by a simulation of the thermomechanical behaviour of the cooling ribbon. Experimental measurements of the stress in as-grown and annealed trilayers are also presented. The results permit to establish the conditions for optimized growth and annealing.

DOI: 10.12693/APhysPolA.125.1006 PACS numbers: 78.30.Am, 61.72.Ff, 88.40.jj