Title:	Influence of an Active Crystal Cooling Device on the Shape of the Phase Boundary in Mono Ingots Grown by the Czochralski Technique
Author(s):	F. Mosel, A.V. Denisov, K. Hess, B. Klipp, N. Sennova, C. Kranert, M. Trempa, C. Reimann, J. Friedrich
Keywords:	Interface(s), Melting, Czochralski Process, Shape, Crystal Cooling
Topic:	Silicon Materials and Cells
Subtopic:	Feedstock, Crystallisation, Wafering, Defect Engineering
Event:	38th European Photovoltaic Solar Energy Conference and Exhibition
Session:	2DV.4.3
Pages:	339 - 346
ISBN:	3-936338-78-7
Paper DOI:	10.4229/EUPVSEC20212021-2DV.4.3
Price:	0,00 EUR
Document(s):	paper, poster

Abstract/Summary:

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In Cz-Si the shape of the crystallization front, which is essentially controlled by the interaction of the various convection phenomena, determines the radial distribution of the crystal properties and is the subject of numerous publications. In our former investigations [1] on the limits of the pull speed in the Czochralski process, we were able to determine a clear influence of an active crystal cooling on the extent of the deflection of the phase boundary in the growing crystal. In order to investigate the influence of the crystal cooling element on the shape of the interface in more detail, two different series of crystal growth experiments were carried out and interpreted with 2D numerical simulations. For this purpose the shapes of the phase boundaries of the grown crystals were made visible by means of LPS measurements and compared with the calculated interface shapes. In one of the two series, the influence of a certain crystal cooling element in connection with the growth configuration was investigated. In the other series, the influence of different crystal cooling elements on the phase boundary was examined. Based on the heat flux balance at the crystallization front, the essential parameters for stable crystal growth conditions were evaluated. For all experiments performed, the cooling rate of the growing crystal in its growth environment were calculated from the point of view of the distribution of intrinsic defects.