Dislocation clusters in multicrystalline silicon were known to be detrimental for photovoltaic cell efficiency. They reduced minority carrier lifetime and were able to build shunts. To get control of them was one of the main purposes of recent developments in crystal growth. For reducing dislocation generation and multiplication there were several issues to focus on during silicon block casting like crystallization condition, grain structure evolution, history of temperature field and phase boundary shape. Different industrial standard ingots were investigated by optical photography. It was shown, that dislocation cluster reduction could be achieved by using suitable conditions during ingot growth.

Control of Dislocation Cluster Formation and Development in Silicon Block Casting. D.Oriwol, M.Hollatz, M.Reinecke: Energy Procedia, 2012, 27, 66-9