Defect clusters in multicrystalline silicon: Their nature and influence on the solar cell performance

This paper presents theoretical and experimental results of our studies to determine the performance limitations set by defect clusters (DCs) in multicrystalline silicon (mc-Si) solar cells. DCs in mc-Si wafers are manifested as spatially localized, large regions of high dislocation density, around grains of certain preferred orientations. The presence of DCs strongly influences material properties and cell performance. The objective of our comprehensive study is to understand their nature, influence on cell performance, and to assess the performance improvement that can be realized if the influence of DCs can be eliminated. The effect of grain orientation on the defect density is also investigated. Finally, we explore possibilities of eliminating the formation of DCs during crystal growth or treating them during cell processing to minimize their electronic influence.