Our analyses show that defect clusters can lower the efficiency of multicrystalline silicon (mc-Si) solar cells by 2 to 4 absolute percentage points. This large loss can be recovered if impurities precipitated at the defect cluster sites can be gettered. We describe a new technique for gettering precipitated impurities.

Multicrystalline silicon wafers used for solar cells exhibit defect clusters--localized crystal defects in and near grains of some specific orientations. Defect clusters are also dominant sites for impurity precipitation, and they remain ungettered and unpassivated through the solar cell processing. This paper describes characteristics of defect clusters, and shows, through theory and experiment, that defect clusters typically lower cell efficiency by 3 to 4 absolute percentage points. To recover this efficiency loss, it is necessary to getter precipitated impurities.

This paper presents a combination of numerical and experimental methods used to characterize defect clusters in multicrystalline silicon solar cells.

Containing over 200 papers, this volume contains the proceedings of two symposia in the E-MRS series. Part I presents a state of the art review of the topic - Carbon, Hydrogen, Nitrogen and Oxygen in Silicon and in Other Elemental Semiconductors. There was strong representation from the industrial laboratories, illustrating that the topic is highly relevant for the semiconductor industry. The second part of the volume deals with a topic which is undergoing a process of convergence with two concerns that are more particularly application oriented. Firstly, the advanced instrumentation which, through the use of atomic force and tunnel microscopies, high resolution electron microscopy and other high precision analysis instruments, now allows for direct access to atomic mechanisms. Secondly, the technological development which in all areas of applications, particularly in the field of microelectronics and microsystems, requires as a result of the miniaturisation race, a precise mastery of the microscopic mechanisms.