Shunt types in crystalline silicon solar cells

Nine different types of shunt have been found in state‐of‐the‐art mono‐ and multicrystalline solar cells by lock‐in thermography and identified by SEM investigation (including EBIC), TEM and EDX. These shunts differ by the type of their I–V characteristics (linear or nonlinear) and by their physical origin. Six shunt types are process‐induced, and three are caused by grown‐in defects of the material. The most important process‐induced shunts are residues of the emitter at the edge of the cells, cracks, recombination sites at the cell edge, Schottky‐type shunts below grid lines, scratches, and aluminum particles at the surface. The material‐induced shunts are strong recombination sites at grown‐in defects (e.g., metal‐decorated small‐angle grain boundaries), grown‐in macroscopic Si3N4 inclusions, and inversion layers caused by microscopic SiC precipitates on grain boundaries crossing the wafer. Copyright © 2004 John Wiley & Sons, Ltd.