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The use of hydrogen as passivator in silicon solar cells is well known. The function of hydrogen is to occupy the dangling bonds in silicon that occur at defects, such as dislocations and grain boundaries. In this study we used the micro-ERDA (Elastic Recoil Detection Analysis) technique to determine the lateral and depth distribution of hydrogen in poly-crystalline silicon solar cell material. To discriminate against atmospheric hydrogen contamination, the solar cells were manufactured with deuterium as passivation. The ability of ERDA, using 4He as primary ions, to discriminate between hydrogen and deuterium signals enabled us to study the location of both passivation deuterium and atmospheric hydrogen. Within the spatial resolution of the technique, the distribution of deuterium was found not to peak at the grain boundaries, but to be homogeneously distributed in the grains, although some grains did tend to have higher concentrations of deuterium than others. |
