Crystallographic structure effects on the electrical properties of polysilicon solar cells

Solar cells were fabricated on a section of large-grained cast polysilicon material, which had undergone a detailed structural analysis, in order to relate directly the electrical and structural characteristics of the grains and grain boundary regions. Diffusion characteristics were studied by angle lapping experiments, X-ray topographic pictures of the polysilicon grain structure were matched with optical scanning photoresponse measurements of the same region for which angle lapping results were obtained to also show directly the effect of the microstructural features on the photoresponse of the solar cell. A model is presented of these observations which gives emphasis to the individual effect of particular grain boundaries on possibly reducing the photoresponse of a cell according to the dislocation content required to account for a portion of the misorientation across adjacent grains.