Mikio Deguchi

Prospect of the high efficiency for the VEST (via-hole etching for the separation of thin films) cell

The optimum design of the via-holes for the VEST cell (polycrystalline Si solar cell) was studied. Using a simple model, fill factors of the VEST cell were calculated. As for the via-hole distribution pattern, a square grid pattern was found to be most suitable from the view points of the cell performance and the ease of electrode design. It was found that a fill factor large enough (>0.79) for high efficiency can be obtained. A fabricated test cell showed the efficiency of 14.4%. Further Improvement (efficiency over 18%) is possibly expected.

Characterization of thickness dependence on defect density and hydrogen passivation for thin film polycrystalline silicon solar cells

Thickness dependence on defect density and hydrogen passivation for thin film polycrystalline silicon solar cells fabricated by the zone-melting recrystallization (ZMR) technique are experimentally investigated. We confirmed that thinning of the active layer is available for increasing Voc for the cells with relatively high defect density (1/spl times/10/sup 6/-1/spl times/10/sup 7/ cm/sup -2/). At the same time, it was clarified that the effectiveness of hydrogen passivation is strongly dependent on the total amount of 3-dimensionally distributed defect in the active layer. Light-induced degradation phenomenon of hydrogen passivated cells was also investigated under the conditions of AM1.5, 125 mW/cm/sup 2/, and 48/spl deg/C. Significant degradation was not observed over 300 hours such as in hydrogenated amorphous silicon solar cells.

Large grain thin film polycrystalline silicon solar cells using zone melting recrystallization

Large-grain polycrystalline silicon thin films have been successfully obtained using the zone melting recrystallization (ZMR) technique. The grain size extended from the order of millimeters to centimeters along the scanning direction without seeding. Film thickness was 30 mu m. Solar cells fabricated using these films showed efficiency of several percent. EBIC measurement revealed that the recrystallized film contained many defects which limited the efficiency.<<ETX>>

Formation of PN junction with hydrogenated nicrocrystalline silicon

The pn junction solar cells consisting of p-type hydrogenated microcrystalline silicon (p- mu c-Si:H) and n-type single-crystalline silicon (n-c-Si) or cast polycrystalline silicon (n-cast-Si) were investigated. By using a thin p- mu c-Si:H layer and inserting an oxide layer between the p- mu c-Si:H and the n-c-Si or n-cast-Si, efficiencies as high as 14.27% for a p- mu c-Si:H/n-c-Si cell and 13. 19% for a p- mu c-Si:H/n-cast-Si cell were obtained. It was found that the interface oxide layer effectively improves the stability of a p- mu c-Si:H/n-cast-Si cell.<<ETX>>