Antimony-doped dendritic web silicon solar cells

Antimony has been explored as a dopant in dendritic web silicon in an attempt to achieve uniformity in resistivity through the thickness and along the length of the web ribbon, and to inhibit the formation of deleterious oxide precipitates. The desired uniformity was achieved, making possible the fabrication of efficient, n-base bifacial cells using high-resistivity (10-100 Omega -cm) web and the growth of web over long periods of time (five days) without replenishing the dopant in the melt. Antimony-doped web cells were fabricated with measured hole diffusion lengths up to 333 mu m and hole lifetimes up to 66 mu s. Such diffusion lengths significantly exceed the typical web thickness (100-125 mu m), thereby satisfying an important requirement for high-efficiency cells. Web cell efficiencies up to 16.7% were measured. It is concluded that the superior electrical properties obtained for some cells may be associated more with appropriate growth conditions (few dislocations) than with the action of antimony in inhibiting the formation of SiO_x precipitates.