Self-Doping Contacts and Associated Silicon Solar Cell Structures
Meier, D. L.
Davis, H. P.
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Contacts to <111> Si which are self-doping and self-aligning were investigated. Such contacts are applicable both to conventional cell structures as selective emitters and to more demanding structures such as interdigitated back contact cells. Emphasis was placed on alloyed contacts of AI for providing a self-doping p-type contact and of Ag-Sb for a self-doping n-type contact. Alloying at 900°C of 1.1% (wt.) Sb in Ag doped Si to a value of 2 x 10 (18) Sb/cm(3), suggesting a 5% (wt.) Sb is needed for ohmic contact. An AI alloy p-n junction was found to be suitable for a solar cell if placed at the back of the cell, with 13.2% efficiency and good IQE demonstrated for a fully screen-printed dendritic web cell. A prototype interdigitated back contact cell was fabricated by screen printing (AI and Ag) with tight alignment (100 11m lines and spaces) on a dendritic web substrate with an efficiency of 10.4%.