A LOW-COST METALLIZATION SCHEME FOR DOUBLE-SIDED BURIED CONTACT SILICON SOLAR-CELLS

The buried contact solar cells (BCSC) technology has recently penetrated commercial manufacturing and markets giving performance increases in the vicinity of 30% over previous commercial technologies. However, the development of the new generation of higher efficiency BCSCs with grooves on both surfaces has been greatly retarded by the inability of standard electroless plating solution to simultaneously plate both n-type and p-type silicon. A simple, low cost and effective method of applying an ohmic contact simultaneously to both n-type and p-type silicon surfaces has been developed. The preliminary results for double sided buried contact silicon solar cells utilizing this low cost scheme are also presented. The fill factors of these cells are found to be comparable to cells making use of other metallization schemes using commercially available solutions. This is an indication that a good ohmic contact is formed between the nickel and silicon despite the exclusion of the sensitiser which is commonly believed to initiate the metal plating process. It could therefore be inferred that the activation and sensitising steps are not necessary in solar cell fabrication provided the plating bath temperature is high enough to release the nickel ions for effective metallisation.