Sliver solar cell technology: Pushing the material boundaries

One of the primary objectives of the global photovoltaic research community is to effect significant manufacturing cost reductions, either by reducing material and processing costs or by increasing solar cell efficiency. One very promising technology for achieving both of these goals is Sliver technology, which offers potential for a 10- to 20-fold reduction in the consumption of purified silicon, while at the same time achieving very high cell efficiencies by fully exploiting the advantages of mono-crystalline silicon. Sliver solar cells are thin, mono-crystalline silicon solar cells fabricated using a combination of micro-machining techniques and standard silicon device fabrication technologies. Rather than fabricating a single solar cell on the surface of a wafer, many hundreds to several thousand individual Sliver solar cells are fabricated within a single wafer. The dimensions of a Sliver cell depend upon wafer size, wafer thickness, and the micro-machining method employed. Cells typically have a length of 5 - 12cm, a width of 0.5 - 2mm, and a thickness of 20 - 60 micron. 20% efficient Sliver solar cells using standard cell processing methods and a robust processing sequence, have been fabricated at ANU. Current research efforts are directed towards developing and establishing new fabrication techniques to further simplify the fabrication sequence and to improve cell efficiency. This paper presents an overview of Sliver technology. The fabrication method and some key challenges in producing Sliver cells is presented along with the measured performance of cells fabricated in the ANU solar research laboratory.