Safety considerations for high-efficiency crystalline-silicon solar cell fabrication

The features necessary for safe operation of a crystalline-silicon solar cell processing lab are detailed. For comparison, the analogous safety measures that need to be taken in a thin-film solar cell production facility are also noted. The most serious hazard is associated with the storage and use of silane, phosphine, and diborane gases, although it may be possible to avoid them entirely through the use of alternative doping sources. This is in contrast with the case of amorphous silicon, where no substitutes have been used successfully. Even if alternate doping sources cannot be used, costly exhaust-gas processing can be avoided, because the hydrides are consumed in the process. This is again in contrast with the thin-film processes, which require elaborate and expensive exhaust-gas conditioning systems. The vast quantities of toxic and explosive gases required for thin-film processing can be avoided, since the bulk material for these cells is wafered silicon which is already available in large quantities. Hence, it is concluded that the present findings demonstrate the inherently safer nature of crystalline-silicon solar cell processing, and consequently its lower safety-related costs.