High efficiency pert cells on N-type silicon substrates

High minority carrier lifetimes of a few milliseconds have been demonstrated both on CZ and FZ n-type silicon substrates. It is particularly interesting that the phosphorus doped n-type CZ wafers give minority carrier lifetimes nearly as high as those from the best p-type FZ silicon materials. This gives a good potential for very high performance on n-type CZ substrates. 21.1% and 21.9% efficiencies are reported for PERT (passivated emitter, rear totally-diffused) cells fabricated on these n-type mono-crystalline CZ and FZ silicon substrates, respectively. High open-circuit voltages approaching 700 mV have been demonstrated by these cells. Unfortunately, a non-uniform emitter saturation current has caused low fill factors for these cells, which will be investigated in future research.