20 N-PERT SOLAR DEVICE IN ONLY 7 STEPS: THE SOLENNA(3) CONCEPT

摘要

Bifacial solar cell n-PERT concept involves boron and phosphorus doped regions requiring both proper surface passivation. In order to reduce n-PERT technology related {EUR}/W, one way considered is to simplify the cell process-flow. In order to do so, we developed passivating/anti-reflective/doping SiO_xN_y:B and SiN_x:P layers. The co-anneal of these multifunctional layers allows for emitter & BSF simultaneous formation, subsequent doped regions passivation and provides in the same time good optical properties. We present our ultimately simplified "SOLENNA_(3)" technology, involving only 7 processing steps. Furthermore, the influence of the wafers initial properties (P and O_i concentrations, Thermal History Index) on the performances of the SOLENNA_(3) cells is studied. By further optimization of our front SiO_xN_y:B, large area (239cm~2) LID-free n-PERT devices could be fabricated with a PV conversion efficiency of 20.3%.