Abstract
A selective emitter by means of lowly doped regions with a low saturation current between the contact fingers and highly doped regions below the fingers can significantly improve the cell efficiency of crystalline silicon solar cells. A low saturation current could be achieved for diffused emitters by etching back the surface layer containing the high concentration of electrical inactive phosphorous ("dead-layer"). The significant benefit of performing this etch-process with plasma is the possibility to include it in one vacuum chamber with a subsequent anti-reflection coating (ARC). In this work a homogeneous etch-back of the emitter by means of SF6-plasma-etching is presented. The passivation quality of a silicon nitride ARC and of a silicon-rich silicon oxynitride / silicon nitride double layer ARC deposited on plasma-etched emitters is investigated. Emitter saturation currents down to J0e = 57 fA/cm2 are achieved.