Single Side Etching - Key Technology for Industrial High Efficiency Processing

Single side etching technologies will gain more and more importance when high efficiency cell structures with passivated and locally contacted rear side will enter industrial production. Within this paper different etching approaches for the solar cells rear, either dry or wet chemically, have been investigated in terms of resulting surface topography, and, combined with subsequent PECVD stack passivation, in terms of surface recombination velocity and optical performance. Correlations between surface roughness, surface recombination velocity and final Voc potential have been taken. Thin (130 µm) passivated and locally LFC contacted Cz-Si solar cells have been processed implementing the different etching sequences reaching up to 4 % relative higher short circuit currents compared to Al-BSF reference cells with maximum efficiency of 16.2 %.