• Angermann, H.; Laades, A.; Stürzebecher, U.; Conrad, E.; Klimm, C.; Schulze, T.F.; Jacob, K.; Lawerenz, A.; Korte, L.: Wet-chemical preparation of textured silicon solar cell substrates: Surface conditioning and electronic interface properties. Solid State Phenomena 187 (2012), p. 349-352

10.4028/www.scientific.net/SSP.187.349

Abstract:
Decisive preconditions to the development of economically attractive solar cells are further improvements of the energy conversion efficiency by appropriate interface preparation and passivation meth-ods as well as the reduction of material consumption by the application of thin-film technologies [ ]. For this purpose also the simplification of technological proc-esses, particularly the suitability and cost-effectiveness of wet-chemical cleaning and etching processes has to be taken carefully into consideration. This paper reports on the investigation of wet-chemical etching und surface conditioning of different Si sub-strates, carried out before preparation of thin oxides, amorphous / crystalline (a-Si:H/c-Si) hetero-junctions, Si nitride (a-SiNx:H) passivation layers and contacts. Wet-chemical smoothing and hydrogen-termination procedures were investigated in order to reduce surface micro-roughness, surface charge and densities of inter-face states Dit(E) on textured surfaces. . According to our results wet-chemical smooth-ing prior to a-Si:H deposition for amorphous-crystalline hetero-junction solar cells (ZnO/a-Si:H(n)/c-Si(p)/Al) increases significantly the fill factor and energy conver-sion efficiency [5]. Electronic interface properties of textured Si substrates for solar cells application were found to be mainly influenced by the crystallographic surface configuration of light-trapping structures and secondly, the effective-ness of wet-chemical smoothing, H-termination or oxidation procedures. Strong effects of surface condi-tioning were found on c-Si/a-Si:H, on Si carbide a-SiC:H and also on c-Si/a-SiNx:H interfaces, even though the field effect passivation is based on the band bending caused by a fixed charge in the film [6].