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  Angermann, H.; Wünsch, F.; Kunst, M.; Laades, A.; Stürzebecher, U.; Conrad, E.; Korte, L.; Schmidt, M.: Effect of wet-chemical substrate pretreatment on electronic interface properties and recombination losses of a-Si:H/c-Si and a-SiN_xH/c-Si hetero-interfaces. Physica Status Solidi C 8 (2011), p. 879-882

10.1002/pssc.201000236

Abstract:
Surface charge, surface state density and interface recombination behavior on polished float zone (FZ) solar cell substrates were investigated after various wetchemical pre-cleaning procedures and deposition of amorphous silicon (a-Si:H) or silicon nitride (a-SiNx:H). Applying surface photo voltage (SPV), microwave detected photo conductance decay (μW-PCD) and transient microwave conduction (TRMC) measurements, electronic interface properties were monitored repeatedly during the preparation processes. As shown for an inverted a-Si:H/c-Si hetero-junction structure, with front side passivation by a-SiNx:H and a p-type a-Si:H emitter on the rear side, the effect of optimised wet-chemical pre-treatment can be preserved during the subsequent soft plasma enhanced chemical vapour deposition of a-Si:H or a-SiNx:H. This leads to hetero-interfaces with low interface recombination velocities. These results were compared to previously reported findings, obtained on textured Czochralski (CZ) single crystalline substrates. a-SiNx:H is known to result in a field effect passivation. Nevertheless a strong influence of wet-chemical treatments on surface charge and recombination losses was observed on both flat and textured a-SiNx:H/c-Si interfaces. © 2010 WILEY-VCH