Improvement of silicon solar cell substrates by wet-chemical oxidation studied by surface photovoltage measurements

摘要

The simultaneous application of fast, non-destructive and surface-sensitive spectroscopic SPV and SE methods provides detailed information about the influence of wet-chemical oxidation methods on surface micro-roughness and related electronic interface properties. Smoothing procedures for flat and differently textured Si substrates were developed applying sequences of wet-chemical oxidation in H_2SO_4/H_2O_2 and oxide removal. By wet-chemical oxidation in concentrated HNO_3 and optimised post-treatments thin SiO_x layers with excellent passivation properties can be achieved. According to our results wet-chemical oxidation in diluted solutions of HC1 [9] or ozone O_3 [4] could be a high quality and low cost alternative to current approach using liquid chemicals for the preparation of hydrophobic Si substrate surfaces and ultra-thin passivating oxide layers. Acknowledgments are given to Prof. E. Pincik, Dr. U. Stiirzebecher, Dr. L. Breitenstein for supplying of various textured samples. This work is part of the project "μ-Tex" and is financially supported by the HTW Berlin.