Surface states and recombination loss on wet-chemically passivated Si studied by Surface Photovoltage (SPV) and Photoluminescence (PL)

摘要

As shown here, SPV- and PL measurements can be used as a very sensitive tool, to analyse preparations-induced surface electronic properties during wet-chemical processes. Summarizing the results of our recently published investigations [4,17,19] the preparation-induced surface micro-roughness and resulting density of rechargeable states on wet-chemically H-terminated surfaces were found to be mainly influenced by two factors: firstly, the morphology of the initial silicon/oxide interface after wet-chemical oxidizing pre-treatment and, secondly the behaviour of the final etching HF- or NH_4F containing solution. It is important to apply non-aggressive oxidizing solutions under controlled conditions to avoid an increase of interface roughness during the oxidation process. Low recombination loss and densities of rechargeable states on Si(111) and Si(100) surfaces were achieved by optimisation of special sequences of wet-chemical oxidation and etching treatments, with respect to the crystallographic surface orientation.