Comparative study of the oxidation of thin porous silicon layers studied by reflectometry, spectroscopic ellipsometry and secondary ion mass spectroscopy |
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Authors: | M Fried O Polgr T Lohner S Strehlke C Levy-Clement |
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Institution: | a Research Institute for Technical Physics and Materials Science, H-1525 Budapest P.O.B. 49, Hungary b CNRS-LPSB, 1 Place A. Briand, 92195, Meudon, France |
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Abstract: | We present a systematic study on ultrathin porous silicon (PS) layers (40–120 nm) of different porosities, formed by electrochemical etching and followed by thermal oxidation treatment (300°C and 600°C) and by electrochemical oxidation. The oxidised and non-oxidised PS layers have been analysed by spectroscopic reflectometry (SR), spectroscopic ellipsometry (SE) and secondary ion mass spectroscopy (SIMS). The SR and SE spectra were fitted by a multiparameter fit program and the composition and the thickness of the PS layers were evaluated by different optical models. PS layers, formed electrochemically in the outermost layer of a p/n+ monocrystalline silicon junction were successfully evaluated using a gradient porosity optical model. The non-oxidised PS, formed in p-type silicon, can be well described by a simple optical model (one-layer of two-components, silicon and voids). The spectra of the oxidised PS layers can be fitted better using an optical model with three interdependent components (crystalline-silicon, silicon-dioxide, voids). The SIMS results give a strong support for the optical model used for SR and SE. |
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Keywords: | Porous silicon Ellipsometry Reflectometry SIMS |
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