In situ spectroscopic ellipsometric investigation of vacuum annealed and oxidized porous silicon layers

Fried, M. and Wormeester, H. and Zoethout, E. and Lohner, T. and Polgar, O. and Barsony, I. (1998) In situ spectroscopic ellipsometric investigation of vacuum annealed and oxidized porous silicon layers. Thin Solid Films, 313-31 . pp. 459-463. ISSN 0040-6090

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Abstract:	Vacuum annealed and oxidized porous silicon layers (PSL) were investigated by in situ spectroscopic ellipsometry (SE). The nominal porosity of the layers was between 60 and 77% and the nominal thickness was 500 nm. The annealing was performed by direct ohmic heating (R.T.<450°C) in 5×10−10 Torr vacuum. The oxidation was performed in two steps, the first step at 5×10−5 Torr, the second at 10 Torr. Two optically different types of silicon compounds, a bulk-type silicon (c-Si) and a fine-grain polycrystalline silicon with enhanced absorption due to extensive grain-boundary regions (p-Si) were mixed with voids in the appropriate ratio to fit the spectra of as-prepared PSL. For the annealed PSL amorphous silicon (a-Si) was needed in conjunction with p-Si. The oxidized PSL could be fitted with a reduced a-Si content. We can interpret the annealing effect as a depassivation process of the inner surfaces of the PSL (a-Si fraction). At the same time, oxidation leads to a repassivation process.
Item Type:	Article
Copyright:	© 1998 Elsevier
Faculty:	Science and Technology (TNW)
Research Group:	Physics of Interfaces and Nanomaterials (PIN)
Link to this item:	http://purl.utwente.nl/publications/73674
Official URL:	http://dx.doi.org/10.1016/S0040-6090(97)00864-X
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