Detection of different states of water and oxide layer in porous silicon by IR spectroscopy

Abstract

AbstractDifferent states of water and oxide layer in porous silicon (PS) have been studied by IR spectroscopy method. The water states have been shown to depend on contact conditions between PS and condensed or vaporous forms of water and to determine all the variety of oxidation scenarios. Weakly‐ and strongly‐bonded water states are characterized by different frequencies of stretching bands νOH. Fine structure of absorption bands of oxygen‐silicon complexes (Si‐O‐Si, SiSiXO4–X) has been observed in the IR spectra. We associate it with fractal structure for thin oxide layers. Transition of fractal structure into nearly bulk SiO2 structure (where LO‐TO splitting is observed) with oxide layer thickness growth is considered. The oxide layer states are characterised by the intensity ratio of stretching to deformation bands for considered silicon‐oxygen complexes. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)