engleski

Micro and nano structure of electrochemically etched silicon epitaxial wafers

Silicon epitaxial wafers consisting of 280 um thick n-type substrate layer and 4-5 um thick epitaxial layer were electrochemically etched in hydrofluoric acid ethanol solution to produce porous silicon samples. The resistivity of substrate was 0.015 ohm cm, while the resistivity of epitaxial layer was 1 ohm cm. By varying the etching time, the different structures were obtained within the epitaxial layer, and on the substrate surface. Due to the lateral etching the epitaxial layer was partially detached from the substrate and could be peeled off. The influence of etching time duration on the structural properties of porous samples was investigated by Raman spectroscopy. The samples were analysed immediately after the etching and six month later while being stored in ambient air. The Raman spectra showed the shift in position of transversal optical (TO) phonon bands between freshly etched samples and the one stored in ambient air.

Porous silicon; Eitaxial wafers; Raman spectroscopy

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