Comparing the IR spectra of H-terminated inner and outer silicon surfaces

An array of nanocavities in silicon offers an inner surface defined by nearly flat, highly ordered, planes which can be passivated by hydrogen injection from aqueous solution of HF. The infrared spectrum shows that the inner surface is mainly constituted by monohydrides in different morphologies. The corresponding signals are very narrow (full width at half maximum at room temperature below 5 cm-1, depending on the line), this being evidence for high local order. Such an inner surface can be used as a benchmark for the assignment of infrared signals observed on outer surfaces, where the sources of errors-and the consequent uncertainty in the spectral attribution-may be large. The comparison between the spectra from a well-characterized external Si(1 0 0) surface and from an internal one (in both cases hydrogen-terminated) has allowed a better qualification of the external surface. Copyright © 2010 John Wiley & Sons, Ltd.