Chemical etching of porous silicon in diluted hydrofluoric acid

Chemical etching of n-type porous silicon in diluted hydrofluoric acid was studied by Fourier transform infrared spectroscopy. A new peak was observed at 616 cm(-1) after the etching, which is assigned to Si-H bending of H-Si[SiH(Si)(2)](2)[Si(Si)(3)] configuration. The absorption at 627 cm(-1), owing to Si-H bending of H-Si[Si(Si)(3)](3) structure, was narrowed by the etching. The etching produces {011} microfacets, which are absent in as-prepared porous silicon. These features can be interpreted in terms of the dissolution chemistry and the pore morphology of n-type porous silicon. (C) 1998 Elsevier Science Ltd. All rights reserved.