Luminescent porous silicon: Synthesis, chemistry, and applications

This chapter describes the preparation, chemistry, and photophysics of luminescent porous silicon and discusses some of its potential applications. Porous silicon's properties vary tremendously, with sample preparation and handling, which has exacerbated the controversy, surrounding the emission mechanism. Due to the heterogeneous nature of porous silicon, traditional surface analysis methods do not always provide a complete picture. It is possible that several emission mechanisms may be operative in porous silicon, with varying degrees of importance, depending upon the particular sample studied. Molecular oxide species, such as siloxene (Si6O3H6), have been hypothesized to be responsible for the photoluminescence of porous silicon. This postulate arose from observed similarities between the Raman, Fourier transform infrared spectroscopy (FTIR), and photoluminescence spectra of oxidized porous silicon and siloxene. The surface of as-formed porous silicon is usually terminated, with oxide or hydride species. Chemical reactions at the porous silicon surface generate new surface species that can act as efficient carrier traps. © 1997 Elsevier B.V.