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Organic cyano compounds such as 1,2-dicyanoethylene, 1,3-dicyanobenzene, 1,4-dicyanobenzene and 1-cyanonaphthalene have been used in enhancing the photoluminescence (PL) of oxidized porous silicon (PS). It was found that PL was dependent on the steric effects and electronic properties of the cyano compounds. Fourier transform infrared spectra revealed that surface Si-H bonds have not been altered and no new luminescent compounds have been formed on the surface of PS.

Light-emitting porous Si that luminesce at room temperature exhibit a degradation of the electroluminescence with time and strong laser heating effects. Light emitting porous Si can be obtained by the anodic etching of p-type Si samples in a HF-ethanol solution, and its properties can be studied using an Auger or Raman spectroscopy. Photoluminescence is more efficient than electroluminescence.

The oscillator strength of silicon nanoparticles and its implication on the absorption and photoluminescence spectra are studied. The results have supported the assumption that Si nanoparticles are direct or indirect semiconductors.

Photoexcitation dependent Raman studies were carried out on the optical phonon mode in silicon nanostructures (Si-NS) prepared by laser-induced etching. A broad photoluminescence spectrum from Si NS containing multiple peak behavior reveal the presence of continuum of electronic states in the Si NS which could be applied to the transport properties of the photonic devices and solar cell made of these Si NSs.

The photoluminescence (PL) properties changed significantly after porous silicon (PS) was irradiated by low energy nitrogen or argon ions. X-ray photoelectron spectroscopy and Fourier transforms infrared spectroscopy results indicate that the Si-N bonds were formed during low-energy-nitrogen-ion irradiation. On the other hand, Raman scattering spectroscopy suggests the crystal structure of PS did not change during ion irradiation.

Silicon nanoparticles are prepared by off axis pulsed laser deposition (PLD) technique and their optical properties are characterized by optical absorption, photoluminescence, Raman and transmission electron microscopy (TEM). The photoluminescence (PL) peak energy and intensity are discovered to be sensitive to the nature of substrate and the mechanism of optical absorption and PL origin is discussed in terms of quantum confinement luminescent center model.