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Nanometer-sized silicon particles have been produced by ultrasonic dispersion of thin sections of porous silicon (PS) in organic solvents. The particles have been characterized by HRTEM (high-resolution transmission electron microscopy), FTIR (Fourier transform infrared) spectroscopy, and fluorescence spectroscopy. HRTEM shows both aggregates of and monodispersed crystallite particles of Si. The larger aggregates range in size from20 to 50 nm and are made up of small crystallites with diameters of 2-10 nm. Monodispersed crystallites ranged in size from 2-10 nm. All the particles have an amorphous layer of SiO{sub 2}. The photoluminescence (PL) spectrum shows two peaks: a red peak at around 680 nm, which is typical for PS and a blue peak between 415 and 446 nm, which is not typical for as-prepared PS. As a function of increased excitation intensity, the blue peak grows at the expense of the red. This is discussed in light of photoluminescence lifetime data. The red luminescence is attributed to quantum confinement. The blue luminescence is attributed to either extremely small Si crystallites or (Si(II)){sup 0} defects embedded in the oxide matrix. 28 refs., 9 figs., 1 tab.

We report here a new solution phase synthesis for producing crystalline silicon nanoclusters at significantly lower temperatures than previously required. In addition, it is performed at ambient pressure and yields a particle surface that can be modified by chemical methods. This method has the potential to yield large amounts of silicon nanocrystals in addition to providing reliable control over size distribution and surface termination. In this synthesis we use the Zintl salt KSi as a starting reagent. KSi is synthesized by reacting excess K with silicon at 650{degree}C for three days and subliming off the excess K at 275{degree}C under vacuum. The purity of the air-sensitive, black solid is verified by powder X-ray diffraction. 23 refs., 1 fig.