Synthesis, Surface Functionalization, and Properties of Freestanding Silicon Nanocrystals
ABSTRACT Freestanding silicon nanoparticles (FS-nc-Si) have intriguing chemical and optical properties. The present contribution outlines known synthetic methodologies and protocols for surface functionalization. Recent advancements in tailoring the photoluminescence properties of FS-nc-Si and future research directions will be briefly discussed.
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ABSTRACT: Silicon nanoparticles can be considered a green material, especially when prepared via a microwave-assisted method without the use of highly reactive reducing agents or hydrofluoric acid. A simple solution synthesis of hydrogen-terminated Si- and Mn-doped Si nanoparticles via microwave-assisted synthesis is demonstrated. The reaction of the Zintl salt, Na(4)Si(4), or Mn-doped Na(4)Si(4), Na(4)Si(4(Mn)), with ammonium bromide, NH(4)Br, produces small dispersible nanoparticles along with larger particles that precipitate. Allylamine and 1-amino-10-undecene were reacted with the hydrogen-terminated Si nanoparticles to provide water solubility and stability. A one-pot, single-reaction process and a one-pot, two-step reaction process were investigated. Details of the microwave-assisted process are provided, with the optimal synthesis being the one-pot, two-step reaction procedure and a total time of about 15 min. The nanoparticles were characterized by transmission electron microscopy (TEM), x-ray diffraction, and fluorescence spectroscopies. The microwave-assisted method reliably produces a narrow size distribution of Si nanoparticles in solution.Nanotechnology 07/2012; 23(29):294006. DOI:10.1088/0957-4484/23/29/294006 · 3.67 Impact Factor
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ABSTRACT: The properties of silicon nanocrystals (Si NCs) that are usually a few nanometers in size can be exquisitely tuned by boron (B) and phosphorus (P) doping. Recent progress in the simulation of B- and P-doped Si NCs has led to improved explanation for B- and P-doping-induced changes in the optical properties of Si NCs. This is mainly enabled by comprehensive investigation on the locations of B and P in Si NCs and the electronic properties of B- and P-doped Si NCs. I remarks on the implications of newly gained insights on B- and P-doped Si NCs. Continuous research to advance the understanding of the doping of Si NCs with B and P is envisioned.Journal of Nanomaterials 01/2012; 2012:9. DOI:10.1155/2012/912903 · 1.61 Impact Factor
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ABSTRACT: We have determined the particle size distribution profiles of octane-terminated silicon nanoparticle suspensions, produced using the sonication of electrochemically etched Si wafers. Small-angle neutron scattering data was analyzed separately in high (0.4 nm(-1)<q<3.0 nm(-1)) and low (q<0.4 nm(-1)) scattering vector ranges. Data in the high q range is consistent with the log-normal distribution of isolated spherical particles with median diameter d = 3 ± 0.2 nm. Particle sizes were also indirectly assessed from photoluminescence and optical transmission spectroscopy using the size/bandgap relation: E(g) = 3.44d(-0.5), where E(g) is in eV and d in nm. Both measurements were consistent with the particle size distribution profiles, estimated from ANS data fitting and TEM image analysis. A subpopulation of larger, irregular shape structures in the size range 10-50 nm was also indicated by neutron scattering in the low q range and HRTEM images. However, further studies are warranted to explain a relationship between the slope of scattering intensity versus scattering vector dependence in the intermediate scattering vector range (0.4 nm(-1)<q<1.0 nm(-1)) and the role of non-geometrical Si nanoparticle characteristics (mutual interaction forces, surface termination, etc).Nanotechnology 02/2008; 19(8):085715. DOI:10.1088/0957-4484/19/8/085715 · 3.67 Impact Factor