title: Single-step plasma synthesis of carbon-coated silicon nanoparticles.
abstract: We have developed a novel single-step technique based on nonthermal, radio frequency (rf) plasmas to synthesize sub-10 nm, core-shell, carbon-coated crystalline Si (c-Si) nanoparticles (NPs) for potential application in Li(+) batteries and as fluorescent markers. Hydrogen-terminated c-Si NPs nucleate and grow in a SiH4-containing, low-temperature plasma in the upstream section of a tubular quartz reactor. The c-Si NPs are then transported downstream by gas flow, and are coated with amorphous carbon (a-C) in a second C2H2-containing plasma. X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and in situ attenuated total reflection Fourier transform infrared spectroscopy show that a thin, < 1 nm, 3C-SiC layer forms at the c-Si/a-C interface. By varying the downstream C2H2 plasma rf power, we can alter the nature of the a-C coating as well as the thickness of the interfacial 3C-SiC layer. The transmission electron microscopy (TEM) analysis is in agreement with the Si NP core size determined by Raman spectroscopy, photoluminescence spectroscopy, and XRD analysis. The size of the c-Si NP core, and the corresponding light emission from these NPs, was directly controlled by varying the thickness of the interfacial 3C-SiC layer. This size tunable emission thus also demonstrates the versatility of this technique for synthesizing c-Si NPs for potential applications in light emitting diodes, biological markers, and nanocrystal inks.
authors.affiliation: Department of Chemical and Biological Engineering, Colorado School of Mines , Golden, Colorado 80401, United States.
authors.forename: Rohan P
authors.initials: RP
authors.lastname: Chaukulkar
authors.forename: Koen
authors.initials: K
authors.lastname: de Peuter
authors.forename: Paul
authors.initials: P
authors.lastname: Stradins
authors.forename: Svitlana
authors.initials: S
authors.lastname: Pylypenko
authors.forename: Jacob P
authors.initials: JP
authors.lastname: Bell
authors.forename: Yongan
authors.initials: Y
authors.lastname: Yang
authors.forename: Sumit
authors.initials: S
authors.lastname: Agarwal
mesh_terms: D002244:Carbon / Q000737:chemistry*; D004867:Equipment Design; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D058626:Plasma Gases; D011846:Radio Waves; D012825:Silicon / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D058626:Plasma Gases; D002244:Carbon; D012825:Silicon
keywords: Si nanoparticles; nanoparticle synthesis; radio frequency plasmas