Surface Hydride Composition of Plasma-Synthesized Si Nanoparticles

Abstract

We have determined the surface hydride composition of amorphous and crystalline Si nanoparticles (NPs) (3À5 nm) synthesized in a low-temperature SiH 4 /Ar plasma using in situ attenuated total reflection Fourier-transform infrared spectroscopy and H 2 thermal effusion measurements. With increasing power to the plasma source, the particles transition from amorphous to crystalline with a corresponding increase in the fraction of SiH species on the surface. The surface hydride composition indicates that Si NPs synthesized at higher plasma powers crystallize in the gas-phase due to a greater degree of plasma-induced heating, which enhances the desorption rates for SiH 2 and SiH 3 . Furthermore, these Si NPs do not contain any detectable H in the bulk.

Fluorescent sensor for Cr(VI) based in functionalized silicon quantum dots with dendrimers

“…The common bottom-up approaches are driven by chemical reactions developed from precursors with final reduction treatments [20,21], decompositions based in laser induced pyrolysis [22] or plasma induced thermolysis [23,24]. The usual top-down approaches may include physical methods, as the laser ablation [25,26], ballmilling [27,28] and chemical catalyzed etching [29,30].…”

Silicon Nitride Encapsulated Silicon Nanocrystals for Lithium Ion Batteries

“…Si NCs synthesized using the continuous flow SiH 4 /Ar capacitively‐coupled plasma described above, without the injection of N 2 into the afterglow region, are known to be crystalline and H‐terminated . Adding N 2 into the afterglow of the Si NC synthesis plasma led to surface nitridation, as can be clearly concluded from the peak position of the infrared features shown in Figure .…”

“…The SiN x ‐coated Si NCs were synthesized in a capacitively‐coupled plasma sustained in a flow reactor (Figure ), which was similar to the design introduced by Kortshagen and coworkers . The details about the plasma source can be found in previous publications . Briefly, in this reactor, two Cu ring electrodes were placed around a quartz tube and radio‐frequency powered at 13.56 MHz and 30 W. A mixture of Ar [275 standard cm 3 /min (sccm)] and SiH 4 (1.4 sccm) was introduced into the quartz tube upstream from the plasma source (see Figure ).…”

“…The continuous‐flow plasma reactor described above was attached to a surface analysis chamber equipped with in situ attenuated total reflection Fourier transform infrared (ATR‐FTIR), photoluminescence (PL), and optical emission spectroscopy (OES) setups (see Figure ). The in situ ATR‐FTIR spectroscopy setup has been described in detail previously . Briefly, for in situ infrared characterization, the Si NCs entrained in the gas stream were transported directly onto a trapezoidal 10 × 50 × 1 mm ZnSe internal reflection crystal (IRC), which was in direct line of sight with the plasma source.…”

Optimizing the parameter space for increased crystallinity of silicon nanoparticles grown in the gas phase

“…Thus increasing plasma power results in a significant increase in particle heating, creating particles with higher crystallinity. Evidence of particle heating with increasing plasma power has been reported, the effect of which is an increase of the fraction of SiH species on the particle surface, and virtually no trace of SiH 2 and SiH 3 (which are normally present in amorphous NPs) due to desorption from hot particle. The a‐NPs containing higher hydrides lead to less dense particle ensembles, as can be seen for low power density NPs synthesized in our experiments, which have less dense structure compared to the compact NPs synthesized at high power density (Fig.…”