Paper NS-MoM6
Plasma Synthesis and Hydrosilylation of Silicon Nanoparticles

Monday, October 29, 2012, 10:00 am, Room 12

Silicon nanoparticles (NPs) are of interest in a variety of optoelectronic applications due to the observation of multiple exciton generation, room temperature photoluminescence, size tunable band gap, and optical gain. Design of any device employing Si NPs requires control over both the size and interfacial passivation as these parameters dictate the electronic properties of the NPs. Our synthesis process employs a capacitively-coupled tubular Ar/SiH₄ plasma to produce H-terminated Si NPs. The surface composition and functionalization of the Si NPs was characterized via in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Organic passivation of the H-terminated Si NPs was achieved through a two-stage gas-phase hydrosilylation process using 1-alkynes with different numbers of C atoms that led to surface coverages comparable to the thermodynamic limit for alkenyl monolayers on bulk H:Si(111) surfaces. The hydrosilylation reaction requires abstraction of a surface hydride to stabilize an intermediate surface radical formed upon absorption of the 1-alkyne. Injection of H₂ into the afterglow region of the synthesis plasma was employed to manipulate the surface hydride composition, which led to an increase in the relative fraction of SiH_x(x = 2, 3) species on the surface compared to SiH. The impact of these higher hydrides on the hydrosilylation reaction of 1-alkynes was investigated through in situ ATR-FTIR spectroscopy. Finally, using in situ photoluminescence measurements, we also determined the effect of the various hydrosilylation processes on the relative quantum yield from these Si NPs.