Open AccessNanoparticle synthesis in pulsed low temperature discharges
Author(s) -
Richard J. Buss
Publication year - 1996
Language(s) - English
Resource type - Reports
DOI - 10.2172/244621
Subject(s) - silane , hydrogen , materials science , silicon nitride , silicon , glow discharge , silicon carbide , chemical engineering , analytical chemistry (journal) , nitride , silicon oxynitride , particle size , plasma , inorganic chemistry , nanotechnology , chemistry , metallurgy , organic chemistry , composite material , physics , layer (electronics) , quantum mechanics , engineering
Silicon nitride powders with an average size as low as 7 nm are synthesized in a pulsed radio frequency glow discharge. The as-synthesized silicon nitride powder from a silane/ammonia plasma has a high hydrogen content and is sensitive to oxidation in air. Post-plasma heating of the powder in a vacuum results in nitrogen loss, giving silicon-rich powder. In contrast, heat treatment at 800 C for 20 minutes in an ammonia atmosphere (200 Torr pressure) yields a hydrogen-free powder which is stable with respect to atmospheric oxidation. Several approaches to synthesizing silicon carbide nano-size powders are presented. Experiments using silane/hydrocarbon plasmas produce particles with a high hydrogen content as demonstrated by Fourier transform infrared analysis. The hydrogen is present as both CH and SiH functionality. These powders are extremely air-sensitive. A second approach uses a gas mixture of methyltrichlorosilane and hydrogen. The particles have a low hydrogen content and resist oxidation. Particle morphology of the silicon carbide is more spherical and there is less agglomeration than is observed in the silicon nitride powder