Silicon nitride-capped silicon nanocrystals via a nonthermal dual-plasma synthesis approach

Abstract

Improving the photoluminescence quantum yields and air-stability of silicon nanocrystals is crucial to expanding their influence in optoelectronic devices and other burgeoning application areas. Here, a dual-plasma approach for the synthesis of silicon nanocrystals capped with silicon nitride is reported. The reactor consists of two plasma stages in series: a primary radiofrequency (rf) plasma for silicon nanocrystal growth from silane and argon gas followed by a secondary rf plasma for silicon nitride growth using nitrogen gas as the reactant. The core-shell nanocrystals were characterized using optical and structural analyses, and the plasma was characterized using optical emission spectroscopy. The resulting core-shell nanocrystals show a reduced susceptibility to ambient air oxidation as compared to bare silicon nanocrystals alone. This result is a step toward achieving highly efficient and air-stable photoluminescence from silicon nanocrystals while avoiding organic functionalization.