Room temperature multilayer luminescent silicon nanocrystals

Abstract

Silicon nanocrystals with dimensions of about 3 to 4 nm are fabricated by hydrogenation of amorphous silicon layers with thickness of about 15 nm. The strong binding of nanocrystals to the amorphous matrix, which prevents them from showing luminescence, is broken up by a plasma treatment process in the presence of H₂, N₂O, and SF₆. Regions with high nanocrystal density show more resistance against plasma etching. By controlling the etching parameters such as precursor flow rates during hydrogenation and plasma treatment processes, it seems possible to realize luminescent layers. Photoluminescence (PL) studies show that nanocrystals emit light around a wavelength of 550 nm. Multilayer structures have been fabricated to increase the PL intensity by separating luminescent nanocrystal layers with a 5 nm-thick layer of silicon oxynitride. The entire fabrication process has been performed in a conventional RF-PECVD reactor offering hope for realization of cost-effective silicon lightemitting structures. The low temperature nature of the proposed process could lead to the fabrication of light-emitting devices on low cost substrates like glass or even plastic.