Preparation and Characterization of Silicon Nanocrystals in a SiO2 Matrix and Study of Suboxide Stability

Abstract

AbstractThe kinetics of the decomposition of silicon suboxides (SiOx, x<2) to Sic + SiO2 was studied as a function of composition and post-deposition annealing. Amorphous hydrogenated SiOx films (0.8<x<1.4) were deposited by remote plasma enhanced chemical vapor deposition (RPECVD) and rapid thermal annealed (RTA) at temperatures of 500–1000°C. By monitoring the Si-O infra-red (IR) bond-stretch mode frequency, it was found that at temperatures below 850°C, or at a oxygen poor composition near SiO0.8, the decomposition reaction only proceeded to a metastable form of SiO1.6 + Si. Characterization by Raman and spectroscopie ellipsometry confirm similar trends. Cross sectional transmission electron microscopy (TEM) confirms that Si nanocrystals (Sine) are formed with anneals at 900°C (30 sec). As deposited suboxides show band edge photoluminescence at 1.6 eV which disappears upon annealing at 900°C, indicating a sharp suboxide free interface between Sinc and SiO2 matrix.