Evolution of Optical and Structural Properties of Silicon Nanocrystals Embedded in Silicon Nitride Films with Annealing Temperature

Abstract

In this work, Hydrogenated silicon rich nitride (SRN) films were deposited by varying NH3/SiH4 ratio and thermally annealed within the temperature range of 700-1000 °C in N2 ambient to precipitate silicon nanocrystals in the film. The optical and structural properties of SiNx:H films were studied. Chemical composition and structural investigations were performed by Secondary ion mass spectrometry (SIMS), Infrared and Raman spectrometry experiments.Fourier Transform Infrared Spectroscopy (FTIR) indicates a new band which appeared as a “shoulder” in the 850-900 cm−1 range and is attributed to a reordering in the films towards an increased SiN4 bonding configuration resulting from the precipitation of silicon nanocrystals.The Raman analysis clearly evidences a high density of Si nanoclusters as shown by the broadened and asymmetric Raman peak approaching 520 cm-1.Strong visible photoluminescence (PL) can be observed in silicon nitride and the evolution of the photoluminescence with annealing temperature is correlated to the evolution of the structure. Radiative defects in the films and the quantum confinement effect in silicon nanoparticles were proposed to explain the origin of light emission from the samples.