Depth profiling of Si nanocrystals in Si-implanted SiO2 films by spectroscopic ellipsometry

Abstract

In this letter, we report an approach to depth profiling of Si nanocrystals embedded in SiO2 film based on spectroscopic ellipsometry. The SiO2 film is divided into many sublayers with equal thickness, and each sublayer is characterized by its nanocrystal concentration. In the spectral fittings, the effective dielectric function of each sublayer is obtained from an effective medium approximation by using the dielectric function of Si nanocrystal that is calculated with either the bond contraction or the phenomenological models for the band gap expansion of nanocrystals. The fittings yield the nanocrystal depth profiles and the nanocrystal sizes as well. The depth profiles from the two models are similar, and they are in good agreement with secondary ion mass spectroscopy analysis.