Size dependence of Si 2p core-level shift at Si nanocrystal/SiO2 interfaces

Abstract

Synchrotron-radiation x-ray photoelectron spectroscopy (XPS) has been used to analyze size-dependent Si 2p core-level spectra of Si nanocrystals (NCs) embedded in SiO2. The Si0 and suboxide XPS peaks of Si NCs shift to higher binding energies with decreasing NC size, which is based on the resolved spectra fitted by using Gaussian-Lorentzian lines for the Si oxidation states. It is also found that the shell region around Si NC bordered by SiO2 consists of the three Si suboxide states, Si1+, Si2+, and Si3+, whose densities are also strongly dependent on NC size. These results suggest that the analysis of the Si 2p core-level shift by XPS is useful for characterizing the size effect of Si NC at the Si NC∕SiO2 interfaces.