Electronic properties and charge storage effect of amorphous SiN passivated nanocrystalline silicon

Abstract

Nanocrystalline Si (nc-Si) with mean size of about 4 nm embedded in amorphous SiN film was prepared by annealing Si-rich amorphous SiN film. The film compositions and microstructures were revealed by x-ray photoelectron spectroscopy, Raman spectroscopy, and transmission electron microscopy. It was found the room temperature conductivity is increased from 7 × 10−9 to 1 × 10−5 S/cm due to the formation of nc-Si. The carrier transport process of nc-Si embedded in amorphous SiN matrix is dominated by trap-assisted tunneling mechanism. Moreover, by forming a-SiN0.81/nc-Si(SiN)/a-SiN0.81 sandwiched floating gate structures, both electron and hole can be injected and stored in nc-Si by controlling the applied bias polarity. A large memory window up to about 7 V was observed, and the stored carrier density was about 1012 cm−2. Our experimental results suggested that the interface states of nc-Si can be well passivated by the amorphous SiN matrix, which results in the good charge storage effect.