Silicon Nanocrystals and Amorphous Nanoclusters in SiO_x and SiN_x: Atomic, Electronic Structure, and Memristor Effects

Abstract

Semiconductor nanocrystals in dielectric films are interesting from fundamental aspect, because quantum-size effects in them appear even at room temperature, so such objects can be called as "quantum dots". Silicon nanocrystals and amorphous silicon nanoclusters in substoichiometric SiO x and SiN x films are traps for electrons and holes that apply in nonvolatile memory devices. In this chapter the formation of silicon nanocrystals and silicon amorphous nanoclusters in SiO x and SiN x films was studied using structural and optical methods. The phonon confinement model was refined to obtain sizes of silicon nanocrystals from analysis of Raman scattering data. Structural models that lead to nanoscale potential fluctuation in amorphous SiO x and SiN x are considered. A new structural model which is intermediate between random mixture and random bonding models is proposed. Memristor effects in SiO x films are discussed.