Structural analysis of silicon nanostructures obtained from thermal annealing of PVD deposited SRO/SiO2 multilayers

Abstract

We report the synthesis and characterization of silicon nanostructures obtained by thermal annealing of silicon-rich oxide/silicon dioxide (SRO/SiO2) multilayers deposited by magnetron sputtering in an argon and oxygen atmosphere. The main motivation to study silicon comes from its success and dominance in microelectronics. Light sources, modulators, waveguides, and logical gates are a few examples of microelectronic materials applications in the various photonic devices which have been developed based on silicon nanocrystals.SRO/SiO2 multilayers were deposited by 13.56 MHz radio-frequency magnetron sputtering. The as-deposited multilayers and the crystallized films were investigated using in-situ X-ray diffractometry (XRD), High-resolution transmission electron microscopy (HRTEM) and Secondary ion mass spectrometry (SIMS).Multilayers composed of alternating stacks of amorphous SRO and SiO2 layers were crystallized by thermal annealing in vacuum. The different stages from nucleation until full crystallization were investigated by in situ X-ray diffractometry. XRD in agreement with HRTEM confirmed the presence of silicon crystalline fraction in annealed films. It is calculated that there is 17–25% of crystalline volume fraction in the multilayers after the annealing procedure with density of particles of 2–2.8 × 1018cm−3. The crystalline fraction obtained consists of nanoparticles, whose average size is 3.5–5 nm.