Silicon nanocrystal growth in the long diffusion length regime using high density plasma chemical vapour deposited silicon rich oxides

摘要

In this study, silicon nanocrystal (Si-nc) growth is studied in a relatively long thermal budget regime, 3 h at 1100-1200 degrees C, to examine large diameter nanocrystals (i.e. average diameters greater than 5 nm). Morphology, defects within the nanocrystals and size dependence as a function of thickness in the oxide are exaggerated in this regime and are more readily characterized in the longer diffusion length regime. In particular, nearby surfaces, the silicon substrate and oxide surface, appear to deplete the excess silicon in the oxide, leading to a strong nanocrystal size dependence with position in the oxide. To pursue this work, silicon naocrystals were formed through a combination of high density plasma enhanced chemical vapour deposition (HDP-CVD) of silicon rich oxides (SRO) followed by phase separation of the SRO into Si-ncs and stoichiometric oxide (SiO2). Details of the characterization of the as-grown HDP-CVD SROs are included, and differences in the Si-O-Si stretch mode peak position dependence on +AFs-O+AF0- between HDP-CVD and previously reported plasma enhanced CVD are discussed.