Photoluminescence of Plasma Enhanced Chemical Vapor Deposition Amorphous Silicon Oxide with Silicon Nanocrystals Grown at Different Fluence Ratios and Substrate Temperatures

摘要

Near-infrared photoluminescent dynamics of thermally annealed Si-rich SiO_x films grown by plasma enhanced chemical vapor deposition at different substrate temperatures and N_2O/SiH_4 fluence ratios are studied. The size of nanocrystallite Si (nc-Si) critically depends on the density of oxygen atoms in a Si-rich layer when the N_2O/SiH_4 ratio is smaller than 4; that is, it significantly increases at low N_2O/SiH_4 ratios. Deposition at a high N_2O/SiH_4 ratio strongly reduces the density of nc-Si and degrades the luminescence at 700-800 nm since the density of oxygen atoms is sufficient in the reaction of nc-Si with silicon atoms and formation of a stoichiometric SiO_2 matrix. Under a high RF power condition, the increasing substrate temperature usually inhibits the precipitation of nc-Si since high-temperature growth facilitates stochiometric SiO_2 deposition. The disappearance of visible PL reveals the complete regrowth of a stoichiometric SiO_2 matrix around a nanocrystallite Si cluster after annealing. The results of the transient luminescent analysis of Si-rich SiO_x samples corroborate well with the observed values and reveal a lifetime of 43μs under an optimized nc-Si precipitation condition of 1100℃ annealing for 3h.