Linking photoluminescence of α-Si3N4 to intrinsic point defects via band structure modelling
Abstract
Photoluminescence (PL) property data for reported α-Si3N4 to date are scattered and it is difficult to clarify the reason only through experimental study. In this paper, the relationship between photoluminescence and intrinsic point defects in α-Si3N4 has been established accordingly via band structure modelling based on density functional theory calculation. The results show that band structures of α-Si3N4 are significantly affected by the locations of defect levels, which are changed with various partial atomic structures around point defects. Formation energies are also calculated to determine the main types of intrinsic point defects in α-Si3N4 under different conditions (Si-rich or N-rich). The results suggest that multiple types of intrinsic point defects coexist in α-Si3N4, leading to various electronic transition modes. Furthermore, combined with the calculated results, the discrete photoluminescence data for α-Si3N4 are revealed by electronic transition modes under different conditions. The main visible luminescent peaks are attributed to the electron transitions of Ec → ![[triple bond, length as m-dash]](https://www.rsc.org/images/entities/char_e002.gif)
Si˙ σ and Si˙ σ → Ev for Si abundant α-Si3N4, while N4+ → N20 for N plentiful α-Si3N4.
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