Journal
JOURNAL OF LUMINESCENCE
Volume 237, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.jlumin.2021.118132
Keywords
Spinel Si3N4; He+ irradiation; Cathodoluminescence; Photoluminescence; Structural defects
Categories
Funding
- Euratom research and training programme [633053]
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The formation and evolution of defect levels in the electronic structure of silicon nitride with cubic spinel structure, gamma-Si3N4, after irradiation with He+ ions were investigated using spectroscopic techniques. The changes in cathodoluminescence, photoluminescence, photoluminescence excitation, and Raman spectra were detected. The appearance of a new near-infrared band with close to band gap excitation was attributed to effective trapping of photoinduced electrons and holes by charged defects.
Formation and evolution of defect levels in the electronic structure of silicon nitride with cubic spinel structure, gamma-Si3N4, after the irradiation with He+ ions was investigated using spectroscopic techniques. Strong changes of cathodoluminescence (CL), photoluminescence (PL), photoluminescence excitation (PLE) and Raman spectra were detected. In particular, excitonic PL was significantly inhibited and a new near-IR band appeared with the band gap excitation h nu >= E-g = 5.05 eV. This was explained by an effective trapping of photoinduced electrons and holes by charged defects. The spectral shift of PL with the excitation photon energy indicated heterogeneous nature of the defect sites. The energetic position of near-IR and visible PL bands correlate, suggesting an interaction with the common cation defect to be an origin. The visible PL of exciton bound to a neutral defect Si-x was red shifted, which was attributed to the permutations between empty and occupied octahedral and tetrahedral sites, inherent to the spinel structure, after collisions with He+ ions. The positively charged cation sites in the spinel structure are compensated by V-N'''nion vacancies. The local deformation of the spinel lattice affects PL intensity of the self-trapped exciton at 4.35 eV.
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