Blue and red light-emitting non-stoichiometric silicon nitride-based structures

Abstract

The two triple-layered SiO 2 /SiN x /SiO 2 structures with Si-rich and N-rich silicon nitride active layer were fabricated on p -type Si-substrates by chemical vapour deposition. The SiN x layer of different composition ( x = 0.9 and x = 1.4) was obtained by changing the ratio of the SiH 2 Cl 2 /NH 3 flow rates during deposition of a silicon nitride active layer (8/1 and 1/8, respectively). The spectroscopic ellipsometry and photoluminescence (PL) measurements showed that the refractive index, the absorbance and luminescence properties depend on a chemical composition of silicon nitride layers. The structures with Si-rich and N-rich SiN x active layers emit in the red (1.9 eV) and blue (2.6 eV) spectral ranges, respectively. The PL intensities of different structures are comparable. The rapid thermal annealing results in the intensity decrease and in the PL spectra narrowing in the case of SiN 1,4 active layer, whereas the increase in the emission intensity and the PL spectra broadening are observed in the case of the annealed sample with a SiN 0,9 active layer. The PL origin and the effect of annealing treatment have been discussed, taking into account the band tail mechanism of radiative recombination. Multilayered (SiO 2 /SiN x ) n /Si structures are of practical interest for creation of effective light sources on the basis of current Si technology.