Photoluminescence of SiO₂/SiN_x/SiO₂/Si Structures with Off-Stoichiometric Silicon Nitride Layers

Abstract

Two triple-layered SiO ₂ /SiN _x /SiO ₂ structures with Si-rich and N-rich silicon nitride active layers were fabricated on p-type Si-substrates by chemical vapour deposition. The different stoichiometry of SiNx layer (x = 0.9 and × = 1.4) was obtained by changing the ratio of the SiH ₂ Cl ₂ /NH ₃ flow rates during deposition of silicon nitride active layer (8/1 and 1/8, respectively). The spectroscopic ellipsometry measurements show the refractive index as well as absorbance could be controlled by × adjusting. As a result, it could tune the emission colour of the deposited structures by changing their chemical composition. 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 the different structures with Si-rich and N-rich SiNx are comparable. Annealing effect on PL intensity is differed for structures with Si-rich and N-rich SiNx. The origin of PL and the effect of annealing treatment have been discussed.