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

Two triple-layered SiO2/SiNx/SiO2 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 x = 1.4) was obtained by changing the ratio of the SiH2Cl2/NH3 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 x 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 SiNx 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.