Materials .a-si/a-sinx Superlattice Light-emitting And Nonlinear Optical Effects

The study of Si-based nc materials have became the hotspot of Si-based optoelectronics in recently. The core question is how to improve the luminous efficiency of these materials. SiNx has good insulating property, compactness, stability. So SiNx is an important thin film material, and ilicon nitride films as passive and insular are widely used in Si devices and integrated circuits. The preparation process recipes, micro-structure, optical absorption and PL mechanism were studied in this paper. Nonlinear optical property of a-Si/a-SiNx superlattice was probed by a Z-Scan Technique.a-Si/a-SiNx superlattice has been fabricated by RF magnetron sputtering technique and thermal annealing. In the experiment, Ar is sputtering gas and N2 is reactive gas. The thicknesses of a-Si and a-SiNx layer were controlled through adjusting the experiment process recipes. IR, XRD, EDS and PL technologies were used to study the composition, structure optical absorption and the luminescent properties. The results showed that the optical band gap became big with the decrease of the thickness of a-Si layer under the same a-SiNx layer thickness; the optical band gap became big with the decrease of the thickness of a-SiNx layer under the same Si layer thickness. It is ascribed to the one-dimensional quantum confinement effect of a-Si/a-SiNx superlattice. Under 265nm wavelength light excitation, room-temperature emission bands were observed in the PL spectra. The PL origins of these emission bands were discussed in detail. In term of the result, the intense PL was proposed to originate from the quantum confinement effect of a-Si/a-SiNx superlattice.Nonlinear optical properties of a-Si/a-SiNx superlattices were probed by a Z-Scan Technique atλ=1064nm andλ=532nm. The experimental results show that the nonlinear refractive index of the sample was negative value, the nonlinear absorption was two-photon absorption and theχ(3) have been found to be 1.28×10-7(esu) atλ=1064nm. The experimental results show that the nonlinear refractive index of the sample was negative value, the nonlinear absorption was counter-saturated absorption and theχ(3) have been found to be 1.46×10-7(esu) according to the experimental data of Z-scan curve atλ=532nm. The value of a-Si/a-SiNx superlattice is larger 5 scales than that of bulk Silicon. The nonlinear mechanism of the material was discussed. The enhancement of nonlinear refractive index is mainly attributed to intensive quantum confinement.