Investigation on nonlinear optical properties of MoS 2 nanoflakes grown on silicon and quartz substrates

In this study, MoS 2 nanoflakes were directly grown on different substrates—Si/SiO 2 and quartz—by one-step thermal chemical vapor deposition using MoO 3 and sulfide powders as precursors. Scanning electron microscopy and x-ray diffraction patterns demonstrated the formation of MoS 2 structures on both substrates. Moreover, UV-visible and photoluminescence analysis confirmed the formation of MoS 2 few-layer structures. According to Raman spectroscopy, by assessment of the line width and frequency shift differences between the and A 1g , it was inferred that the MoS 2 grown on the silicon substrate was monolayer and that grown on the quartz substrate was multilayer. In addition, open-aperture and close-aperture Z -scan techniques were employed to study the nonlinear optical properties including nonlinear absorption and nonlinear refraction of the grown MoS 2 . All experiments were performed using a diode laser with a wavelength of 532 nm as the light source. It is noticeable that both samples demonstrate obvious self-defocusing behavior. The monolayer MoS 2 grown on the silicon substrate displayed considerable two-photon absorption while, the multilayer MoS 2 synthesized on the quartz exhibited saturable absorption. In general, few-layered MoS 2 would be useful for the development of nanophotonic devices like optical limiters, optical switchers, etc.