Study On Photoluminescence Enhancement Of MoS₂ Through Defect Engineering

In recent years, the transition metal dichalcogenide MoS2 has gained attention as an interesting material system for basic research and possible optoelectronic applications. Monolayer MoS2 crystal is a direct-gap semiconductor with a band gap of 1.9ev, which makes it promising candidate for optoelectronic applications, such as light emitter and photodetector. However, the natural n-type of monolayer MoS2 on Si substrate produces great limitations on the luminous performance of the material. For above reasons, we studied the photoluminescence enhancement of MoS2, the contents are as followed:1. Enhanced Photoluminescence (PL) properties of monolayer MoS2 through annealing treatment in ambient were investigated. The PL intensity can be improved by two orders in this convinient method. The enhancement is mainly attributed to the p-type doping by Mo-O bonds as well as the defects-assisted localization of the electrons to suppress non-radiative processes.2. We have investigated the PL properties of the monolayer MoS2 films by dipping into the H2O2 aqueous solution. We found that PL properties of MoS2 could be tuned by this chemical dipping technique. The PL intensity of monolayer MoS2 is drastically enhanced by H2O2 for its strong affinity to electrons, resuting in the p-doping effect for MoS2 films; and this enhancement can be preserved under vacuum condition.3. Series of SixC1-x:H films were prepared by using plasma-enhanced chemical vapor deposition system. By increasing the flux ratio of the gas source (R=CH4/SiH4), we found that the peak position of the PL blue shift due to the quantum confinement of Silicon nanoclusters. At the same time, the optical properties of the films are analyzed by Ellipsometry and FT-IR measurement. Meanwhile, the PL was greatly enhanced by 3D nanowire structure of the film For its higher external quantum efficiency.