Large and Uniform Single Crystals of MoS2 Monolayers for ppb-Level NO2 Sensing

Recently, unprecedented interest has been immersed toward the synthesis of two-dimensional (2D) transition metal dichalcogenides via the chemical vapor deposition (CVD) system. Synthesis of a uniform and large-sized monolayer MoS2 atomic thin film via CVD is still a major bottleneck owing to strong dependence on diverse associated growth parameters. In this work, we have proposed the most viable recipe which is suitable for controlling the nucleation density of Mo and producing a 90 mu m-long MoS2 monolayer crystal and (695 x 394.8) mu m(2) large MoS2 monolayered film on SiO2/Si and c-plane sapphire, respectively. Moreover, MoS2 monolayer sensing performance has been thoroughly investigated for NO2 exposure at room temperature with a varying response of 4- 57.5 for the 100-100 ppm level. Furthermore, the MoS2 monolayer sensor exhibits an ultrasensitive NO2 detection with limit of detection and limit of qualification values of 1.4 and 4.6 ppb, respectively. In addition, the first-principles-based density functional theory has been employed to analyze the adsorption of NO2 on the surfaces of the 2D MoS2 monolayer. It is observed that the electronic band gap of the MoS2 monolayer after NO2 adsorption is reduced by 0.7 eV due to molecular orbital hybridization.

Automated summary

There has been great interest recently in synthesizing two-dimensional transition metal dichalcogenides using the chemical vapor deposition system. In this study, a viable recipe for controlling the nucleation density of Mo and producing large-sized MoS2 monolayer films was proposed. The sensing performance of the MoS2 monolayer for NO2 exposure was thoroughly investigated, and it showed ultrasensitive detection capabilities.