Enhanced optical absorption in conformally grown MoS2 layers on SiO2/Si substrates with SiO2 nanopillars with a height of 50 nm

Abstract

The integration of transition metal dichalcogenide (TMDC) layers on nanostructures has attracted growing attention as a means to improve the physical properties of the ultrathin TMDC materials. In this work, the influence of SiO₂ nanopillars (NPs) with a height of 50 nm on the optical characteristics of MoS₂ layers is investigated. Using a metal organic chemical vapor deposition technique, a few layers of MoS₂ were conformally grown on the NP-patterned SiO₂/Si substrates without notable strain. The photoluminescence and Raman intensities of the MoS₂ layers on the SiO₂ NPs were larger than those observed from a flat SiO₂ surface. For 100 nm-SiO₂/Si wafers, the 50 nm-NP patterning enabled improved absorption in the MoS₂ layers over the whole visible wavelength range. Optical simulations showed that a strong electric-field could be formed at the NP surface, which led to the enhanced absorption in the MoS₂ layers. These results suggest a versatile strategy to realize high-efficiency TMDC-based optoelectronic devices.