INVITED TALK -> Integrated Freestanding Transition Metal Dichalcogenides

We report on the integration of freestanding transition metal dichalcogenides (TMDs). Monolayer (1-L) MoS2, WS2, and WSe2 as representative TMDs were transferred on ZnO nanorods (NRs), used here as nanostructured substrates.... [ view full abstract ]

We report on the integration of freestanding transition metal dichalcogenides (TMDs). Monolayer (1-L) MoS2, WS2, and WSe2 as representative TMDs were transferred on ZnO nanorods (NRs), used here as nanostructured substrates. The photoluminescence (PL) spectra of 1-L TMDs on NRs showed a giant PL intensity enhancement, compared with those of 1-L TMDs on SiO2. The strong increases in Raman and PL intensities, along with the characteristic peak shifts, confirmed the absence of stress in the TMDs on NRs. In depth analysis of the PL emission also reveal that the ratio between the exiton and trion peak intensity is almost not modified after transfer. The later shows that the effect of charge transfer between the 1-L TMDs and ZnO NRs is here negligible. Furthermore, confocal PL and Raman spectroscopy revealed a fairly consistent distribution of PL and Raman intensities. These observations are in agreement with a very limited points contact between the support and the 1-L TMDs. The entire process reported here is scalable and may pave the way to the development of very efficient ultrathin optoelectronic devices.