Ultrafast response of spontaneous photovoltaic effect in 3R-MoS<sub>2</sub>-based heterostructures.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36525495.
- Also identified by DOI 10.1126/sciadv.ade3759 and PMC identifier 9757740.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Rhombohedrally stacked MoS<sub>2</sub> has been shown to exhibit spontaneous polarization down to the bilayer limit and can sustain a strong depolarization field when sandwiched between graphene. Such a field gives rise to a spontaneous photovoltaic effect without needing any p-n junction. In this work, we show that the photovoltaic effect has an external quantum efficiency of 10% for devices with only two atomic layers of MoS<sub>2</sub> at low temperatures, and identify a picosecond-fast photocurrent response, which translates to an intrinsic device bandwidth at ∼100-GHz level. To this end, we have developed a nondegenerate pump-probe photocurrent spectroscopy technique to deconvolute the thermal and charge-transfer processes, thus successfully revealing the multicomponent nature of the photocurrent dynamics. The fast component approaches the limit of the charge-transfer speed at the graphene-MoS<sub>2</sub> interface. The remarkable efficiency and ultrafast photoresponse in the graphene-3R-MoS<sub>2</sub> devices support the use of ferroelectric van der Waals materials for future high-performance optoelectronic applications.