Control of exciton transport/dynamics in 2D materials using surface acoustic waves

Monolayer 2D semiconductors are highly suitable for realizing ultrafast, energy efficient, room temperature excitonic devices for information transfer, encoding and processing. This is primarily due to the existence of high binding energy excitons in a material system in which transport is primarily governed by bands. The atomic level thickness further enables vertical scaling beyond the limits of bulk 3D semiconductors. More importantly, the vast and enriched excitonic properties of 2D materials are extremely sensitive to external stimuli and therefore can be successfully probed as well as manipulated using electric field, magnetic field, doping, mechanical forces, dielectric environment etc. Propagating surface acoustic wave (SAW) is one approach that can utilize the mechanical flexibility of the 2D material system to efficiently control the exciton photophysics. Over the past few years, many exciting studies have been reported on SAW interaction with charge carriers as well as excitons in 2D materials. In this chapter, we discuss the results of excitonic interactions with the traveling strain and electric field associated with the propagating SAW. In particular, we focus on room temperature experimental demonstration of directional exciton transport under traveling strain wave and exciton modulation due to the traveling electric field.