Optical Visualization of Carrier Surfing in 2D Monolayers Driven by Surface Acoustic Waves

Abstract

Charge carrier transport is pivotal in advancing nanoelectronics. Despite progress in exciton transport within ultra-thin semiconductors, the intertwined transport of free carriers and excitons presents challenges. Surface Acoustic Waves (SAWs) offer a compelling solution, enabling remote, real-time control of excitonic states at room temperature via surfing carriers in 2D materials—a relatively unexplored domain. SAWs create a versatile platform for tailoring excitonic states from microwave to optical frequencies. This study first demonstrates a simple route to visualize directional light transport and carriers drift driven by non-perfect Rayleigh-SAWs. Carrier surfing is observed under SAW modulation, with a charge redistribution rate of ≈16.4 µm s−1, significantly exceeding their natural redistribution in monolayers without SAW, while the drift velocity of free electrons remains on the order of ≈103 m s−1. Enhanced exciton emission is achieved through standing SAWs, generating periodic oscillations. By combining traveling and standing wave portions, controllable on-demand single-chip emission is feasible. The findings open avenues for light manipulation, photonic circuits, and on-chip communications technologies. Show more