Spontaneous Polarity Flipping in a 2D Heterobilayer Induced by Fluctuating Interfacial Carrier Flows

Polarity often refers to the charge carrier type of a semiconductor or the charging state of a functional group, generally dominating their functionality and performance. Herein we uncover a spontaneous and stochastic polarity-flipping phenomenon in monolayer WSe2, which randomly switches between the n-type and p-type states and is essentially triggered by fluctuating carrier flows from or to the adjacent WS2 monolayer. We have traced such fluctuating carrier flows by interfacial photocurrent measurements in a zero-bias two-terminal device. Such polarity flipping results in switching between the negative and positive correlations between the emission intensities of WS2 and WSe2 in the heterobilayer, which is further well-controlled by the electrostatic gate-tuning experiments in a capacitor-structure device. Our work not only demonstrates giant and intermittent carrier flows through long-range coupling in 2D heterostructures and a consequent spontaneous polarity flipping phenomenon but also provides a two-emitter system with a switchable correlation sign that could project future applications in optical logic devices.

Automated summary

A spontaneous and stochastic polarity-flipping phenomenon has been discovered in monolayer WSe2, triggered by fluctuating carrier flows from or to the adjacent WS2 monolayer. This leads to switching between negative and positive correlations between the emission intensities of WS2 and WSe2 in the heterobilayer.