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Electrically controllable router of interlayer excitons

Electrically controllable router of interlayer excitons

Abstract

Optoelectronic devices that allow rerouting, modulation, and detection of the optical signals would be extremely beneficial for telecommunication technology. One of the most promising platforms for these devices is excitonic devices, as they offer very efficient coupling to light. Of especial importance are those based on indirect excitons because of their long lifetime. Here, we demonstrate excitonic transistor and router based on bilayer WSe2. Because of their strong dipole moment, excitons in bilayer WSe2 can be controlled by transverse electric field. At the same time, unlike indirect excitons in artificially stacked heterostructures based on transition metal dichalcogenides, naturally stacked bilayers are much simpler in fabrication.

INTRODUCTION

Increasing demand for faster telecommunication technologies calls for the shift of signal processing from electronic to optical domain. A very promising opportunity in this area is provided by excitonic devices (15). These devices convert light into excitons, manipulate excitons by means of electric or magnetic fields, and convert excitons back to light. Of particular importance are devices based on indirect excitons, which offer much longer (up to two orders of magnitude) lifetime in comparison with the direct excitons (68).

Originally designed on the type II quantum wells in GaAs/AlGaAs heterostructures, these devices offered extended lifetime of indirect excitons (35, 9). With the advent of two-dimensional (2D) materials and, especially, transition metal dichalcogenides (TMDC), it became possible to form new types of type II quantum wells by combining TMDCs of different chemical compositions (1018). These materials are potentially more promising for optoelectronic devices because of larger exciton binding energy (hundreds of millielectronvolts), which should enable them to be operational at elevated temperatures. It has been demonstrated that the optoelectronic devices based on stacked monolayers

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