Single exciton trapping in an electrostatically defined 2D semiconductor quantum dot

TL;DR

This paper demonstrates the trapping of single interlayer excitons in a 2D semiconductor quantum dot using electrostatic gating, revealing quantized energy jumps and enabling potential valleytronic applications.

Contribution

It introduces a novel electrostatic trapping method for single excitons in 2D semiconductors, with experimental evidence of quantized energy states and theoretical modeling.

Findings

Observation of discrete energy jumps indicating quantized exciton occupancy

Identification of the lowest energy emission as single exciton recombination

Power-dependent blue-shift of interlayer exciton energy

Abstract

Interlayer excitons (IXs) in 2D semiconductors have long lifetimes and spin-valley coupled physics, with a long-standing goal of single exciton trapping for valleytronic applications. In this work, we use a nano-patterned graphene gate to create an electrostatic IX trap. We measure a unique power-dependent blue-shift of IX energy, where narrow linewidth emission exhibits discrete energy jumps. We attribute these jumps to quantized increases of the number occupancy of IXs within the trap and compare to a theoretical model to assign the lowest energy emission line to single IX recombination.