Fig. 1: Illustration of interlayer exciton formation and relaxation in transition metal dichalcogenide heterobilayers. | Light: Science & Applications

Fig. 1: Illustration of interlayer exciton formation and relaxation in transition metal dichalcogenide heterobilayers.

From: A roadmap for interlayer excitons

Fig. 1

The top row illustrates the real-space side view of the heterobilayer separated by a distance d, and the bottom row shows the momentum-space type-II band alignment with the K valleys separated by a momentum Δq. a Photoexcitation (green arrow) generates intralayer excitons. b Electrons or holes tunnel into the opposite layer with a lower potential energy, and interlayer excitons form. c Interlayer excitons diffuse, recombine, and emit light (red arrow). Momentum conservation can be met by the contribution of additional momentum (brown arrow) from other quasiparticles such as phonons or by localization of the exciton on a defect. The interlayer distance Δd can be regulated by inserting thin insulators or by applying pressure, while the distance Δq in momentum space can be engineered by twisting

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