Band Structure and Confined Interlayer Excitons in Switchable Ferroelectric R-WSe₂ Bilayers

This presentation will explore the rich physics of R-stacking bilayer WSe₂, a tunable ferroelectric system. We first introduce its unique electronic band structure. R-stacked 2D materials exhibit distinct optoelectronic properties influenced by interlayer coupling and a built-in polarization. In bilayer WSe₂, this intrinsic polarization, arising from its ferroelectric nature, strongly modulates the band structure.

By employing cryogenic optical spectroscopy, we investigate this highly tunable system with a particular focus on the interplay between the band structure and ferroelectric domains. Through the precise application of external electric fields and adjustment of carrier doping, we can effectively neutralize the built-in electric field. This enables carriers to be selectively localized in a specific layer, granting us fine control over the exciton and exciton-polaron (trion) energies and revealing intricate details of the material's electronic states. Importantly, these electric field manipulations also modulate the distribution of ferroelectric domains, providing deeper insights into the material’s local electronic environments.

The main focus will then shift to the profound impact of these ferroelectric domains. We demonstrate that they act as effective potential traps that confine and spatially localize interlayer excitons, leading to the formation of quantum dot-like emitters. Furthermore, we show that the flipping of these ferroelectric domains provides a powerful mechanism to tune both the band structure and the properties of the confined interlayer excitons. This work illuminates the intricate interplay between band structure tuning, ferroelectric domain behavior, and interlayer excitons, laying a robust foundation for novel quantum optoelectronic devices.