Reconstruction of low dimensional electronic states by altering the chemical arrangement at the SrTiO${}_3$ surface

Developing reliable methods for modulating the electronic structure of the 2D electron gas (2DEG) in SrTiO${}_3$ is crucial for utilizing its full potential and inducing novel properties. Herein, it is shown that relatively simple surface preparation reconstructs the 2DEG at the SrTiO${}_3$ (STO) surface, leading to a Lifshitz-like transition. Combining experimental methods, such as angle-resolved photoemission spectroscopy (ARPES) and X-ray photoemission spectroscopy with ab initio calculations, that the modulation of the surface band structures can be effectively achieved via transforming the chemical composition at the atomic scale is found. In addition, ARPES experiments demonstrate that vacuum ultraviolet light can be efficiently employed to alter the band renormalization of the 2DEG system and control the electron-phonon interaction . This study provides a robust and straightforward route to stabilize and tune the low-dimensional electronic structure via the chemical degeneracy of the STO surface. (© 2023 The Authors. Advanced Functional Materials published by Wiley‐VCH GmbH)