We employ first principles density-functional theory (DFT) and the Bethe-Salpeter equation (BSE) in the framework of tight-binding based maximally localized Wannier functions (MLWF-TB) model to investigate the electronic and optical properties of free-standing two-dimensional (2D) germanium dioxide phases. All investigated 2D GeO2 polymorphs exhibit ultra-wide band gaps and strong excitonic effects, with flat O-p-derived valence bands tunable under strain. These features allow the design of flat band materials with ultra large electronic gaps in low-dimensional systems, making these materials promising for devices operation at higher voltages and temperatures than conventional semiconductor materials.
@article{arxiv.2510.24685,
title = {Flat bands in ultra-wide gap two-dimensional germanium dioxide},
author = {Rafael Franco Ribeiro Reis and Gabriel Elyas Gama Araujo and Danilo Kuritza and Alexandre Cavalheiro Dias and Andreia Luisa da Rosa and Renato Borges Pontes},
journal= {arXiv preprint arXiv:2510.24685},
year = {2025}
}