Two-dimensional Bi₂SeO₂ and Its Native Insulators for Next-Generation Nanoelectronics.

Abstract

Silicon's dominance in integrated circuits is largely due to its stable native oxide, SiO₂, known for its insulating properties and excellent interface to the Si channel. However, silicon-based FETs face significant challenges when further scaled, which inspires the search for better semiconductors. While 2D materials such as MoS₂, WSe₂, BP, and InSe are promising, they lack a stable and compatible native oxide. High mobility (812 cm² V^-1 s^-1) 2D Bi₂SeO₂ stands out in this regard, as it can be oxidized into different forms of Bi₂SeO₅, thereby forming compatible high-κ native oxides. Despite growing interest in this material system, a comprehensive understanding of its fundamental properties is lacking. This study uses density functional theory and molecular dynamics simulations to investigate the intrinsic properties of Bi₂SeO₂, its native oxides, and its interfaces. Additionally, scanning transmission electron microscopy is employed to complement these theoretical analyses, providing detailed insights into the atomic-scale structure and interfaces of these materials. Building on these findings, we model semiconductor-oxide heterostructures and extract their intrinsic properties. Our results demonstrate that the atomically sharp and clean interface between oxide and semiconductor, the high dielectric constant (>30) of the oxide, and the sufficiently large conduction band offsets between the semiconductor and the most relevant β-phase of its native insulator (1.13 eV for holes and 1.55 eV for electrons) make this material system a strong candidate for future transistor technologies. These properties mitigate the limitations of traditional semiconductors and enhance device performance at the ultimate scaling limit, positioning 2D Bi₂SeO₂ as a suitable choice for next-generation nanoelectronics.