Topological Dielectrics: Phase-Transitioned Topological Insulators for 2D Nanoelectronics

Abstract

Interfacial dead layers at the gate dielectric stacks act as series capacitors, limiting fundamental device scaling. In this work, we propose a topological dielectric （TD） concept with a dead layer-free gate dielectric/metal interface in a BiF3/Bi2Se3 stack formed by fluorinating the Bi2Se3 surface using SF6 plasma. The fluorinated Bi2Se3 surface, BiF3, acts as an insulator with a high dielectric constant, while the underlying Bi2Se3 maintains its metallic surface states, allowing the TD itself to function as a nearly ideal gate dielectric/metal stack with minimal interfacial dead layers. In particular, TD/MoS2 transistors achieve near-ideal subthreshold swing at room temperature, high on-off ratio within subvolt gate sweep, immunity to DIBL, and negligible hysteresis. Our work establishes surface-functionalized topological insulators as gate dielectric stacks for topologically designed nanoelectronics, eliminating interfacial dead layers and enabling superior device performance.