Reconciling High-κ and Wide-Bandgap Dielectrics (TbOCl) with Intrinsic Stability in 2D Electronics

The practical implementation of two-dimensional (2D) transistors is fundamentally limited by the lack of gate dielectrics that can simultaneously deliver a high dielectric constant, a wide bandgap, strong breakdown strength, and long-term environmental stability-an often-overlooked yet critical requirement for reliable device integration. Here, we report 2D single-crystalline TbOCl nanosheets as gate dielectrics that uniquely reconcile these competing demands. TbOCl exhibits a high dielectric constant (12.5), an ultrawide bandgap (∼6.6 eV), and a high breakdown field (11.9 MV cm^-1). MoS₂ field-effect transistors (FETs) gated by TbOCl exhibit excellent electrostatic control, yielding a near-ideal subthreshold swing of 72 mV dec^-1, a small hysteresis of only 8 mV, and an ultra-low gate leakage current of ∼10^-13 A. Notably, TbOCl-based devices maintain ultrastable electrical performance after more than 9 months of ambient storage with negligible performance degradation. The superior stability originates from an intrinsic dual-antioxidation mechanism that effectively suppresses oxidative degradation of the dielectric. Furthermore, logic inverters fabricated with TbOCl gate dielectrics exhibit fast switching behavior, with rise and fall times of 80 and 16 µs, respectively. Together, these results establish TbOCl as a stable, high-performance 2D dielectric platform, offering a viable pathway toward reliable 2D electronic devices.