Wide Bandgap Lanthanide Oxybromides High-κ Dielectrics for High-Performance Two-Dimensional Electronics

High-κ single-crystal dielectrics serve as fundamental components in next-generation 2D electronics. However, the inevitable high leakage current caused by Schottky emission, which stems from the absence of a sufficiently wide bandgap in high-κ dielectrics, limits device performance. Here, we show that 2D lanthanide oxybromides (LnOBr, Ln = La, Ce, Nd, Sm, Eu, Gd, Ho, and Er) synthesized by the chemical vapor deposition method exhibit a wide bandgap (>5.7 eV), tunable thickness, and feature of high-quality single crystal. Meanwhile, 2D LaOBr single crystal displays high dielectric constant (14.8), low leakage current density (<10^-6 A cm^-2), and high breakdown field strength (14.2 MV cm^-1), suggesting good insulating property. As a result, the LaOBr top-gate MoS₂ transistors demonstrate competitive electrical performances, including a negligible hysteresis (0.72 mV/(MV cm^-1)), high on/off ratio (10⁷), near-Boltzmann-limit subthreshold swing (63 mV dec^-1), excellent electrical reliability and thermal stability (up to 450 K). Accordingly, the well-performed inverter is integrated, with a steep voltage transition and high gain. This work develops abundant dielectric materials with a wide bandgap and a high dielectric constant for innovative high-performance 2D electronics.