Nanosheets Derived from Titanium Diboride as Gate Insulators for Atomically Thin Transistors

Development and integration of gate insulators that offer a low equivalent oxide thickness (EOT) while maintaining a physically thicker layer are critical for advancing transistor technology as device dimensions continue to shrink. Such materials can deliver high gate capacitance and yet reduce gate leakage, thereby minimizing static power dissipation without compromising performance. These insulators should also provide the necessary interface quality, thermal stability, switching endurance, and reliability. Here, we demonstrate that nanosheets derived from titanium diboride (NDTD), synthesized at room temperature using a scalable dissolution-recrystallization method, exhibit EOT ∼ 2 nm irrespective of the physical thickness when used as top gate dielectrics for monolayer MoS₂ field effect transistors (FETs). Furthermore, these nanosheets enable near-ideal subthreshold swing of 60 mV/decade, low gate leakage current (<10^-4 A/cm²), and current on/off ratio of 10⁶ at a supply voltage of 1 V, indicating clean interface and excellent electrostatic control. These titanium diboride (TiB₂) derived nanosheet-gated MoS₂ FETs also demonstrate stable operation at 125 °C and switching endurance in excess of 10⁹ cycles. While nanosheets derived from metal diborides have been employed in energy storage, catalysis, and CO₂ capture, this study showcases their potential as excellent gate insulators for microelectronics.