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

Area of Science:

• Materials Science
• Nanotechnology
• Solid-State Physics

Background:

• Two-dimensional (2D) transistors require gate dielectrics with high dielectric constant, wide bandgap, breakdown strength, and environmental stability for practical use.
• Existing dielectrics often fail to meet these combined requirements, hindering the development of reliable 2D electronic devices.

Purpose of the Study:

• To introduce 2D single-crystalline terbium oxychloride (TbOCl) nanosheets as a novel gate dielectric material.
• To evaluate the performance and stability of TbOCl as a dielectric for 2D field-effect transistors (FETs).

Main Methods:

• Fabrication of 2D single-crystalline TbOCl nanosheets.
• Characterization of TbOCl dielectric properties (dielectric constant, bandgap, breakdown field).
• Integration of TbOCl as a gate dielectric in Molybdenum disulfide (MoS2) FETs and fabrication of logic inverters.

Main Results:

• TbOCl exhibits a high dielectric constant (12.5), ultrawide bandgap (~6.6 eV), and high breakdown field (11.9 MV cm⁻¹).
• MoS2 FETs with TbOCl show excellent electrostatic control (subthreshold swing of 72 mV dec⁻¹), low hysteresis (8 mV), and minimal gate leakage current (~10⁻¹³ A).
• TbOCl-based devices demonstrate remarkable ambient stability for over 9 months and fast switching in logic inverters (rise/fall times of 80/16 µs).

Conclusions:

• TbOCl is a promising 2D dielectric material that reconciles competing demands for high performance and stability.
• The intrinsic dual-antioxidation mechanism contributes to the superior environmental stability of TbOCl.
• TbOCl offers a viable pathway for the development of reliable and high-performance 2D electronic devices.