High-κ samarium oxysulfate dielectric for two-dimensional electronics with enhanced gate coupling.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Layered dielectric materials and van der Waals (vdW) heterostructures are crucial for next-generation 2D electronic devices.
• A scarcity of materials combining wide bandgaps and high dielectric constants hinders device advancement.

Purpose of the Study:

• To controllably synthesize quasi-vdW layered samarium oxysulfate (Sm2O2SO4) single crystals.
• To investigate the dielectric properties of Sm2O2SO4 for 2D electronic applications.
• To fabricate and characterize field-effect transistors (FETs) and non-volatile memory devices using Sm2O2SO4.

Main Methods:

• Molten-salt-assisted chemical vapor deposition (CVD) for Sm2O2SO4 synthesis.
• Integration of Sm2O2SO4 with 2D molybdenum disulfide (MoS2) via vdW forces.
• Fabrication of FETs and heterostructure-based memory devices.

Main Results:

• Atomically thin Sm2O2SO4 crystals with a wide bandgap (~5.54 eV), high dielectric constant (~18), and robust breakdown voltage (>12 MV cm-1).
• FETs demonstrated excellent performance: subthreshold swing (65.2 mV dec-1), low hysteresis (5.4 mV), high on/off ratios (~10^9), and low gate leakage currents (~7 × 10^-7 A cm-2).
• Non-volatile memory devices exhibited ultrafast operations (~50 ns P/E), high endurance (>2000 cycles), and long retention (>10 years) with a high gate coupling ratio (~0.83).

Conclusions:

• Sm2O2SO4 is a promising high-κ dielectric material for future 2D electronic devices.
• The synthesized Sm2O2SO4 enables the development of low-power, high-performance electronics.
• This work highlights the potential of Sm2O2SO4 in advanced electronic applications, including non-volatile memory.