Long-Range Lattice Engineering of MoTe₂ by a 2D Electride

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Achieving high doping levels in 2D semiconductors is crucial for exploring superconductivity and phase transitions.
• Current methods like chemical functionalization and ionic gating have limited doping ranges (∼1 nm).

Purpose of the Study:

• To investigate long-range electron diffusion and extreme doping in 2D semiconductors.
• To explore the effects of high carrier densities on material properties, specifically lattice symmetry.

Main Methods:

• Utilizing a 2D electride, [Ca₂N]⁺·e^-, as an electron source for doping.
• Employing MoTe₂ as the target 2D semiconductor material.
• Characterizing electron diffusion over extended distances (up to 100 nm) and lattice changes.

Main Results:

• Demonstrated electron diffusion from [Ca₂N]⁺·e^- to MoTe₂ over 100 nm.
• Achieved an electron doping density exceeding 1.6 × 10¹⁴ cm^-2.
• Observed a change in MoTe₂ lattice symmetry due to extreme doping, extending beyond conventional junction widths.

Conclusions:

• 2D electrides enable unprecedented long-range, high-density electron doping in 2D semiconductors.
• The low work function and mobile electron layers of 2D electrides facilitate this effect.
• This approach offers a novel strategy for material design, combining doping and lattice engineering in layered materials.