Synthesis and electronic structure of atomically thin 2H-MoTe₂.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Understanding the electronic structure of two-dimensional materials like molybdenum ditelluride (MoTe2) is vital for advanced nanoscale electronic and spintronic devices.
• Mechanical exfoliation is a key technique for producing high-quality, large-area atomic layers of transition metal dichalcogenides.

Purpose of the Study:

• To investigate the electronic band structure of monolayer (ML) and bilayer (BL) 2H-MoTe2 at the atomic layer limit.
• To compare experimental findings with theoretical calculations for a comprehensive understanding.
• To establish a reference for studying exotic quantum phenomena in MoTe2-based heterostructures.

Main Methods:

• Mechanical exfoliation to obtain millimeter-sized ML MoTe2 and smaller BL MoTe2 samples.
• Angle-resolved photoemission spectroscopy (ARPES) for experimental electronic structure determination.
• Density functional theory (DFT) calculations for theoretical modeling and comparison.

Main Results:

• ML MoTe2 is confirmed as a semiconductor with a direct band gap at the K point, with a measured gap of at least 0.924 eV in Rb-doped samples.
• BL MoTe2 exhibits similar band energies at the Γ and K points, suggesting a potential direct gap scenario.
• Interlayer coupling monotonically increases the spin-split band separation at K from ML to bulk MoTe2.

Conclusions:

• The study provides the first ARPES and DFT investigation of ML and BL MoTe2 electronic structures.
• The findings clarify the semiconducting nature of ML MoTe2 and suggest possibilities for BL MoTe2.
• This work serves as a foundational reference for understanding quantum anomalous Hall effects in MoTe2 moiré heterostructures.