DEVICE TECHNOLOGY. Phase patterning for ohmic homojunction contact in MoTe₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) van der Waals heterostructures are crucial for next-generation electronics.
• Current fabrication methods face challenges like impurities, metastability, and inhomogeneity, limiting genuine 2D heterostructure devices.

Purpose of the Study:

• To develop a stable and efficient method for fabricating 2D heterostructures.
• To create an ohmic heterophase homojunction in molybdenum ditelluride (MoTe2) for improved device performance.

Main Methods:

• Utilized laser-induced phase patterning, a polymorph engineering technique.
• Fabricated a heterophase homojunction between semiconducting hexagonal (2H) and metallic monoclinic (1T') MoTe2.
• Employed in situ scanning transmission electron microscopy and theoretical calculations.

Main Results:

• Achieved a stable ohmic heterophase homojunction in MoTe2, stable up to 300°C.
• Increased MoTe2 transistor carrier mobility by approximately 50 times.
• Maintained a high on/off current ratio of 10^6.
• Identified Te vacancy as the trigger for local phase transition in MoTe2.

Conclusions:

• Laser-induced phase patterning enables the creation of true 2D devices with ohmic contacts.
• The fabricated MoTe2 heterostructure offers significantly enhanced electronic properties for advanced devices.