Spatially Controlled Phase Transition in MoTe₂ Driven by Focused Ion Beam Irradiations

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Phase transitions are crucial for tailoring the properties of two-dimensional (2D) materials for advanced device applications.
• Molybdenum ditelluride (MoTe2) exhibits distinct semiconducting (2H) and metallic (1T’) phases with unique electronic properties.

Purpose of the Study:

• To investigate the controlled induction of phase transitions in few-layered MoTe2 using focused ion beam (FIB) irradiation.
• To fabricate nanoscale in-plane heterostructures and improve device performance by leveraging these phase transitions.

Main Methods:

• Irradiation of few-layered MoTe2 flakes with gallium (Ga+) ions using a FIB system.
• Utilizing Te defect engineering to drive the semiconducting 2H to metallic 1T’ phase transition.
• Fabrication of submicrometer 1T’-2H MoTe2 in-plane homojunctions.

Main Results:

• Demonstrated controllable phase transition from 2H to 1T’-like MoTe2 via Ga+ ion irradiation.
• Successfully fabricated nanoscale 1T’-2H MoTe2 in-plane homojunctions.
• Achieved over two orders of magnitude improvement in the on-state current of MoTe2 transistors by using 1T’-like phase regions as contact electrodes.

Conclusions:

• Focused ion beam irradiation offers a novel strategy for inducing phase transitions in MoTe2.
• The ability to create patterned phases and heterojunctions enhances MoTe2-based device performance.
• This work expands the application of FIB technology in the field of 2D materials and devices.