Effective concentration ratio driven phase engineering of MBE-grown few-layer MoTe₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Ultrathin transition metal dichalcogenides (TMDCs) exhibit polymorphism, making phase engineering critical.
• Controlling phase in TMDCs is essential for tailored electronic and optoelectronic properties.

Purpose of the Study:

• To investigate the effect of growth parameters on phase engineering of few-layer MoTe2.
• To understand the mechanisms governing phase selectivity in MoTe2 growth.

Main Methods:

• Molecular beam epitaxy (MBE) for few-layer MoTe2 growth on sapphire.
• X-ray Photoelectron Spectroscopy (XPS) and Kelvin Probe Force Microscopy (KPFM) for characterization.

Main Results:

• The 2H phase of MoTe2 is stabilized within a specific range of flux ratio and growth temperature.
• The 1T' phase is favored outside this optimal regime.
• Effective Te/Mo concentration ratio at the growth surface dictates phase selectivity.
• Excess carrier doping contributes to phase transitions.

Conclusions:

• Growth parameter control enables versatile and precise phase engineering of few-layer MoTe2.
• This facilitates the fabrication of large-scale heterostructures for electronic and optoelectronic devices.