Carrier-Type Modulation and Mobility Improvement of Thin MoTe₂

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Molybdenum ditelluride (MoTe2) is a promising 2D material for next-generation electronics.
• Controlling the carrier type in MoTe2 field-effect transistors (FETs) is crucial for device applications.
• Existing methods for modulating MoTe2 properties often lack precision or stability.

Purpose of the Study:

• To systematically modulate the carrier type in MoTe2 FETs.
• To enhance carrier mobilities and device stability using Al2O3 capping.
• To demonstrate the potential of this doping technique in fabricating functional electronic devices.

Main Methods:

• Rapid thermal annealing (RTA) under controlled O2 for p-type modulation.
• Benzyl viologen (BV) doping for n-type modulation.
• Al2O3 capping to improve device performance and stability.

Main Results:

• MoTe2 FETs showed tunable carrier types from n-type to p-type via RTA and BV doping.
• Oxygen absorption/dissociation at tellurium vacancies was identified as the mechanism for O2-induced modulation.
• Optimized n-type MoTe2 FETs achieved an on-off ratio exceeding 10^6.
• Al2O3 capping improved carrier mobilities (41 cm2 V−1 s−1 for holes, 80 cm2 V−1 s−1 for electrons) and stability.
• Lateral MoTe2 p-n diodes with an ideality factor of 1.2 were fabricated.

Conclusions:

• Systematic carrier type modulation in MoTe2 FETs is achievable through RTA and BV doping.
• Al2O3 capping significantly enhances device performance and stability.
• The developed doping technique shows great potential for fabricating advanced Mo2Te2-based electronic devices.