Dynamically controllable polarity modulation of MoTe₂ field-effect transistors through ultraviolet light and...

Area of Science:

• Nanoelectronics
• Materials Science
• Condensed Matter Physics

Background:

• Energy band engineering is crucial for advancing nanoelectronic devices.
• Electrical and optical methods offer more flexible in situ band tuning than chemical approaches.
• Molybdenum Ditelluride (MoTe2) is a promising 2D material for electronic applications.

Purpose of the Study:

• To demonstrate a novel method for modulating the energy bands of MoTe2 field-effect transistors.
• To achieve continuous, reversible, and in situ band tuning.
• To explore the potential for creating integrated devices like photodiodes on a single MoTe2 flake.

Main Methods:

• Utilizing a combined approach of electrostatic gating and ultraviolet (UV) light illumination.
• Applying this scheme to MoTe2 field-effect transistors.
• Characterizing the doping modulation, switching speed, field-effect mobility, and device performance.

Main Results:

• Achieved reversible doping modulation from deep n-type to deep p-type with ultrafast switching speeds.
• Observed significant improvements in field-effect mobility: ~30x for holes and ~2x for electrons.
• Successfully fabricated a photodiode on a single MoTe2 flake with excellent photo detection and photovoltaic properties.
• Demonstrated good spatial selectivity of the doping scheme.

Conclusions:

• The combined electrostatic gating and UV illumination method provides an effective and versatile approach for energy band engineering in MoTe2.
• This technique offers a generic doping strategy applicable to a broad range of 2D materials.
• The demonstrated capabilities pave the way for advanced nanoelectronic devices and integrated optoelectronic systems.