Implementing Lateral MoSe₂ P-N Homojunction by Efficient Carrier-Type Modulation

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Atomically thin two-dimensional (2D) materials are crucial for nanoscale electronic and optoelectronic devices.
• Lateral p-n homojunctions offer advantages over vertically stacked ones but require precise carrier-type modulation within a single material flake, a significant technical challenge.

Purpose of the Study:

• To achieve effective carrier-type modulation in a single molybdenum diselenide (MoSe2) flake.
• To fabricate a lateral MoSe2 p-n homojunction using a novel sequential treatment method.

Main Methods:

• Sequential treatment of MoSe2 flakes involving air rapid thermal annealing (RTA) and triphenylphosphine (PPh3) solution coating.
• Characterization of carrier type modulation and mobility enhancement using field-effect transistor measurements.
• Fabrication and electrical/photoresponse characterization of the lateral MoSe2 p-n homojunction.

Main Results:

• Air RTA successfully converted naturally n-type MoSe2 to degenerated p-type, significantly improving hole mobility from 0.2 to 71.5 cm^2·V^-1·s^-1.
• PPh3 solution coating enhanced n-doping and electron mobility from 78.6 to 412.8 cm^2·V^-1·s^-1.
• The fabricated lateral MoSe2 p-n homojunction exhibited a high rectification ratio of 10^4, an ideality factor of 1.2, and an enhanced photoresponse of 1.3 A·W^-1 to visible light.

Conclusions:

• Demonstrated a viable method for carrier-type modulation within a single MoSe2 flake, enabling the creation of lateral p-n homojunctions.
• The achieved device performance highlights the potential of this approach for advanced nanoscale functional devices.
• This technique offers a promising pathway for future electronic and optoelectronic applications utilizing 2D materials.