Ultra-Low Power CMOS Logic and Photodetection in WSe₂ Semiconductors by Selective Area Plasma Doping

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Tungsten diselenide (WSe2) is a 2D semiconductor with tunable carrier polarity, suitable for CMOS architectures.
• Surface oxidation is a method to control WSe2 polarity, but its electrostatic effects are not fully understood.

Purpose of the Study:

• To investigate oxide-induced electrostatic landscapes in WSe2.
• To engineer lateral p-n junctions in WSe2 using surface oxidation and selective oxide removal.
• To explore the electronic and optoelectronic properties of these engineered junctions.

Main Methods:

• Forming lateral junctions in few-layer WSe2 via surface oxidation and selective oxide removal.
• Utilizing modified broadband electrostatic force microscopy for nanoscale capacitance mapping.
• Employing Kelvin probe force microscopy to measure built-in surface potential.
• Fabricating field-effect transistors and complementary inverter circuits.

Main Results:

• Demonstrated oxide-defined lateral p-n junctions in WSe2 with a built-in potential of ~120 meV.
• Achieved ultralow static power consumption (~13 pW) in WSe2 complementary inverters.
• Showcased self-powered photovoltaic photodetection with submillisecond response times.

Conclusions:

• Spatially controlled polarity engineering in WSe2 is achievable through surface oxidation.
• Oxide-defined lateral junctions in WSe2 are a promising platform for ultralow-power electronics.
• This approach facilitates robust and reliable optoelectronic devices, including photodetectors.