Competition between Bipolar Conduction Modes in Extrinsically p-Doped MoS₂: Interaction with Gate Dielectric Matters

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) semiconductors possess unique electronic properties sensitive to their environment.
• Understanding extrinsic charge carrier behavior is crucial for device functionality.

Purpose of the Study:

• To investigate the physical origin of competing intrinsic and extrinsic charge conduction in p-doped MoS2.
• To explore the role of amorphous gate dielectric interactions on charge transport.

Main Methods:

• Utilized hexagonal boron nitride (h-BN) spacers to control dielectric interaction modes (noncontact, proximity, direct-contact).
• Employed Kelvin probe force microscopy and Raman spectroscopy.
• Performed first-principles calculations.

Main Results:

• Direct contact with SiO2 induced ambipolar conduction in p-doped MoS2 due to charge transfer and orbital mixing.
• Dielectric interactions caused n-type doping in the MoS2 channel, attributed to silicon dangling bonds.
• h-BN spacers modulated conduction: noncontact maintained p-type, proximity enabled gate-responsive p-type.

Conclusions:

• Dielectric engineering is critical for optimizing 2D semiconductor devices.
• Interface control is essential for enhancing p-type transistor performance in MoS2.