Threshold Voltage Control through Solvent Doping of Monolayer MoS₂ Transistors

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Two-dimensional (2D) materials offer potential for next-generation electronics due to their atomic thinness.
• Doping 2D materials is crucial for high-performance logic devices, enabling tunable threshold voltage (VT).
• Achieving controlled doping in 2D materials without compromising device characteristics remains a significant challenge.

Purpose of the Study:

• To investigate the n-doping of monolayer molybdenum disulfide (MoS2) using solvents of varying polarity.
• To enhance transistor performance and understand the impact of solvent polarity on threshold voltage (VT).
• To explore solvent doping as a method for tuning carrier concentration and contact resistance in 2D devices.

Main Methods:

• Monolayer MoS2 field-effect transistors were fabricated.
• Exposure to solvents with different polarities was used for n-doping.
• Electrical characteristics, including threshold voltage (VT), on-current, and subthreshold swing, were measured.
• Schottky barrier width and contact resistance were analyzed.

Main Results:

• Solvent polarity predictably shifts the threshold voltage (VT) of MoS2 transistors.
• N-doping via solvents enhances the maximum on-current and reduces contact resistance.
• The doping process did not significantly degrade the subthreshold swing, preserving switching behavior.
• Solvent doping was found to reduce the Schottky barrier width.

Conclusions:

• Solvent polarity offers a controllable method for n-doping 2D materials like MoS2.
• This approach enables tuning of carrier concentration and threshold voltage (VT) for improved transistor performance.
• Solvent processing provides a pathway for optimizing contact resistance and advancing 2D electronic devices.