In Situ Active Switching of Bipolar Current Rectification in 2D Semiconductor Vertical Diodes

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Two-dimensional semiconducting transition-metal dichalcogenides (TMDCs) are key materials for miniaturized electronics.
• Current TMDC device functionality is fixed after fabrication, limiting reconfigurability.
• Developing active and reconfigurable TMDC devices is a significant challenge.

Purpose of the Study:

• To demonstrate current rectification switching in TMDC vertical diodes.
• To investigate the role of a liquid metal electrode and its surface layer in device reconfigurability.
• To explore the potential for tunable TMDC-based nanoelectronic devices.

Main Methods:

• Fabrication of TMDC vertical diodes utilizing a liquid metal (EGaIn) top electrode.
• Systematic variation of the EGaIn electrode's contact area.
• Analysis of electrical transport properties and photocurrent under different contact conditions.
• Investigation of the ultrathin gallium oxide layer's influence on electrical transport.

Main Results:

• Demonstrated current rectification switching in TMDC vertical diodes by altering the liquid metal electrode's contact area.
• Observed negative rectification under small contact due to photocurrent dominance, attributed to the gallium oxide layer.
• Achieved switching to positive rectification with increased contact area as the gallium oxide layer breaks down.
• Confirmed rectification switching in TMDC flakes as thin as 3 nm, enabled by soft electrical contact.

Conclusions:

• Liquid metal electrodes offer a pathway to actively reconfigurable TMDC vertical diodes.
• The interplay between contact area, gallium oxide layer, and photocurrent enables tunable rectification.
• This work promotes the development of flexible and tunable TMDC-based nanoelectronic devices.