Modulation of electrical properties in MoTe₂ by XeF₂-mediated surface oxidation

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Transition metal dichalcogenides (TMDs) possess excellent electrical properties, making them attractive for semiconductor applications.
• Surface oxidation of TMDs, like molybdenum ditelluride (MoTe2), can effectively modulate their electrical characteristics.
• Controlling surface oxidation is key to optimizing TMD-based electronic devices.

Purpose of the Study:

• To demonstrate a XeF2-mediated surface oxidation method for 2H-MoTe2.
• To investigate the properties of the resulting oxidized layer and its impact on device performance.
• To utilize the oxidized layer for improved metal contacts in MoTe2 field-effect transistors (FETs).

Main Methods:

• Exposure of 2H-MoTe2 to XeF2 gas to form a surface oxide layer.
• Characterization of the oxide layer thickness and uniformity.
• Fabrication and electrical testing of MoTe2 FETs with and without the oxide interlayer.

Main Results:

• Formation of a thin, uniform ~2.5 nm MoOx layer on MoTe2 within 120 s, attributed to passivation and etching.
• Significant reduction in contact resistance by using the MoOx interlayer, overcoming Fermi level pinning.
• MoTe2 FETs with MoOx interlayer showed a two-order-of-magnitude increase in hole mobility (6.31 cm2 V-1 s-1) and a high on/off ratio (~10^5).

Conclusions:

• XeF2-mediated oxidation provides a straightforward and effective route to form thin oxide layers on MoTe2.
• The MoOx interlayer enhances MoTe2 FET performance by improving contact properties.
• This method holds promise for advancing the field of 2D electronics.