Isoelectronic Tungsten Doping in Monolayer MoSe₂ for Carrier Type Modulation

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Two-dimensional transition metal dichalcogenides (TMDs) exhibit unique electronic properties.
• Controlling carrier type in monolayer TMDs is crucial for advanced electronic devices.
• Molybdenum diselenide (MoSe2) is a prominent n-type semiconductor in the TMD family.

Purpose of the Study:

• To demonstrate carrier-type modulation in 2D transition metal dichalcogenides.
• To convert n-type monolayer MoSe2 into a p-type semiconductor via isoelectronic doping.
• To investigate the origin of p-type conduction in the resulting alloy.

Main Methods:

• Isoelectronic doping of monolayer MoSe2 with tungsten (W).
• Synthesis of mesoscopically uniform monolayer Mo1-xWxSe2 alloys.
• Analysis of valence band shifts and conduction mechanisms.

Main Results:

• Successful conversion of n-type monolayer MoSe2 to nondegenerate p-type monolayer Mo1-xWxSe2.
• Mesoscopic uniformity of the synthesized Mo1-xWxSe2 alloys.
• Identification of highly localized "W-rich" regions as the origin of p-type conduction.

Conclusions:

• Isoelectronic doping is an effective strategy for carrier-type modulation in 2D TMDs.
• Localized compositional fluctuations can dictate electronic properties in alloyed TMDs.
• Understanding these localized effects is key for designing next-generation 2D electronic devices.