A vertical WSe₂-MoSe₂ p-n heterostructure with tunable gate rectification.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Transition Metal Dichalcogenides (TMDs) are promising for electronic and optoelectronic applications.
• Vertical heterostructures offer unique electronic properties compared to lateral ones.
• Controlling the interface and properties of TMD heterostructures is crucial for device performance.

Purpose of the Study:

• To synthesize a continuous vertical molybdenum diselenide/tungsten diselenide (MoSe₂/WSe₂) p-n heterostructure.
• To investigate the electronic properties and device performance of the fabricated heterostructure.
• To demonstrate the tunability of the p-n diode characteristics using back-gate bias.

Main Methods:

• Utilized a sputtering-Chemical Vapor Deposition (CVD) method for synthesizing the vertical MoSe₂/WSe₂ p-n heterostructure.
• Fabricated back-gated field-effect transistors (FETs) using WSe₂ and MoSe₂.
• Characterized the current-voltage (I-V) behavior of the vertical p-n diode under varying back-gate voltages.

Main Results:

• Achieved a continuous MoSe₂/WSe₂ p-n heterostructure, unlike conventional CVD methods.
• Demonstrated good gate modulation in WSe₂ and MoSe₂ FETs with high hole and electron mobilities (∼2.2 and ∼15.1 cm² V^-1 s^-1, respectively).
• Observed tunable rectifying behavior in the vertical p-n diode, with the rectification ratio increasing from ∼18 to ∼1600 as gate bias increased from -40 V to +40 V.

Conclusions:

• The sputtering-CVD method enables the synthesis of high-quality vertical TMD heterostructures.
• The back-gate tunability of the barrier height significantly enhances the diode's rectification ratio.
• The achieved rectification ratio surpasses previously reported values for CVD-grown TMD p-n heterostructures, highlighting potential for advanced electronic devices.