Epitaxial Molybdenum Disulfide/Gallium Nitride Junctions: Low-Knee-Voltage Schottky-Diode Behavior at Optimized...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Semiconductor Device Physics

Background:

• Gallium nitride (GaN) and molybdenum disulfide (MoS₂) are advanced semiconductor materials with potential for electronic applications.
• Achieving high-performance heterojunctions requires precise control over interface properties.

Purpose of the Study:

• To develop a low turn-on voltage Schottky diode using a four-layer (4L) MoS₂/GaN junction.
• To investigate the impact of in situ interface preparation on the MoS₂/GaN heterostructure performance.

Main Methods:

• In situ interface preparation of GaN substrates followed by MoS₂ overlayer growth in a vacuum system.
• Characterization using low-energy electron diffraction (LEED), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS).
• Device performance evaluation through transport measurements and theoretical calculations using density functional theory (DFT).

Main Results:

• A nitrogen-terminated GaN surface was achieved, leading to a well-bonded MoS₂ film with a 2 × 2 interface reconstruction.
• Transport measurements demonstrated Schottky diode behavior with a low turn-on voltage of ~0.3 V and an on/off ratio of ~10⁵.
• DFT calculations supported the observed interface superstructure, and analysis indicated interface charge transfer from MoS₂ to GaN.

Conclusions:

• Optimized in situ preparation of the MoS₂/GaN interface is crucial for achieving low turn-on voltage Schottky diode behavior.
• The high performance of the MoS₂/GaN diode highlights its technological potential for future electronic devices.
• Understanding interface charge transfer is key to optimizing GaN/MoS₂ heterojunctions.