Low Temperature MOCVD Synthesis of High-Mobility 2D InSe.

Area of Science:

• Materials Science
• Solid State Physics
• Semiconductor Research

Background:

• 2D indium selenide (InSe) is a layered semiconductor with desirable electronic properties, including high electron mobility and a tunable band gap.
• Growing phase-pure InSe is challenging due to the complex indium-selenium (In-Se) phase diagram and precursor sensitivity during synthesis.
• Metal-organic chemical vapor deposition (MOCVD) is a promising technique for wafer-scale, uniform InSe deposition essential for device integration.

Purpose of the Study:

• To systematically investigate the synthesis of 2D InSe using MOCVD on c-plane sapphire substrates at low temperatures.
• To establish a phase diagram for InSe synthesis by varying the Se/In precursor ratio and growth temperature.
• To identify optimal growth conditions for producing phase-pure 2D InSe with high electronic and optical properties.

Main Methods:

• Metal-organic chemical vapor deposition (MOCVD) was employed for InSe synthesis.
• Raman spectroscopy, atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), and scanning transmission electron microscopy (STEM) were used for material characterization.
• In-plane X-ray diffraction (XRD) verified epitaxial alignment.

Main Results:

• A comprehensive In-Se phase diagram was mapped, detailing In-rich, stoichiometric, and Se-rich phases based on precursor ratios and temperature.
• Optimized MOCVD conditions led to the formation of phase-pure 2D InSe.
• The synthesized InSe exhibited strong visible light absorption and high electron mobility.

Conclusions:

• Low-temperature MOCVD is effective for controlled synthesis of phase-pure 2D InSe.
• The established phase diagram provides crucial guidance for reproducible InSe growth.
• High-quality MOCVD-grown InSe demonstrates significant potential for advanced electronic and optoelectronic applications.