Solid Phase Epitaxy of Single Phase Two-Dimensional Layered InSe Grown by MBE

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Indium selenide exhibits polymorphism, making single-phase film growth challenging.
• Two-dimensional (2D) indium monoselenide (γ-InSe) possesses high electron mobility and photoresponsivity, desirable for electronic and optoelectronic applications.
• Existing methods face difficulties in achieving single-phase γ-InSe due to the material's polymorphic nature.

Purpose of the Study:

• To develop a reliable method for growing single-phase 2D γ-InSe films.
• To overcome the challenges associated with the polymorphic nature of indium selenide.
• To enable the use of 2D γ-InSe in advanced electronic and optoelectronic devices.

Main Methods:

• Growth of 2D α-In₂Se₃ film on a sapphire substrate using molecular beam epitaxy (MBE).
• Deposition of high In/Se ratio sources onto the α-In₂Se₃ surface.
• Induction of phase transition to γ-InSe via solid-phase epitaxy.

Main Results:

• Successful growth of single-phase 2D γ-InSe film.
• Transformation of 2D α-In₂Se₃ to 2D γ-InSe after 50 minutes of deposition.
• Confirmation of the phase transition using Raman spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM).
• Characterization of structural ordering using synchrotron-based grazing-incidence wide-angle X-ray scattering (GIWAXS).

Conclusions:

• Solid-phase epitaxy is an effective method for producing single-phase 2D γ-InSe films.
• The developed technique enables controlled phase transition from α-In₂Se₃ to γ-InSe.
• The findings pave the way for novel applications in field-effect transistors and optoelectronics.