Weak Interlayer Interaction in 2D Anisotropic GeSe₂.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Germanium diselenide (GeSe2) is a 2D material with anisotropic properties, a wide bandgap, and air stability.
• Its potential in polarization-sensitive photodetection is recognized.
• Interlayer interactions are crucial for layer-dependent properties in 2D materials but remain unstudied for GeSe2.

Purpose of the Study:

• To systematically investigate the interlayer coupling in germanium diselenide (GeSe2).
• To compare the interlayer interaction of GeSe2 with that of black phosphorus (BP).
• To elucidate the role of interlayer interaction in the physical properties of GeSe2.

Main Methods:

• Density functional theory (DFT) calculations were employed to study band structures, cleavage energy, binding energy, translation energy, and interlayer differential charge density.
• Experimental validation involved analyzing thickness-dependent and temperature-dependent Raman spectra of GeSe2 flakes.

Main Results:

• DFT calculations revealed significantly weaker interlayer interactions in GeSe2 compared to black phosphorus (BP).
• Thickness-dependent Raman spectra showed no detectable changes with increasing flake thickness.
• Temperature-dependent Raman spectra indicated a small first-order temperature coefficient (-0.0095 cm⁻¹ K⁻¹).

Conclusions:

• The study confirms GeSe2 possesses weak interlayer coupling, distinguishing it from other 2D materials.
• These findings establish GeSe2 as an unusual 2D material with unique characteristics due to its weak interlayer interaction.
• The weak interlayer interaction is key to understanding GeSe2's layer-dependent physical properties and potential applications.