Layer-dependent electronic, vibrational and optical properties of 2D AlSe crystals

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Layered materials offer unique electronic and structural properties.
• Aluminum selenide (AlSe) is a promising material for electronic applications.
• Understanding the properties of AlSe across different dimensionalities is crucial.

Purpose of the Study:

• To theoretically investigate the structural, electronic, and dynamical properties of bulk and few-layer AlSe.
• To explore the impact of stacking and layer number on AlSe properties.
• To analyze the vibrational and spectroscopic characteristics of AlSe systems.

Main Methods:

• Utilizing density functional theory (DFT) for structural and electronic property calculations.
• Employing density functional perturbation theory (DFPT) for dynamical property analysis.
• Applying various exchange-correlation functionals and including quasiparticle corrections.

Main Results:

• Identified a stable Se-Al-Al-Se tetralayer structure for AlSe.
• Determined all studied AlSe systems are indirect semiconductors with tunable band gaps.
• Observed similar phonon behavior across layers, indicating dynamical stability, with distinct spectral differences between bulk and 2D AlSe.

Conclusions:

• Layered AlSe structures are dynamically stable and possess tunable electronic properties.
• Quasiparticle corrections significantly impact the calculated band gaps of AlSe.
• Raman and IR spectra provide distinct fingerprints for bulk and layered AlSe, useful for material characterization.