Copper halide diselenium: predicted two-dimensional materials with ultrahigh anisotropic carrier mobilities

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Two-dimensional (2D) materials offer unique electronic and optical properties.
• Exploration of novel 2D materials is crucial for advancing semiconductor technology.
• The parent bulk CuXSe2 was reported in 1969, but its 2D counterparts remain underexplored.

Purpose of the Study:

• To investigate the stability and electronic properties of CuXSe2 (X = Cl, Br) nanocomposite monolayers and bilayers.
• To assess the potential of these materials for optoelectronic applications.
• To determine the feasibility of exfoliating these 2D materials from their bulk form.

Main Methods:

• First-principles calculations were employed to simulate and analyze the material properties.
• Dynamical, mechanical, and thermodynamic stability were evaluated.
• Electronic band structures, carrier mobilities, and optical absorption coefficients were computed.

Main Results:

• CuXSe2 monolayers (X = Cl, Br) are dynamically, mechanically, and thermodynamically stable with low cleavage energies (~0.26 J m⁻²).
• Monolayers are indirect-gap semiconductors with a band gap of ~1.74 eV and exhibit extremely anisotropic, high carrier mobilities.
• Bilayers show slightly smaller band gaps (~1.54-1.59 eV), indicating weak interlayer quantum confinement. Monolayers possess high absorption coefficients (>10⁵ cm⁻¹) across the visible spectrum.

Conclusions:

• CuXSe2 (X = Cl, Br) nanocomposite monolayers are stable, easily exfoliable 2D materials.
• Their combination of moderate band gaps, high anisotropic carrier mobilities, and strong visible light absorption makes them promising candidates for optoelectronic devices.
• Further experimental investigation into these novel 2D materials is warranted.