Computational discovery of two-dimensional tetragonal group IV-V monolayers.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Two-dimensional (2D) hexagonal group IV-V materials are of great interest for electronics, spintronics, and photocatalysis.
• Exploring new structural allotropes is crucial for expanding the potential applications of these materials.

Purpose of the Study:

• To discover and characterize a novel stable allotrope of 2D group IV-V monolayers.
• To investigate the electronic and structural properties of this new phase and its derivatives.

Main Methods:

• Utilized an adaptive genetic algorithm for structural searching.
• Employed first-principles calculations to determine geometric structures, stabilities, and band structures.
• Investigated the effects of surface hydrogenation on electronic properties.

Main Results:

• Discovered a stable tetragonal allotrope, Td4 phase, for 2D IV-V monolayers (Si, Ge, Sn with P, As, Sb).
• All pristine Td4-phase 2D IV-V monolayers are dynamically and thermodynamically stable and exhibit metallic behavior.
• Surface hydrogenation induces indirect semiconductor behavior in most Td4-phase 2D IV-V monolayers, with band gaps from 0.15 to 1.12 eV.

Conclusions:

• The Td4 phase represents a new structural motif in 2D group IV-V materials.
• Hydrogenated Td4-phase 2D IV-V monolayers show potential for semiconductor applications.
• This discovery enriches the landscape of low-dimensional materials for future technological advancements.