Band-gap tunability and dynamical instability in strained monolayer and bilayer phosphorenes

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Physics

Background:

• Phosphorene, a novel 2D material, has emerged with potential for advanced electronic devices.
• Recent fabrication of few-layer phosphorene field-effect transistors highlights its growing importance.
• Understanding phosphorene's response to mechanical stress is crucial for device applications.

Purpose of the Study:

• Investigate the effects of out-of-plane strain on monolayer and bilayer phosphorene.
• Analyze the evolution of electronic and phononic structures under vertical stress.
• Determine the critical factors governing strain-induced semiconductor-semimetal transitions.

Main Methods:

• First-principles calculations were employed to simulate strained phosphorene.
• Electronic band structures were analyzed to observe band gap changes.
• Phononic band structures were computed to assess lattice stability.

Main Results:

• Vertical strain effectively tunes the band gap of semiconducting phosphorene.
• Excessive vertical stress can induce dynamic instability, leading to reconstruction or phase transitions.
• Bilayer phosphorene exhibits a wider dynamically stable range under stress than monolayer phosphorene due to interlayer coupling.

Conclusions:

• Strain engineering offers a viable route for tuning phosphorene's electronic properties.
• Lattice stability, in addition to band gap closure, dictates semiconductor-semimetal transitions in strained phosphorene.
• This research provides essential insights for phosphorene-based device design and fabrication.