[Paper Review] Chemical scissors cut phosphorene nanostructures and their novel electronic properties

Xihong Peng, Qun Wei|arXiv (Cornell University)|May 5, 2014

2D Materials and Applications31 references18 citations

TL;DR

This study demonstrates that hydrogen, fluorine, chlorine, and hydroxyl groups act as 'chemical scissors' to selectively cut phosphorene into phosphorene nanoribbons and P-chains via strong covalent bonding with phosphorus atoms. First-principles calculations reveal that pristine P-chains exhibit a Dirac cone with a Fermi velocity of 8×10⁵ m/s, while edge-functionalized zigzag nanoribbons display tunable metallic or semiconducting behavior, enabling novel electronic applications in nanoelectronics.

ABSTRACT

Phosphorene, a recently fabricated two dimensional puckered honeycomb structure of phosphorus, showed promising properties for applications of nano-electronics. In this work, we report our findings of chemical scissors effects on phosphorene, using first principles density functional theory methods. It was found that several chemical species, such as H, F, Cl and OH group, can act effectively as scissors to cut phosphorene. Phosphorus chains and nanoribbons can be obtained using different surface coverage of the chemical species. The scissor effects of these species are resulted from their strong chemical bonds with the P atoms. Species such as O, S and Se were not able to cut phosphorene nanostructures due to their lack of strong binding with P. The electronic structure calculations of the produced P-chains reveal that the saturated chain is an insulator while the pristine chain demonstrates a Dirac point at X with a Fermi velocity of 8*10E5 m/s. The obtained zigzag phosphorene nanoribbons show either metallic or semiconducting behaviors, depending on the treatment of the edge P atoms.

Motivation & Objective

• To explore the feasibility of using chemical species as 'scissors' to precisely cut phosphorene into low-dimensional nanostructures.
• To identify which chemical species can effectively bind to phosphorene and induce structural cleavage.
• To investigate the resulting electronic properties of the generated P-chains and phosphorene nanoribbons.
• To determine the role of edge passivation in tuning the electronic behavior of zigzag phosphorene nanoribbons.

Proposed method

• Employed first-principles density functional theory (DFT) calculations to model the interaction between phosphorene and various chemical species.
• Simulated surface coverage of H, F, Cl, OH, O, S, and Se on phosphorene to assess their binding strength and cleavage efficiency.
• Analyzed the formation energy and bond characteristics to determine which species act as effective 'chemical scissors'.
• Performed electronic structure calculations on the resulting P-chains and nanoribbons to evaluate band dispersion and Fermi velocity.
• Compared the electronic properties of pristine versus passivated edge atoms in zigzag phosphorene nanoribbons.
• Used the DFT method to compute the band structure and identify the presence of Dirac cones in P-chains.

Experimental results

Research questions

• RQ1 Which chemical species can effectively act as 'chemical scissors' to cleave phosphorene into nanostructures?
• RQ2 How does the binding strength of chemical species with phosphorus atoms influence their scission capability?
• RQ3 What are the electronic properties of the resulting phosphorene nanoribbons and P-chains after chemical functionalization?
• RQ4 How does edge passivation affect the electronic behavior of zigzag phosphorene nanoribbons?
• RQ5 Does the pristine P-chain exhibit Dirac-like electronic dispersion, and what is its Fermi velocity?

Key findings

• H, F, Cl, and OH groups effectively act as 'chemical scissors' due to their strong covalent bonding with phosphorus atoms, enabling controlled cutting of phosphorene.
• O, S, and Se do not induce cleavage due to weak binding energies with phosphorus atoms.
• The pristine phosphorus chain exhibits a Dirac point at the X point in the Brillouin zone with a Fermi velocity of 8×10⁵ m/s.
• Saturated P-chains are insulating due to the absence of a gapless Dirac cone.
• Zigzag phosphorene nanoribbons show either metallic or semiconducting behavior depending on the passivation state of edge phosphorus atoms.
• The electronic structure of the nanostructures is highly tunable through selective chemical functionalization, enabling design of novel 2D electronic materials.