Excitons and optical spectra of phosphorene nanoribbons

Nourbakhsh, Zahra; Asgari, Reza

doi:10.1103/physrevb.94.035437

Cited by 40 publications

(43 citation statements)

References 50 publications

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“…This is also consistent with the presence of stronger quantum confinement effects in hydrogenpassivated PNRs of ZZ-1 edge as compared to AC edge. 20–23,25–29 By “stronger” it is meant that for a given NR width the PAGE quantum-confinement-induced increase in the band gap is larger, at least in the range of widths considered. Also, the band gap values decay away from the edge when the supercell size and radius dimensions result in a sizable “bulk” region.…”

Section: Resultsmentioning

confidence: 99%

“…For hydrogen-passivated AC and ZZ-1 PNRs it was found that with decreasing width the electronic band gap, optical band gap, and exciton binding energies all increase ( i.e ., the quantities all follow the quantum confinement trends). 29 Since an antidot lattice is closely related to a network of curved NRs, it is reasonable to assume that the scaling of the optoelectronic properties with the geometric features in the PNRs and the PALs will be similar. Furthermore, it is expected that the spatial distribution of the optical band gap in the PALs will also be bimodal.…”

Section: Resultsmentioning

confidence: 99%

“…The largest band gap atoms are present in the zigzag nanoconstrictions, which is consistent with the strength of quantum confinement effects in phosphorene nanoribbons. 20–23,25–29 …”

Section: Figurementioning

confidence: 99%

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Periodic Arrays of Phosphorene Nanopores as Antidot Lattices with Tunable Properties

Cupo

Das²,

Chien³

et al. 2017

ACS Nano

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A tunable band gap in phosphorene extends its applicability in nanoelectronic and optoelectronic applications. Here, we propose to tune the band gap in phosphorene by patterning antidot lattices, which are periodic arrays of holes or nanopores etched in the material, and by exploiting quantum confinement in the corresponding nanoconstrictions. We fabricated antidot lattices with radii down to 13 nm in few-layer black phosphorus flakes protected by an oxide layer and observed suppression of the in-plane phonon modes relative to the unmodified material via Raman spectroscopy. In contrast to graphene antidots, the Raman peak positions in few-layer BP antidots are unchanged, in agreement with predicted power spectra. We also use DFT calculations to predict the electronic properties of phosphorene antidot lattices and observe a band gap scaling consistent with quantum confinement effects. Deviations are attributed primarily to self-passivating edge morphologies, where each phosphorus atom has the same number of bonds per atom as the pristine material so that no dopants can saturate dangling bonds. Quantum confinement is stronger for the zigzag edge nanoconstrictions between the holes as compared to those with armchair edges, resulting in a roughly bimodal band gap distribution. Interestingly, in two of the antidot structures an unreported self-passivating reconstruction of the zigzag edge endows the systems with a metallic component. The experimental demonstration of antidots and the theoretical results provide motivation to further scale down nanofabrication of antidots in the few-nanometer size regime, where quantum confinement is particularly important.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Periodic Arrays of Phosphorene Nanopores as Antidot Lattices with Tunable Properties

Cupo

Das²,

Chien³

et al. 2017

ACS Nano

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“…According to the PNR edge structures, they are elementarily classified into two types, namely armchair PNRs (aPNRs) and zigzag PNRs (zPNRs). It has recently been shown by us that the charge distributions around the gap in aPNRs are localized in the middle of the nanoribbons, while in zPNRs they are mostly distributed in the width of the ribbons [10]. Consequently, physical properties of zPNRs are very sensitive to the width, structural defects, and edge morphologies.…”

Section: Introductionmentioning

confidence: 99%

Charge transport in doped zigzag phosphorene nanoribbons

Nourbakhsh

Asgari

2018

Phys. Rev. B

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The effects of lattice distortion and chemical disorder on charge transport properties of twoterminal zigzag phosphorene nanoribbons (zPNRs), which shows resonant tunneling behavior under an electrical applied bias, are studied. Our comprehensive study is based on ab initio quantum transport calculations on the basis of the Landauer theory. We use nitrogen and silicon substitutional dopant atoms, and employ different physical quantities such as the I − V curve, voltage drop behavior, transmission spectrum, transmission pathway, and atomic current to explore the transport mechanism of zPNR devices under a bias voltage. The calculated transmission pathways show the transition from a ballistic transport regime to a diffusive and in some particular cases to localized transport regimes. Current flowing via the chemical bonds and hopping are monitored, however, the conductance originates mainly from the charge traveling through the chemical bonds in the vicinity of the zigzag edges. Our results show that, in the doped systems, the device conductance decreases and the negative differential resistance characteristic becomes weak or is eliminated. Besides, the conductance in a pure zPNR system is almost independent of the ribbon width.PACS numbers:

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“…Electron-beam sculpting produces nanoscale constrictions over limited (< 15 nm) lengths rather than isolated nanoribbons 16 . Alternatively, e-beam lithography has, to date, only produced ribbons with minimum widths of ~60 nm and heights of ~3 nm (Ref 25) meaning their band gaps and electronic properties are close to those of bulk BP 2,3,14,20,22 . Such lithography also relies on first exfoliating and then crystallographically aligning BP, limiting the scalability essential for many applications.…”

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confidence: 99%

Production of phosphorene nanoribbons

Watts

Picco

Russell-Pavier

et al. 2019

Nature

234

193

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Phosphorene is a mono-elemental two-dimensional (2D) material with outstanding, highly directional properties and a thickness-tuneable band gap 1-8. Nanoribbons combine the flexibility and unidirectional properties of 1D nanomaterials, the high surface area of 2D nanomaterials and the electron-confinement and edge effects of both. Their structures can thus offer exceptional control over electronic bandstructure, lead to the emergence of novel phenomena and present unique architectures for applications 5,6,9-24. Motivated by phosphorene's intrinsically anisotropic structure, theoretical predictions of the extraordinary properties of phosphorene nanoribbons (PNRs) have been rapidly emerging in recent years 5,6,12-24. However to date, discrete PNRs have not been produced. Here we present a method for creating quantities of high quality, individual PNRs via ionic scissoring of macroscopic black phosphorus crystals. The top-down process results in stable liquid dispersions of PNRs with typical widths of 4 to 50 nm, predominantly single layer thickness, measured lengths up to 75 μm and aspect ratios of up to ~1000. The nanoribbons are atomically-flat single crystals, aligned exclusively in the zigzag crystallographic orientation. The ribbon widths are remarkably uniform along their entire length and they display extreme flexibility. These properties, in conjunction with the ease of downstream manipulation via liquidphase methods, now enable the search for predicted exotic states 6,12-14,17-19,21 and an array of applications where PNRs have been widely predicted to offer transformative advantages, ranging from thermoelectric devices to high-capacity fast-charging batteries and integrated high-speed electronic circuits 6,14-16,20,23,24. Phosphorene's anisotropic properties, including for electron, thermal and ionic transport, derive from its atomic structure where the atoms are arranged in corrugated sheets with two different P-P bond lengths (Fig. 1a) 1-8. Calculations predict that PNRs can possess enhanced characteristics compared with phosphorene and that their electronic structure, carrier mobilities and optical and mechanical properties can be tuned by varying the ribbon width, thickness, edge passivation, and by introducing strain or functionalization 6,12-14,20,22-24. Additionally, there have been numerous predictions of exotic effects in PNRs, including the spin-dependent Seebeck effect 17 , room temperature magnetism 6,21 , topological phase transitions 18 , large exciton splitting 14 and spin density waves 19. These results have led to suggestions of unique capabilities of PNRs in a number of applications such as thermoelectric devices 6,23 , photocatalytic water splitting 15 , solar cells 14 , batteries 6,24 , electronics 6,20,22 and quantum information technologies 14 .

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Excitons and optical spectra of phosphorene nanoribbons

Cited by 40 publications

References 50 publications

Periodic Arrays of Phosphorene Nanopores as Antidot Lattices with Tunable Properties

Periodic Arrays of Phosphorene Nanopores as Antidot Lattices with Tunable Properties

Charge transport in doped zigzag phosphorene nanoribbons

Production of phosphorene nanoribbons

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