Electronic Structure Of Black Phosphorus Research Articles

Strain Effects on Properties of Phosphorene and Phosphorene Nanoribbons: a DFT and Tight Binding Study**Supported by the National Natural Science Foundation of China under Grant Nos 51572219 and 11447030, the Natural Science Foundation of Shaanxi Province of China under Grant Nos 2014JM2-1008 and 2015JM1018, and the State Key Laboratory of Transient Optics and Photonics Technology 2015 Annual Open Fund under

We perform comprehensive density functional theory calculations of strain effect on electronic structure of black phosphorus (BP) and on BP nanoribbons. Both uniaxial and biaxial strain are applied, and the dramatic change of BP’s band structure is observed. Under 0–8% uniaxial strain, the band gap can be modulated in the range of 0.55–1.06 eV, and a direct–indirect band gap transition causes strain over 4% in the y direction. Under 0–8% biaxial strain, the band gap can be modulated in the range of 0.35–1.09 eV, and the band gap maintains directly. Applying strain to BP nanoribbon, the band gap value reduces or enlarges markedly either zigzag nanoribbon or armchair nanoribbon. Analyzing the orbital composition and using a tight-binding model we ascribe this band gap behavior to the competition between effects of different bond lengths on band gap. These results would enhance our understanding on strain effects on properties of BP and phosphorene nanoribbon.

The Covalent Functionalization of Layered Black Phosphorus by Nucleophilic Reagents

AbstractLayered black phosphorus has been attracting great attention due to its interesting material properties which lead to a plethora of proposed applications. Several approaches are demonstrated here for covalent chemical modifications of layered black phosphorus in order to form P−C and P‐O‐C bonds. Nucleophilic reagents are highly effective for chemical modification of black phosphorus. Further derivatization approaches investigated were based on radical reactions. These reagents are not as effective as nucleophilic reagents for the surface covalent modification of black phosphorus. The influence of covalent modification on the electronic structure of black phosphorus was investigated using ab initio calculations. Covalent modification exerts a strong effect on the electronic structure including the change of band‐gap width and spin polarization.

The Covalent Functionalization of Layered Black Phosphorus by Nucleophilic Reagents.

Layered black phosphorus has been attracting great attention due to its interesting material properties which lead to a plethora of proposed applications. Several approaches are demonstrated here for covalent chemical modifications of layered black phosphorus in order to form P-C and P-O-C bonds. Nucleophilic reagents are highly effective for chemical modification of black phosphorus. Further derivatization approaches investigated were based on radical reactions. These reagents are not as effective as nucleophilic reagents for the surface covalent modification of black phosphorus. The influence of covalent modification on the electronic structure of black phosphorus was investigated using ab initio calculations. Covalent modification exerts a strong effect on the electronic structure including the change of band-gap width and spin polarization.

Disentangling bulk from surface contributions in the electronic structure of black phosphorus

Most recently, black phosphorus has come into focus as a promising material for future applications in nanoelectronic devices due to its unique electronic and transport properties. Here, we use angle-resolved photoemission spectroscopy in conjunction with ab initio calculations within the framework of density-functional theory to disentangle surface from the bulk contributions in the electronic structure of black phosphorus. We find good agreement between our theoretical predictions for the intra- and interlayer energy-momentum dispersions and the experimentally obtained three-dimensional band structure of this material. Our results provide compelling evidence for the existence of surface-resonant states near the top of the valence band, which can play an important role in the performance of electronic devices based on black phosphorus.

Tuning the band gap of black phosphorus

2D Materials Most materials used in electronics are semiconductors. The sizable energy gap in their electronic structure makes it easy to turn the conduction of electricity on and off. Graphene naturally lacks this band gap unless it undergoes certain modifications. Kim et al. studied the electronic structure of black phosphorus—a related two-dimensional material. By sprinkling potassium atoms on top of single layers of black phosphorus, the material changed from being a semiconductor to having a gapless linear dispersion similar to that of graphene. Science , this issue p. [723][1] [1]: /lookup/doi/10.1126/science.aaa6486

Measuring the Atomic and Electronic Structure of Black Phosphorus with STEM

Measuring the Atomic and Electronic Structure of Black Phosphorus with STEM

Atomic and electronic structure of exfoliated black phosphorus

Black phosphorus, a layered two-dimensional crystal with tunable electronic properties and high hole mobility, is quickly emerging as a promising candidate for future electronic and photonic devices. Although theoretical studies using ab initio calculations have tried to predict its atomic and electronic structure, uncertainty in its fundamental properties due to a lack of clear experimental evidence continues to stymie our full understanding and application of this novel material. In this work, aberration-corrected scanning transmission electron microscopy and ab initio calculations are used to study the crystal structure of few-layer black phosphorus. Directly interpretable annular dark-field images provide a three-dimensional atomic-resolution view of this layered material in which its stacking order and all three lattice parameters can be unambiguously identified. In addition, electron energy-loss spectroscopy (EELS) is used to measure the conduction band density of states of black phosphorus, which agrees well with the results of density functional theory calculations performed for the experimentally determined crystal. Furthermore, experimental EELS measurements of interband transitions and surface plasmon excitations are also consistent with simulated results. Finally, the effects of oxidation on both the atomic and electronic structure of black phosphorus are analyzed to explain observed device degradation. The transformation of black phosphorus into amorphous PO3 or H3PO3 during oxidation may ultimately be responsible for the degradation of devices exposed to atmosphere over time.

Electronic structure of black phosphorus studied by angle-resolved photoemission spectroscopy

Electronic structures of single crystalline black phosphorus were studied by state-of-art angleresolved photoemission spectroscopy. Through high resolution photon energy dependence measurements, the band dispersions along out-of-plane and in-plane directions are experimentally determined. The electrons were found to be more localized in the ab-plane than that is predicted in calculations. Beside the kz-dispersive bulk bands, resonant surface state is also observed in the momentum space. Our finds strongly suggest that more details need to be considered to fully understand the electronic properties of black phosphorus theoretically.

The influence of exact exchange corrections in van der Waals layered narrow bandgap blackphosphorus

We study the electronic structure of black phosphorus by combining state-of-the-art densityfunctional theory, multiple scattering calculations and electron energy loss spectroscopy.The hybrid functionals HSE03 and PBE0 are tested to investigate whether they give animproved description compared to the more traditional PZ-LDA and PBE-GGAfunctionals. These calculations are compared with investigations of the conduction bandusing electron energy loss spectroscopy and calculations based on the real-space multiplescattering approach, and previous determinations of the bandgap. The hybrid functionalHSE03 gives an improved correspondence with these experiments. Comparisons of thecalculated valence band with previous XPS studies yield acceptable agreement for thetraditional functionals, while the results from the hybrid functionals are less satisfactory,since the hybrid functionals overestimate the valence band width significantly.

Electronic structure of black phosphorus studied by polarized soft-x-ray emission and absorption spectroscopy

Soft-x-ray emission ($K\ensuremath{\beta}$ emission) and absorption ($K$ absorption) spectra of a black P single crystal polarized along each crystalline axis are presented for the first time. The experimental results indicate (1) the upper part of the valence band near the Fermi level is largely contributed by the $3{p}_{z}$ states, (2) the $3{p}_{y}$ orbital forms the middle to lower part of the $3p$-derived (or the first) valence band, (3) the $3{p}_{x}$ states spread over a whole range in the band, and (4) the conduction band has a clear but less drastic dependence on the nature of the constituent atomic orbitals. The emission and absorption curves were numerically calculated with the results of the band calculation of black P based on the self-consistent pseudopotential method and were compared with the experimental results. Excellent agreement has been found in the features of each spectrum, although a relative displacement of the emission and absorption spectra was observed between the experiment and the calculation. This discrepancy may be attributed to the overestimation of the $3p$-band width in the band calculation, although a many-body effect in the emission or absorption process cannot be entirely excluded.

Electronic structure of black phosphorus studied by X-ray photoelectron spectroscopy

The X-ray photoelectron spectrum of black phosphorus has been measured for the first time. The features in the valence band spectrum are found to be in good agreement with those of the valence state density recently calculated on the basis of a pseudopotential method. The 2 s and 2 p core spectrum of black phosphorus is also discussed.

Electronic Structure of Black Phosphorus in Self-Consistent Pseudopotential Approach

The energy band structure of black phosphorus is calculated by using self-consistent pseudopotential method. The resulting band structure has the direct minimum gap at the point Z in the Brillouin zone in agreement with the result of the tight-binding approach. Effective electron and hole masses and the level shift of the band edge by pressure are calculated from the bands obtained. The pressure dependence of the energy gap is in good agreement with experiment, but the anisotropy of the effective masses contradicts that of the electrical conductivity measured for the single crystal. The nature of the optical absorption edge is discussed in terms of the calculated band structure.

Electronic Structure of Black Phosphorus in Tight Binding Approach

The energy band structure of black phosphorus is calculated for the first time using the tight binding approach. It is shown that black phosphorus is a narrow gap semiconductor with the direct energy gap at the zone edge in the (0 0 k z ) direction. The pressure dependence of the energy gap is calculated to be -2.61 ×10 -2 eV/kbar, its experimental counterpart being -2.51 ×10 -2 eV/kbar. The optical absorption and the electrical conductivity of black phosphorus single crystals are discussed in terms of the calculated band structure.

Electronic structure of black phosphorus: Tight binding approach

The energy bands of black phosphorus, which is a narrow gap semiconductor with a layer structure consisting of puckered layers, are calculated for the first time using the tight binding approximation. On the basis of the resulting band structure, the electronic properties of black phosphorus are discussed.