Structures, stabilities, and electronic properties of defects in monolayer black phosphorus.

Xi-Bo Li,Teng-Fei Cao,Pan Guo,Woon-Ming Lau,Hao Liu,Li-Min Liu

doi:10.1038/srep10848

Xi-Bo Li, Teng-Fei Cao + Show 4 more

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https://doi.org/10.1038/srep10848

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Abstract

The structures, stabilities, and electronic properties of monolayer black phosphorus (M-BP) with different kinds of defects are investigated within the frame of density-functional theory. All the possible configurations of defects in M-BP are explored, and the calculated results suggest that the stabilities of the configurations with different kinds of defects are greatly related to broken bonds, structural deformation and the character of the bonding. The configurations with two or three vacancies are energetically more favorable than the ones with a single vacancy. Meanwhile, the doping of two foreign atoms, such as sulfur, silicon or aluminum, is more stable than that of the corresponding single dopant. The electronic properties of M-BP are greatly affected by the types of defects. The single S-doped M-BP not only retains the character of a direct semiconductor, but it also can enlarge the band gap by 0.24 eV relative to the perfect one. Such results reveal that the defects not only greatly affect the electronic properties, but they also can be used as an effective way to modulate the band gap for the different applications of M-BP in electronic devices.

Highlights

That there were no deep gap states in GB and the deep gap states in the nanoribbons could be eliminated by passivation
Edv is the total energy of M-BP with vacancies, and Eper represents the total energy of perfect M-BP. n stands for the number of the removed phosphorus atoms and μ P is the chemical potential of bulk phosphorus
The calculated band gap of M-BP is smaller than the experimental value of 2.0 eV23, which should be the reason that pure density functional theory (DFT) usually underestimates the band gap of semiconductor because of self-interaction error

Summary

Computational details

The calculations were carried out within the frame of density functional theory (DFT), as implemented in the Vienna ab-initio simulation package (VASP)[39]. A 4 × 4 × 1 and a 3 × 3 × 1 supercell M-BP was adopted to accommodate vacancies and foreign atoms doping, respectively. To explore the relative stability of the configurations, we define the formation energies, Efv, of the vacancies M-BP as the following equation,. N stands for the number of the removed phosphorus atoms and μ P is the chemical potential of bulk phosphorus. In order to know the relative stabilities of foreign atom substitution, the formation energies of. Where Eds is the total energy of M-BP doped with the number m S, Si or Al atoms. K and m stand for the number of P, doped S, Si or Al atoms in the doped M-BP configuration, respectively. K and m stand for the number of P, doped S, Si or Al atoms in the doped M-BP configuration, respectively. μ b is the chemical potential of bulk sulfur, silicon or aluminum

Results and discussions

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