Defects and Strain Engineering of Structural, Elastic, and Electronic Properties of Boron-Phosphide Monolayer: A Hybrid Density Functional Theory Study.

Fang-Qiang Li,Sheng-Li Zhang,Yang Zhang

doi:10.3390/nano11061395

Fang-Qiang Li, Sheng-Li Zhang + Show 1 more

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https://doi.org/10.3390/nano11061395

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Abstract

Defects and in-plane strain have significant effects on the electronic properties of two-dimensional nanostructures. However, due to the influence of substrate and environmental conditions, defects and strain are inevitable during the growth or processing. In this study, hybrid density functional theory was employed to systematically investigate the electronic properties of boron-phosphide monolayers tuned by the in-plane biaxial strain and defects. Four types of defects were considered: B-vacancy (B_v), P-vacancy (P_v), double vacancy (D_v), and Stone–Wales (S-W). Charge density difference and Bader charge analysis were performed to characterize the structural properties of defective monolayers. All of these defects could result in the boron-phosphide monolayer being much softer with anisotropic in-plane Young’s modulus, which is different from the isotropic modulus of the pure layer. The calculated electronic structures show that the P_v, D_v, and S-W defective monolayers are indirect band gap semiconductors, while the B_v defective system is metallic, which is different from the direct band gap of the pure boron-phosphide monolayer. In addition, the in-plane biaxial strain can monotonically tune the band gap of the boron-phosphide monolayer. The band gap increases with the increasing tension strain, while it decreases as the compression strain increases. Our results suggest that the defects and in-plane strain are effective for tuning the electronic properties of the boron-phosphide monolayer, which could motivate further studies to exploit the promising application in electronics and optoelectronics based on the boron-phosphide monolayer.

Highlights

IntroductionTwo-dimensional (2D) nanostructures with an atomic thickness have attracted an increasing amount of attention due to their large surface-to-volume ratio and unique electronic properties
Our calculations were performed using the first-principles study based on spinpolarized density functional theory (DFT) within the projector augmented plane wave method, as implemented in Vienna ab initio simulation package (VASP) [27,28]
All of the studied boron-phosphide monolayers, including the pure, defective, and strained ones, were modeled in the x–y plane

Summary

Introduction

Two-dimensional (2D) nanostructures with an atomic thickness have attracted an increasing amount of attention due to their large surface-to-volume ratio and unique electronic properties. A representative for 2D nanostructures, was first prepared by mechanical exfoliation (repeated peeling) of highly oriented pyrolytic graphite in 2004 [1]. Due to its ultra-high electron mobility, anomalous quantum Hall effect, ballistic transport at room temperature, and atomic thickness, graphene has been regarded as an ideal candidate material for the generation of nanoelectronic devices [2,3,4]. Both silicene and graphene have a very high Fermi velocity, the gapless features limit their direct application in nanoelectronic and nanophotonic devices

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