Stacking stability of C2N bilayer nanosheet

Klichchupong Dabsamut,Adisak Boonchun,Sirichok Jungthawan,Jiraroj T-Thienprasert

doi:10.1038/s41598-019-43363-8

Klichchupong Dabsamut, Adisak Boonchun + Show 2 more

Open Access

https://doi.org/10.1038/s41598-019-43363-8

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Abstract

In recent years, a 2D graphene-like sheet: monolayer C2N was synthesized via a simple wet-chemical reaction. Here, we studied the stability and electronic properties of bilayer C2N. According to a previous study, a bilayer may exist in one of three highly symmetric stacking configurations, namely as AA, AB and AB′-stacking. For the AA-stacking, the top layer is directly stacked on the bottom layer. Furthermore, AB- and AB′-stacking can be obtained by shifting the top layer of AA-stacking by a/3-b/3 along zigzag direction and by a/2 along armchair direction, respectively, where a and b are translation vectors of the unit cell. By using first-principles calculations, we calculated the stability of AA, AB and AB′-stacking C2N and their electronic band structure. We found that the AB-stacking is the most favorable structure and has the highest band gap, which appeared to agree with previous study. Nevertheless, we furthermore examine the energy landscape and translation sliding barriers between stacking layers. From energy profiles, we interestingly found that the most stable positions are shifted from the high symmetry AB-stacking. In electronic band structure details, band characteristic can be modified according to the shift. The interlayer shear mode close to local minimum point was determined to be roughly 2.02 × 1012 rad/s.

Highlights

In order to accurately describe the effect of van der Waals interactions, we used the empirical correction method proposed by Grimme (GGA + D233 and GGA + D334) which is a good description of long-range vdW interactions[35,36,37]
It is well-known that density functional theory (DFT) underestimate band gap attributed to the self-interaction error (SIE), we used hybrid exchange-correlation functional to calculate the electronic band structure
The electronic band structures of the stable configuration express the same fashion as the high-symmetry AB stacking but they differ from AB-stacking in term of the energy gap and band line splitting

Summary

Introduction

Zhang et al.[25] performed DFT-GGA calculations to investigate the physical and electronic structures of monolayer and bilayer C2N. In their research[25], they are the first group who reported the structure and the stability of bilayer C2N, which provides three high-symmetry stacking orders (AA, AB and AB′-stacking) with different energy gaps.

Results

Conclusion