Decoding ripple formation in single-layer transition metal chalcogenide lateral heterojunctions towards novel optoelectronic properties

Haitao Yu^{¹^,²}, Mingzi Sun^³, Xiao Wu^{¹^,²}, Zhiguo Xing^{¹^,²}, Jiahao Kou^{¹^,²}, Shipeng Liang^{¹^,²}, Bolong Huang^{¹^,²^,³^,⁴}

(), Zhong Lin Wang^{¹^,²^,⁵}()

1CAS Center for Excellence in Nanoscience, Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China

2School of Nanoscience and Technology, University of Chinese Academy of Sciences, Beijing 100049, China

3Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong 999077, China

4Research Centre for Carbon-Strategic Catalysis, The Hong Kong Polytechnic University, Hong Kong 999077, China

5School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA

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This work systematically explores the transition metal dichalcogenides (TMDCs) lateral heterojunctions with three types of ripples (unilateral, decaying, and bilateral ripples) from the computational perspective for the first time. The ripple formation process has been classified into different stages and its influences on different optoelectronic properties have been demonstrated, which is highly critical for achieving advanced photoelectric devices in broad applications.

Abstract

For the ultrathin two-dimensional (2D) materials and lateral heterojunction, the formation of unstable but elastic ripples is commonly observed but is rarely studied, especially their correlations with different material properties. To fill the knowledge gap in this field, this work systematically explores transition metal dichalcogenides (TMDCs) in a single component and lateral heterojunction with a series of ripple structures. The ripple formation energy is quantitatively classified into the initial elastic strain stage and fracture threshold stage based on Fermi-like distribution. Electronic structures reveal that the formation of ripples is accompanied by electron accumulations from flat surfaces to ripples. By comparing the unilateral, decaying, and bilateral ripples in 2D lateral heterojunction, we confirm that Fermi-like distribution is still valid regardless of the shape of the ripples, where the thermodynamic and electronic properties are modulated by ripples-induced uneven strain. The main features of optical properties are not affected while the sensitivity to ripple-induced strains is distinguished. More importantly, the phonon properties further demonstrate the potential of ripples in promoting thermal conductivity, which are strongly correlated with the optical branch of anion vibrations. This work provides important theoretical guidance for the design and optimization of high-performance optoelectronic devices based on TMDC heterojunctions.

Keywords

transition metal calcogenide lateral heterojunctions ripples optoelectronic properties two-dimensional (2D) materials

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References

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