Twist Induced Tunability of Electronic and Optical Properties in a Van der Waal Janus Heterostructure

POSTER

Abstract

Tremendous research attention is currently in focus onto two-dimensional (2D) nano-materials and their heterostructure due to their rich physical properties and diverse technological applications [1, 2, 3]. Recent discoveries of 2D Janus materials with broken symmetry have shown promising potential for the current semiconductor industry due to their distinctive physical and chemical characteristics (strong Rashba effect, out-of-plane piezoelectric polarisation) [4, 5]. The 2D van der Waals heterostructures (vdWH) are smart artificial materials composed of two similar or different types of monolayers [6]. We have systematically studied the stability, electronic, and optical properties of nine different Janus vdWHs (MoS2/MoSeTe, MoS2/WSeTe, WS2/MoSeTe, WS2/WSeTe, MoSe2/MoSeTe, MoSe2/WSeTe, WSe2/MoSeTe, WSe2/WSeTe, and MoSeTe/WSeTe) through first-principles based calculations. Our results show that when TMD monolayers are stacked vertically with Janus monolayers, an intrinsic electric field appears because of the lack of mirror symmetry and charge accumulation, which leads to the origin of versatile properties in Janus vdWHs. In addition, the interlayer twist also induces an electronic phase crossover from indirect to direct bandgap semiconducting state at some specific rotation angles.

It is interesting to note that the Janus MoS2/MoSeTe (θ = 19.11°, 40.89°), WS2/WSeTe (θ = 19.11°, 30°), MoS2/WSeTe (θ = 19.11°), WSe2/MoSeTe (θ = 16.10°), WS2/MoSeTe (θ = 40.89°) vdWHs have direct bandgap with type-II band alignment, which is an essential parameter for photocatalytic water splitting applications. Furthermore, the Janus vdWHs are more efficient optical absorption from the UV to the visible light range. Our findings not only provide a compelling platform for exploring the behavior of the Janus vdWHs but also provides theoretical guidance for the designing of novel 2D nanodevices.

*SJR acknowledges the financial support received through DST INSPIRE Grant (Ref: DST/INSPIRE/04/2015/003087), DSTECR Grant (project's reference no. ECR/2017/002223).The authors gratefully acknowledge the support and resources provided by the PARAM SHIVAY Facility at the IIT BHU and PARAM YUVA Facility at CDAC, Pune under the National Supercomputing Mission of Government of India.

Publication: 1. Kar, S., A. K. Nair, and S. J. Ray. "Supreme enhancement of ferromagnetism in a spontaneous-symmetry-broken 2D nanomagnet." Journal of Physics D: Applied Physics 54, no. 10 (2020): 105001.
2. Rani, S., and S. J. Ray. "Detection of gas molecule using C3N island single electron transistor." Carbon 144 (2019): 235-240.
3. Kar, S., S. Rani, and S. J. Ray. "Stimuli assisted electronic, magnetic and optical phase control in CrOBr monolayer." Physica E: Low-dimensional Systems and Nanostructures 143 (2022): 115332.
4. Lu, Ang-Yu, Hanyu Zhu, Jun Xiao, Chih-Piao Chuu, Yimo Han, Ming-Hui Chiu, Chia-Chin Cheng et al. "Janus monolayers of transition metal dichalcogenides." Nature nanotechnology 12, no. 8 (2017): 744-749.
5. Palsgaard, Mattias, Tue Gunst, Troels Markussen, Kristian Sommer Thygesen, and Mads Brandbyge. "Stacked janus device concepts: abrupt pn-junctions and cross-plane channels." Nano letters 18, no. 11 (2018): 7275-7281.
6. Rani, S., and S. J. Ray. "DNA and RNA detection using graphene and hexagonal boron nitride based nanosensor." Carbon 173 (2021): 493-500.

Presenters

  • Subhasmita Kar

    • Indian Institute of Technology Patna

Authors

  • Subhasmita Kar

    • Indian Institute of Technology Patna

  • Puja Kumari

    • Indian Institute of Technology patna

  • Soumya J Ray

    • Indian Institute of Technology Patna
    • Indian Institute of Technology, Patna, India
    • Indian Institute of Technology Patna, India
    • INDIAN INSTITUTE OF TECHNOLOGY PATNA ,INDIA
    • IIT Patna
    • INDIAN INSTITUTE OF TECHNOLOGY PATNA,INDIA