Growth of Highly Oriented (VNbMoTaW)S2 Layers

Koichi Tanaka; Hicham Zaid; Toshihiro Aoki; Aditya Deshpande; Koki Hojo; Cristian V Ciobanu; Suneel Kodambaka

doi:10.1021/acs.nanolett.3c04521

Growth of Highly Oriented (VNbMoTaW)S₂ Layers

Nano Lett. 2024 Jan 10;24(1):493-500. doi: 10.1021/acs.nanolett.3c04521. Epub 2023 Dec 26.

Authors

Koichi Tanaka¹, Hicham Zaid¹, Toshihiro Aoki², Aditya Deshpande¹, Koki Hojo³, Cristian V Ciobanu⁴, Suneel Kodambaka^{1

5}

Affiliations

¹ Department of Materials Science and Engineering, University of California, Los Angeles, 410 Westwood Plaza, Los Angeles, California 90095, United States.
² Irvine Materials Research Institute (IMRI), University of California, Irvine, 644 Engineering Tower, Irvine, California 92697, United States.
³ Graduate Department of Micro-Nano Mechanical Science and Engineering, Nagoya University, Furo-cho, Nagoya 464-8601, Japan.
⁴ Department of Mechanical Engineering and Materials Science Program, Colorado School of Mines, Golden, Colorado 80401, United States.
⁵ Department of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States.

PMID: 38148179
DOI: 10.1021/acs.nanolett.3c04521

Abstract

Compositional tunability, an indispensable parameter for modifying the properties of materials, can open up new applications for van der Waals (vdW) layered materials such as transition-metal dichalcogenides (TMDCs). To date, multielement alloy TMDC layers are obtained via exfoliation from bulk polycrystalline powders. Here, we demonstrate direct deposition of high-entropy alloy disulfide, (VNbMoTaW)S₂, layers with controllable thicknesses on free-standing graphene membranes and on bare and hBN-covered Al₂O₃(0001) substrates via ultra-high-vacuum reactive dc magnetron sputtering of the VNbMoTaW target in Kr and H₂S gas mixtures. Using a combination of density functional theory calculations, Raman spectroscopy, X-ray diffraction, scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, we determine that the as-deposited layers are single-phase, 2H-structured, and 0001-oriented (V_0.10Nb_0.16Mo_0.19Ta_0.28W_0.27)S_2.44. Our synthesis route is general and applicable for heteroepitaxial growth of a wide variety of TMDC alloys and potentially other multielement alloy vdW compounds with the desired compositions.

Keywords: high-entropy; highly oriented growth; multielement; sputter deposition; transition-metal dichalcogenides.