Duan Research Group

Hetero-integrated Nanostructures and Nanodevices


Chemical Vapor Deposition Growth of Single Crystalline CoTe2 Nanosheets with Tunable Thickness and Electronic Properties

Huifang Ma, Weiqi Dang, Xiangdong Yang, Bo Li, Zhengwei Zhang, Peng Chen, Yuan Liu, Zhong Wan, Qi Qian, Jun Luo, Ketao Zang, Xiangfeng Duan, Xidong Duan

Chem. Mater. 30, 8891-8896 (2018)

Two-dimensional (2D) metallic transition metal dichalcogenides (MTMDs) have recently drawn increasing interest for fundamental studies and potential applications in catalysis, charge density wave (CDW), interconnections, spin-torque devices, as well superconductors. Despite some initial efforts, the thickness-tunable synthesis of atomically thin MTMDs remains a considerable challenge. Here we report controlled synthesis of 2D cobalt telluride (CoTe2) nanosheets with tunable thickness using an atmospheric pressure chemical vapor deposition (APCVD) approach and investigate their thickness-dependent electronic properties. The resulting nanosheets show a well-faceted hexagonal or triangular geometry with a lateral dimension up to ∼200 μm. Systematic studies of growth at varying growth temperatures or flow rates demonstrate that nanosheets thickness is readily tunable from over 30 nm down to 3.1 nm. X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution scanning transmission electron microscope (STEM) studies reveal the obtained CoTe2 nanosheets are high-quality single crystals in the hexagonal 1T phase. Electrical transport studies show the 2D CoTe2 nanosheets display excellent electrical conductivities up to 4.0 × 105 S m–1 and very high breakdown current densities up to 2.1 × 107 A/cm2, both with strong thickness tunability.
UCLA, Department of Chemistry and Biochemistry
607 Charles E. Young Drive East, Box 951569
Los Angeles, CA 90095-1569
E-mail: xduan@chem.ucla.edu