Unraveling the Orientation-Dependent Electrical Anisotropy of Chemical Vapor Deposited Layered CoTe2 Nanostructures.

Anisotropic intralayer covalent bonds and interlayer van der Waals gaps of layered materials enable preferred epitaxial horizontal growth rather than vertically aligned and other orientational growth, thus hindering the systematic investigations of electrical properties for thermodynamically unstable crystallographic planes. Here, we achieve three different types of exposed crystallographic planes for layered CoTe2 nanostructures, by the fine-tuning of the elementary steps including nucleation and kinetic epitaxial growth processes, which could dramatically change traditional horizontal growth behaviors to obtain thermodynamically unstable crystallographic planes such as (11̅0) nanoflakes and (0102̅7̅) nanoribbons. The thermodynamic and kinetic modulation of various layered CoTe2 nanostructures could provide an ideal model platform for experimentally studying orientation dependent physical properties for low-dimensional layered materials. Thus, our systematic electrical conductance characterization reveals that both tilted van der Waals gaps in (0102̅7̅) nanoribbons and vertically aligned van der Waals gaps in (11̅0) nanoflakes reduced electron transport efficiency by 5.1 and 1.4 times compared to that of in-plane transport conditions, which result from weak charge hopping across the van der Waals gap and strong charge drift ability along in-plane chemical bonds. This work overcomes the bottleneck of traditional layer-by-layer horizontal growth of the (001) plane, providing a theoretical and experimental framework for designing anisotropic electronic devices based on thermodynamically unstable crystallographic planes.