WS₂ Nano-petals and Nano-bristles Supported on Carbon Nanotubes for Electron Emission Applications

Atomically thin WS₂ nano-petals and nano-bristles were synthesized on vertically aligned carbon nanotubes (CNT) via magnetron sputtering at room temperature. The formation of the nano-petal morphology requires reaching a critical threshold in sputter deposition time, below which an amorphous film of WO₃ is obtained instead. Increasing the deposition time past a second threshold results in a change to the nano-bristle morphology. Both WS₂ nano-petals and nano-bristles were able to significantly enhance the electron emission of properties. The lowest turn-on voltage measured was to be 295 V and 355 V for the nano-petals and nano-bristles respectively, versus 425 V for pristine CNTs. The variation in the turn-on voltage is due to the electrical contacts at the interface between the different WS₂ structures, which induces current saturation at high emission currents. These results demonstrate that 2D WS₂ layers can be synthesized without the need for chemical routes and high growth temperatures if an appropriate template is employed.