Abstrakt

Carbon nanomaterials like nanotubes, nanoflakes/nanowalls and graphene have been used as electron sources due to their superior field electron emission (FEE) characteristics. Nevertheless, these materials show poor stability and a short lifetime, preventing them from being used in practical device applications. The intention of this study was to find an innovative nanomaterial, possessing both high robustness and reliable FEE behavior. A hybrid structure of self-organized multilayered graphene (MLG)boron doped diamond (BDD) nanowall materials with superior FEE characteristics are successfully synthesized using a microwave plasma enhanced chemical vapor deposition process. Transmission electron microscopy reveals that the carbon clusters thus prepared are of uniform, dense and sharp nanowall morphology with sp3 diamond cores encased by an sp2 MLG shell. Detailed nanoscale investigations by peak force-controlled tunneling atomic force microscopy show that each of the core-shell structured carbon clusters field emits electrons equally well. The MLG-BDD nanowall materials show a low turn-on field of 2.4 V/μm, a high emission current density of 4.2 mA/cm2 at an applied field of 4.0 V/μm, a large field enhancement factor of 4500 and prominently high lifetime stability lasting for 700 min, enlightening their superiority on comparison with other hybrid nanostructured materials. The potential in practical device applications for these MLG-BDD hybrid nanowall materials is further illustrated by the plasma illumination behavior of a microplasma device, which used these materials as cathode, where low threshold voltage of 330 V (low threshold field of 330 V/mm) and long plasma stability of 358 min are demonstrated. The fabrication of these hybrid nanowalls is straight forward and thereby opens up a pathway for the advancement in next generation cathode materials for high brightness electron emission and microplasma-based display devices.

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