Overall control of field emission from carbon nanotube paste-emitters through macro-geometries for high-performance electron source applications

Field-emitted electron beams from nanometer-scale materials like carbon nanotubes (CNTs) have the potential to regenerate electron source devices based on performance, form factor, and usability. Practically, digital X-ray tubes fabricated with strongly adhesive CNT paste-emitters produce very short and exact X-ray pulses compared with conventional thermionic devices, providing greatly enhanced X-ray images with minimal X-ray dose. Although screen-printed CNT paste-emitters have been studied for a relatively long time, their field electron emissions have not been fully understood or optimally designed for specific electron source applications, because of the complexity arising from the intrinsic printing property, along with process reproducibility and device configurations. Here, we report an approach for the overall control of field electron emissions from multi-dot CNT paste-emitters, including electron-beam trajectories based on emitter dot size, dot array distribution, and triode configurations, using experiments and computational simulations. The crucial factors, such as the unit dot size of the CNT emitters and the aspect ratio of the triode structure, were successfully extracted, and can be used in designing and producing high-performance field-emitted electron source devices. An in-depth study of the key factors affecting field emission characteristics was conducted using experiments and theoretical simulations with various geometries of triode-configured devices. The optimal design for a high-performance field emission device can be realized by manipulating of the key factors, such as the unit dot size of the CNT emitters and the geometrical ratio of the triode structure, which affects the trajectory and divergence of the field emitted electron beams. [Display omitted] •An in-depth study for the key factors affecting field emission characteristics.•The overall control of field emissions from multi-dot CNT paste-emitters by experiments and computational simulations.•The effect of e-beam trajectories based on emitter dot size and macro-geometric factors.