Enhanced interfacial reaction of silicon carbide fillers onto the metal substrate in carbon nanotube paste for reliable field electron emitters

Adhesion of carbon nanotube (CNT) onto a cathode substrate is very crucial for field electron emitters that are operating under high electric fields. As a supporting precursor of CNT field emitters, we adopted silicon carbide (SiC) nano-particle fillers with Ni particles and then enhanced interfacial reactions onto Kovar-alloy substrates through the optimized wet pulverization process of SiC aggregates for reliable field electron emitters. As-purchased SiC aggregates were efficiently pulverized from 20 to less than 1 micro-meter in a median value (D50). CNT pastes for field emitters were distinctively formulated by a mixing process of the pulverized SiC aggregates and pre-dispersed CNTs. X-ray photoelectron spectroscopy studies showed that the optimally pulverized SiC-CNT paste-emitter had a stronger Si 2p(3/2) signal in the Ni2Si phase than the as-purchased one. The Si 2p(3/2) signal would represent interfacial reaction of the SiC nano-particle onto Ni from the CNT paste and the Kovar substrate, forming the supporting layer for CNT emitters. The optimal paste-emitter even in a vacuum-sealed tube exhibited a highly reliable field emission current with a high current density of 100 mA cm(-2) for over 50 h along with good reproducibility. The enhanced interfacial reaction of SiC filler onto the metal substrates could lead to highly reliable field electron emitters for vacuum electronic devices.

Automated summary

This study successfully prepared reliable field electron emitters by combining carbon nanotubes with Kovar-alloy substrates, using silicon carbide nano-particle fillers with Ni particles, and enhancing interfacial reactions through the wet pulverization process of SiC aggregates. The optimized paste-emitter exhibited highly reliable field emission performance under high electric fields, demonstrating a strong Si 2p(3/2) signal in the Ni2Si phase to represent the enhanced interfacial reaction of SiC filler onto the metal substrates for vacuum electronic devices.