Cold cathodes for applications in poor vacuum and low pressure air environments: Carbon nanotubes versus ZnO nanoneedles

Effects of gas pressure on the electron field emission (FE) properties of zinc oxide (ZnO) nanoneedles and carbon nanotubes (CNTs) were investigated. The FE properties for ZnO nanoneedles almost fully recovered after being subjected to FE tests in poor vacuum and low pressure gas environments and then characterized again in better vacuum around 2 × 10− 6 Torr. In the contrast, the FE properties for CNTs did not recover after being subjected to FE tests in poor vacuum and low pressure gas environments. Reversibility and sensitivity of the FE of ZnO and CNTs to air pressures were studied for potential applications to field emission display (FED) and vacuum microelectronic devices. The pressure-dependant, time-dependant, and pressure–time-dependant field emission behaviors of ZnO nanoneedles and CNTs will be compared and discussed.