Details are given of experiments carried out to compare the field electron emission characteristics of single crystal silicon tip arrays with and without amorphous diamond (a-D) coating. The coatings on the tip arrays were prepared using the filtered vacuum arc plasma deposition technique. In addition, the optical and electrical properties of the a-D coatings were measured. An anode probe technique was employed to measure the current–voltage characteristics and turn-on fields of the tip-array emitters before and after coating. It is found that the coating enhances the emission. The physical reasons for these effects are discussed.

Details are given of an experimental study on the deposition process of CaCuB (B = betaine) thin films and their optical and electrical properties. It is demonstrated that such films may be prepared using thermal evaporation technique. The films were characterized by using Fourier transform infrared spectroscopy (FTIR), electron probe microanalyses (EPM) and scanning electron microscope (SEM). Similar infrared spectra were obtained for both the films and the powder samples. Results of EPM show that each element of the chemical compound was distributed evenly in the evaporated films. In addition, electrical conductivity, optical absorption and fluorescent spectra of the film were measured. The results reveal that the evaporated compound is a wide band gap insulator. Significant fluorescence was detected and the spectrum with peak at 409 nm was recorded.

Cold cathode field electron emission from thin films of a new organic compound Ca–Cu–B (B=betain) is observed. The microstructure of the film grown on an Al substrate by thermal evaporating technique is examined by scanning electron microscope and electron probe microanalysis, and it is found that a large number of carbon microparticles are embedded in the film. A transparent anode is used to image the spatial distribution of the emission sites and to measure the I–V characteristics, stability and turn-on field of the films. It is proposed that the presence of embedded carbon inclusions are responsible for the emission.

Silicon (Si) tip emitter arrays with uniform, smooth, and ultrathin (∼2 nm) amorphous diamond (a-D) apexes were fabricated. Aqueous buffer hydrofluoric acid and H2/Ar plasma have been employed to remove the native oxide layer of Si tips, prior to the a-D film deposition. Scanning electron microscopy study showed that uniform a-D coatings were highly localized on the apex of individual Si tips. Study using high-resolution transmission electron microscopy and x-ray energy dispersive spectroscopy confirmed that the Si/a-D junction is free from the oxide interlayer. Field-emission measurements demonstrated that the removal of the native oxide layer and the a-D apex coating are important to stabilize and enhance the electron emission from Si field emitters.

Findings are given from the experimental observation of the vacuum breakdown of carbon-nanotube (CNT) field emitters on a Si tip. The CNTs were grown on the apex of a Si microtip by microwave plasma-enhanced chemical vapor deposition. The electrical contact of the CNT-Si junction was shown to be of ohmic type. A fine tungsten microprobe in combination with a scanning electron microscopy (SEM) system was employed for both the field emission and the contact conductivity measurements. This arrangement allows to precisely measure the characteristics of individual CNT and to in situ inspect the morphology of the CNT emitters on Si tips before and after vacuum breakdown events. An upper limit in emission current density of ∼103 A/m2 from the CNT emitters was recorded before a vacuum breakdown event is initiated. Clear evidence was found to show that the vacuum breakdown of the CNTs results in melting of the Si tip. These findings enhance the understanding of the failure mechanism of CNT emitters. It also has important technical implication to the development of ultrabright electron source.