Field Emission Energy Spectra Research Articles

Intrinsic energy spectrum in field emission of carbon nanotubes

The intrinsic electron energy spectra in field emission from the single-wall carbon nanotubes are systematically investigated based on the quantum tunneling theory with the tight-binding approximation. We examine the dependence of the characteristics of the field-emission energy spectrum on the electric field and temperature. For the metallic tubes, as temperature or electric field increases, the main peak of the energy spectrum becomes high and wide, and some sub-peaks occur above or below Fermi energy. For the semiconducting tubes, the energy gap at Fermi energy may occur leading to a double peak spectrum. Electric field competes with temperature to balance the height of the two peaks. Strong field makes the low-energy peak high, while high temperature enhances the high-energy peak. We give a phase diagram on the peak number of the energy spectrum in the space of the electric field and temperature, which summarizes some key characteristics of the energy spectrum.

Field emission energy spectra from superconducting and normal states of a niobium tip

We have measured field emission (FE) electron energy distributions from superconducting and normal states of a niobium tip, and we succeeded in observing an extra peak correlated to the superconducting state. The energy width of the peak was much larger than expected on the basis of simple theory.

Energy distribution of field emitted electrons from diamond coated molybdenum tips

Field emission energy distribution (FEED) measurements were performed on Mo and diamond coated Mo tips under ultrahigh vacuum conditions to investigate the origin of field emitted electrons. Mo emitters were prepared by electrochemical etching and were subsequently coated with diamond powder by a dielectrophoretic procedure. Field emission energy spectra were taken on the same samples before and after diamond coating. In vacuo thermal annealing of coated samples was essential to obtain stable field emission. FEED data indicated that the field emission current originated from the diamond/vacuum interface, and that electrons were emitted from the conduction band minimum of diamond.

Field emission from silicon emitters

Miniature silicon field emission cathodes are being produced as part of a research programme in Vacuum Microelectronics. Results are presented on chemical and ion bombardment treatment of the tips. Total emission current and field emission energy spectra are measured as a function of the treatments. Although methods of obtaining emission from clean silicon microemitters have been demonstrated, field emission spectra show rapid recontamination effects. The strong changes in the spectra are explained with the aid of a model which invokes resonant tunnelling through adsorbate layers.

The influence of surface treatment on field emission from silicon microemitters

Field emission from micron-scale structures is investigated as part of a research programme on vacuum microelectronics. Chemical cleaning and ion bombardment of silicon cones is described. The influence of these treatments on the field emission energy spectra is discussed and analysed using a model of resonance-enhanced tunnelling through an adsorbate layer. It is concluded that resonant tunnelling is a mechanism of importance for explaining low energy structure in field emission energy spectra.

Field emission from silicon through an adsorbate layer

Within a research programme on micro-metre-sized field emission electron sources, semiconductor processing techniques have been applied to the fabrication of silicon emitter cones. Field emission energy spectra show multiple peaks and I-V characteristics deviate from the standard Fowler-Nordheim form. To contribute to the understanding of these results, calculations of the energy distribution and the current density as a function of applied field are presented for a model of emission from silicon through an adsorbed layer. Non-monotonic dependence of the current on applied field is demonstrated, which is due to resonant tunnelling through the adsorbate potential.