Evaluation of field emission parameters in a copper nano-tip based diode

Abstract

Copper nano-tip based diode structure with a gap of ∼120 nm has been fabricated by milling of a thin metallic film with a 30 kV focused gallium ion beam at a current of 100 pA. Its current-voltage characteristics measured at a pressure of ∼10−6 mbar is shown to follow the Fowler-Nordheim (F-N) field emission tunneling above ∼40 V. A simple method has been proposed to evaluate parameters like effective area (Aeff), apparent work function (ϕ), and field enhancement factor (β) of the nano-emitter. The extremely small Aeff, substantial lowering of ϕ, and high β value observed have been explained in terms of changes occurring at the emitter tip with increasing applied field. The formation of metallic nanoparticles over the substrate by local evaporation of cathode material at high currents is also demonstrated.

Electron Emission Devices for Energy‐Efficient Systems

“…Apart from transistors or triodes, vacuum field emission electronic devices have applications as diodes, travelling‐wave tube (TWT), oscillators, klystrons and magnetrons, and gyrotrons for high‐frequency (RF, GHz, and THz) and high‐efficiency applications.…”

On the evaluation of field emission parameters of V2O5 and TiO2 nanostructure cathodes

“…Popov et al [29] compared the emission parameters of a single-tip tungsten cathode (radius of curvature ∼ 50 nm) in real time, deduced using both the FN plot and MG formulation, and observed significant morphological changes in the emitter, leading to a variation in the values of the field enhancement factor and emission area with the voltage ranges. A simple way of extracting the emission parameters from the curved (instead of linear) FN plots is suggested by the present authors [31]. Accordingly, the Fowler-Nordheim (F-N) field emission current (I) at a voltage (V ) is given by…”

“…Thus, the ln (I/V 2 ) versus (1/V ) plot gives a straight line with negative slope of magnitude B and intercept at the ordinate ln A. The probable values of the parameters A eff and f are deduced from [31]:…”

“…So the present authors focused on a limited and crucial aspect of the issue and proposed a scientific basis of field emission by examining all the methodologies available for the evaluation and interpretation of the measured FE current-voltage data and provided a logical and meaningful description of the phenomenon. It involves use of analytical expressions with realistic parameters based on physical considerations, leading to development of a general treatment of the emission process within the framework of Fowler-Nordheim (F-N) theory [31].…”

“…A simple procedure developed by the authors is applied successfully in actual evaluation of the field emission parameters from the current-voltage data. This involves F-N formulation with physical considerations like variation of work function, effective emission area, and field enhancement factor [31].…”