Field emission from AlGaN nanowires with low turn-on field

TL;DR

This study demonstrates that AlGaN nanowires exhibit low turn-on fields and high field enhancement factors, making them promising for field emission applications, with stable emission over several minutes and insights into non-uniform emission behavior.

Contribution

The paper reports the fabrication and detailed analysis of AlGaN nanowires' field emission properties, including high field enhancement and low turn-on fields, with insights into emission stability and non-homogeneous effects.

Findings

High field enhancement factor of 556 at d=500 nm

Minimum turn-on field of 17 V/μm at d=500 nm

Stable emission observed over several minutes

Abstract

We fabricate AlGaN nanowires by molecular beam epitaxy and we investigate their field emission properties by means of an experimental setup using nano-manipulated tungsten tips as electrodes, inside a scanning electron microscope. The tip-shaped anode gives access to local properties and allows collecting electrons emitted from areas as small as 1$\mu m^2$. The field emission characteristics are analyzed in the framework of Fowler-Nordheim theory and we find a field enhancement factor as high as $\beta$ = 556 and a minimum turn-on field $E_{turn-on}$ = 17 V/$\mu$m for a cathode-anode separation distance d = 500 nm. We show that for increasing separation distance, $E_{turn-on}$ increases up to about 35 V/$\mu$m and $\beta$ decreases to 100 at d = 1600 nm. We also demonstrate the time stability of the field emission current from AlGaN nanowires for several minutes. Finally, we explain the observation of modified slope of the Fowler-Nordheim plots at low fields in terms of non-homogeneous field enhancement factors due to the presence of protruding emitters.