Electron emission through a multilayer planar nanostructured solid-state field-controlled emitter

Abstract

We have measured the field electron emission (FE) from a surface covered with two ultrathin layers of semiconductor, 4 nm GaN on 2 nm Al0.5Ga0.5N. The threshold field was 50 V/μm, with stable FE current densities up to 3×10−2 A/cm2. We have also measured the FE dependence with field and temperature and determine then an effective surface tunneling barrier ⩽0.5 eV, coexisting with an effective thermal activation energy of ∼0.85 eV. To interpret these experimental results, we propose a dual-barrier model, related to the nanostructured layers, with a serial two-step mechanism for the electron emission, taking into account the space charge formation in the quantum well structure at the surface.

Electron field emission properties of Co quantum dots in SiO2 matrix synthesised by ion implantation

“…Although, the FE mechanisms of the nanostructured materials are still under investigation, their physically confinement structures play an important role on it. Ultra-thin dielectric coatings on the emitter and quantum well FE structure show resonant tunnelling characteristics in their FE measurements attributed to two-dimensional electron confinement effect [1][2][3][4]. Furthermore, one-dimensional nanostructure such as carbon nanotubes and various types of nanowires achieve an emission current at extremely low applied electric fields (typically less than 5 V/µm) [5][6][7].…”

Negative differential conductance observed in electron field emission from band gap modulated amorphous-carbon nanolayers

“…The fully depleted sp 2 a-C layer could create electric fields much greater than the macroscopic field external to it. [12][13][14] Similar to the space charge induced band bending model for amorphous materials in which the Si substrate acts as the electron source, [12][13][14][15] Semet et al 5 and Wang et al 7 proposed an identical hypothesis for GaN based double layered structures. We postulate electron injection from Si into the sp 2 "well layer" through the 3 nm thick sp 3 layer by field penetration.…”

“…1͑b͒ at the front positive end of the sample. According to the equation derived by Semet et al, 5 the space potential energy by the electrons accumulated in the first subenergy level ͑E 1 ͒ can be estimated as V SC = ͑ 0 /4 0 r ͕͒͑w / ͒ 2 sin 2͑x / w͒ + wx − x 2 ͖, where w is the thickness of the sp 2 layer and 0 is the space charge density ͑is proportional to the energy difference between the first and the second subenergy level͒. The E 2 − E 1 is calculated to be 0.45 eV ͑E 1 = 0.2 eV and E 2 = 0.65 eV͒ for the effective mass m * ϳ 0.06, r ϳ 4, and w = 3 nm which is further confirmed by modeling.…”

“…Hence, quantum-well ͑QW͒ structures showing NDC in their FE process are extremely promising and have attracted a lot of research interest. [3][4][5][6][7] Most of these studies were focused on the GaN or Si-based quantum well systems, perhaps because of the early success of applying these materials in RTDs. However, the fabrication processes of these materials ͑e.g., low-pressure metal organic chemical vapor deposition for GaN͒ are expensive and require a high process temperature.…”

Field emission properties of self-assembled InN nano-structures: Effect of Ga incorporation

“…Similarly, a GaN surface roughened by H 2 -plasma treatment also exhibited electron emission in a relatively low electric field [8,9]. AlN nanotubes and GaN nano-structures were recently proposed to be good vacuum emitters [10,11]. However, only a few field emission studies of InN or In-rich-InGaN nanostructures have been reported [12].…”