The induction of nanographitic phase on Fe coated diamond films for the enhancement in electron field emission properties

Abstract

A thin layer of iron coating and subsequent post-annealing (Fe-coating/post-annealing) is seen to significantly enhance the electron field emission (EFE) properties of ultrananocrystalline diamond (UNCD) films. The best EFE properties, with a turn on field (E0) of 1.98 V/μm and current density (Je) of 705 μA/cm2 at 7.5 V/μm, are obtained for the films, which were Fe-coated/post-annealed at 900 °C in H2 atmosphere. The mechanism behind the enhanced EFE properties of Fe coated/post-annealed UNCD films are explained by the microstructural analysis which shows formation of nanographitic phase surrounding the Fe (or Fe3C) nanoparticles. The role of the nanographitic phase in improving the emission sites of Fe coated/post-annealed UNCD films is clearly revealed by the current imaging tunneling spectroscopy (CITS) images. The CITS images clearly show significant increase in emission sites in Fe-coated/post-annealed UNCD films than the as-deposited one. Enhanced emission sites are mostly seen around the boundaries of the Fe (or Fe3C) nanoparticles which were formed due to the Fe-coating/post-annealing processes. Moreover, the Fe-coating/post-annealing processes enhance the EFE properties of UNCD films more than that on the microcrystalline diamond films. The authentic factor, resulting in such a phenomenon, is attributed to the unique granular structure of the UNCD films. The nano-sized and uniformly distributed grains of UNCD films, resulted in markedly smaller and densely populated Fe-clusters, which, in turn, induced more finer and higher populated nano-graphite clusters.

Morphological Dependence of Field Emission Properties of Silicon Nanowire Arrays

“…7,8 Over past few years, many other nanomaterials, such as aligned carbon nanotubes, 10 ultra-nanocrystalline diamond lms, [11][12][13] arrays of gallium nitride nanorods, 14 titanium dioxide nanotubes, 15 cone-shaped zinc oxide nanostructures, 16 tin oxide nanotubes 17 and needle-shaped molybdenum trioxide 18 are showing much more e±ciency in¯eld emission with very low turn-on¯eld. Moreover ion implantation, 19 metallic coating 20 and H 2 surface treatment on diamond lms 21 are observed to signi¯cantly enhance the electron¯eld emission (EFE) properties. However, the lack of cost-e®ectiveness, ease in processing, highly packed emitting surfaces and compatible in fabrication limit the materials for applications in emitting device technologies.…”

“…However, the lack of cost-e®ectiveness, ease in processing, highly packed emitting surfaces and compatible in fabrication limit the materials for applications in emitting device technologies. In spite of high turn-on¯eld of bare SiNWs, availability of wide spectrum of synthesis procedure, [17][18][19][20][21][22] comparatively more dense emitting tips and above all compatibility in semiconducting vacuum microelectronic systems 8,28 make SiNWs°exible in electronics and optoelectronics device fabrication. The¯eld emission properties of SiNWs such as turn-on¯eld, emitting current density per unit area and¯eld enhancement factor can be signi¯cantly improved by functionalized coating of ultra-nanocrystalline diamond, 13,29 carbon nanotubes, 30 and various metallic thin¯lms 31 have been reported.…”

Direct Observation and Mechanism for Enhanced Electron Emission in Hydrogen Plasma-Treated Diamond Nanowire Films

“…Various surface treatments have been conducted to enhance the field-emission properties of diamond films. Fe-coating and subsequent post-annealing is seen to enhance the EFE properties of diamond films. , Other studies show monolayer coatings of metals such as Co, Ni, Cu, Zr improved the emission properties of diamond films by shifting the position of the vacuum level. , It has been also reported that hydrogen treatment of diamond surfaces results in enhanced EFE properties . In the last few year,s the study of hydrogenated diamond surfaces has been a topic of great interest.…”

Straight imaging and mechanism behind grain boundary electron emission in Pt-doped ultrananocrystalline diamond films

“…It is to be noted that the conductivity of the a-C grain boundary phases of as-UNCD films is not sufficiently high, therefore limiting its conductivity and EFE properties [44,34]. However, it has been observed that the existence of grain boundary graphitic phases, surrounding the nanosized diamond grains are the prime factors for enhancing the conductivity and EFE properties [11,12,[35][36][37][38][39][40][41][42][43][44][45][46][47]. Similar conduction mechanism is proposed to explain the improved electron emission/conduction properties for doped-UNCD films.…”