Structural and electronic properties of nitrogen ion implanted ultra nanocrystalline diamond surfaces

Abstract

Enhanced electron field emission (EFE) properties have been observed for nitrogen implanted ultra-nanocrystalline diamond (UNCD) films grown by microwave plasma enhanced CVD. X-ray photoelectron spectroscopy (XPS) measurements show that sp2 fraction and C-N bonding increase upon N-implantation and annealing. Significant difference in current-voltage (I-V) curves at the grain and grain boundary has been observed from scanning tunneling spectroscopic (STS) measurement. From the variation of normalized conductance (dI/dV)/(I/V) versus V, bandgap is measured to be 4.8 eV at the grain and 3.8 eV at the grain boundary for as prepared UNCD. Upon nitrogen implantation and annealing, the bandgap decreases for both grain and grain boundary and density of states are introduced in the bandgap. Current imaging tunneling spectroscopy (CITS) imaging shows that the grain boundaries have higher conductivity than the grains and are the prominent electron emitters. The enhancement in EFE properties upon nitrogen implantation is accounted for by the decrease in bandgap, increase in density of states in the bandgap caused by increase in sp2 content and new bonds at the diamond grains, and increase in conductivity at the grain boundary.

On the relation between chemical composition and optical properties of detonation nanodiamonds

“…The structure and chemical composition of DNDs strongly influence their mechanical, optical, electrical, and thermal properties [14][15][16][17][18]. One prominent example is the nitrogen doping which plays an important role in the fluorescence of the DNDs [19].…”

Morphological Dependence of Field Emission Properties of Silicon Nanowire Arrays

“…The unique sp 3 -bonded crystal structure and the low work function of SiNWs show it to be a potential candidate to be employed as a cold cathode material for¯eld emission device applications. 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.…”

Ellipsometric investigation of nitrogen doped diamond thin films grown in microwave CH4/H2/N2 plasma enhanced chemical vapor deposition

“…An opposite trend was reported by Hayashi et al 13 for RF PECVD grown films, where the incorporated nitrogen leads to the broadening of the p and p* bands and the disorder in the crystalline boundaries effects in a reduced energy gap generally due to band tailing. In our case, the N 2 incorporation is relatively smaller avoiding high disorder of boundaries; consequently, the effect Eg value is not comparable and needs to be further investigated.…”