Investigations on Diamond Nanostructuring of Different Morphologies by the Reactive-Ion Etching Process and Their Potential Applications

Abstract

We report the systematic studies on the fabrication of aligned, uniform, and highly dense diamond nanostructures from diamond films of various granular structures. Self-assembled Au nanodots are used as a mask in the self-biased reactive-ion etching (RIE) process, using an O2/CF4 process plasma. The morphology of diamond nanostructures is a close function of the initial phase composition of diamond. Cone-shaped and tip-shaped diamond nanostructures result for microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) films, whereas pillarlike and grasslike diamond nanostructures are obtained for Ar-plasma-based and N2-plasma-based ultrananocrystalline diamond (UNCD) films, respectively. While the nitrogen-incorporated UNCD (N-UNCD) nanograss shows the most-superior electron-field-emission properties, the NCD nanotips exhibit the best photoluminescence properties, viz, different applications need different morphology of diamond nanostructures to optimize the respective characteristics. The optimum diamond nanostructure can be achieved by proper choice of granular structure of the initial diamond film. The etching mechanism is explained by in situ observation of optical emission spectrum of RIE plasma. The preferential etching of sp(2)-bonded carbon contained in the diamond films is the prime factor, which forms the unique diamond nanostructures from each type of diamond films. However, the excited oxygen atoms (O*) are the main etching species of diamond film.

Tunable and Specific Formation of C@NiCoP Peapods with Enhanced HER Activity and Lithium Storage Performance

“…Tunable fabrication of nanostructured materials with intriguing structuralf eatures, such as large surface area, narrow size, ak inetically favorable open structure, and surface permeability,b ecome more and more fascinating and vital in am yriad of applications, including energy-storage systems, catalysis, gas sensors, and so on. [26][27][28] In recent years, as ar esult of its unique combination of properties, such as sufficient electrochemical interface and accessible electronic and ionic channels, al arger surface area to enhancet he interfacial kinetics and sufficient space to accommodate the stress relaxation, peapodlike nanomaterial holds ab right prospect for various fields. [13,[29][30][31] Unfortunately,t ot his day,r eports on the HER performance and energy storageo fp eapodlike nanomaterials are very rare, because the project of synthesizing peapodlike nanomaterials bristles with difficulties.…”

Vertically aligned diamond-graphite hybrid nanorod arrays with superior field electron emission properties

“…The presence of sp 2 phase is possibly caused by the ion bombardment damage on sp 3 -bonded carbon induced in the RIE O 2 plasma etching process. 17,46 On the basis of micro-Raman spectroscopy and HAADF-STEM investigations, the DGH nanorod is actually a nanohybrid material, consisting of nano-sized diamond grains (sp 3 -bonded carbon) and nanographites (sp 2 -bonded carbon) located in the boundaries between the diamond grains. The nanographitic phase transported the electrons upward and transferred the electrons to the tip of DGH nanorods for field emitting.…”

Nanodiamonds for field emission: state of the art

“…A series of uniform and high-density nanostructures have been selectively engineered from diamond films characterized by a variety of granular morphologies. 90 Cone-shaped and tipshaped nanostructures were obtained from microcrystalline diamond using a CF 4 /O 2 plasma; conversely, pillar-like and grass-like forms were obtained from nitrogen-doped ultrananocrystalline diamond using an Ar plasma. The authors thoroughly investigated the relationship between the structure/ morphology of the nano-shaped deposits and important functional properties such as photoluminescence and electron emission.…”