Influence of hydrogen on nanocrystalline diamond surfaces investigated with HREELS and XPS

Abstract

Nanocrystalline diamond (NCD) films are of great importance for many applications. They can be implemented as transparent protective coatings or for the use in electronic devices, sensor systems, and bioelectronic systems. In many applications the surface properties dictate the eventual performance of the device and, therefore, need to be thoroughly understood. This paper is devoted to investigating the changes occurring in the vibrational structure and surface chemical composition of hydrogencontaining NCD films as a function of annealing treatments as well as exposure to atomic hydrogen. High resolution electron energy loss spectroscopy (HREELS) as a surface sensitive method was utilized to analyze the temperaturecorrelated desorption of hydrogen and graphitization of the surface. These measurements were correlated with X-ray-induced photoelectron spectroscopy (XPS) measurements to study the chemical composition. Results indicate that water and graphitic-like contaminations are removed from the sample surface after annealing up to about 350 • C. Annealing the sample up to 950 • C decreases the hydrogen content drastically. At temperatures up to 1050 • C the C-H stretching and bending modes are not detectable, indicating that the hydrogen is totally removed from the surface. Analysis of the C 1s XPS spectra revealed that a graphitic-like phase is formed. An atomic hydrogen treatment was applied to get further information about the surface composition. Additionally, from our HREELS and XPS data we are able to determine the sp 2 /sp 3 ratio for the different surface treatments.

Osteogenic cell differentiation on H-terminated and O-terminated nanocrystalline diamond films

“…In summary, H-terminated diamond surfaces typically consist of 1%-4% of oxygen because of inherent surface contamination from air; hence, they have hydrophobic surfaces. 49 Oxygen plasmatreated diamond typically exhibits an increased amount of C-O-C, C=O oxygen moieties; hence, O-terminated diamond surfaces become hydrophilic. 50,51 These results were similar to the observations from our XPS studies, not published here.…”

HREELS Investigation of the Surfaces of Nanocrystalline Diamond Films Oxidized by Different Processes

“…The band at 360 meV originates from stretching vibrations of C−H 1 and CH 2 . It comprises two peaks: the main component at 360 meV where the carbon of CH 1,2 is sp 3 bound to the rest of the carbon atoms and the shoulder at 377 meV due to stretching vibrations of CH 1,2 with sp 2 -bound carbon. ,, After the cleaning procedure, no oxygen-related groups were observed in the HREELS spectrum of the as-grown sample, indicating that they were only physisorbed. The peak at 512 meV is not commented on very often in the literature.…”

Nanocrystalline Diamond Films: Applications and Advances in Nanomedicine

“…The cellular adhesion properties of as-grown diamond surfaces or functionalized diamond surfaces have been studied recently. The as-grown diamond films were characterized as hydrophobic surfaces with abundance of C-C and C-H bonds [54].…”