Atomic hydrogen interactions with amorphous carbon thin films

Abstract

The atomic-scale interactions of H atoms with hydrogenated amorphous carbon ͑a-C:H͒ films were identified using molecular dynamics ͑MD͒ simulations and experiments based on surface characterization tools. Realistic a-C:H films developed using MD simulations were impinged with H atoms with a kinetic energy corresponding to a temperature of 700 K. The specific chemical reactions of the H atoms with the a-C:H surface were identified through a detailed analysis of the MD trajectories. The MD simulations showed that hydrogenation occurs primarily at the sp 2 sites and converts them to sp 3-hybridized C atoms. Depending on the hybridization of the next-nearest neighbor, a dangling bond may or may not be created. The hydrogenation reaction is highly exothermic, Ͼ2.5 eV, and proceeds with a negligible activation energy barrier via a mechanism similar to Eley-Rideal. In certain cases hydrogenation may also cleave a CC bond. The reaction events observed through MD simulations are consistent with the surface characterization of D-exposed a-C:H films using Raman spectroscopy, spectroscopic ellipsometry, and in situ attenuated total reflection Fourier-transform infrared spectroscopy.

Synergistic etch rates during low-energetic plasma etching of hydrogenated amorphous carbon

“…Regardless thereof, the reported surface roughness after deposition (or post-deposition treatment) is on the order of nanometers. 37,91,93,96 A surface roughness of a few nanometers is of the same order as the roughness found in this work during Ar/H 2 (or Ar/D 2 ) plasma etching. The roughness in a pure H 2 plasma on the other hand increased strongly as established in Sec.…”

“…33,34 Chemical erosion can occur when an a-C:H sample is exposed to an atomic hydrogen beam. [35][36][37] An important step in chemical erosion is the conversion of sp 2 into sp 3 groups through hydrogenation. This will lead in some situations to the formation of a dangling bond (DB).…”

Tribological properties of chemically modified diamond like carbon films in hydrogen plasma

“…Physical sputtering techniques are mainly employed to deposit hydrogen free films where as chemical vapor deposition (CVD) based techniques result in hydrogenated films [5]. Moreover, hydrogen during film growth process creates dangling bonds and allows the adsorption of CH x species to the unsaturated carbon atoms which enhances sp 3 C-C bonding network in the film [6]. Presence of hydrogen in the films is also an advantageous factor because it determines the cross linking across sp 3 C-C bonding fraction.…”

THE 217.5 nm BAND, INFRARED ABSORPTION, AND INFRARED EMISSION FEATURES IN HYDROGENATED AMORPHOUS CARBON NANOPARTICLES

“…This recombination, producing transient heating to temperatures in excess of 1000 K, has been well documented in laboratory experiments Yamaguchi & Wakabayashi 2004) and is quite likely to occur in structures such as that shown in Figure 11. In this case, the energy source would involve the recombination of stored H atoms (Sugai et al 1989), but radical recombination is also possible given the heterogeneous composition of these carbonaceous nanoparticles (Biener 1994;Jariwala et al 2009). Laboratory experiments have demonstrated that thermal energy released from an amorphous carbon layer on a core-mantle grain can produce significant heating (Kaito et al 2007).…”