Time‐Resolved Observation of Deposition Process of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films in Pulsed Laser Deposition

Abstract

Optical emission spectroscopy was used to study pulsed laser ablation of graphite in a hydrogen atmosphere wherein ultrananocrystalline diamond (UNCD)/hydrogenated amorphous carbon (a-C:H) composite films were grown on heated substrates. Time-resolved photographs of a plume that expanded from a laser-irradiation spot toward a substrate were taken using a high-speed ICCD camera equipped with narrow-bandpass filters. While the emissions from C atoms and dimers lasted above the laser-irradiation spot on the target, the emission from ions lasted above the substrate surface for approximately 7 microseconds, although the emission lifetime of species is generally approximately 10 nanoseconds. This implies that ions actively collided with each other above the substrate surface for such a long time. We believe that the keys to UNCD growth in PLD are the supply of highly energetic carbon species at a high density to the substrate and existence of atomic hydrogen during the growth.

Selective Carbon Material Engineering for Improved MEMS and NEMS

“…To be observed that the denser and smoother micro- and nano-crystalline diamond is almost containing a significant part of graphitic material where more or less ordered/disordered diamond crystallites are imbedded. However, besides interesting tribological properties, those have generally reduced others (optical, optoelectronic, chemical and mechanical) [114,115,116,117,118,119]. Amorphous diamond and degraded tetrahedral amorphous carbon , ranging from materials with high internal stress such as the amorphous diamond and ta-C:H and others for which the internal stress could be reduced without graphitic degradation [120,121,122,123,124,125,126].…”

“…To be observed that the denser and smoother micro- and nano-crystalline diamond is almost containing a significant part of graphitic material where more or less ordered/disordered diamond crystallites are imbedded. However, besides interesting tribological properties, those have generally reduced others (optical, optoelectronic, chemical and mechanical) [114,115,116,117,118,119].…”

“…Then, they merely correspond to some nanocomposite material containing different adjacent phases and this is often leading to dramatic confusions between materials supposed to belong to the same category, whether being stress annealed or not and presenting important material structures and property differences [27,111,112,113]. Diamond-like carbon produced with non-optimized depositing equipment design and lower optimized depositing process or which is resulting from the thermal annealing of crystalline diamond and from highly stresses harder ta-C has been often considered as an amorphous diamond, although being merely less hard, less homogeneous less smooth, less dense composite material with reduced optical properties and reduced thermal stability (in comparison to the diamond and harder tetrahedral amorphous carbon) [114,115,116,117,118,119,120,121,122,123,124,125].…”

“…This effect can be amplified when a graphitic material is transformed into a denser diamond-like material. These sorts of materials can be obtained with other means than combined pressure/heat and thermal spikes [111,112,113,114,115,116,117,118,119,120,121,122,123,124]. In such a case, contradicting effects have to be considered (either favorizing graphitization, or favorizing diamond-like structures) and which can be in competition to each other [25].…”

Chemical Bonding of Nitrogenated Ultrananocrystalline Diamond Films Deposited on Titanium Substrates by Pulsed Laser Deposition

“…11 Whereas UNCD/a-C:H films have been mainly prepared by CVD method, several years ago, our group successfully prepared UNCD/a-C:H films in a hydrogen atmosphere, UNCD/nonhydrogenated nitrogenized amorphous carbon (a-C:H:N) composite (UNCD/a-C:N) films in a nitrogen atmosphere, and UNCD/hydrogenated nitrogenized amorphous carbon (a-C:H:N) composite (UNCD/a-C:H:N) films in a nitrogen and hydrogen mixed gas atmosphere, by pulsed laser deposition (PLD), as they have been reported previously. [12][13][14][15][16][17][18] PLD is a kind of physical vapor deposition (PVD), and the formation of UNCD grains by PLD might be attributable to the supply of highly energetic carbon species such as C + ions and C atoms at a high density onto a substrate, 19 and its mechanism should be distinctively different from that in CVD. The formation by PLD need not the pretreatment of substrates with diamond powder, in other words, the nucleation of diamond spontaneously occurs during the deposition.…”